JP7740827B2 - Sputtering film formation apparatus and sputtering film formation method - Google Patents

Description

This disclosure relates to a sputtering deposition apparatus and a sputtering deposition method.

For example, the magnetron sputtering film formation device described in Patent Document 1 forms a high-density plasma using a DC electric field created by a DC voltage applied to the target material and a magnetic field from a magnet behind the target material, sputtering the target material and forming a film.

For example, the sputtering deposition apparatus described in Patent Document 2 uses inductively coupled plasma to sputter a target material and deposit a film. This sputtering deposition apparatus has an induction coil arranged to correspond to a dielectric plate, and also has a magnet on the backside of the target material. When high-frequency power is introduced into the induction coil, an induced electric field is formed in the processing space via the dielectric plate.

International Publication No. 2009/116430 JP 2012-209483 A

This disclosure provides technology that allows for efficient sputtering of target material.

According to one aspect of the present disclosure, there is provided a sputtering deposition apparatus comprising: a processing vessel having a mounting table for placing a substrate thereon; a metal window made of a non-magnetic metal facing the mounting table and having a first surface constituting a ceiling surface of the processing vessel; an inductively coupled antenna positioned away from a second surface of the metal window opposite the first surface of the metal window and generating plasma within the processing vessel; a high-frequency power supply connected to the inductively coupled antenna; one of a DC power supply, a DC pulse power supply, and an AC power supply connected to the metal window; and a gas supply unit for supplying a processing gas for generating the plasma into the processing vessel, wherein the metal window functions as a target material for performing sputtering processing on the substrate .

According to one aspect, the target material can be sputtered efficiently.

1 is a cross-sectional view showing a sputtering film formation apparatus according to an embodiment. FIG. 1 is a diagram for explaining generation of inductively coupled plasma using a metal window. FIG. 2 is a plan view of a metal window and an inductively coupled antenna according to the embodiment. FIG. 2 is a plan view of a metal window and an inductively coupled antenna according to the embodiment. 1A and 1B are diagrams showing an example of a vertically wound rectangular coil antenna according to an embodiment. FIG. 10 is a diagram showing experimental results of source power dependency in sputtering film formation according to the embodiment. 3A and 3B are diagrams for explaining sputtering of a target material according to an embodiment. 10A and 10B are diagrams showing experimental results of DC voltage dependency and plasma electron density in sputtering film formation according to an embodiment. 3A and 3B are diagrams for explaining a parallel magnetic field and sputtering by the sputtering film formation apparatus according to the embodiment. 3 is a flowchart showing a sputtering film formation process according to an embodiment.

The following describes embodiments of the present disclosure with reference to the drawings. In each drawing, identical components are designated by the same reference numerals, and duplicate descriptions may be omitted.

[Sputtering film formation device]
First, a sputtering film formation apparatus 10 according to one embodiment will be described. FIG. 1 is a cross-sectional view showing the sputtering film formation apparatus 10 according to the embodiment. The sputtering film formation apparatus 10 shown in FIG. 1 can be used to form films such as aluminum oxide (AlO) films and oxide semiconductors (IGZO) using plasma on a rectangular substrate, for example, a glass substrate for an FPD (hereinafter referred to as substrate G). Examples of FPDs include liquid crystal displays (LCDs), electroluminescence (EL) displays, and plasma display panels (PDPs). However, the substrate is not limited to a glass substrate for an FPD.

The sputtering deposition apparatus 10 has a rectangular, airtight main body container 1 made of a conductive material, such as aluminum whose inner wall surface has been anodized. This main body container 1 is assembled so that it can be disassembled, and is electrically grounded by a grounding wire 1a.

The main vessel 1 is divided into an antenna chamber 3 and a processing vessel 4 by a rectangular metal window 2 formed and insulated from the main vessel 1. The metal window 2 forms the ceiling wall of the processing vessel 4. The metal window 2 is made of, for example, a non-magnetic, conductive metal, such as aluminum or an alloy containing aluminum.

A support shelf 5 that protrudes into the inside of the main vessel 1 is provided between the side wall 3a of the antenna chamber 3 and the side wall 4a of the processing vessel 4. The support shelf 5 is made of a conductive material, preferably a metal such as aluminum.

