JP7613762B2 - A deposition device that performs sputtering deposition using inductively coupled plasma - Google Patents

Description

One embodiment of the present invention relates to a film forming apparatus that utilizes inductively coupled plasma (ICP).

Sputtering is a type of physical vapor deposition (PVD) method used to form thin films. Sputtering is known as a technique in which plasma is generated in a vacuum, and ions in the plasma are collided with a sputtering target at high speed to cause sputtering, depositing particles (atoms or molecules) of the film-forming material that makes up the target onto the surface of a substrate to form a thin film.

As a sputtering device, the magnetron type, in which a magnetron is placed behind the sputtering target, is well known, but in addition, sputtering devices that use inductively coupled plasma (ICP) have also been disclosed (see, for example, Patent Document 1). Also, an antenna structure for generating inductively coupled plasma has been disclosed (see Patent Document 2).

JP 2016-065299 A JP 2016-072168 A

The magnetron sputtering method has the problem that the magnetic field (strength of the magnetic field) generated by the magnet is non-uniform, which causes non-uniform erosion of the sputtering target, resulting in low effective utilization of the target material and the tendency for nodules to form. In addition, because the magnetic field causes plasma to concentrate locally, thermal stress is easily applied to the target material, which can easily cause cracks in the target material.

In addition, when a metal film is formed by magnetron sputtering, a strong magnetic field produced by a magnet can increase the density of the deposited film. However, when an oxide material (e.g., an oxide semiconductor film, an oxide conductive film) is formed, oxygen gas is decomposed only in the area of strong magnetic field strength near the sputtering target, and unreacted oxygen molecules (O ₂ ) are adsorbed on the deposition surface and are incorporated into the film in the form of oxygen molecules, resulting in a problem of a decrease in the density of the deposited film.

In addition, in conventional sputtering devices that use inductively coupled plasma (ICP), the antenna body and a cylindrical insulating tube covering the antenna were placed inside the deposition chamber to efficiently generate inductively coupled plasma. However, when dealing with enlargement of the deposition chamber to exceed 3 m, it becomes extremely difficult to stably hold the antenna body and the cylindrical insulating tube covering the antenna.

Furthermore, in an inductively coupled plasma (ICP) sputtering apparatus as disclosed in Patent Document 1, the generated inductively coupled plasma diffuses throughout the entire inside of the deposition chamber, and the plasma cannot be confined near the sputtering target as in a magnetron sputtering apparatus. Therefore, compared to a magnetron sputtering apparatus, there is a fundamental problem that moisture (H ₂ O), oxygen (O ₂ ), and hydrocarbons adsorbed on the inner wall of the deposition chamber are more likely to be detached in large quantities from the inner wall of the deposition chamber at the start of deposition and to be incorporated into the coating being deposited. The only way to increase the plasma density near the sputtering target is to increase the current flowing through the antenna body, which instead increases the amount of contaminant gas detached from the inner wall of the deposition chamber, which is a factor that reduces the reproducibility of the film quality of the deposited film.

In view of these problems, one embodiment of the present invention aims to provide a film formation method and apparatus that can reproducibly and efficiently form high-quality thin films by sputtering.

A film formation apparatus according to one embodiment of the present invention includes a film formation chamber in which a sputtering target is placed, a plasma diffusion prevention plate covering the sputtering target and having an opening at a position overlapping the surface of the sputtering target, an antenna for generating inductively coupled plasma adjacent to the sputtering target and arranged so as to protrude inside the area surrounded by the plasma diffusion prevention plate, and a gas introduction tube arranged inside the plasma diffusion prevention plate for introducing gas into the film formation chamber, and a negative pulse voltage is applied to the sputtering target.

According to one embodiment of the present invention, a plasma diffusion prevention plate is provided to cover the antenna for generating inductively coupled plasma and the sputtering target, thereby preventing the inductively coupled plasma from spreading throughout the inner space of the deposition chamber and preventing impurities from being incorporated into the thin film being deposited. Furthermore, the plasma density near the sputtering target can be increased, making it possible to increase the sputtering rate.

1 shows an overall configuration of a film forming apparatus according to an embodiment of the present invention. FIG. 1 is a diagram showing the configuration of a film formation apparatus according to an embodiment of the present invention, illustrating the main components provided in or connected to a pre-treatment chamber, a transfer chamber, and a film formation chamber, excluding a load/unload chamber. 1 is a schematic partial cross-sectional view of a film formation chamber of a film formation apparatus according to an embodiment of the present invention, as viewed from above; 2 shows a detailed cross-sectional structure of an antenna for generating inductively coupled plasma used in a film formation apparatus according to one embodiment of the present invention. 2 shows a detailed cross-sectional structure of an antenna for generating inductively coupled plasma used in a film formation apparatus according to one embodiment of the present invention. 1 is a schematic diagram showing a plasma diffusion prevention plate provided in a film formation chamber of a film formation apparatus according to an embodiment of the present invention, as viewed from the front. 1 is a schematic front view of a plasma diffusion prevention plate provided in a film formation chamber of a film formation apparatus according to an embodiment of the present invention; 1 is a diagram for explaining the influence of an antenna for generating inductively coupled plasma provided in a film formation chamber on a substrate surface, showing a case in which there is no plasma diffusion prevention plate. 1A and 1B are diagrams for explaining the influence of an antenna for generating inductively coupled plasma provided in a film formation chamber on a substrate surface, showing the case where a plasma diffusion prevention plate is provided. FIG. 1 is a diagram for explaining the effect of an antenna for generating inductively coupled plasma installed in a deposition chamber on the substrate surface, and is a diagram for explaining the problem of non-uniformity of the deposited thin film that can occur when there is no plasma diffusion prevention plate. 1 shows an example of a film formation target mounted in a film formation apparatus according to an embodiment of the present invention, in which two types of target materials are used. 1 shows an example of a film formation target mounted in a film formation apparatus according to an embodiment of the present invention, in which three types of target materials are used. 1 is a diagram illustrating a configuration of an antenna for generating inductively coupled plasma provided in a film formation chamber of a film formation apparatus according to an embodiment of the present invention. FIG. 2 shows a cross-sectional structure of an antenna coupling region of an antenna body for generating coupled plasma used in a film formation apparatus according to one embodiment of the present invention. FIG. 2 is a diagram showing waveforms of an AC voltage applied to an antenna for generating inductively coupled plasma provided in a film formation chamber of a film formation apparatus according to one embodiment of the present invention, and a pulse voltage applied to a film formation target. 13 is a schematic diagram showing the relationship between the target voltage and the film density when an InGaZnO film is formed as an oxide semiconductor film. 1 is a schematic cross-sectional view showing a configuration of a pretreatment chamber of a film forming apparatus according to an embodiment of the present invention; 1 is a front view of an antenna for generating inductively coupled plasma provided in a deposition chamber of a deposition apparatus according to an embodiment of the present invention; 16B is a cross-sectional view of an antenna for generating inductively coupled plasma provided in a deposition chamber of a deposition apparatus according to one embodiment of the present invention, showing a cross-sectional structure corresponding to the section A1-A2 shown in FIG. 16A. 1 is a front view of an antenna for generating inductively coupled plasma provided in a deposition chamber of a deposition apparatus according to an embodiment of the present invention; 17B is a cross-sectional view of an antenna for generating inductively coupled plasma provided in a film formation chamber of a film formation apparatus according to one embodiment of the present invention, showing a cross-sectional structure corresponding to the section B1-B2 shown in FIG. 17A. 1 shows an example of an element fabricated using a film formation apparatus according to an embodiment of the present invention. 2 shows a detailed structure of an oxide semiconductor layer in an element manufactured using a film formation apparatus according to one embodiment of the present invention. 2 shows a detailed structure of an oxide semiconductor layer in an element manufactured using a film formation apparatus according to one embodiment of the present invention. 1 shows an overall configuration of a film forming apparatus according to an embodiment of the present invention. FIG. 1 is a diagram showing the configuration of a film formation apparatus according to an embodiment of the present invention, illustrating the main components provided in or connected to a pre-treatment chamber, a transfer chamber, and a film formation chamber, excluding a load/unload chamber. 1 shows an example of an element manufactured using a film formation apparatus according to an embodiment of the present invention. 1 is a schematic partial cross-sectional view of a film formation chamber of a film formation apparatus according to an embodiment of the present invention, as viewed from above; 22B is a front view of a ceramic member used in the deposition chamber shown in FIG. 22A. 1 is a schematic partial cross-sectional view of a film formation chamber of a film formation apparatus according to an embodiment of the present invention, as viewed from above; 23B is a front view of a ceramic member used in the deposition chamber shown in FIG. 23A.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention includes many different aspects and is not to be construed as being limited to the following exemplary embodiments. The drawings attached to this specification may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual aspect in order to make the explanation clearer, but this is merely an example and does not necessarily limit the contents of the present invention. In addition, in the present invention, when a specific element shown in a drawing and a specific element shown in another drawing are identical or correspond to each other, the same symbol (or a symbol with a, b, etc. added after the number shown as the symbol) may be added, and repeated explanations may be omitted as appropriate. Furthermore, the letters "first" and "second" added to each element are convenient marks used to distinguish each element, and have no further meaning unless otherwise specified.

In this specification, when a certain component or region is described as being "on (or under)" another component or region, unless otherwise specified, this includes not only the case where it is directly above (or directly below) the other component or region, but also the case where it is above (or below) the other component or region. In other words, it also includes the case where another component is included between the certain component or region and above (or below) the other component or region.

[First embodiment]
1 shows an overall configuration of a film formation apparatus 100 for performing sputtering film formation according to an embodiment of the present invention. The film formation apparatus 100 includes a load/unload chamber 102 in which substrates before and after film formation are stored, a pretreatment chamber 104 for performing pretreatment of the substrate, a first transfer chamber 106a provided with a transfer robot 116, a second transfer chamber 106b provided with a platen mechanism 118, and a first film formation chamber 108a and a second film formation chamber 108b in which sputtering film formation is performed. These chambers are connected by gate valves and are provided with vacuum exhaust means (not shown).

The substrate on which the thin film is to be formed is stored in the load/unload chamber 102 while being held in a cassette. The substrate is, for example, a glass substrate. The substrate stored in the load/unload chamber 102 is transported to the pretreatment chamber 104 by the transport robot 116 provided in the first transport chamber 106a. In the pretreatment chamber 104, pretreatment is performed on the substrate on which the thin film is to be formed. The pretreatment chamber 104 includes a high-frequency discharge electrode connected to a high-frequency power source 120. As a pretreatment, a degassing process is performed on the substrate by a high-frequency discharge plasma generated by a stage provided with a heating mechanism and a high-frequency discharge electrode. FIG. 1 shows an embodiment in which two pretreatment chambers 104 are installed on either side of the first transport chamber 106a, but the number of pretreatment chambers 104 is not limited. As shown in FIG. 1, when two pretreatment chambers 104 are installed in the film formation apparatus 100, sputtering film formation can be performed continuously with time to spare while performing sufficient degassing. The film forming apparatus 100 is not limited to the configuration shown in FIG. 1, and the number of pre-treatment chambers 104 may be one, or three or more.

