JP3028394B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus.

[0002]

2. Description of the Related Art As plasma sources of a plasma processing apparatus for processing a semiconductor wafer or a liquid crystal substrate for a liquid crystal display, an inducing means, for example, an inducing means for generating a plasma by applying a high frequency, for example, a radio frequency to a planar coil, JP-A-2-235332, "Plasma Processing Apparatus", JP-A-3-79025, "Apparatus for Generating Magnetically Coupled Planar Plasma and Method and Apparatus for Processing This Plasma Article" -29042
No. 8, "Plasma Reactor Using UHF / VHF Resonant Antenna Supply Source and Method Thereof", JP-A-5-2060
No. 72, entitled "Plasma Processing Apparatus Using Inductive RF Coupling and Its Method".

Next, the prior art described in these publications will be described with reference to FIG. FIG. 6 is a longitudinal sectional view of a conventional plasma processing apparatus. An object 103 is provided on a mounting table 102 provided in an airtight container 101. The wall surface of the container 101 facing the object 103 is formed of a dielectric 104.

Further, a guiding means 105, for example, a planar coil, is disposed outside the container 101 so as to face the object 103. The induction means 105 is configured to be applied with a high frequency, for example, a radio frequency voltage from a high frequency power supply 107 via a matching circuit 106. A gas supply port 10 is provided inside the container 101.
A predetermined gas is supplied from the gas supply frequency 109 via the power supply 8.

[0005] The container 10 is exhausted by an exhaust means 111 through an exhaust port 110 provided at the bottom of the container 101.
The inside of 1 is configured to be evacuated to a predetermined degree of vacuum. A gate valve 112 is provided on the side wall of the container 101.
Is provided, and the object 10 to be processed is
3 is configured to be carried in / out from the opening of the gate valve 112.

In the plasma processing apparatus configured as described above, the plasma 113 is mainly generated between the object 103 and the dielectric means 104, and the object is subjected to plasma processing.

[0007]

In the above-described plasma apparatus, a guiding means is arranged to face the surface of the object to be processed which is to be subjected to the plasma processing, and a space provided with the guiding means is provided. For other purposes, for example, when providing a gas supply shower head or light heating means, there is a problem that the space cannot be used freely.

Since the inducing means generates plasma by inductive coupling, if a component made of a conductive material is provided between the inducing means and the object to be processed, the inductive coupling is affected and the object to be processed is affected. There has been a problem that it is difficult to perform a uniform surface treatment.

More specifically, when the inducing means and the light heating means for heating the shower head and the object to be processed are simultaneously provided in a space facing the surface to be processed of the object to be processed, There is a problem that the processing results of the object to be processed are adversely affected by the materials and their positions constituting these.
In the prior art shown in FIG. 6, a processing gas for processing the object 103 is supplied to a gas supply port 1 by a gas supply unit 109.
08, the gas supply port 108 is arranged near the object 103, and if an effective gas supply for increasing the processing speed is to be performed, the material of the pipe 109 of the gas supply port 108, for example, There is a problem that the inductive coupling formed by the inducing means 5 is affected by stainless steel and cannot be approached.

[0010] It is an object of the present invention to provide a plasma processing apparatus in which the guiding means is moved from a space facing the surface to be processed of the object to be processed by the plasma generated by the guiding means to another space. It is in.

[0011]