The metal window 2 is composed of multiple divided windows 2a-2d that are electrically insulated from one another via insulating members 7. The divided windows 2a-2d are supported on a support shelf 5 via insulating members 7. The metal window 2 is suspended from the ceiling of the main container 1 by multiple suspenders (not shown). Note that Figure 1 shows a schematic representation of the divided configuration of the metal window 2, and does not depict the actual divided configuration. Various divided configurations of the metal window 2 will be described later.

Multiple gas supply holes 21a are formed in the support shelf 5. The gas supply unit 20 is connected to the multiple gas supply holes 21a via gas supply pipes 21. The gas supply unit 20 supplies a process gas containing a raw material gas for plasma generation. The process gas is introduced into the process vessel 4 from the multiple gas supply holes 21a via the gas supply pipes 21. A gas space (not shown) may be provided inside the metal window 2 and connected to the gas supply pipe 21 to supply gas.

In the antenna chamber 3 above the metal window 2, there is an antenna unit 40 having an inductively coupled antenna 13 that faces the metal window 2 and is arranged in a circular pattern around it. As will be described later, the inductively coupled antenna 13 is made of a conductive material, such as copper, and is spaced apart from the metal window 2 by a spacer (not shown) made of an insulating material.

The inductively coupled antenna 13 of the antenna unit 40 is connected to a first high-frequency power supply 18 via a power supply line 16 and a matching box 17. During plasma processing (sputtering film formation processing), high-frequency power (hereinafter also referred to as source power), for example, 13.56 MHz, is supplied to the inductively coupled antenna 13 via the power supply line 16 extending from the first high-frequency power supply 18. The inductive electric field formed by the inductively coupled antenna 13 induces a loop current in the partition windows 2a-2d of the metal window 2. This generates an inductive electric field within the processing vessel 4 via the loop current induced in the partition windows 2a-2d of the metal window 2. This inductive electric field converts the processing gas supplied from the gas supply hole 21a into plasma in the plasma generation space S directly below the metal window 2 within the processing vessel 4, generating inductively coupled plasma.

The metal window 2 has a first surface and a second surface. The lower surface 22a of the metal window 2 is the first surface, and the upper surface 22b of the metal window 2, which is the opposite surface of the first surface, is the second surface. The first surface constitutes the ceiling surface of the processing chamber 4. An inductively coupled antenna 13 is disposed on the second surface side, spaced apart from the metal window 2, and generates plasma within the processing chamber 4. A target material T is fixed to the lower surface 22a of the metal window 2 by indium brazing or by screwing, while maintaining electrical continuity with the metal window 2. Since the target material T is a consumable item, it is replaced when it is worn down to a thickness below a certain threshold, and a new target material T is fixed to the lower surface 22a of the metal window 2 by brazing or by screwing. The target material T is made of a material appropriate for the film to be formed. When forming an AlO film or an AlN film, the target material T may be made of aluminum. When forming a _SiO2 film or a SiN film, the target material T may be made of silicon. When forming an IGZO film, the target material T may be composed of indium (In), gallium (Ga), zinc (Zn), and oxygen (O).

A mounting table 23 facing the first surface is fixed to the bottom of the processing vessel 4 via an insulating member 24. The mounting table 23 is made of a conductive material, such as aluminum with an anodized surface, and a substrate G is placed on the mounting surface of the mounting table 23. The placed substrate G is attracted and held by an electrostatic chuck (not shown) provided on the mounting surface.

An insulating shield ring 25a is provided around the upper periphery of the mounting table 23, and an insulating ring 25b is provided around the periphery of the mounting table 23. Lifter pins 26 used when loading and unloading substrates G are inserted into the mounting table 23 via the bottom wall of the main container 1 and insulating member 24. The lifter pins 26 are raised and lowered by an elevation mechanism (not shown) provided outside the main container 1, allowing the transfer of substrates G when loading and unloading.

Furthermore, a temperature control mechanism consisting of a heating means such as a heater and a refrigerant flow path, as well as a temperature sensor (none of which are shown), are provided within the mounting table 23 to control the temperature of the substrate G. The piping and wiring for these mechanisms and components are all routed outside the main container 1 through openings 1b provided on the bottom surface of the main container 1 and in the insulating member 24.

The sidewall 4a of the processing vessel 4 is provided with a loading/unloading port 27a for loading and unloading the substrate G, and a gate valve 27 for opening and closing it. An exhaust device 30 including a vacuum pump and other components is connected to the bottom of the processing vessel 4 via an exhaust pipe 31. The exhaust device 30 evacuates the processing vessel 4, and a predetermined vacuum atmosphere (e.g., 10 mTorr (1.33 Pa)) is set and maintained within the processing vessel 4 during plasma processing.