The substrate that has been pre-processed in the pre-processing chamber 104 is transported to the second transport chamber 106b by the transport robot 116. The substrate is transported horizontally from the load/unload chamber 102 to the pre-processing chamber 104. The second transport chamber 106b is equipped with a platen mechanism 118, and the substrate that has been transported horizontally is set upright in a vertical position or tilted within a range of about 20 degrees from the vertical position so that it can be held by a transport carrier (not shown in FIG. 1).

The first deposition chamber 108a and the second deposition chamber 108b are provided with an antenna 126 for generating inductively coupled plasma, and a sputtering target 124 is attached. In the first deposition chamber 108a and the second deposition chamber 108b, sputtering deposition is performed by inductively coupled plasma (ICP) generated by the antenna 126 for generating inductively coupled plasma. A pulse power supply 123 is connected to the sputtering target 124, making it possible to control the acceleration energy of the ions. With this mechanism, the deposition apparatus 100 is able to control the density of the thin film deposited on the substrate.

The first deposition chamber 108a and the second deposition chamber 108b can be fitted with sputtering targets 124 of different materials (components, compositions, densities), and thin films of different compositions can be continuously deposited in a vacuum. The first deposition chamber 108a and the second deposition chamber 108b can also be fitted with sputtering targets 124 of the same type (components, compositions, densities), and thus different deposition conditions can be applied to deposit thin films of different film qualities. Although FIG. 1 shows two deposition chambers 108, the deposition apparatus 100 is not limited to such a configuration, and the number of deposition chambers 108 can be appropriately changed depending on the structure and type of the thin film to be produced. For example, when a single-layer thin film is formed, the deposition apparatus 100 may have one deposition chamber 108, and when a multi-layer thin film is formed, three or more deposition chambers 108 may be connected.

2 is a diagram showing the configuration of the film formation apparatus 100, and shows the main components provided or connected to the pretreatment chamber 104, the first transfer chamber 106a, the second transfer chamber 106b, the first film formation chamber 108a, and the second film formation chamber 108b, excluding the load/unload chamber. A vacuum exhaust system 110 is connected to each chamber. The vacuum exhaust system 110 is composed of vacuum pumps such as a turbo molecular pump (TMP) and a dry pump (DRP). The configuration of the vacuum exhaust system 110 may be different or the same for the first transfer chamber 106a and the second transfer chamber 106b and the first film formation chamber 108a and the second film formation chamber 108b. The first film formation chamber 108a and the second film formation chamber 108b may be provided with a conductance valve for pressure control. In addition, a gas supply system 112 is connected to the pretreatment chamber 104, the first film formation chamber 108a, and the second film formation chamber 108b. The gas supply system 112 includes a mass flow controller, a filter, and the like.

The pre-treatment chamber 104 is provided with a substrate stage 114 and a high-frequency discharge electrode 115. The high-frequency discharge electrode 115 is connected to a high-frequency power supply 120. In the pre-treatment chamber 104, the substrate is pre-treated by a high-frequency discharge plasma generated by the substrate stage 114 and the high-frequency discharge electrode 115.

Between the pretreatment chamber 104 and the first deposition chamber 108a, the first transfer chamber 106a equipped with a transfer robot 116 and the second transfer chamber 106b equipped with a platen mechanism 118 are provided. The substrate subjected to the desorption process of the adsorbed molecules in the pretreatment chamber 104 is transferred to the first deposition chamber 108a via the first transfer chamber 106a and the second transfer chamber 106b without being exposed to the air. The substrate pretreated in the pretreatment chamber 104 is transferred to the second transfer chamber 106b by the transfer robot 116 of the first transfer chamber 106a. The transfer robot 116 transfers the substrate while keeping it horizontal. The substrate transferred to the second transfer chamber 106b is set upright or tilted within a range of about 20 degrees from the vertical by the platen mechanism 118 and is transferred to the first deposition chamber 108a.

In sputtering, it is preferable to form a film on a substrate in an upright position, not horizontally, so that pinholes are not formed in the deposited thin film. However, when the size of the substrate increases, for example, in display applications (for example, the eighth generation glass substrate for liquid crystal processing is 2200 mm x 2400 mm), it is difficult to transport the substrate in a vertical position at all times, since it will bend under its own weight. In addition, in an apparatus that forms a film by keeping the substrate horizontal, such as a cluster-type single-wafer sputtering apparatus, the problem is that the floor area of the apparatus increases due to the increase in the size of the substrate (i.e., the floor area of the clean room increases). To address this problem, the film forming apparatus 100 is provided with a platen mechanism 118 in the middle of the substrate transport path, and the substrate is handled horizontally until the pre-film forming stage, and in the film forming stage, the substrate is held vertically or tilted within a range of about 20 degrees from the vertical, making it easier to handle the substrate. In addition, the film forming apparatus 100 has the advantage of being able to reduce the floor area required for installation.

The first deposition chamber 108a is provided with an antenna 126 for generating inductively coupled plasma, and a sputtering target 124 is attached. The antenna 126 for generating inductively coupled plasma is connected to a high frequency power supply 120 that outputs high frequency waves in the megahertz range. The antenna 126 for generating inductively coupled plasma may also be connected to an AC power supply 122 so that an AC voltage in the kilohertz range can be applied so as to be superimposed on the high frequency power. The sputtering target 124 is connected to a pulse power supply 123 as described above. The first deposition chamber 108a may also be provided with a heater 127 for heating the substrate.

Although detailed description is omitted, the second deposition chamber 108b has a configuration similar to that of the first deposition chamber 108a. Although not shown in FIG. 2, the first deposition chamber 108a and the second deposition chamber 108b are provided with a transport mechanism that transports the substrate vertically or tilted within a range of about 20 degrees from the vertical.

Figure 3 shows a partial schematic cross-sectional view of the deposition chamber 108 (first deposition chamber 108a, second deposition chamber 108b) as viewed from above. The deposition chamber 108 is configured to form a closed space whose internal space is isolated from the atmosphere, and Figure 3 shows a schematic structure between the two walls (first chamber wall 109a, second chamber wall 109b).

The deposition chamber 108 includes a plasma diffusion prevention plate 140 provided to cover the sputtering target 124, an antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma provided to protrude into the area surrounded by the plasma diffusion prevention plate 140, and a gas introduction pipe 138 for introducing sputtering gas. The deposition apparatus 100 is used with the sputtering target 124 attached to the deposition chamber 108, but the sputtering target 124 is a consumable item and is not a component fixed to the deposition apparatus 100, but an accessory that is replaced as necessary. The deposition chamber 108 is equipped with components such as the sputtering target 124 and the antenna 126 for generating inductively coupled plasma, and the attachment parts of each component are provided with sealing members such as O-rings and gaskets.

The sputtering target 124 includes a target material 132 and a backing plate 130. The target material 132 is bonded to the backing plate 130, which is made of a metal such as copper (Cu) or titanium (Ti), with a bonding material such as an indium alloy. The target material 132 is preferably a one-piece molded product. The sputtering target 124 is attached to the first chamber wall 109a of the deposition chamber 108. The first chamber wall 109a is provided with a first through hole 128a, and the sputtering target 124 is attached so that the backing plate 130 is fitted into the first through hole 128a. Since a bias voltage is applied to the sputtering target 124, an insulating part 136 is provided between the backing plate 130 and the first chamber wall 109a.

When viewed from the front, the sputtering target 124 is rectangular and the longitudinal direction is parallel to the vertical direction. Various sputterable materials can be attached to the target material 132. For example, a sintered body of metal oxide for forming a transparent conductive film or an oxide semiconductor film can be applied as the target material 132. The temperature of the target material 132 increases due to ions colliding with it during sputtering film formation. For this reason, the film formation device 100 is provided with a mechanism for cooling the backing plate 130 to suppress the temperature rise of the target material 132. FIG. 3 shows, as an example, a structure in which a water flow hole for flowing cooling water is provided in the backing plate 130.

When the sputtering target 124 is attached to the first chamber wall 109a, the target material 132 is exposed to the internal space of the deposition chamber 108. A shield plate 134 is provided in the deposition chamber 108 to cover the peripheral portion of the target material 132. The shield plate 134 is provided to cover the surface of the backing plate 130 exposed in the area between the target material 132 and the first chamber wall 109a. This structure prevents the backing plate 130 from being exposed to the inductively coupled plasma and being sputtered.

The deposition chamber 108 is provided with an antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma. The antenna 126 for generating inductively coupled plasma is arranged along the longitudinal direction of the sputtering target 124 and so as to sandwich the sputtering target 124. In other words, the first antenna 126a and the second antenna 126b as the antenna 126 for generating inductively coupled plasma are arranged so as to sandwich the sputtering target 124.

The first antenna 126a and the second antenna 126b as the antenna 126 for generating inductively coupled plasma include an antenna body 148 for generating inductively coupled plasma (first antenna body 148a, second antenna body 148b) and an insulating member 146 (first insulating member 146a, second insulating member 146b) having a U-shaped groove shape. The first antenna body 148a is provided in the first insulating member 146a, and the second antenna body 148b is provided in the second insulating member 146b. The antenna 126 for generating inductively coupled plasma is provided such that the insulating member 146 is inserted into the second through-hole 128b of the first chamber wall 109a and protrudes on both sides of the sputtering target 124. In this way, by providing the antenna body 148 for generating inductively coupled plasma in the insulating member 146, it is possible to prevent the material sputtered from the target material 132 from adhering to the antenna body 148 for generating inductively coupled plasma. Furthermore, it is possible to prevent the antenna body 148 for generating the inductively coupled plasma from being exposed to the inductively coupled plasma.

The antenna 126 for generating inductively coupled plasma is provided so that the antenna body 148 for generating inductively coupled plasma protrudes to a position higher than the surface of the target material 132 (a position toward the center of the deposition chamber 108, or a position on the substrate 200 side). For example, the antenna body 148 for generating inductively coupled plasma is provided so as to protrude by a length D2 from the surface of the target material 132. In this way, by providing the antenna body 148 for generating inductively coupled plasma protruding from the surface of the target material 132, the plasma density on the surface of the target material 132 can be increased.

Figure 22A shows another configuration of the film deposition chamber 108 (first film deposition chamber 108a, second film deposition chamber 108b). Figure 22A shows a partial cross-sectional schematic diagram of the film deposition chamber 108 when viewed from above, similar to Figure 3. The film deposition chamber 108 shown in Figure 22A has a structure in which a portion of the first chamber wall 109a to which the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma and the sputtering target 124 are attached is formed of a ceramic member 180a. Figure 22B shows a front view of this ceramic member 180a.

22A and 22B, the ceramic member 180a is provided with a first through hole 128a for mounting the sputtering target 124. Since the ceramic member 180a has insulating properties, the sputtering target 124 can be directly mounted. That is, when mounting the sputtering target 124 to the deposition chamber 108, the insulating part 136 as shown in FIG. 3 can be omitted. In addition, the ceramic member 180a is provided with a second through hole 128b for mounting the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma. The insulating member 146 (first insulating member 146a, second insulating member 146b) having a U-shaped groove shape is inserted from this second through hole 128b and is vacuum sealed by an O-ring on the back side of the ceramic member 180a. Furthermore, since the ceramic member 180a is insulating, the shield plate 134 covering the peripheral portion of the target material 132 can be integrated.