According to the first aspect of the present invention, there is provided an induction means for generating a plasma in an airtight container, and an object to be processed by the plasma is provided between the induction means and the plasma. It is characterized by being provided. The invention according to claim 2 includes a derivative forming a part of the wall surface of the airtight container, an inducing means provided outside the container, a power supply for applying a high-frequency voltage to the inducing means, and a gas in the container. Gas supply means for supplying a gas, and an object to be processed by the plasma is provided in a space between the plasma in the container generated by the induction means and the induction means. . The invention according to claim 3, wherein a substrate to be processed provided in an airtight container, gas supply means for supplying gas into the container, and guiding means provided outside the container,
A plasma source for applying a high-frequency voltage to the inducing means to generate plasma for processing the surface (front surface) of the substrate to be processed, wherein the inducing means is provided on the back side of the substrate to be processed. It is characterized by being. The invention according to a fourth aspect is characterized in that the guiding means is a planar coil disposed to face the substrate to be processed. The invention according to claim 5 is characterized in that the guiding means is arranged to face the substrate to be processed via a dielectric window constituting a part of the wall surface of the container. The invention according to claim 6 is characterized in that the guiding means is a planar coil. The invention according to claim 7 is characterized in that the guiding means is a spiral coil or a spiral coil. The invention according to claim 8 is characterized in that the guiding means is a loop antenna. A ninth aspect of the present invention is characterized in that the guidance means has a plurality of loop antennas arranged in the same circle. A tenth aspect of the present invention is characterized in that the guidance means has a plurality of coils arranged side by side. The invention of claim 11 is
A position adjusting means is provided which can freely set a relative distance between the guiding means and the object to be processed. A twelfth aspect of the invention is characterized in that a magnetic field forming means for confining the plasma is provided outside the container.

[0012]

According to the plasma processing apparatus of the present invention, the guiding means can be eliminated from the opposing space on the surface to be processed by the plasma of the object to be processed. It can be used to provide a shower head or the like. Further, it is possible to provide a plasma processing apparatus capable of controlling the plasma generated by the inducing means through the object.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a first embodiment of the plasma processing apparatus of the present invention.

First, the configuration will be described. The airtight container 1 is made of aluminum, and its inner wall surface is polished and then an oxide film is formed. This oxide film is configured to prevent generation of dust from the aluminum, particularly heavy metal contamination, during processing of the processing target 2 in a vacuum atmosphere.

A gate valve 3 is provided on the side wall of the container 1 so as to be openable and closable.
It is configured to be carried into and placed inside. On the upper wall surface (ceiling) of the container, a shower head 5 provided with a gas supply port 4 arranged to face the object 2 is provided.

After the supply amount to the shower head 5 is adjusted by a processing gas mass flow controller 7 corresponding to the processing of the processing object 2, for example, a film forming process or an etching process, by a gas supply means 6, the shower head 5 is opened and closed. It is configured to be supplied via a possible valve 8.

The gas supply means 6 is configured to be able to supply a plurality of processing gases and an inert gas, for example, N ₂ gas, according to the processing content. The shower head 5 is provided with a multi-stage diffusion plate (not shown) therein, and after mixing the plurality of processing gases, a small hole, for example, 0.1 mm, is formed in an opening surface capable of covering the processing area of the processing target 2.
By providing a diameter of 1 to 3 mm at equal intervals, for example, 2 to 5 mm over the entire opening surface, it is configured such that a uniform gas can be supplied to the object to be processed.

On the bottom surface of the container 1, there is provided a dielectric material 9 constituting a part of the wall surface of the container 1, for example, quartz, synthetic quartz or fused quartz. The material of the dielectric 9 can be selected according to the processing temperature at which the processing target 2 is processed. Synthetic quartz is expensive, but is excellent in heat resistance and strength, and is desirable.

The size of the dielectric material 9 needs to be set according to the degree of vacuum in the container 1.
If it is about × 10 ⁻⁴ Torr, a thickness of 40 mm may be sufficient, and the outer diameter is desirably 10 to 40% or more larger than the outer size of the object 2 to be processed.

For example, when an 8-inch semiconductor wafer is selected as the object 2 to be processed, the outer size of the front dielectric 9 is 220 to 280 mm or more, and the liquid crystal substrate is 540 mm ×
If it is 640 mm square, the outer size of the dielectric 9 is
About 600mm x 700mm square to 760mm x 900m
Requires an external size of m square or more.

The object 2 is placed on the dielectric 9 inside the container 1. On the dielectric 9, a placing table made of a material such as ceramics or quartz is further provided. The object 2 may be mounted on a mounting table.