A fine gap (not shown) that functions as a cooling space is formed on the backside of the substrate G placed on the mounting table 23, and a He gas flow path 32 is provided for supplying He gas as a heat transfer gas at a constant pressure. By supplying heat transfer gas to the backside of the substrate G in this way, it is possible to suppress temperature increases and temperature changes caused by the sputtering film formation process on the substrate G under vacuum.

The sputter deposition apparatus 10 further includes a control unit 100. The control unit 100 is made up of a computer and includes a CPU that controls each component of the plasma processing apparatus, an input device, an output device, a display device, and a storage device. The storage device includes a storage medium that stores parameters for various processes performed in the plasma processing apparatus and programs for controlling the processes performed in the sputter deposition apparatus 10, i.e., processing recipes. The CPU calls up a specific processing recipe stored in the storage medium and causes the plasma processing apparatus to perform a specific processing operation based on that processing recipe.

[Metal window]
Next, the metallic window 2 will be described in detail. DC pulse power supplies 62a and 62b are connected to the metallic window 2, and the DC pulse power supplies 62a and 62b (collectively referred to as DC pulse power supplies 62) apply a square-wave (pulse wave) DC voltage (hereinafter also referred to as DC pulse voltage) with a predetermined duty ratio to the metallic window 2. The frequency of the DC pulse voltage may be 5 kHz to 150 kHz. The DC pulse voltage has two values constituting a square wave, and the two values are controlled to be 0 or a negative DC voltage. Instead of the DC pulse power supply 62, a DC power supply or an AC power supply may be connected to the metallic window 2. When a DC power supply is connected to the metallic window 2, a negative DC voltage is applied to the metallic window 2. When an AC power supply is connected to the metallic window 2, the AC power supply applies an AC voltage of a predetermined frequency (e.g., 50 kHz) to the metallic window 2. As described above, the metal window 2 is electrically connected to either a DC power supply, a DC pulse power supply, or an AC power supply, and therefore is made of a conductive material. The metal window 2 is also made of a non-magnetic metal. An example of the non-magnetic metal is aluminum. In the following description, increasing (increasing) the DC voltage (DC pulse voltage) applied to the metal window 2 refers to increasing (increasing) the absolute value of the DC voltage (DC pulse voltage).

Low-pass filters (LPFs) 61 are provided between the metal window 2 and each of the DC pulse power supplies 62a and 62b to prevent the high-frequency power from the first high-frequency power supply 18 from propagating to the DC pulse power supplies 62a and 62b. This structure allows high-density plasma to be generated within the processing vessel 4 using the inductively coupled antenna 13 and the metal window 2, and applying a DC pulse voltage to the metal window 2 attracts ions in the high-density plasma into the metal window 2, enabling reactive sputtering.

FIG. 2 is a diagram illustrating the generation of inductively coupled plasma using a metal window 2. As shown in FIG. 2, a high-frequency current I _RF flowing through the inductively coupled antenna 13 generates an induced current on the upper surface of the metal window 2. Due to the skin effect, the induced current flows only on the surface of the metal window 2, but the metal window 2 is insulated from the support shelf 5 and the main vessel 1. Therefore, if the planar shape of the inductively coupled antenna 13 is linear, the induced current flowing on the upper surface of the metal window 2 flows to the side of the metal window 2, then flows to the lower surface of the metal window 2, and then returns to the upper surface of the metal window 2 via the side of the metal window 2, generating an eddy current I _ED . In this way, an eddy current I _ED is generated in the metal window 2, looping from the upper surface to the lower surface. Of this looping eddy current I _ED , the current flowing on the lower surface of the metal window 2 generates an induced electric field I _P within the processing vessel 4, and this induced electric field I _P generates plasma of the processing gas.

On the other hand, when the inductive coupling antenna 13 is provided so as to wrap around in the circumferential direction within the plane corresponding to the metal window 2, if a solid single plate is used as the metal window 2, no eddy current flows on the lower surface of the metal window 2 and no plasma is generated. In other words, the eddy current _IED generated on the upper surface of the metal window 2 by the inductive coupling antenna 13 only loops around the upper surface of the metal window 2, _and does not flow on the lower surface of the metal window 2. Therefore, the metal window 2 can be configured in various ways as described below so that an eddy current flows on the lower surface of the metal window 2 and a desired induced electric field is generated.