Figure 23A shows a structure in which a part of the first chamber wall 109a in the film deposition chamber 108 (first film deposition chamber 108a, second film deposition chamber 108b) is integrated with a ceramic member 180b and a U-groove-shaped insulating member 146 (first insulating member 146a, second insulating member 146b) that covers the antenna body 148 (first antenna body 148a, second antenna body 148b) for generating inductively coupled plasma. Also, Figure 23B shows a front view of the ceramic member 180b. As shown in Figures 23A and 23B, by integrally molding the U-groove-shaped insulating member 146 (first insulating member 146a, second insulating member 146b) with a part of the first chamber wall 109a, the number of parts can be reduced and leaks (vacuum airtight leakage) can be prevented. A glass layer may be formed on the atmosphere side (the side where the antenna body 148 for generating inductively coupled plasma is provided) of the portion of the ceramic member 180b that corresponds to the U-groove-shaped insulating members (the first insulating member 146a and the second insulating member 146b). By providing the glass layer, leakage from the atmosphere side can be further reduced.

The ceramic members 180a and 180b are not only excellent insulators, but also have a high heat resistance, a small thermal expansion coefficient, can be precisely machined, and emit a small amount of gas, making them suitable for use as wall materials for the deposition chamber 108. By using the ceramic members 180a and 180b as wall materials near the antenna 126 for generating inductively coupled plasma, the power loss of the antenna 126 for generating inductively coupled plasma can be reduced. This makes it possible to increase the plasma density near the surface of the target material 132.

22A and 23A, by forming the first chamber wall 109a to which the sputtering target 124 is attached from ceramic members 180a and 180b, the amount of gas desorbed from the chamber inner wall can be reduced and the plasma density can be increased. In addition, by forming the periphery of the target material 132 from insulating ceramic members 180a and 180b, the area in which a perpendicular electric field is generated relative to the surface of the target material 132 can be expanded, and a film with higher density can be produced.

FIG. 4 shows a detailed cross-sectional structure of the antenna 126 for generating inductively coupled plasma. The antenna body 148 for generating inductively coupled plasma is formed of a hollow metal tube 150. For example, the antenna body 148 for generating inductively coupled plasma is formed of a hollow metal tube 150 made of copper (Cu), brass, aluminum (Al), or the like. The antenna body 148 for generating inductively coupled plasma forms a rod-shaped antenna using such a metal tube, and cooling water is passed through the hollow portion. It is preferable that a conductive layer 151 formed of a plating film of nickel (Ni) or tin (Sn) is formed on the inner surface of the metal tube 150 to prevent corrosion. The insulating member 146 is formed of quartz, or ceramics such as alumina, yttria (Y ₂ O ₃ ), forsterite (Mg ₂ SiO ₄ ), steatite (MgO.SiO ₂ ), or the like. The insulating member 146 is a U-shaped groove-shaped member in which the antenna body 148 for generating inductively coupled plasma is disposed, and is disposed so as to separate the vacuum from the atmosphere. A glass layer 147 is preferably provided on the surface (particularly the surface on the atmosphere side) of the insulating member 146 in order to increase airtightness (to prevent leakage). The antenna body 148 for generating inductively coupled plasma is disposed on the atmosphere side by being passed through the insulating member 146. In this way, by disposing the antenna body 148 for generating inductively coupled plasma on the atmosphere side, the accuracy of the installation position can be improved, and the uniformity of the plasma density in the vicinity of the target material 132 can be improved. In addition, the holding mechanism of the antenna body 148 for generating inductively coupled plasma can also be freely designed.

5, the inductively coupled plasma generating antenna 126 may be configured to include a plurality of inductively coupled plasma generating antenna bodies 148. That is, the inductively coupled plasma generating antenna body 148 may be configured from a plurality of inductively coupled plasma generating antenna bodies 148 and may be arranged on the atmospheric side of the insulating member 146. The metal tube 150 constituting the inductively coupled plasma generating antenna body 148 has a higher AC resistance as the frequency increases due to the skin effect. For example, when a high frequency power of 13.56 MHz is applied to the inductively coupled plasma generating antenna body 148, even if the thickness of the metal tube 150 is 5 mm, the current will only flow in a region about 17.7 μm deep from the surface of the metal tube 150. In order to prevent power loss due to the skin effect, the inductively coupled plasma generating antenna 126 may have a plurality of inductively coupled plasma generating antenna bodies 148 arranged in parallel as shown in FIG.

3, the gas introduction pipe 138 is provided adjacent to the first antenna 126a in the inner region of the plasma diffusion prevention plate 140. The gas introduction pipe 138 is provided to introduce the sputtering gas into the deposition chamber 108. The gas introduction pipe 138 is provided along the longitudinal direction of the sputtering target 124, similar to the antenna 126 for generating inductively coupled plasma. The gas introduction pipe 138 may have a structure in which a shower nozzle is provided on a metal pipe, but is preferably formed of an insulating porous body, for example, a ceramic porous body pipe. By using a porous body for the gas introduction pipe 138, the sputtering gas can be introduced uniformly along the longitudinal direction of the sputtering target 124.

The plasma diffusion prevention plate 140 is provided so as to surround the area where the sputtering target 124 is placed. The plasma diffusion prevention plate 140 is a box-shaped member, and is provided inside the deposition chamber 108 so as to form a space surrounded by the first chamber wall 109a and the plasma diffusion prevention plate 140. The plasma diffusion prevention plate 140 has a first surface 142 that is approximately parallel to the surface of the first chamber wall 109a, and a second surface 143 that faces the first chamber wall 109a from the first surface 142. In addition, in the area surrounded by the plasma diffusion prevention plate 140, an adhesion prevention plate 141 is provided so as to cover the surface of the first chamber wall 109a. A first opening 144 is provided in the first surface 142 of the plasma diffusion prevention plate 140. The first opening 144 is provided at a position that overlaps with the target material 132.

Figure 6 shows a schematic diagram of the structure of the plasma diffusion prevention plate 140 when viewed from the front. The sputtering target 124 is provided in an area surrounded by the plasma diffusion prevention plate 140. When the sputtering target 124 is viewed from the front, the target material 132 is exposed from the first opening 144 of the plasma diffusion prevention plate 140.

The antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma is arranged in a position covered by the plasma diffusion prevention plate 140. The first antenna body 148a has a structure in which the first metal tube 150a and the second metal tube 150b are connected via the first capacitor 152a, and the second antenna body 148b has a structure in which the third metal tube 150c and the fourth metal tube 150d are connected via the second capacitor 152b.

The plasma diffusion prevention plate 140 is provided with a slit-shaped second opening 154 extending from the second surface 143 to the first surface 142. The second opening 154 is elongated and extends in a direction intersecting with the longitudinal direction of the antenna 126 for generating inductively coupled plasma, and a plurality of second openings 154 are provided. The second opening 154 is an orifice for the sputtering gas, and has a function of controlling the flow of the sputtering gas supplied to the space surrounded by the plasma diffusion prevention plate 140. That is, the second opening 154 has a function of controlling the conductance of the gas flow so that the sputtering gas remains in the space surrounded by the plasma diffusion prevention plate 140 for a predetermined time and forms a uniform gas pressure in the film formation area. Furthermore, the slit-shaped second opening 154 has a function of preventing an induced current generated in the plasma diffusion prevention plate 140 by the antenna 126 for generating inductively coupled plasma, and can increase the efficiency of energy transfer from the antenna 126 for generating inductively coupled plasma to the inductively coupled plasma.

The plasma diffusion prevention plate 140 is preferably formed of a material having a secondary electron emission rate greater than 1. For example, the plasma diffusion prevention plate 140 is preferably formed of a magnesium alloy, a barium alloy, or a calcium alloy mainly composed of aluminum. Furthermore, the plasma diffusion prevention plate 140 formed of these metal materials is preferably anodized on the inner surface facing the sputtering target 124. By forming an anodized film of a magnesium alloy, a barium alloy, or a calcium alloy on the inner surface of the plasma diffusion prevention plate 140, the secondary electron emission rate can be made greater than 1. This makes the surface of the anodized film positively resistant to electricity, and prevents argon ions (positive ions) from entering and colliding with the plasma diffusion prevention plate 140. In other words, sputtering of the plasma diffusion prevention plate 140 by argon ions (positive ions) is prevented, and impurities taken into the thin film formed in the film formation chamber 108 can be reduced.

When the carrier concentration of the n-type oxide semiconductor film is precisely controlled by sputtering, it is necessary to prevent the inclusion of impurities that cause the electron killer effect. As a countermeasure, it is preferable to cover the inner surface of the plasma diffusion prevention plate 140 exposed to the inductively coupled plasma with an insulating film that does not cause the electron killer effect. Examples of insulating films that do not cause the electron killer effect include silicon oxide (SiO ₂ ), magnesium oxide (MgO), and alumina (Al ₂ O ₃ ). In particular, magnesium oxide (MgO), which has a high secondary electron emission rate, is preferable as the insulating film, and it is also preferable to cover the surface of the plasma diffusion prevention plate 140 with silicon oxide, aluminum oxide, or the like containing magnesium oxide (MgO).

The plasma diffusion prevention plate 140 is provided to prevent the inductively coupled plasma formed by the inductively coupled plasma generating antenna 126 from spreading throughout the entire deposition chamber 108. By forming a physical wall called the plasma diffusion prevention plate 140, it is possible to prevent the inductively coupled plasma from spreading unnecessarily within the deposition chamber 108. In other words, the deposition chamber 108 has a structure in which the inductively coupled plasma is generated in the area surrounded by the plasma diffusion prevention plate 140 and the adhesion prevention plate 141, and the inductively coupled plasma does not spread to other areas. The plasma diffusion prevention plate 140 and the adhesion prevention plate 141 have an anodized film formed on their surfaces, which can enhance the plasma confinement effect and increase the plasma density.

In conventional magnetron sputtering equipment, in order to improve the film density of oxide semiconductor films, it is required to keep the gas pressure during film formation at 0.5 Pa or less. Furthermore, it is necessary to pay attention not only to impurity gases that escape from the inner walls of the film formation chamber, but also to the fact that materials inside the film formation chamber are sputtered and incorporated into the film as impurities.

Since oxide semiconductors typified by InGaSnO _x have n-type conductivity, when a film-forming chamber is made of stainless steel material containing iron (Fe), chromium (Cr), manganese (Mn), etc., which have a large electron killer effect, it is necessary to completely prevent the chamber wall from coming into contact with plasma. If a process for removing water (H ₂ O), hydrocarbons, etc. adsorbed on the substrate surface is not performed when forming an oxide semiconductor film, the film density does not increase, and a highly reliable thin film transistor cannot be manufactured.