A guiding means 10 is provided opposite to the surface 16 to be processed of the object 2 and opposed to the surface of the container 1. Examples of the guiding means 10 include a planar spiral coil, a spiral coil, a one-turn coil, a plurality of coils arranged concentrically, a plurality of coils arranged in parallel, and a shape of the object 2 to be processed. Various antennas can be used according to the conditions.

The guiding means 10 is preferably made of a conductive material such as copper (Cu). As a more specific example, a copper plate having a thickness of 2 to 5 mm is punched into a spiral by pressing, or as another example, a copper pipe having an outer diameter of 5 mm and an inner diameter of 3 mm is bent into a spiral. A coil can be formed.

The external size of the guiding means 10 is at least larger than the external size of the object 2 to be processed.
This is desirable because the object 2 can be processed in a portion where the distribution of generated plasma is more uniform. For example, in the case of an 8-inch semiconductor wafer, the outer size of the guiding means 10 is 220% to 280% or more.
mm size or more.

The dielectric means 10 is configured such that a high frequency, for example, a radio frequency, for example, a voltage of 13.56 MHz, for example, is applied to the dielectric means 10 via a matching circuit 12 by a high frequency power supply 11 provided outside the container 1. ing.
The frequency of the high-frequency power supply 11 can be set to a higher frequency, for example, from 40 MHz to 60 MHz according to the processing process of the processing target 2. Specific examples of the dielectric means will be described later in detail. An exhaust port 13 is opened at the bottom of the container 1. The exhaust means 1 is discharged from the exhaust port 13 through the openable / closable valve 15.
It is configured to perform evacuation so that the inside of the chamber reaches and maintains a predetermined degree of vacuum. As described above, the plasma processing apparatus of the first embodiment is configured.

Next, the operation of the first embodiment will be described. The target object 2 is carried into the container 1 by the transfer means (not shown) via the gate valve 3 and placed thereon. When the gate valve 3 is closed and the inside of the container 1 is airtight, the inside of the container 1 is evacuated to a predetermined degree of vacuum, for example, 1 × 10 ⁻⁷ Torr by the exhaust means 14.

Next, a predetermined processing gas is uniformly supplied to the facing area of the object 2 through the shower head 5 by the gas supply means 6. Next, a high frequency, for example, a voltage of 13.56 MHz is applied to the inducing means 10 from the high frequency power supply 11, and the plasma 13 is generated in the facing area of the processing target 2 on the processing surface 16 side.

The distribution of the plasma 13 mainly depends on the configuration and shape of the guiding means 10, and the spread of the distribution depends on the degree of vacuum in the vessel. The degree of vacuum is 1 × 10 ^-4 Torr, 1 × 10 ^-5 Torr
Becomes Therefore, a wider plasma distribution is obtained. That is, when the inducing means 10 is a planar spiral coil, the plasma 13 having a substantially planar distribution as a whole is provided in the space inside the container 1 facing the planar spiral coil. Is raised. The distribution of the plasma 13 can be determined by measuring the distribution of the plasma 13 at a plurality of locations in the space in the container 1 with a probe for measuring the electron temperature of the plasma.

The distribution of the electron temperature obtained based on the probe measurement, that is, the distribution of the plasma,
Since the plasma processing apparatus of the first embodiment is configured so as to have a more uniform distribution in a range covering the surface 16 to be processed,
Can be uniformly processed over the surface 16 to be processed.

When the predetermined processing for the object 2 is completed, the supply of the voltage from the high-frequency power supply 11 is stopped, and the plasma is extinguished. At the same time, after the supply of the processing gas is stopped by the gas supply means 6, the residual gas in the container 1 by the exhaust means 14 is discharged out of the container 1. Next, the gas supply means 6
An inert gas, for example, N ₂ gas is supplied, and the inside of the container 1 is replaced with an N ₂ gas atmosphere.