[Configuration of metal window]
In the first aspect, the metal window 2 is divided into a plurality of divided regions that are insulated from one another. This allows eddy current _IED to flow on the lower surface of the metal window 2. In other words, by dividing the metal window 2 into a plurality of regions that are insulated from one another, an induced current flows on the upper surface of each divided metal window 2 (split window) and reaches the side surface, generating a loop-shaped eddy current _IED that flows from the side surface to the lower surface, then flows back along the side surface and returns to the upper surface. For this reason, the metal window 2 is divided into a plurality of split windows. Below, several examples of dividing the metal window 2 and examples of the arrangement of the inductive coupling antenna 13 will be described.

Figure 3 is a plan view of the metal window 2 and inductive coupling antenna 13 according to an embodiment. The metal window 2 has a rectangular shape with long and short sides corresponding to the substrate G. In Figure 3(a), the inductive coupling antenna 13 has multiple antenna segments 131, 132, and 133, each consisting of a ring-shaped rectangular coil antenna, arranged around the metal window 2. The ring-shaped rectangular coil antennas constituting each of the multiple antenna segments 131, 132, and 133 may be formed into a frame shape by spirally winding a single antenna wire (not shown), or may be formed into a frame shape by spirally winding two or four antenna wires symmetrically. In this example, in order to generate a uniform induced electric field along the lower surface 22a of the metal window 2, the rectangular metal window 2 is divided approximately radially toward each corner of the metal window 2. This divides the metal window 2 into four divided windows 2a to 2d. The four divided windows 2a-2d are trapezoidal on the long sides and triangular on the short sides. These trapezoids and triangles are configured so that the height of the trapezoid with its base on the long sides is the same as the height of the triangle with its base on the short sides. The divided windows 2a-2d are insulated from each other via insulating member 7.

As an example of an inductively coupled antenna 13, multiple antenna segments each consisting of a circular rectangular coil antenna are arranged.

In Figure 3(b), as shown in Figure 1, two DC pulse power supplies 62a and 62b are provided. DC pulse power supply 62a is connected to partition windows 2a and 2b and supplies a DC pulse voltage to partition windows 2a and 2b. DC pulse power supply 62b is connected to partition windows 2c and 2d and supplies a DC pulse voltage to partition windows 2c and 2d. Note that the low-pass filter 61 is not shown in Figures 3(b) and (c).

In Figure 3(c), a DC pulse power supply 62 is connected to the partition windows 2a-2d and supplies a DC pulse voltage to the partition windows 2a-2d. For example, if the external plasma is weak, the duty of the DC voltage applied to the partition windows 2c and 2d can be made greater than the duty of the DC voltage applied to the partition windows 2a and 2b (i.e., the time for which the negative DC voltage is applied is lengthened), thereby achieving a more uniform in-plane distribution of the film formation. This makes it possible to change the in-plane distribution of ion attraction in the plasma depending on the area of the partition windows. In this case, only one DC pulse power supply 62 is required, reducing the number of DC pulse power supplies.

Figure 4 is a plan view of the metal window 2 and inductive coupling antenna 13 according to the embodiment, and is another example of Figure 3. In this example, the metal window 2 is divided into six rectangular partition windows 2e to 2j. The partition windows 2e to 2j are connected to one of DC pulse power supplies 62c, 62d, and 62e via a low-pass filter 61. DC pulse power supply 62c is connected to partition windows 2e and 2f and supplies a DC pulse voltage to partition windows 2e and 2f. DC pulse power supply 62d is connected to partition windows 2g and 2h and supplies a DC pulse voltage to partition windows 2g and 2h. DC pulse power supply 62e is connected to partition windows 2i and 2j and supplies a DC pulse voltage to partition windows 2i and 2j.

The inductively coupled antenna 13 may consist of only a parallel antenna, as shown in Figure 4. The parallel antenna generates an inductive electric field that contributes to plasma generation and has a rectangular region formed facing the metal window 2 and facing the substrate G. These rectangular regions are divided into linear or grid-like plasma control regions. Antenna segments 134 that form part of the rectangular region are then arranged in each of the divided regions, and the antenna wires of the multiple antenna segments 134 are all parallel, forming a multi-divided parallel antenna.

As shown in FIG. 5, the antenna segment 134 in FIG. 4 is composed of a vertically wound rectangular coil antenna formed by spirally winding an antenna wire 135 made of a conductive material, such as copper, in a direction intersecting the substrate G (metal window 2), e.g., a direction perpendicular to the substrate G (metal window 2). High-frequency power is supplied to each vertically wound rectangular coil antenna from a first high-frequency power source 18.