If the substrate temperature is not kept at 150° C. or higher during the period from degassing the substrate surface to transporting it to the deposition chamber, moisture (H ₂ O) in the vacuum chamber will be re-adsorbed, and reproducibility cannot be improved. Furthermore, in order to improve the film density of the oxide semiconductor film as deposited, it is necessary to increase the substrate temperature to 200° C. or higher to improve the crystallization rate. By adding a small amount of hydrogen gas (H ₂ ) to the sputtering gas (Ar+O ₂ ), contamination by impurity gases released from the inner walls of the deposition chamber can be reduced, and heat treatment after deposition can be omitted. In the case of thin film transistors, the heat treatment temperature after element completion can be reduced to about 200° C., so that the manufacturing cost can be significantly reduced.

In this way, the film formation chamber 108 has a structure in which the inductively coupled plasma is confined by the plasma diffusion prevention plate 140 and the adhesion prevention plate 141, so that impurities (moisture ( _H2O ), hydrogen ( _H2 ), hydrocarbons, etc.) adsorbed on the chamber walls 109 (first chamber wall 109a, second chamber wall 109b, etc.) can be prevented from being incorporated into the thin film deposited on the substrate. Furthermore, even if the film formation chamber 108 is made of stainless steel (SUS304), problems with contamination by iron (Fe), chromium (Cr), etc. can be prevented.

As shown in FIG. 7, a mesh 170 may be provided in the first opening 144. By providing the mesh 170, the confinement effect of the inductively coupled plasma can be enhanced. The mesh 170 is preferably formed of a metal material that does not have an electron killer effect. For example, the mesh 170 is preferably formed of a metal material selected from titanium (Ti), tungsten (W), nickel (Ni), and tantalum (Ta). This reliably prevents the plasma from spreading into the deposition chamber 108, and also prevents impurities that become electron killers from being taken into the film when depositing the oxide semiconductor film. By providing the mesh 170, negative oxygen ions can be easily incident perpendicularly on the substrate 200, and crystallization of the formed oxide semiconductor film can be promoted.

It is preferable that the opening ratio of the mesh 170 is 70% or more. The wires (or mesh pattern) forming the mesh 170 are arranged to intersect at an angle of 30 degrees to 60 degrees with respect to the moving direction of the substrate (horizontal direction) as shown in Figure 7, thereby preventing the pattern of the mesh 170 from being transferred to the deposited film.

It is also preferable that the plasma diffusion prevention plate 140 is provided so as to be interposed between the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma and the substrate 200. If the plasma diffusion prevention plate 140 is not provided, as shown in FIG. 8A, the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma affects the quality of the thin film deposited on the substrate 200. That is, the surface 202 of the substrate 200 adjacent to the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma is affected by the self-bias of the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma, so that the quality of the thin film deposited is significantly different. 8B, when a plasma diffusion prevention plate 140 is interposed between the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma and the substrate 200, the effect of the self-bias is blocked, so that the quality of the thin film deposited on the substrate 200 can be kept constant. In addition, when the antenna 126 for generating inductively coupled plasma has a coupling region (a region where two conductors are capacitively coupled, the details of which will be described later), the problem of non-uniformity of the plasma can be solved by having the plasma diffusion prevention plate 140.

Furthermore, when the plasma diffusion prevention plate 140 is not provided, even in a moving deposition method in which the substrate 200 moves in one direction in front of the first opening 144, as shown in FIG. 9, there is a problem in that the film quality of the area overlapping with the capacitors 152 (first capacitor 152a, second capacitor 152b) connecting the metal tubes 150 (first metal tube 150a and second metal tube 150b, third metal tube 150c and fourth metal tube 150d) constituting the antenna body 148 for generating inductively coupled plasma is different.

That is, if the plasma diffusion prevention plate 140 is not provided, the plasma density in the first capacitor 152a and the second capacitor 152b provided on the first antenna 126a and the second antenna 126b, respectively, will be different, affecting the quality of the thin film deposited in the antenna connection region 204 that overlaps with the different portions, making it impossible to form a uniform thin film over the entire surface of the substrate 200. In contrast, if the plasma diffusion prevention plate 140 is provided, there will be no region corresponding to the antenna connection region 204, and the effect of plasma non-uniformity will be eliminated, making it possible to form a uniform film over the entire surface of the substrate 200.

The film forming apparatus 100 is of a moving film forming type, and as shown in FIG. 3, the substrate 200 is attached to a transport tray 160 and transported in front of the sputtering target 124. The substrate 200 is transported to a position close to the plasma diffusion prevention plate 140. As shown in FIG. 3, the distance from the surface of the target material 132 to the surface of the substrate 200 is D1, and the distance between the surface of the substrate 200 and the surface of the plasma diffusion prevention plate 140 is D3. In this case, the plasma diffusion prevention plate 140 and the transport tray 160 are positioned so that the distance D3 is one-fifth or less of the distance D1. For example, when the distance D1 is 55 mm, the distance D3 has a length of 5 mm.

In this way, by transporting the substrate 200 close to the plasma diffusion prevention plate 140, it is possible to reduce the conductance of the sputtering gas supplied to the area surrounded by the plasma diffusion prevention plate 140 when it flows out into the film formation chamber 108 through the first opening 144. Furthermore, this configuration has the effect of preventing impurities (moisture (H ₂ O), hydrogen (H ₂ ), hydrocarbons, etc.) adsorbed on the chamber wall 109 from diffusing and flowing into the film formation area, and can exert the effect of improving the reproducibility of the physical properties of the thin film to be formed.

10A and 10B show an example of a sputtering target 124 that can be applied to the moving deposition method. Fig. 10A shows a structure in which two types of target materials 132 (first target material 132a, second target material 132b) are fixed to a backing plate 130 with a bonding material 131. Indium or an indium alloy is used as the bonding material 131.

The first target material 132a and the second target material 132b are combined with materials having different compositions or materials. For example, when the target material is an oxide semiconductor, a ternary oxide semiconductor target containing indium (In), gallium (Ga), and tin (Sn) is used as the first target material 132a, and an oxide semiconductor target having a higher concentration of gallium (Ga) than the first target material 132a is used as the second target material 132b. In this way, by arranging two types of target materials side by side in the transport direction of the substrate, two layers with different compositions can be continuously deposited.

The first target material 132a and the second target material 132b are arranged on the backing plate 130 at a predetermined interval to prevent damage due to thermal expansion. The interval G1 is about 0.5 mm. In this case, the first target material 132a and the second target material 132b are formed with tapered ends in a cross-sectional view so that the backing plate 130 or the bonding material 131 is not exposed at the separated portion. Specifically, as shown in FIG. 10A, the first target material 132a has a tapered surface formed so that the end on the upper surface side protrudes from the bottom surface that contacts the bonding material 131, and the second target material 132b has a tapered surface formed so that the bottom surface protrudes from the upper surface side. By arranging the first target material 132a and the second target material 132b so that these two tapered surfaces interlock, it is possible to prevent the backing plate 130 and the bonding material 131 from being exposed when the sputtering target 124 is viewed in a plane. In other words, even if two types of target materials are placed on one backing plate 130, it is possible to prevent the backing plate 130 and the bonding material 131 from being sputtered in the boundary region, and to prevent impurities from being incorporated into the deposited film.

In the deposition chamber 108, the substrate 200 is transported in one direction in front of the sputtering target 124 at a constant speed, so that the thickness of the deposited thin film can be made different by narrowing the width of the second target material 132b relative to the width of the first target material 132a. For example, by narrowing the width of the second target material 132b relative to the width of the first target material 132a, the thickness of the thin film deposited on the first target material 132a can be made thicker and the thickness of the thin film deposited on the second target material 132b can be made thinner.

Figure 10B shows an example in which three types of target materials 132 (first target material 132a, third target material 132c, second target material 132b) are arranged. In this case, as in the example shown in Figure 10A, the side ends where the target materials are adjacent to each other are formed in a tapered shape. Specifically, the third target material 132c sandwiched between the first target material 132a and the second target material 132b has a trapezoidal cross-sectional shape. By arranging the first target material 132a and the second target material 132b, which have tapered surfaces facing in opposite directions, on both sides of the third target material 132c having such a cross-sectional shape, the sputtering target 124 has a structure in which the backing plate 130 and the bonding material 131 are not exposed in a planar view.

Figure 11 shows details of the antenna 126 (first antenna 126a, second antenna 126b) for generating inductively coupled plasma. The first antenna 126a includes a first insulating member 146a and a first antenna body 148a, and the second antenna 126b includes a second insulating member 146b and a second antenna body 148b. The first antenna body 148a is a rod-shaped antenna in which the first metal tube 150a and the second metal tube 150b are connected via a first capacitor 152a formed in the antenna connection region 204, and the second antenna body 148b is a rod-shaped antenna in which the third metal tube 150c and the fourth metal tube 150d are connected via a second capacitor 152b formed in the antenna connection region 204. The first antenna body 148a and the second antenna body 148b can reduce impedance by having such a structure. This makes it possible to prevent an increase in impedance even when the inductively coupled plasma generating antenna body 148 is lengthened, and to prevent a large potential difference from occurring across the inductively coupled plasma generating antenna body 148. As a result, it is also possible to accommodate an increase in the size of the sputtering target 124.

Figure 12 shows the cross-sectional structure of the antenna connection region 204 of the antenna body 148 for generating inductively coupled plasma. The antenna connection region 204 has a structure in which the first metal tube 150a and the second metal tube 150b (or the third metal tube 150c and the fourth metal tube 150d) are fitted into a hollow tube 172 made of an insulating material. An O-ring 153 is provided at the portion where the hollow tube 172 fits into the first metal tube 150a and the second metal tube 150b to maintain airtightness, and the structure is such that no leakage occurs even when cooling water flows. The O-ring 153 is preferably heat-resistant, and for example, a fluororubber-based one is used.

A conductive layer 174 is formed on the inner surface of the hollow tube 172 and is used as an electrode of the capacitor 152. The conductive layer 174 is formed of a first conductive layer 174a formed of copper plating to reduce resistance, and a second conductive layer 174b formed of nickel (Ni) plating or tin (Sn) plating to prevent corrosion of the copper plating film. In addition, as described above, a conductive layer 151 is also formed on the inner surfaces of the first metal tube 150a and the second metal tube 150b.

The conductive layer 174 is arranged to face the first metal tube 150a and the second metal tube 150b through the hollow tube 172 formed of an insulating material, thereby forming a capacitor 152. That is, the first metal tube 150a and the second metal tube 150b are capacitively coupled by being fitted into the hollow tube 172 having the conductive layer 174 formed on the inner surface, forming an antenna body 148 for generating inductively coupled plasma. By arranging the hollow tube 172 formed of an insulating material on the inner circumference of the first metal tube 150a and the second metal tube 150b in this manner, the unevenness of the antenna body 148 for generating inductively coupled plasma can be reduced, and the inductively coupled plasma can be made uniform.