Next, the valve 15 is closed, the inside of the container 1 is set at a positive pressure higher than the atmosphere by the N ₂ atmosphere, the gate valve 3 is opened, and the treated 21 The processing body 2 is unloaded from the container 1, and a series of processing by the plasma processing apparatus of the first embodiment ends.

According to the plasma processing apparatus of the first embodiment which operates as described above, the guiding means 10 is provided on the side opposite to the processing surface 16 of the processing object 2 so that the processing surface is opposed to the processing surface. We succeeded in eliminating guidance means from space.
Thus, the shower head 5 that covers the processing target surface 16 and can supply a uniform gas can be provided at a position facing the processing target surface 16 side. Since the shower head 5 is provided outside the space between the inducing means 10 and the plasma 13 generated by the inducing means 10, the inductive coupling by the inducing means 10 and the plasma 13 It is provided in a space that does not adversely affect the uniformity of distribution.

The embodiment in which the shower head 5 is provided in the space opposed to the surface 16 to be processed of the object 2 has been described above. Instead of the shower head 5, a plurality of gas supply ports 13 are used as nozzles. Even if provided, these nozzles are located outside the space between the inducing means 10 and the plasma 13, and therefore have a less adverse effect on the uniformity of the plasma 13 than the conventional configuration of FIG. 6. There is.

Next, a second embodiment of the plasma processing apparatus of the present invention will be described with reference to the drawings. FIG. 2 is a longitudinal sectional view of the plasma processing apparatus of the second embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals and description thereof will be omitted.

A mounting table 17 having a flat mounting surface made of quartz is provided on the dielectric material 9 in the center of the airtight container 1. The processing target 2 is configured to be mounted on the mounting table 17 with the processing target surface 16 facing upward. The processing object 1 is opposed to the processing object 2 and the processing surface 1
In the opposing space on the side opposite to the sixth side, the guiding means 10 is provided so as to be able to move up and down while maintaining the opposing posture. The guiding means 10 includes the processing surface 16 and the guiding means 1.
The distance H to 0 is provided to be freely settable. The lifting mechanism 18 is provided on the mounting table 1 on which the guiding means 10 is mounted.
9, a ball screw 20 rotatably coupled to the support of the mounting table 19, and a rotation drive mechanism 21 for rotating the ball screw 20 to adjust the distance H. A plurality of electromagnets 21 are provided on an outer peripheral portion of a side surface of the container.

A voltage is applied to these electromagnets from the DC power supply 22, and magnetic poles formed inside the container 1 between adjacent electromagnets surrounding the side wall of the container are alternately different, for example, N, S, N, S, N, S are arranged.

By the action of the magnetic field formed by the plurality of electromagnets 21, the surface 16 to be processed is
The plasma generated in the opposing region is confined toward the opposing region of the object 16, and the plasma density increases, so that the processing speed of the object 16 can be improved. Next, a plurality of openings 23 for lamps for irradiating light are provided on the upper wall surface (ceiling) of the container. A plurality of quartz windows 80 are provided above the openings 23, and the lamps 24 for optically heating the object to be processed 2 are provided with these quartz windows 8.
0 is provided. These lamps 24 are provided with a reflecting mirror 25 for reflecting light at the back.

The lamp 24 is supplied with a digital high-frequency voltage from a lamp control means 26 for supplying electric power. Since the lamp 24 directly irradiates and heats the object 2, the lamp 24 is configured to heat the object 2 to a processing temperature of about 600 ° C. in a short time, for example, 60 seconds. .