In Figure 4, five antenna segments 134 are arranged across the two divided windows 2e and 2f in the longitudinal direction of the divided windows 2e and 2f. Similarly, five antenna segments 134 are arranged across the two divided windows 2g and 2h, and five antenna segments 134 are arranged across the two divided windows 2i and 2j.

For the vertically wound rectangular coil antenna, the antenna segments 134 are not limited to being arranged linearly in the longitudinal direction of each partition window as shown in Figure 4, but may also be arranged in a grid pattern. For example, the antenna segments 134 may be divided into a four-part type (two segments vertically and two segments horizontally), a nine-part type (three segments vertically and three segments horizontally), a 25-part type (five segments vertically and five segments horizontally), or even more, and a vertically wound rectangular coil antenna may be arranged in a grid pattern in each partition window.

In this way, antenna segments 134 consisting of vertically wound rectangular coil antennas are arranged in a linear or grid pattern, so that the direction of the induced electric field (high-frequency current) of all antenna segments 134 is the same. This eliminates areas where the induced electric fields cancel each other out, as occurs when annular rectangular coil antennas are arranged in a row. This results in better efficiency and improved plasma uniformity compared to when annular rectangular coil antennas are arranged in a row.

In the area of the metal window 2 corresponding to the inductively coupled antenna 13, the relationship between the number of divisions of the metal window 2 and the number of divisions of the inductively coupled antenna 13 (number of antenna segments) is arbitrary. However, if a bipolar DC pulse power supply is used as the DC pulse power supply, the number of divisions of the metal window must be an even number.

In the sputtering deposition apparatus 10 described above, the metal window 2 functions to mediate the induced electric field generated by the inductively coupled antenna 13 and generate plasma within the processing chamber 4. In addition, the metal window 2 functions to attract ions to the target material T for performing sputtering deposition processing on the substrate G.

This structure uses the inductively coupled antenna 13 and metal window 2 to generate high-density plasma within the processing vessel 4, and applying a DC pulse voltage to the metal window 2 attracts ions, enabling reactive sputtering using the high-density plasma. Sputtered particles released from the target material T by sputtering are deposited on the substrate G, making it possible to form films such as AlO, AlN, SiO, SiN, TiN, and IGZO.

Plasma is generated by an electromagnetic field created by supplying source power to the inductively coupled antenna 13. The target is sputtered by applying a DC pulse voltage to the metal window 2 to which the target material T is attached, thereby attracting ions. Therefore, the sputtering deposition apparatus 10 disclosed herein makes it possible to independently control plasma generation and ion attraction. Furthermore, while the magnetic field and DC electric field generated by the inductively coupled antenna 13 increase the plasma density, the magnetic field generated by the inductively coupled antenna 13 is an alternating magnetic field, which prevents the plasma from becoming biased as occurs with a static magnetic field and a DC electric field, resulting in the advantage of uniform sputtering of the target material.

The metal window 2 itself may also be used as the target material. Furthermore, although the DC voltage applied to the target material is described in this disclosure as a DC pulse voltage, it is not limited to this and may be a continuous DC voltage or an AC voltage. The inductively coupled antenna 13 may be configured with multiple antenna segments made of vertically wound rectangular coil antennas arranged in a linear or lattice pattern. The inductively coupled antenna 13 may be configured with multiple concentrically arranged annular rectangular coil antennas, or may be configured by combining a vertically wound rectangular coil antenna and an annular rectangular coil antenna.

The four effects of the sputtering deposition apparatus 10 of the present disclosure are explained below in order. The four effects are a high deposition rate due to high-density plasma (Effect 1), independent control of source power and DC voltage (Effect 2), deposition of IGZO films and other films with few defects (Effect 3), and sputtering effect due to a parallel magnetic field (Effect 4). The metal window 2 and inductively coupled antenna 13 were evaluated using the configuration shown in Figure 3.

[Effect 1: High film deposition rate due to high-density plasma]
By applying a DC pulse voltage to the metal window 2 to generate a DC electric field, a high film formation rate can be achieved by densifying the plasma with the DC electric field and the alternating magnetic field generated by the inductively coupled antenna 13. An experiment was conducted under the following process conditions using the sputtering processing apparatus 10 shown in Figure 1.