In addition, since the inductively coupled plasma generating antenna body 148 is provided on the atmospheric side, a variable capacitor 176 can be provided in parallel with the capacitor 152. This allows the impedance of the inductively coupled plasma generating antenna body 148 to be adjusted precisely and over a wide range. This makes it easier to match the inductively coupled plasma generating antenna 126 with the high frequency power supply 120.

Furthermore, since the capacitor 152 of the antenna body 148 for generating inductively coupled plasma is provided in the flow path of the cooling water (since the capacitor 152 is in contact with the cooling water), heat generation of the capacitor 152 can be effectively suppressed. With this configuration, it is possible to prevent failure and destruction due to heat generation of the capacitor 152, and it is also possible to increase the high frequency power applied to the antenna 126 for generating inductively coupled plasma.

When applying 13.56 MHz high-frequency power to the inductively coupled plasma generating antenna 126 as shown in Fig. 11, if the length of the inductively coupled plasma generating antenna body 148 exceeds 3 m, the problem of standing waves cannot be ignored. However, the problem of standing waves can be solved by dividing the inductively coupled plasma generating antenna body 148 into two or more pieces as shown in Figs. 16 and 17 and connecting them in series via a variable capacitor 176 for resonance.

The antenna body 148 for generating inductively coupled plasma is connected to a high-frequency power source 120 with an oscillation frequency of 13.56 MHz or 27 MHz. Specifically, the first antenna body 148a is connected to the first high-frequency power source 120a, and the second antenna body 148b is connected to the second high-frequency power source 120b. The first high-frequency power source 120a and the second high-frequency power source 120b may have the same phase of the output high-frequency power, but it is preferable that they are shifted by half a wavelength (180 degrees). This can increase the plasma density on the surface of the target material 132. The first antenna body 148a is also connected to the first variable capacitance capacitor 158a, and the second antenna body 148b is connected to the second variable capacitance capacitor 158b. The variable capacitor 158 (first variable capacitor 158a and second variable capacitor 158b) is provided to adjust the impedance of the antenna body 148 (first antenna body 148a and second antenna body 148b) for generating inductively coupled plasma and to facilitate impedance matching with the high frequency power supply 120 (first high frequency power supply 120a, second high frequency power supply 120b).

The antenna body 148 (first antenna body 148a, second antenna body 148b) for generating inductively coupled plasma is also connected to an AC power source 122 with a frequency of 10 kHz to 1000 kHz. A coil 156 for blocking high frequency is inserted between the antenna body 148 (first antenna body 148a, second antenna body 148b) for generating inductively coupled plasma and the AC power source 122. By applying an AC voltage in addition to high frequency power to the antenna body 148 (first antenna body 148a, second antenna body 148b) for generating inductively coupled plasma, the plasma density on the surface of the target material 132 can be increased.

Furthermore, by superimposing an AC voltage on the high frequency power, the deposits (products sputtered from the target material 132) adhering to the insulating member 146 can be removed by the sputtering phenomenon. This makes it possible to suppress the change over time in the discharge characteristics. In particular, when forming a transparent conductive film with a low resistance value, the circuit configuration of the antenna 126 for generating inductively coupled plasma shown in FIG. 11 has an advantageous effect in obtaining a stable discharge. Note that, when forming an oxide semiconductor film with a high resistance value, the AC power supply 122 is not essential because the deposition of deposits on the insulating member 146 does not have a significant effect. On the other hand, when the distance between the first antenna 126a and the second antenna 126b becomes 300 mm or more, the plasma density in the central region of the sputtering target 124 decreases, so the plasma density can be made uniform by applying an AC voltage between the first antenna body 148a and the second antenna body 148b using the AC power supply 122.

A pulse power supply 123 is connected to the sputtering target 124. The pulse power supply 123 applies a negative pulse voltage of about -100V to -600V to the sputtering target 124. As shown in Figure 13, the negative pulse voltage is applied at a timing when the AC voltage applied to the antenna body 148 for generating inductively coupled plasma becomes 0V, making it possible to emit sputtering particles in a direction perpendicular to the substrate. This allows a dense film to be deposited.

Figure 14 shows a schematic diagram of the relationship between target voltage and film density when an InGaZnO film is sputtered as an oxide semiconductor film. The advantage of the sputtering method using inductively coupled plasma is that it is possible to separate and independently control two power sources: one that generates and maintains the plasma, and the other that controls the sputtering film formation. With the conventional DC magnetron method, if the voltage applied to the sputtering target is reduced to -300V or less, the plasma generation becomes non-uniform and it becomes impossible to maintain a stable discharge.

On the other hand, when using inductively coupled plasma, if the high frequency power applied to the antenna used to generate the inductively coupled plasma is increased to increase the plasma density, it becomes possible to generate large amounts of negative oxygen ions and oxygen radicals. With a method that uses inductively coupled plasma, there is no effect of confining the plasma near the sputtering target due to the magnetic field of a magnet, so the plasma can be brought into uniform contact with the substrate surface. This promotes the oxidation reaction between the metal and oxygen atoms.

In the sputtering method using inductively coupled plasma, when forming an InGaZnO film, the voltage applied to the sputtering target is set to about -200 V, which can increase the crystallization rate while minimizing damage to the film deposited on the substrate surface. In this case, the film density of the InGaZnO film can be achieved to be 6.30 g/ ^cm3 . This film density is close to the theoretical value of 6.378 g/ ^cm3 .

In the conventional magnetron method, unless the target voltage is increased to -300 V or more, stable discharge cannot be maintained, which increases damage to the film and makes it difficult to achieve a film density of 6.25 g/cm3 or ^more . In contrast, the film formation apparatus 100 using inductively coupled plasma of the present embodiment can increase the film density of oxide semiconductor films of various compositions, including InGaZnO films, and can reduce the shift amount of the threshold voltage Vth of thin film transistors. In other words, the film formation apparatus 100 using inductively coupled plasma of the present embodiment can improve the long-term reliability of thin film transistors.

Figure 15 shows the configuration of the pre-treatment chamber 104. The pre-treatment chamber 104 is provided with a substrate stage 114 and a high-frequency discharge electrode 115. The substrate stage 114 is provided with a lifting mechanism 164 that floats the substrate 200 placed thereon. The substrate stage 114 is provided with pins 162 at multiple locations that come into contact with the substrate 200, and has the function of lifting the substrate 200 into a floating state by causing the pins 162 to protrude upwards due to the lifting mechanism 164.

The substrate stage 114 is made of a conductor so as to function as a ground electrode, and is set to have the same potential as the chamber wall of the pretreatment chamber 104. The substrate stage 114 may have a built-in heater for heating the substrate (not shown). The high-frequency discharge electrode 115 is disposed to face the substrate stage 114. The high-frequency discharge electrode 115 and the substrate stage 114 are connected to a high-frequency power source 120 having an oscillation frequency of 13.56 MHz or 27 MHz. The pretreatment chamber 104 is also provided with a gas introduction pipe 166. For example, nitrogen (N ₂ ) gas, oxygen (O ₂ ) gas, or nitrous oxide (N ₂ O) gas is introduced from the gas introduction pipe 166 as a pretreatment gas. Alternatively, instead of the gas introduction pipe 166, a high-frequency discharge electrode 115 formed of a shower plate may be used, and gas may be introduced from there. The pressure when generating plasma during pretreatment is preferably in the range of 10 Pa to 10 ³ Pa.

When the pretreatment gas is introduced into the pretreatment chamber 104 and high-frequency power is applied to the high-frequency discharge electrode 115, high-frequency discharge plasma 168 is generated. After the high-frequency discharge plasma 168 becomes stable, the substrate 200 is lifted by the pins 162 and placed in a floating state above the substrate stage 114. In this state, the high-frequency discharge plasma 168 is generated so as to wrap around not only the front surface of the substrate 200 but also the back surface. This makes it possible to remove impurities and contaminant molecules such as moisture adsorbed not only on the front surface (the surface on which the thin film is deposited) of the substrate 200 but also on the back surface and side surfaces. Since the pins 162 are exposed to the plasma, they are preferably made of insulating ceramics so as not to release impurities.

Plasma treatment in a vacuum has been performed as a pretreatment of the substrate 200. However, the plasma treatment is usually performed only on the front side of the substrate 200, and the back side is not exposed to plasma. In this state, even if the front side of the substrate 200 is cleaned, moisture adsorbed on the back side remains, so that degassing from the back side continues even after the substrate 200 is transported to the film formation chamber. In particular, when the gas pressure during sputtering film formation is low, such as in the formation of an oxide semiconductor film, degassing only on one side of the front side of the substrate 200 is insufficient. As a result, no matter how highly the film formation chamber is evacuated, adsorbed molecules (moisture (H ₂ O), hydrogen (H ₂ ), hydrocarbons, etc.) continue to be released from the back side of the substrate 200, so that the film quality is significantly different between the center and periphery of the substrate 200. For example, when an oxide semiconductor film is formed by sputtering, the carrier concentration is significantly different between the center and periphery of the substrate 200 because the degassing components released from the back side of the substrate 200 cannot be controlled. The larger the size of the substrate 200, the greater this problem becomes.

As a degassing treatment for the substrate 200, it is possible to heat the substrate 200 at a temperature of 200°C or higher in a vacuum, but this takes several hours to completely remove the adsorbed moisture, and is not suitable for mass production. When forming an oxide semiconductor film using a single-wafer process, it is not practical to perform a heat treatment for several hours for each substrate 200.

However, as shown in this embodiment, by performing plasma processing with the substrate 200 floating in the pre-processing chamber 104, not only the front surface but also the back surface is exposed to the plasma, making it possible to degas the entire surface, clean the entire surface of the substrate in a short period of time, and enable precise control of the carrier concentration.

To reiterate, an important point in the film formation apparatus 100 for forming an oxide semiconductor film is that adsorbed components (moisture (H ₂ O), hydrogen (H ₂ ), and hydrocarbons) adsorbed on the entire surface of the substrate 200 are forcibly degassed with nitrogen plasma or oxygen plasma before sputtering film formation. This makes it possible to form a homogeneous oxide semiconductor film with a constant carrier concentration over the entire surface of the substrate 200.

The deposition chamber 108 of the deposition apparatus 100 described above is preferably made of a metal material that is less prone to outgassing. For example, when forming an oxide semiconductor film for forming a thin film transistor, it is necessary to increase the film density in order to improve reliability. In order to increase the film density, it is necessary to perform sputtering deposition at a sputtering pressure of about 0.1 Pa to 1.5 Pa. In this pressure range, the inductively coupled plasma spreads throughout the deposition chamber 108, so that the inner wall is exposed to the plasma. When positive ions in the plasma collide with the inner wall of the deposition chamber, a large amount of molecules such as moisture (H ₂ O), hydrogen (H ₂ ), and hydrocarbons that have been adsorbed are released. These impurities cause an influence on the characteristics of a transistor formed of an oxide semiconductor film.