The temperature rise and the control of the heating are achieved by the lamp control means 26 by pulse width control for controlling the width of the ON time of the digital voltage. Further, an inert gas for preventing a gas supplied from the gas supply means 6 or a reaction product generated by the plasma processing from adhering to the surface of the lamp 24,
For example, after the flow rate of N ₂ gas or Ar gas is adjusted by a mass flow controller 28 from an inert gas supply source 27, the gas is supplied via an inert gas supply pipe 30 via an openable / closable valve 29. Have been. As described above, the plasma processing apparatus of the second embodiment is configured. According to the plasma processing apparatus of the second embodiment configured as described above, the distance H between the guiding means 10 and the processing surface 16 of the processing target 2 can be set by the lifting mechanism.
The distribution of the generated plasma 13 can be set to an optimum state in relation to the object 2. Generally, the distance H from the guiding means 10 to the surface 16 to be processed is 5 to 5.
In the range of 150 mm, the surface to be processed 16 can be processed by generating plasma. Further, when the distance H is reduced, the processing speed by plasma is improved, but depending on the content of the processing, for example, depending on the quality of the film formed during the film forming process,
An optimal distance can be set. Furthermore, in order to determine the thickness of the dielectric material 9 according to the degree of vacuum in the container 1, for example, if the thickness of the dielectric material 9 is 40 mm, the thickness of the mounting table 17 is adjusted by H can be set to a desired distance of 40 mm or more. The first and second described above
As a process suitable for the embodiment, for example, an a-Si film (amorphous silicon film) and a gate insulating film formed of a silicon nitride film are formed on a gate insulating film formed on a glass substrate in a process of manufacturing a liquid crystal substrate. Thin film transistor obtained by forming a film (Thin Film Transistor)
or). 13.56 MH as high frequency
z is applied to the inducing means to decompose a source gas such as SiH _4, and a silicon nitride film which is an amorphous thin film is formed at a substrate temperature of 250 to 350 ° C.

Next, the main part of the guiding means 10 used in the plasma processing apparatus described in the first and second embodiments will be described with reference to the drawings. FIG. 3 is a schematic diagram showing a spiral coil 52 having a rectangular outer shape provided as a substrate to be processed, facing a liquid crystal substrate glass plate 51 having a rectangular outer shape. The outer shape of the spiral coil 52 is a rectangle following the outer shape of the object to be processed. Further, the spiral coil 52
Is configured to be larger than the outer shape of the object 51, and the density of the generated plasma is low at the peripheral portion, so that a more uniform central region is wider than the object 51. Has helped.

FIG. 4 shows that the substrate to be processed is a semiconductor wafer 53.
In the case where the coil has a circular outer shape as described in (1), the coil constituting the induction means is formed into a spiral coil 5 having a circular shape following the outer shape.
FIG. As in FIG. 3, the spiral coil 5
4 is made larger than the outer diameter of the semiconductor wafer 53.

FIG. 5 shows that the guiding means, in which the substrate to be processed is arranged to face the semiconductor wafer 53 having a circular outer shape, comprises an inner one-turn coil 55 and an outer one-turn coil 5.
FIG. 6 is a schematic view showing that the plurality of coils are formed by a plurality of coils. Voltages are supplied to the inner side and the outer side by independent high-frequency power supplies, and the phases can be set to be shifted by an arbitrary angle. The outer size of the inner one-turn coil 55 is smaller than the outer size of the substrate 53 to be processed, and the outer one-turn coil 5
The outer size of 6 is larger than the outer shape of the substrate 53 to be processed.

With the above configuration, the distribution of the plasma generated by the inner one-turn coil 55 becomes coarse at the periphery and the processing speed is reduced by the outer one-turn coil 55. By supplementing with the coil 56 and adjusting the density of the plasma, the in-plane processing of the substrate to be processed can be performed more uniformly. Although the three different types of guiding means have been described above, these guiding means are not always arranged in a plane at a position facing the substrate to be processed. Away from the object to be processed, by taking in the deformation in the vertical direction from the plane that brings the outer peripheral part closer,
The processing result by the plasma can be more uniformly performed at the central portion and the peripheral portion of the object to be processed. It is needless to say that the formation of such a planar coil three-dimensionally in the vertical direction is a technique that can be easily implemented by the guiding means used in the present invention.