<Process conditions>
Gap from metal window to mounting table: 50 mm
Pressure inside the processing chamber: 5 mT (0.67 Pa)
Gas: Argon (Ar) gas, oxygen (O ₂ ) gas 50/50 sccm
Target material: Aluminum DC pulse voltage: -500V 50kHz Duty=50%
The target material was sputtered under the above conditions using plasma generated from a mixed gas of argon and oxygen, and a transparent AlO film was formed. The results are shown in Fig. 6. Fig. 6 is a diagram showing the experimental results of the source power dependency in sputtering film formation according to the embodiment.

The horizontal axis of Figure 6 represents the source power from the first high-frequency power supply 18, the vertical axis (left) represents the deposition rate (DR) of the AlO film, and the vertical axis (right) represents the refractive index (RI) of the AlO film. This shows that by supplying source power to the inductively coupled antenna 13 and applying a DC pulse voltage to the metal window 2, the plasma can be made denser, thereby increasing the deposition rate.

Increasing the source power also enabled the generation of higher density plasma, further improving the deposition rate (DR) and refractive index (RI) of the AlO film. Furthermore, the ratio of the side film thickness to the bottom film thickness of the AlO film formed on the stepped portion of substrate G was 1.00, 1.00, and 0.95 when the source power was 1000 W, 3000 W, and 5000 W, respectively. In other words, the coverage of the AlO film was good regardless of the magnitude of the source power. From the above, it was found that the sputter deposition apparatus 10 disclosed herein can improve the deposition rate and refractive index, and can deposit a dense AlO film with good coverage by sputtering.

The reason why a film with good coverage can be formed by sputtering will be explained with reference to Fig. 7. Fig. 7 is a diagram for explaining sputtering of a target material T in a sputtering film formation apparatus 10 according to an embodiment. When a negative DC voltage is applied to the metal window 2, ions in a plasma formed from argon gas or the like, such as argon ions (Ar ⁺ ), are attracted to the metal window 2 and collide with the target material T, causing Al ions (Al ⁺ ) to be emitted as sputter particles from the target material T formed from aluminum.

Furthermore, the high-density plasma generated by the supply of source power promotes oxidation and nitridation of the film, allowing the deposition of a dense AlO film. In the inductively coupled antenna 13 to which source power is supplied, a parallel magnetic field B is generated due to the shapes of the antenna segments 131 to 134 shown in Figures 3 to 5. This causes the Lorentz force (F = qv x B) to be applied, and Al ions (Al ⁺ ) are emitted at a high angle. This allows the deposition of an AlO film with good coverage by sputtering.

[Effect 2: Independent control of source power and DC voltage]
In the sputtering deposition apparatus 10, the application of a DC pulse voltage to the metal window 2 and the supply of a plasma source to the inductively coupled antenna 13 can be controlled independently. This makes it possible to deposit a film with few defects. An experiment was conducted using the sputtering processing apparatus 10 shown in Figure 1 under the following process conditions.

<Process conditions>
Gap from metal window to mounting table: 50 mm
Pressure inside the processing chamber: 5 mT (0.67 Pa)
Gas: Argon (Ar) gas, oxygen (O ₂ ) gas 50/50 sccm
Target material: Aluminum Source power: 3kW
DC pulse voltage variable 50kHz Duty=50%
The target material T was sputtered under the above conditions with plasma from a mixed gas of argon and oxygen to form an AlO film, and the results are shown in Fig. 8. Fig. 8 is a diagram showing experimental results of the DC voltage dependency and plasma electron density in sputtering film formation according to the embodiment.

The horizontal axis of Figure 8(a) represents the DC pulse voltage (DC), the vertical axis (left) represents the deposition rate (DR) of the AlO film, and the vertical axis (right) represents the refractive index (RI) of the AlO film. This shows that increasing the DC pulse voltage applied to the metal window 2 increases the probability that ions in the plasma, such as argon ions, will collide with the target material T, thereby increasing the sputtering force and increasing the deposition rate (DR). Meanwhile, the refractive index (RI) was maintained even when the DC pulse voltage was increased.

8(b), the horizontal axis represents the source power, and the vertical axis represents the plasma electron density (Ne density [number/ ^cm3 ]). Comparing line A when the DC pulse voltage is 0 V with line B when the DC pulse voltage is -300 V, it is found that the plasma electron density Ne is hardly affected by the value of the DC pulse voltage. In other words, it was found that the plasma electron density Ne depends on the source power, but not on the DC pulse voltage.