In the deposition chamber 108 of the deposition apparatus 100 shown in this embodiment, stainless steel is used in consideration of strength. However, elements such as iron (Fe), molybdenum (Mo), and manganese (Mn), which are components of stainless steel, are undesirable because they act as electron killer impurities for n-type oxide semiconductors. In other words, if the stainless steel is exposed in the deposition chamber 108, it will adversely affect the characteristics of a transistor using an oxide semiconductor film. In conventional sputtering apparatuses, the stainless steel is used in the deposition chamber in an exposed state, which reduces the manufacturing yield of transistors using oxide semiconductor films and reduces the reproducibility of the process.

In order to solve such problems, the film forming apparatus 100 according to this embodiment is configured to confine the plasma by providing a plasma diffusion prevention plate 140 made of metals such as magnesium (Mg), aluminum (Al), titanium (Ti), tungsten (W), and nickel (Ni) in the film forming chamber 108. Furthermore, in order to increase the electron density in the plasma and improve the stability of the discharge, a structure is adopted in which a film of an oxide of an alkaline earth metal such as magnesium oxide (MgO), barium oxide (BaO), strontium oxide (SrO), or calcium oxide (CaO), which has a high secondary electron emission rate, or an insulating film containing these, such as silicon oxide, aluminum oxide, or yttrium oxide, is provided on the surface of the plasma diffusion prevention plate 140.

1 and 2, the film formation apparatus 100 is provided with a first film formation chamber 108a and a second film formation chamber 108b. Such a configuration of the first film formation chamber 108a and the second film formation chamber 108b makes it possible to stack two types of oxide semiconductor films with different film properties. For example, a first oxide semiconductor film can be deposited in the first film formation chamber 108a, and a second oxide semiconductor film can be deposited in the second film formation chamber 108b.

For example, in the first deposition chamber 108a, an oxide semiconductor target is used, and a film is formed using only argon (Ar) or argon (Ar) and oxygen (O ₂ ) as a sputtering gas, and in the second deposition chamber 108b, argon (Ar) and oxygen (O ₂ ) are used (at this time, the oxygen partial pressure is set higher than that in the first deposition chamber 108a). In the sputtering deposition of an oxide semiconductor film, the density of negative oxygen ions can be increased by increasing the oxygen partial pressure, and the irradiation density of negative oxygen ions on the deposition surface of the thin film can be increased. As a result, the carrier density of the oxide semiconductor film deposited in the second deposition chamber 108b can be reduced and the crystallinity can be increased compared to the oxide semiconductor film deposited in the first deposition chamber 108a.

Furthermore, by applying a negative pulse voltage to the sputtering target 124, negative oxygen ions generated during discharge can reach the deposition surface of the oxide semiconductor film during application of the pulse voltage, promoting densification of the film and facilitating crystallization. In this embodiment, a large amount of oxygen radicals can be generated by the antenna 126 for generating inductively coupled plasma, and the inductively coupled plasma can contact or approach the surface of the substrate 200, making it easier for metal elements to react with oxygen, thereby reducing the probability that unreacted oxygen (O ₂ ) molecules are taken into the film.

In this way, the film formation apparatus 100 according to this embodiment employs a moving film formation method and has a configuration in which multiple first film formation chambers 108a and multiple second film formation chambers 108b are connected in series, thereby enabling precise control of carrier concentration when depositing an oxide semiconductor film. Note that, although this embodiment focuses on an example in which an oxide semiconductor film is produced using the film formation apparatus 100, this is not limiting, and the film formation apparatus 100 can also be applied to the production of transparent conductive films, other semiconductor films, and metal films.

In this embodiment, as shown in the front view of Figure 16A and the cross-sectional view of Figure 16B (cross-sectional structure corresponding to A1-A2 shown in Figure 16A), the first antenna 126a and the second antenna 126b are rod-shaped antennas that extend to approximately the same length in the same direction as the longitudinal direction of the sputtering target 124. In this example, the first insulating member 146a and the second insulating member 146b having a U-shaped groove are provided so as to protrude inside the area surrounded by the first chamber wall 109a and the plasma diffusion prevention plate 140, and the first antenna body 148a and the second antenna body 148b are provided so as to be surrounded by the first insulating member 146a and the second insulating member 146b having a U-shaped groove.

However, the first antenna 126a and the second antenna 126b are not limited to the form shown in Figures 16A and 16B, and the U-shaped first antenna 126a and the second antenna 126b may each be divided into multiple parts and arranged. For example, as shown in the front view of Figure 17A and the cross-sectional view of Figure 17B (cross-sectional structure corresponding to B1-B2 shown in Figure 17A), multiple first antenna bodies 148a_1 to 148a_3 and multiple second antenna bodies 148b_1 to 148b_3 may be divided along the longitudinal direction of the sputtering target 124. With such an arrangement of the first antenna 126a and the second antenna 126b, the plasma density can be increased in the same way, and a dense film can be deposited. Note that, although Figures 17A and 17B show an embodiment in which the antenna body 148 for generating inductively coupled plasma is divided into three and arranged in the longitudinal direction of the sputtering target 124, there is no limitation on the number by which the antenna body 148 for generating inductively coupled plasma is divided in the first antenna 126a and the second antenna 126b for generating inductively coupled plasma, and an antenna for generating inductively coupled plasma in which the antenna body 148 for generating inductively coupled plasma is divided into three or more may be arranged.

The present invention is not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit and scope of the invention. In addition, the embodiments can be combined as appropriate.

Figure 18A shows an example of an element manufactured using the film formation apparatus 100. One example of the element is a transistor, and Figure 18A shows a cross-sectional structure of a transistor 230. The transistor 230 includes an oxide semiconductor layer 216 formed on a substrate 200 by the film formation apparatus 100.

Specifically, the transistor 230 is formed on a first insulating layer 210 formed on the surface of the substrate 200. A first conductive layer 212a forming a source electrode and a first conductive layer 212b forming a drain electrode are provided in pairs on the first insulating layer 210. The first conductive layers 212a and 212b are formed of a transparent conductive film such as indium tin oxide (ITO) or indium zinc oxide (IZO). Second conductive layers 214a and 214b formed of a metal material such as aluminum (Al) may be provided on the first conductive layers 212a and 212b to reduce resistance.

The oxide semiconductor layer 216 is formed to cover the first conductive layers 212a, 212b (and the second conductive layers 214a, 214b). A second insulating layer 218 functioning as a gate insulating layer is provided on the oxide semiconductor layer 216, and a gate electrode 220 is provided on the second insulating layer 218 so as to overlap the oxide semiconductor layer 216.

The oxide semiconductor layer 216 may be formed of multiple layers with different compositions and crystallinity. For example, as shown in FIG. 18B, the first oxide semiconductor layer 216a and the second oxide semiconductor layer 216b may be stacked. The first oxide semiconductor layer 216a is a ternary oxide semiconductor containing indium (In), gallium (Ga), and tin (Sn), and the second oxide semiconductor layer 216b preferably has a higher proportion of gallium (Ga) than the first oxide semiconductor layer 216a and also has high crystallinity. The second oxide semiconductor layer 216b is formed thinner than the first oxide semiconductor layer 216a. The second oxide semiconductor layer 216b has a higher concentration of gallium (Ga), and therefore has physical properties such as a wider band gap and a lower carrier concentration than the first oxide semiconductor layer 216a. For example, the first oxide semiconductor layer 216a is formed to a thickness of 40 nm to 60 nm, whereas the second oxide semiconductor layer 216b is formed to a thickness of 4 nm to 6 nm, which is approximately one tenth of the thickness.

In the transistor 230, the second oxide semiconductor layer 216b is provided between the first oxide semiconductor layer 216a and the second insulating layer 218 (gate insulating layer), so that a so-called buried channel is formed in the first oxide semiconductor layer 216a, in which a channel region through which carriers flow is formed. That is, the transistor 230 can flow carriers into the channel region without being affected by defects formed at the interface between the second insulating layer 218 (gate insulating layer) and the oxide semiconductor layer 216. By having such a structure, the transistor 230 can stabilize the characteristics and reduce the characteristic variation.

18C, the oxide semiconductor layer 216 may include a third oxide semiconductor layer 216c between the first oxide semiconductor layer 216a and the second oxide semiconductor layer 216b. The third oxide semiconductor layer 216c is the same ternary oxide semiconductor, but has a higher concentration of indium (In) than the first oxide semiconductor layer 216a and the second oxide semiconductor layer 216b. By providing such a third oxide semiconductor layer 216c, the field effect mobility of the transistor 230 can be increased.

According to the film formation apparatus 100 of this embodiment, the structure of the oxide semiconductor layer 216 shown in Fig. 18B can be produced by using the sputtering target 124 shown in Fig. 10A, and the structure of the oxide semiconductor layer 216 shown in Fig. 18C can be produced by using the sputtering target 124 shown in Fig. 10B. In other words, oxide semiconductors with different compositions and crystallinity can be continuously formed in a vacuum.

Composite split targets such as those shown in Figures 10A and 10B cannot be used in conventional magnetron-type sputtering devices because abnormal discharges are likely to occur in the split parts. On the other hand, in systems that do not use magnets, positively charged argon ions are incident almost uniformly on the entire surface of the sputtering target, making abnormal discharges less likely to occur. In addition, because the entire surface of the sputtering target is sputtered uniformly, heat is also generated uniformly on the surface of the sputtering target. As a result, cracks due to thermal stress in the sputtering target are less likely to occur.

InGaSnO _x targets capable of producing oxide semiconductor films with high electron mobility are prone to fine cracks called hairline cracks in sputtering targets in conventional magnetron sputtering devices, and therefore cannot be used in mass production factories. In contrast, the film forming apparatus 100 according to the present embodiment does not use magnets, so plasma does not concentrate locally and local heat generation does not occur. Therefore, hairline cracks due to thermal stress are less likely to occur.

As in the film formation apparatus 100 of this embodiment, the plasma diffusion prevention plate 140 prevents the inductively coupled plasma (ICP) from diffusing throughout the entire internal area of the film formation chamber 108, making it possible to form a film without reducing the deposition rate even in a moving film formation method in which sputtering film formation is performed while moving the substrate.

Furthermore, by applying a negative pulse voltage to the sputtering target 124, stable sputtering deposition can be performed even if the target material 132 is a high resistance material. Furthermore, negative oxygen ions can be made to be incident perpendicularly to the substrate 200, so that a decrease in film density can be prevented even when the deposition gas pressure is around 1.5 Pa. For example, even on an 11th generation glass substrate (3000 mm x 3320 mm), it is possible to increase the film density and deposit an oxide semiconductor film with high mobility and high reliability.

Note that the structure of the transistor 230 shown in Figure 18A is just one example, and the film forming apparatus 100 of this embodiment can be used to manufacture oxide semiconductor transistors of various structures, regardless of whether they are top-gate type or bottom-gate type.

[Second embodiment]
This embodiment shows an example of a film formation apparatus capable of successively performing sputtering using inductively coupled plasma and vacuum deposition (and/or electron beam deposition). The film formation apparatus shown in this embodiment can be applied to, for example, the manufacture of an organic electroluminescence element (or an organic electroluminescence display device). The following description will focus on the differences from the film formation apparatus 100 shown in the first embodiment.