[0044]

According to the plasma processing apparatus of the present invention, the inducing means for generating plasma can be moved from the space facing the plasma processing surface of the object provided in the airtight container to another. The facing space can be used for other purposes. Further, the generation and control of the plasma can be performed by the inducing means provided in the opposing space opposite to the plasma processing surface.

According to the fourth aspect of the present invention, since a planar plasma can be generated, an in-plane uniform processing of an object to be processed such as a substrate can be performed.

According to a fifth aspect of the present invention, the dielectric can serve to form inductive coupling by the inducing means.

According to the seventh aspect of the present invention, a coil having a spiral or spiral shape corresponding to the shape of the surface to be processed of the object to be processed can be processed with high uniformity.

According to the eighth aspect of the present invention, the guiding means can be constituted by a simple loop, and the plasma density can be maintained.

According to the ninth aspect of the present invention, since each of the loop antennas can be independently controlled by varying the power, the position, and the frequency by the high frequency power supply, the center portion and the outer edge portion of the object to be processed can be controlled. This is effective for controlling the processing speed.

According to the tenth aspect of the present invention, it is possible to generate a plasma that covers the entire surface of the object to be processed having a large area.

According to the eleventh aspect of the present invention, the distribution of the generated plasma and the distance between the object to be processed are adjusted in accordance with the size of the object to be processed and the conditions of the plasma processing so as to achieve the optimum induction. The position of the means can be determined.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of a plasma processing apparatus of the present invention.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the plasma processing apparatus of the present invention.

FIG. 3 is a schematic view showing a first embodiment of an inducing means of the plasma processing apparatus of the present invention.

FIG. 4 is a schematic view showing a second embodiment of the guide means of the plasma processing apparatus of the present invention.

FIG. 5 is a schematic diagram showing a third embodiment of the guiding means of the plasma processing apparatus of the present invention.

FIG. 6 is a longitudinal sectional view showing an embodiment of a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Object to be processed 9 Dielectric 10 Induction means 11 High frequency power supply

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 H01L 21/205

Claims (12)

(57) [Claims] 1. A plasma processing apparatus, comprising: an inducing means for generating plasma in an airtight container; and an object to be processed by the plasma provided between the inducing means and the plasma. 2. A derivative constituting a part of a wall surface of an airtight container, an induction means provided outside the container, a power supply for applying a high-frequency voltage to the induction means, and a gas supply into the container. A plasma supply means for performing a process using the plasma in a space between the plasma in the container generated by the inducing means and the inducing means. apparatus. 3. A substrate to be processed provided in an airtight container, gas supply means for supplying gas into the container, induction means provided outside the container, and a high-frequency voltage applied to the induction means. A plasma source for generating a plasma for applying and processing the surface to be processed (front surface) of the substrate to be processed, wherein the inducing means is provided on the back side of the substrate to be processed. apparatus. 4. The plasma processing apparatus according to claim 3, wherein said guiding means is a planar coil arranged to face said substrate to be processed. 5. The container according to claim 3, wherein said guiding means is arranged to face said substrate through a dielectric window forming a part of a wall surface of said container. Plasma processing equipment. 6. The plasma processing apparatus according to claim 1, wherein said inducing means is a planar coil. 7. The plasma processing apparatus according to claim 1, wherein said inducing means is a spiral coil or a spiral coil. 8. The plasma processing apparatus according to claim 1, wherein said guiding means is a loop antenna. 9. The plasma processing apparatus according to claim 1, wherein said guiding means has a plurality of loop antennas arranged in the same circle. 10. The plasma processing apparatus according to claim 1, wherein said inducing means includes a plurality of coils arranged side by side. 11. The apparatus according to claim 1, further comprising a position adjusting means capable of freely setting a relative distance between said guiding means and said object to be processed. Item 4. The plasma processing apparatus according to Item 3. 12. The plasma processing apparatus according to claim 1, wherein a magnetic field forming means for confining the plasma is provided outside the container.