From the above, it has been proven that by independently controlling the application of a DC pulse voltage to the metal window 2 and the application of a plasma source to the inductively coupled antenna 13, it is possible to generate high-density plasma while depositing insulating films and IGZO films with few defects.

[Effect 3: Film formation with fewer defects]
For example, increasing the DC voltage applied to the metal window 2 can strongly attract ions in the plasma to the target material T. This increases the amount of sputtered particles emitted from the target material T, thereby increasing the film formation rate. On the other hand, increasing the DC voltage applied to the metal window 2 also increases the energy of the emitted sputtered particles, which can impact the film strongly, potentially causing defects in the film. The sputtering film formation apparatus 10 disclosed herein allows for independent control of the DC voltage and source power. Therefore, for example, to form an IGZO film with fewer defects, the DC voltage applied to the metal window 2 can be reduced and the source power can be increased to, for example, approximately 5000 W. This allows for generating high-density plasma to increase the film formation rate while controlling the DC voltage to weaken the attraction of ions in the plasma, thereby forming an IGZO film with fewer defects.

[Effect 4: Sputtering effect due to parallel magnetic field]
9A and 9B are diagrams illustrating the parallel magnetic field formed below the metal window 2 of the sputtering deposition apparatus 10 according to the embodiment and sputtering. Fig. 9A shows the parallel magnetic field B1 below the metal window 2 (target material T) during sputtering by the sputtering deposition apparatus 10 according to the embodiment, and Fig. 9B shows the magnetic field B2 below the metal window 2 (target material T) during sputtering by the magnetron sputtering apparatus according to the reference example.

In the magnetron sputtering deposition apparatus of the reference example shown in FIG. 9( b), a high-density plasma is generated by a DC electric field E generated by a DC voltage applied to the target material T and a magnetic field B2 generated by a magnet 91 behind the target material T, thereby sputtering the target material T and forming a film. In this sputtering deposition, the magnetic field B2 encloses electrons in the plasma, generating a high-density plasma and increasing the deposition rate (sputtering rate). However, the magnetic field B2 between the north and south magnets 91 biases the sputtering area of the target material T, causing the target material T between the magnets 91 to be scraped in a ring shape . As a result, the consumption of the target material T between the magnets 91 is higher than the consumption of the target material T below the magnets 91. Uneven use of the target material T leads to earlier replacement times and poor utilization of the target material T. Furthermore, the portions of the target material T below the magnets 91 where the target material T cannot be scraped are prone to accumulation of reaction by-products and other substances, which can become a source of particles.

In contrast, the sputter deposition apparatus 10 of the present disclosure uses multiple antenna segments of the inductively coupled antenna 13, and the antenna wires facing the metal window 2 are arranged in a ring shape parallel to the metal window 2, or all of the antenna wires facing the metal window 2 are arranged in parallel.

As a result, as shown in Figure 9(a), a wide parallel magnetic field B1 is formed in the horizontal direction below the target material T. Therefore, in the sputtering deposition apparatus 10, there are no locations where the magnetic field is locally strong, as in the reference example shown in Figure 9(b). As a result, the target material T is uniformly abraded by the DC electric field E caused by the DC voltage applied to the metal window 2 and the wide parallel magnetic field B1 formed below the target material T, enabling uniform deposition and the deposition of a film with good coverage. Because the target material T is abraded uniformly, the utilization efficiency of the target material T is high, and the life of the target material T can be extended.

[Sputtering film formation method]
Finally, a sputtering deposition method performed in the sputtering deposition apparatus 10 of the present disclosure will be described with reference to Fig. 10. Fig. 10 is a flowchart showing a sputtering deposition process according to the embodiment. The sputtering deposition process is controlled by the control unit 100 and performed by the sputtering deposition apparatus 10.

When this process begins, in step S1, the control unit 100 opens the gate valve 27, loads the substrate G through the loading/unloading port 27a, and places it on the mounting table 23. This completes preparation of the substrate G.

Next, in step S3, the control unit 100 supplies processing gas from the gas supply unit 20 into the processing vessel 4. Next, in step S5, the control unit 100 supplies high-frequency power from the first high-frequency power supply 18 to the inductively coupled antenna 13 to generate plasma in the processing vessel 4.