Figure 19 shows the overall configuration of the film formation apparatus 101 according to this embodiment. The film formation apparatus 101 includes a load/unload chamber 102 in which substrates before and after film formation are stored, a pretreatment chamber 104 in which pretreatment of the substrate is performed, a first transfer chamber 106a in which a transfer robot 116 is provided, a second transfer chamber 106b in which a platen mechanism 118 is provided, a first film formation chamber 108a in which sputtering film formation is performed, a third transfer chamber 106c in which a platen mechanism 118 is provided, a fourth transfer chamber 106d in which a transfer robot 116 is provided, a third film formation chamber 108c in which an evaporation source 111 is provided, a fourth film formation chamber 108d, and a fifth film formation chamber 108e. These chambers are connected by gate valves and are provided with vacuum exhaust means (not shown).

The configurations of the pretreatment chamber 104, the first transfer chamber 106a, the second transfer chamber 106b, the third transfer chamber 106c, and the fourth transfer chamber 106d are the same as those in the first embodiment. The first film formation chamber 108a is a chamber in which sputtering film formation is performed by inductively coupled plasma, and the electron injection layer described below is formed. The third film formation chamber 108c and the fourth film formation chamber 108d are chambers in which an evaporation source 111 is provided and vacuum deposition is performed, and organic films such as a light-emitting layer and a hole transport layer described below are formed. The fifth film formation chamber 106e is a chamber in which an evaporation source 111 is provided and anode film formation is performed by vacuum deposition (and/or electron beam deposition) to be described later.

19, the chamber where sputtering deposition by inductively coupled plasma is performed and the chamber where deposition by vacuum deposition (and/or electron beam deposition) is performed are connected via a transfer chamber, so that inorganic and organic films can be deposited continuously in a vacuum. In addition, the second transfer chamber 106b and the third transfer chamber 106c, which are provided with a platen mechanism 118, are provided on either side of the first deposition chamber 108a where sputtering deposition by inductively coupled plasma is performed, so that deposition by sputtering is performed with the substrate 200 vertical or tilted about 20 degrees from the vertical, and deposition by vacuum deposition (and/or electron beam deposition) can be performed with the substrate 200 held approximately horizontally.

The number of chambers for forming films using the vacuum deposition method (and/or electron beam deposition method) is arbitrary, and can be connected appropriately depending on the number of layers and type of film to be deposited.

Figure 20 is a diagram showing the configuration of the film formation apparatus 101, and shows the main components provided in or connected to the pretreatment chamber 104, the first transfer chamber 106a, the second transfer chamber 106b, the first film formation chamber 108a, the third transfer chamber 106c, the fourth transfer chamber 106d, and the third film formation chamber 108c, excluding the load/unload chamber 102. The configurations of the other chambers, excluding the third film formation chamber 108c, are the same as in the first embodiment.

The third deposition chamber 108c, where deposition is performed by vacuum evaporation (and/or electron beam evaporation), is equipped with a cryopump in addition to a turbomolecular pump and a dry pump as a vacuum exhaust system 110. Such a vacuum exhaust system 110 realizes high vacuum exhaust and effectively removes moisture remaining in the chamber. Deposition by vacuum evaporation may employ a moving deposition method in which the substrate moves in front of a linear evaporation source 111, or a scanning deposition method in which the evaporation source 111 moves to scan the surface of the substrate.

The deposition apparatus 101 employs a moving deposition method for deposition by sputtering and deposition by vacuum deposition (and/or electron beam deposition), and is therefore capable of handling substrates of various sizes. For example, the deposition apparatus 101 can be used for deposition on 11th generation glass substrates (3000 mm x 3320 mm).

Figure 21 shows an example of an element produced using the film forming apparatus 101. The element illustrated in Figure 21 shows a cross-sectional structure of an organic electroluminescence element 300. The organic electroluminescence element 300 has a structure in which a carrier injection amount control electrode 302, a first insulating layer 304, a first electrode (cathode) 306, an electron transport layer 308, a second insulating layer 310 with an opening 311 formed therein, an electron injection layer 312, a light-emitting layer 314, a hole transport layer 316, a hole injection layer 318, and a second electrode (anode) 320 are laminated on a substrate 200. The organic electroluminescence element 300 has a region where the opening 311 is provided, where the carrier injection amount control electrode 302, the first insulating layer 304, the electron transport layer 308, the electron injection layer 312, the light emitting layer 314, the hole transport layer 316, the hole injection layer 318, and the second electrode (anode) 320 overlap.

The carrier injection amount control electrode 302 is insulated from the electron transport layer 308, and when a positive bias voltage is applied, it has the function of controlling the amount of carriers (electrons) injected from the electron transport layer 308 through the electron injection layer 312 into the light-emitting layer 314 and the light-emitting position in the light-emitting layer 314. Since the organic electroluminescence element 300 is a bottom transmission type, the carrier injection amount control electrode 302 is formed of a transparent conductive film.

The electron transport layer 308 has a two-layer structure. The first electron transport layer 308a is provided on the first insulating layer 304 with a larger area than the carrier injection amount control electrode 302. The first electrode (cathode) 306 is provided outside the opening 311 (area overlapping with the second insulating layer 310). The first electrode (cathode) 306 may be formed, for example, in a two-layer structure of a first conductive layer 306a and a second conductive layer 306b, and is provided so that the end of the first conductive layer 306a overlaps with the carrier injection amount control electrode 302. The first conductive layer 306a is formed of a transparent conductive film such as ITO or IZO, and has the function of forming an ohmic contact with the electron transport layer 308 and injecting electrons. The second conductive layer 306b is appropriately provided to reduce the resistance of the first electrode (cathode) 306.

The first electron transport layer 308a is formed of a metal oxide having semiconductor properties. Examples of such metal oxides include In ₂ O ₃ -Ga ₂ O ₃ -SnO ₂ -ZnO based oxide materials, In ₂ O ₃ -Ga ₂ O ₃ -SnO ₂ based oxide materials, In ₂ O ₃ -SnO ₂ -ZnO based oxide materials, In ₂ O ₃ -Al ₂ O ₃ -ZnO based oxide materials, Ga ₂ O ₃ -SnO ₂ -ZnO based oxide materials, Ga ₂ O ₃ -Al ₂ O ₃ -ZnO based oxide materials, SnO ₂ -Al ₂ O ₃ -ZnO based oxide materials, In ₂ O ₃ -ZnO based oxide materials, SnO ₂ -ZnO based oxide materials, Al ₂ O ₃ -ZnO based oxide materials, Ga ₂ O ₃ -SnO The _first electron _transport layer _{308a may be formed} by _sputtering using the film _forming apparatus _{100 shown in the} first _embodiment .

A second insulating layer 310 is provided on the first electron transport layer 308a. The second insulating layer 310 is provided with an opening 311 that exposes the surface of the first electron transport layer 308a. The second electron transport layer 308b is formed of a metal oxide material having semiconductor properties, similar to the first electron transport layer 308a. The second electron transport layer 308b may be prepared by a sputtering method, or may be prepared by a coating method in the region of the opening 311.

In this case, the second insulating layer 310 is preferably formed of an insulating film having polarity. Such a second insulating layer 310 can be formed using a straight-chain fluorine organic material. As the straight-chain fluorine organic material, for example, a fluoroalkylsilane (FAS)-based material is used. As the fluoroalkylsilane (FAS)-based material, for example, H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS), tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS), etc. are used. The second insulating layer 310 is formed using a straight-chain fluorine organic material, so that a water-repellent surface is formed. An opening 311 is formed in such a second insulating layer 310. The water-repellency of the second insulating layer 310 is strongly expressed on the surface, and the sidewall surface of the opening 311 becomes hydrophilic in comparison with the surface.

When the second electron transport layer 308b is prepared by a coating method, a composition solution containing the above-mentioned quaternary oxide material, ternary oxide material, binary oxide material, or single-element oxide material, or a precursor thereof, is applied from above the second insulating layer 310 in which the opening 311 is formed, and then dried and baked. As a specific example, zinc oxide (ZnO) is doped with aluminum (Al), indium (In), gallium (Ga), or the like as a trivalent metal element, and baked to have a resistivity in the range of 10 ² Ωcm to 10 ⁵ Ωcm. When the surface of the second insulating layer 310 is water-repellent, the viscosity of the composition to be applied is appropriately adjusted to selectively form a coating film in the opening 311. In the second electron transport layer 308b after baking, the contact surface with the second insulating layer 310 rises upward due to the hydrophilicity of the sidewall surface of the opening 311, and a cross-sectional shape having a gently tapered inclined surface toward the inside is formed. The second electron transport layer 308b may have an average thickness of 200 nm or more, and preferably 400 nm or more. When the second electron transport layer 308b has such a thickness, short-circuit defects of the organic electroluminescence element 300 are significantly reduced, and the yield can be improved.

In the organic electroluminescence element 300, the second insulating layer 310 is provided with an opening 311 that exposes the upper surface of the first electron transport layer 308a before the light-emitting layer 314 is formed, thereby defining the light-emitting region. In addition, the end of the second electron transport layer 308b provided in the opening 311 has a tapered cross-sectional shape that is gently inclined from the wall surface of the opening 311, thereby improving the step coverage of the electron injection layer 312 and the light-emitting layer 314 that are formed in the next step.

The electron injection layer 312 is formed of a material with a small work function in order to inject electrons into the light emitting layer 314. For example, the electron injection layer 312 is formed of a material containing calcium (Ca) oxide and aluminum (Al) oxide. As an example, the electron injection layer 312 is formed of C12A7 (12Ca.7Al ₂ O ₃ ) electride. C12A7 electride has semiconductor properties, can be controlled from high resistance to low resistance, and has a work function of 2.4 eV to 3.2 eV, which is similar to that of alkali metals, so that it can be suitably used as the electron injection layer 312.

It is also possible to use Zn _0.7 Mg _0.3 O, Zn _0.75 Si _0.25 O, or the like as the electron injection layer 312. These metal oxides have semiconductor properties and a small work function of 3.1 eV, allowing electron injection into the light emitting layer 314. These metal oxides also have a large band gap of 3.9 eV to 4.1 eV, allowing holes to be prevented from passing through the light emitting layer 314 and flowing into the electron transport layer 308. It is also possible to use a ternary metal oxide semiconductor material, in which two types of metal oxides, Zn _0.7 Mg _0.3 O and Zn _0.75 Si _0.25 O, are mixed in a ratio range of 1:4 to 1:10, as the electron injection layer 312.

Such an electron injection layer 312 is formed in the film forming apparatus 101. That is, a polycrystalline body of C12A7 electride is used as the sputtering target 124, and the film is formed in the first film forming chamber 108a. The electron injection layer 312 made of C12A7 electride is formed with a film thickness of 1 nm to 100 nm. The electron injection layer 312 made of C12A7 electride is formed as an amorphous thin film, but may have crystallinity. Since C12A7 electride is stable even in the air, it has the advantage that it is easy to handle and can be formed into a film by a sputtering method compared to alkali metal compounds such as lithium fluoride (LiF), lithium oxide (Li ₂ O), sodium chloride (NaCl), and potassium chloride (KCl) that have been conventionally used as electron injection layers.

The electron injection layer 312 can be formed by using a polycrystalline material such as Zn _0.7 Mg _0.3 O, Zn _0.75 Si _0.25 O, etc. as the sputtering target 124 and using a sputtering method using inductively coupled plasma. The electron injection layer 312 can be formed by using a polycrystalline material of a ternary metal oxide material in which Zn _0.7 Mg _0.3 O and Zn _0.75 Si _0.25 O are mixed in the range of 1:4 to 1:10 as the sputtering target 124 and performing sputtering film formation with a film formation device 100 using inductively coupled plasma. Although C12A7 electride is stable in the air, it is easily dissolved in water, so moisture-proof measures are required for storage and management when used as a target material. In contrast, a polycrystalline target material of a ternary metal oxide in which Zn _0.7 Mg _0.3 O and Zn _0.75 Si _0.25 O are mixed in the range of 1:4 to 1:10 is less soluble in water and is therefore easy to store and manage.

Since the resistivity _{of Zn0.7Mg0.3O} or _{Zn0.75Si0.25O} used as the electron injection layer 312 is very high, sputtering cannot be performed with a conventional DC magnetron sputtering device _. Although it is possible to use an AC dual magnetron sputtering device in which the sputtering target is divided into two and sputtering is performed alternately with each target using an AC power source, the discharge pressure during sputtering needs to be 0.3 Pa or less in order to increase the film density and the crystallization rate. However, when the substrate size is G8.5 (2500 mm x 2200 mm) or more, it becomes difficult to stably discharge while maintaining the uniformity within the surface at 0.3 Pa or less. In contrast, in the method using inductively coupled plasma as shown in this embodiment, it is possible to form a film by applying a negative pulse voltage to the sputtering target 124, and crystallization can be promoted and the film density can be increased even if the pressure during sputtering film formation is increased to around 1.3 Pa.

Before the electron injection layer 312 is formed in the first deposition chamber 108a, the substrate 200 on which the electron transport layer 308 has been formed may be degassed in the pretreatment chamber 104. By performing the pretreatment, impurities such as moisture that are taken in by the organic electroluminescence element 300 can be reduced.

After the electron injection layer 312 is formed in the first deposition chamber 108a, the substrate 200 is returned to a horizontal state by the platen mechanism 118 of the third transfer chamber 106c and transferred to the third deposition chamber 108c via the fourth transfer chamber 106d. In the third deposition chamber 108c, the light-emitting layer 314 is deposited by vacuum deposition (and/or electron beam deposition).

The light-emitting layer 314 is formed using a metal mask with through holes that correspond to the arrangement of the openings 311. The light-emitting layer 314 is produced by vacuum deposition using known materials that correspond to each emitted color. The thickness of the light-emitting layer 314 is set appropriately, but is formed to a thickness of, for example, 10 nm to 100 nm. When forming a white light-emitting layer as the light-emitting layer 314, the light-emitting layer 314 may be formed over the entire surface of the element formation region without using a metal mask.

After the light-emitting layer 314 is formed, the substrate 200 is transported to the fourth deposition chamber 108d via the fourth transfer chamber 106d, where the hole transport layer 316 and the hole injection layer 318 are formed. The hole transport layer 316 is formed by vacuum deposition (and/or electron beam deposition) using known materials such as arylamine compounds, amine compounds containing carbazole groups, and amine compounds containing fluorene derivatives. The hole injection layer 318 is formed by vacuum deposition (and/or electron beam deposition) using metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide, or phthalocyanine materials such as copper phthalocyanine. For example, the hole transport layer 316 is formed to a thickness of 10 nm to 500 nm, and the hole injection layer 318 is formed to a thickness of 1 nm to 100 nm.

In this embodiment, an example is shown in which the hole transport layer 316 and the hole injection layer 318 are formed in the same deposition chamber. However, this is not limited to this example, and the deposition apparatus 101 may have more deposition chambers, and the hole transport layer 316 and the hole injection layer 318 may be formed in different deposition chambers.

After the hole transport layer 316 and the hole injection layer 318 are formed, the substrate 200 is transported to the fourth deposition chamber 108d via the fourth transfer chamber 106d, where the second electrode (anode) 320 is formed. The second electrode (anode) 320 is formed of a metal film such as aluminum (Al), or a laminate of a transparent conductive film such as ITO or IZO and a metal film such as aluminum (Al). Such a second electrode (anode) 320 is produced by vacuum deposition (and/or electron beam deposition) in the fourth deposition chamber 108d.

As described above, the organic electroluminescence element 300 can be produced by the film-forming apparatus 101. The film-forming apparatus 101 has a chamber in which sputtering film formation by inductively coupled plasma is performed and a chamber in which film formation is performed by vacuum deposition (and/or electron beam deposition) connected via a transfer chamber 106, so that the electron injection layer 312, the light-emitting layer 314, the hole transport layer 316, the hole injection layer 318, and the second electrode (anode) 320 can be continuously deposited in a vacuum. By using the film-forming apparatus 101 having such a configuration, it is possible to produce an organic electroluminescence element 300 and a display panel equipped with the organic electroluminescence element 300 that are highly reproducible and reliable.

100: Film forming apparatus, 101: Film forming apparatus, 102: Load/unload chamber, 104: Pretreatment chamber, 106: Transfer chamber, 108: Film forming chamber, 109: Chamber wall, 110: Vacuum exhaust system, 111: Evaporation source, 112: Gas supply system, 114: Substrate stage, 115: High frequency discharge electrode, 116: Transfer robot, 118: Platen mechanism, 120: High frequency power supply, 122: AC power supply, 123: Pulse power supply, 124: Sputtering target, 126: Antenna for inductively coupled plasma generation, 127: Heater, 128: Through hole, 130: Backing plate, 131: Bonding material, 132: Target material, 134: Shield plate, 136: Insulating part, 138: Gas introduction tube, 140: Plasma diffusion prevention plate, 141: Adhesion prevention plate, 142: First surface, 143: Second surface, 144: First opening, 146: Insulating member, 147: Glass layer, 148: Antenna body for inductively coupled plasma generation, 150: Metal tube, 151: conductive layer, 152: capacitor, 153: O-ring, 154: second opening, 156: coil, 158: variable capacitor, 160: carrier tray, 162: pin, 164: lifting mechanism, 166: gas introduction tube, 168: high frequency discharge plasma, 170: mesh, 172: hollow tube, 174: conductive layer, 176: variable capacitor, 180: ceramic member, 200: substrate, 202: surface, 204: antenna connection region, 210: first insulating layer, 212: first conductive layer, 214: second conductive layer, 216: oxide semiconductor layer, 218: second insulating layer, 220: gate electrode, 230: transistor, 300: organic electroluminescence element, 302: carrier injection amount control electrode, 304: first insulating layer, 306: first electrode (cathode), 308: electron transport layer, 310: second insulating layer, 311: opening, 312: electron injection layer, 314: light emitting layer, 316: hole transport layer, 318: hole injection layer, 320: second electrode (anode)

Claims (16)

a deposition chamber in which a sputtering target is placed;
a plasma diffusion prevention plate covering the sputtering target and having an opening at a position overlapping with a surface of the sputtering target;
an antenna for generating inductively coupled plasma adjacent to the sputtering target and protruding into an area surrounded by the plasma diffusion prevention plate;
a gas introduction pipe arranged in an area surrounded by the plasma diffusion prevention plate and configured to introduce a gas into the deposition chamber;
an insulating member having a U-shaped groove shape, the insulating member being adjacent to the sputtering target in a region surrounded by the plasma diffusion prevention plate, protruding toward the inside of the deposition chamber, and separating an internal space of the deposition chamber from an atmospheric side;
an antenna that is adjacent to the sputtering target within a region surrounded by the plasma diffusion prevention plate, protrudes toward the inside of the film formation chamber, and is disposed on the atmospheric side of the insulating member;
The plasma diffusion prevention plate is made of a material having a secondary electron emission rate of greater than 1. 2. The film forming apparatus according to claim 1, wherein the plasma diffusion prevention plate is made of a magnesium alloy, a barium alloy, or a calcium alloy mainly containing aluminum, and has an anodized film formed on a surface thereof. The sputtering target has a rectangular shape in a plan view,
The film forming apparatus according to claim 1 , wherein the U-shaped insulating member and the antenna are disposed along a longitudinal direction of the sputtering target. 4. The film forming apparatus according to claim 1, wherein the antenna includes a first antenna disposed on one side of the sputtering target, and a second antenna disposed on the other side of the sputtering target. 5. The film forming apparatus according to claim 1, wherein a high frequency power and an AC voltage in the kilohertz range superimposed on the high frequency power are applied to the antenna. The sputtering target has a rectangular shape in a plan view,
2. The film forming apparatus according to claim 1, wherein the gas introduction pipe is disposed along a longitudinal direction of the sputtering target. the plasma diffusion prevention plate has a first surface parallel to a surface of the sputtering target and a second surface extending from the first surface toward a wall surface of the deposition chamber;
The film deposition apparatus according to claim 1 , wherein the opening is provided on the first surface, and a plurality of slit-shaped openings narrower than the opening are provided from the second surface to the first surface. The insulating member is made of quartz, alumina, yttria (Y ₂ O ₃ ), forsterite (Mg
₂ SiO ₄ ), and steatite (MgO.SiO ₂ ). the antenna includes a first metal tube, a second metal tube, and a capacitor that capacitively couples the first metal tube and the second metal tube,
2 . The film forming apparatus according to claim 1 , wherein the capacitor includes an insulating hollow tube into which the first metal tube and the second metal tube are fitted, and a conductive layer provided on the inside of the hollow tube. the antenna is an assembly of a plurality of antennas and is disposed on the atmospheric side of the insulating member;
The film deposition apparatus according to claim 1 , wherein the antenna assembly is not in contact with the insulating member. a transport tray for transporting a substrate within the deposition chamber;
A distance between the substrate mounted on the carrier tray and the first surface of the plasma diffusion prevention plate is
The film forming apparatus according to claim 7 , wherein the gap is narrower than the gap between the sputtering target and the plasma diffusion prevention plate. 2. The film formation apparatus according to claim 1, further comprising: a pretreatment chamber for performing a pretreatment of a substrate to be film-formed in said film formation chamber; and a transfer chamber connecting said film formation chamber and said pretreatment chamber. 13. The film formation apparatus of claim 12, wherein the pretreatment chamber includes insulating pins for lifting the substrate in a horizontal position, and first and second electrodes for generating inductively coupled plasma in an atmosphere of nitrogen gas, oxygen gas, or nitrous oxide gas on both the front and back sides of the substrate. The film forming apparatus according to claim 13, wherein the first electrode is disposed on the front surface side of the substrate. A chamber wall of the deposition chamber at a portion where the sputtering target is installed is
2. The film forming apparatus according to claim 1, which is formed of a ceramic member. a chamber wall of the deposition chamber at a portion where the sputtering target is placed;
2. The film forming apparatus according to claim 1, wherein the insulating member having a U-shaped groove is made of a ceramic material.

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