Next, in step S7, the control unit 100 applies a DC pulse voltage from the DC pulse power supply 62 to the metal window 2, attracting ions toward the metal window 2. Next, in step S9, the target material T is sputtered by the ions, and the sputtered particles emitted from the target material T are deposited on the substrate G. This forms a desired film, such as an AlO film, on the substrate.

According to the above sputtering deposition method, a high-density plasma can be generated using the sputtering deposition apparatus 10 of the present disclosure, and a desired film such as an AlO film can be deposited by reactive sputtering. Furthermore, by independently controlling the source power supplied to the inductively coupled antenna 13 from the first high-frequency power supply 18 and the DC pulse voltage applied to the metal window 2 from the DC pulse power supply 62, a desired film such as an IGZO film with high mobility and reliability can be deposited.

As described above, the sputtering deposition apparatus and sputtering deposition method of this embodiment generate high-density plasma by applying a DC pulse voltage to the metal window, allowing the target material T to be sputtered efficiently and increasing the deposition rate.

The sputter deposition apparatus and sputter deposition method according to the disclosed embodiments should be considered in all respects as illustrative and not restrictive. The embodiments may be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above multiple embodiments may be configured differently and may be combined within the scope of the appended claims.

10 Sputtering film formation apparatus 1 Main body vessel 2 Metal windows 2a, 2b, 2c, 2d Partition window 3 Antenna chamber 4 Processing vessel 13 Inductively coupled antenna 18 First high frequency power supply 20 Gas supply part 22a Lower surface of metal window 22b Upper surface of metal window 23 Mounting table 62 DC pulse power supply T Target material

Claims (9)

a processing vessel having a stage on which a substrate is placed;
a metal window made of a non-magnetic metal, the metal window having a first surface facing the mounting table and constituting a ceiling surface of the processing chamber;
an inductively coupled antenna disposed apart from a second surface of the metal window opposite to the first surface of the metal window, the inductively coupled antenna generating plasma in the processing chamber;
a high frequency power source connected to the inductively coupled antenna;
any one of a DC power supply, a DC pulse power supply, and an AC power supply connected to the metal window;
a gas supply unit that supplies a processing gas for generating the plasma into the processing chamber;
and
The metal window functions as a target material for performing sputtering processing on the substrate . the metal window has a function of mediating an induced electric field generated by the inductively coupled antenna to generate the plasma in the processing chamber.
The sputtering film forming apparatus according to claim 1 . a processing vessel having a stage on which a substrate is placed;
a metal window made of a non-magnetic metal, the metal window having a first surface facing the mounting table and constituting a ceiling surface of the processing chamber;
an inductively coupled antenna disposed apart from a second surface of the metal window opposite to the first surface of the metal window, the inductively coupled antenna generating plasma in the processing chamber;
a target material provided on the first surface;
a high frequency power source connected to the inductively coupled antenna;
any one of a DC power supply, a DC pulse power supply, and an AC power supply connected to the metal window;
a gas supply unit that supplies a processing gas for generating the plasma into the processing chamber;
A sputtering film forming apparatus having the same. The metal window is composed of a plurality of divided windows that are electrically insulated from each other.
The sputtering film forming apparatus according to any one of claims 1 to 3. The inductively coupled antenna has a plurality of antenna segments arranged therein.
The sputtering film forming apparatus according to any one of claims 1 to 4. The inductively coupled antenna has a plurality of antenna segments, each of which is an annular rectangular coil antenna, arranged concentrically.
The sputtering film forming apparatus according to claim 5 . In the inductively coupled antenna, a plurality of the antenna segments, each of which is a vertically wound rectangular coil antenna, are arranged in a lattice or linear pattern, and antenna wires at the bottoms of the vertically wound rectangular coil antennas constituting the plurality of antenna segments are arranged in parallel to each other.
The sputtering film forming apparatus according to claim 5 . The non-magnetic metal is aluminum.
The sputtering film forming apparatus according to any one of claims 1 to 7. A sputtering deposition method performed in the sputtering deposition apparatus according to any one of claims 1 to 8,
placing the substrate on the mounting table;
supplying a processing gas into the processing vessel from the gas supply unit;
supplying high frequency power from the high frequency power supply to the inductively coupled antenna to generate the plasma in the processing chamber;
applying a DC voltage, a DC pulse voltage or an AC voltage from a DC power supply, a DC pulse power supply or an AC power supply connected to the metal window to attract ions from the plasma into the metal window;
depositing sputter particles sputtered by the ions on the substrate;
A sputtering film formation method comprising: