JP2006173372A - Plasma source, surface wave excitation plasma cvd device equipped therewith and depositing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface wave excitation plasma CVD device in which, even if a concentration distribution of material gas is non-uniform, a thin film of a uniform film thickness and film quality can be formed. <P>SOLUTION: The surface wave excitation plasma CVD device 100 comprises a chamber 1, dielectric blocks 4a to 4d, an exhaust pipe 5, a substrate stage 6, a material gas introducing system 7, a discharge gas introducing system 8 and a plasma source 10. The plasma source 10 comprises four microwave waveguides 2a to 2d, and four sets of microwave generators 3a to 3d connected electrically to the microwave waveguides, respectively. These four pairs are plasma source elementary substances 10a to 10d, and the assembled plasma source elementary substances 10a to 10d constitute a set of plasma source 10. Microwave power generated by the plasma source elementary substances 10a to 10d is changed in accordance with the concentration distribution of material gas G1 introduced into the chamber 1 by the material gas introducing system 7, whereby the thin film of the uniform film thickness and film quality is formed on a substrate S of a large area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface wave excited plasma CVD apparatus that processes a substrate to be processed using surface wave excited plasma.

  As a plasma processing apparatus capable of generating high-density plasma, an apparatus using surface wave excitation plasma is known. This device introduces microwaves propagating in a waveguide into a plasma generation chamber through a dielectric window (microwave introduction window), and a medium gas (process gas) in the plasma generation chamber by surface waves generated on the surface of the dielectric window. ) To generate surface wave excitation plasma. Conventionally, an apparatus has been known in which three waveguides are arranged in parallel on the upper surface of a plasma generation chamber, and a microwave oscillator is connected to each of the three waveguides to generate a large plasma uniformly. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 10-22098 (5th page, FIG. 2)

  In a surface wave excitation plasma CVD apparatus, it is necessary to introduce both a process gas for generating high-density plasma and a material gas containing a constituent element of a thin film into a film forming chamber. Usually, a dielectric window is disposed above the film forming chamber, and the material gas is introduced from the side surface of the film forming chamber. Therefore, the concentration distribution of the material gas tends to be nonuniform at the outer peripheral portion and the central portion of the dielectric window. In the apparatus of Patent Document 1 described above, even if a uniform plasma having a large area can be generated, the concentration distribution of the material gas is different, so the amount of component elements separated by the plasma differs depending on the location of the plasma. There is a problem that a uniform film thickness cannot be obtained with respect to this substrate.

(1) A plasma source according to claim 1 of the present invention is provided with a plurality of microwave waveguides arranged in parallel along the direction of propagation of microwaves, and for each of the plurality of microwave waveguides. And a plurality of microwave generators that output microwaves to the wave waveguide, wherein the plurality of microwave generators are capable of independently changing the power of the microwaves.
(2) A surface wave excitation plasma CVD apparatus according to a second aspect of the present invention is the plasma source according to the first aspect, and a surface wave is formed by introducing a microwave from the plasma source, and the surface wave energy is generated in the film forming chamber. It comprises a dielectric member for generating plasma, a material gas introducing means for introducing a material gas into the film forming chamber, and a discharge gas introducing means for introducing a discharge gas into the film forming chamber.
(3) The invention according to claim 3 is the surface wave excitation plasma CVD apparatus according to claim 2, wherein the dielectric member is a dielectric block divided into a plurality corresponding to a plurality of microwave waveguides. A metal plate that reflects surface waves formed on each of the dielectric blocks is disposed at the boundary of the body block.
(4) The invention according to claim 4 is a method of forming a film using the surface wave excitation plasma CVD apparatus according to claim 2 or 3, wherein the material gas is in accordance with the concentration distribution of the material gas in the film forming chamber. The film is characterized in that the microwave power is increased in the region where the concentration is high and the microwave power is decreased in the region where the concentration of the material gas is low.

  According to the present invention, a plurality of sets of microwave waveguides and microwave generators are provided, and the microwave power of each microwave generator is made variable independently, so that the concentration distribution of the material gas is not uniform. However, a thin film having a uniform thickness can be formed.

  Hereinafter, a surface wave plasma CVD apparatus (hereinafter abbreviated as SWP-CVD apparatus) according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram schematically showing an outline of a SWP-CVD apparatus according to an embodiment of the present invention, and represents directions in three-dimensional orthogonal coordinates.

  Referring to FIG. 1, the SWP-CVD apparatus 100 includes a chamber 1, dielectric blocks 4 a to 4 d, an exhaust pipe 5, a substrate stage 6, a material gas introduction system 7, a discharge gas introduction system 8, and a plasma source 10. The chamber 1 is a sealed container for forming a film on the surface of the substrate S held on the substrate stage 6 by using the plasma P generated in the internal space.

  The configuration of the plasma source 10 will be described. All of the four microwave waveguides 2 a to 2 d are waveguides having the same size, shape, standard, etc., and are placed on the upper side of the chamber 1 in parallel at substantially equal intervals. The four microwave generators 3a to 3d have the same dimensions, shapes, and standards, and are electrically connected to the four microwave waveguides 2a to 2d, respectively. In other words, the microwave waveguides 2a to 2d and the microwave generators 3a to 3d make a pair, and these four pairs are the plasma source units 10a to 10d, and the plasma source units 10a to 10d are assembled to form one unit. The plasma source 10 is configured. Note that FIG. 1 only schematically shows the connection state between the microwave waveguides 2a to 2d and the microwave generators 3a to 3d, and the positional relationship will be described later with reference to FIG.

  Each of the four dielectric blocks 4a to 4d is a block having the same size, shape, material, etc., and forms an airtight space in the chamber 1 in contact with the bottom plates of the microwave waveguides 2a to 2d, respectively. It is attached to the chamber 1. The four dielectric blocks 4a to 4d are provided at positions corresponding to the four microwave waveguides 2a to 2d, respectively. The exhaust pipe 5 piped on the lower surface of the chamber 1 is connected to a vacuum pump (not shown). The substrate stage 6 is configured to be movable up and down by a lifting mechanism (not shown) so that the distance from the dielectric blocks 4a to 4d is variable.

The material gas introduction system 7 introduces a material gas G1 containing a component element of a thin film to be formed into the chamber 1. That is, the material gas G1 is released from the shower head 7a from the outer peripheral side and the center of the chamber 1 in a direction substantially parallel to the lower surfaces of the dielectric blocks 4a to 4d (y direction). The material gas G1 is, for example, SiH ₄ , NH ₃ , TEOS (Tetra Ethyl Ortho-Silicate: Si (OC ₂ H ₃ ) ₄ ), or the like.

The discharge gas introduction system 8 introduces a discharge gas G2 for generating plasma P into the chamber 1. That is, the discharge gas G2 is discharged downward (−z direction) from the upper part of the chamber 1 through a plurality of gas ejection ports 8a that vertically penetrate the dielectric blocks 4a to 4d. The discharge gas G2 is a gas that is a raw material for reactive active species such as N ₂ , O ₂ , and H ₂ and a rare gas such as Ar.

The structure and arrangement of the plasma source 10 and the dielectric blocks 4a to 4d will be described with reference to FIGS.
FIG. 2 is a longitudinal sectional view illustrating details of the SWP-CVD apparatus according to the embodiment of the present invention. FIG. 3A shows a cross section taken along the line II in FIG. 2, and is a view in which the microwave waveguides 2a to 2d are cut along the xy plane. FIG. 3B is a cross-sectional view taken along the line II-II in FIG. 2, and is a diagram in which the dielectric blocks 4a to 4d are cut along the xy plane. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and directions are represented by three-dimensional orthogonal coordinates.

  The plasma source unit 10a will be described with reference to FIGS. 2 and 3A. The microwave waveguide 2a extends in the x direction, and the x direction is the traveling direction of the microwave M. A plurality of slot antennas 21 are provided in two rows along the x direction on the bottom plate of the microwave waveguide 2a. The microwave generator 3a includes a high voltage power source 11a and a microwave oscillator 12a, and is configured to oscillate microwaves having a frequency of 2.45 GHz, for example, and output the microwaves to the end face of the microwave waveguide 2a. The output of the oscillating microwave power can be changed by changing the voltage of the high voltage power supply 11a. For example, it is possible to make a difference between 10 to 50% of the microwave power for each plasma source alone. The above-described structure and configuration are the same for the plasma source units 10b to 10d.

  Referring to FIGS. 2 and 3B, the dielectric block 4a also extends in the x direction similarly to the microwave waveguide 2a, and introduces the microwave M through the slot antenna 21. FIG. The dielectric block 4a is formed with a plurality of gas jets 8a for discharging the discharge gas G2 into the chamber 1. The above structure is the same for the dielectric blocks 4b to 4d. A total of five strip-shaped metal plates 9 extending in the x direction are provided on the gap between the dielectric plate blocks 4a to 4d, the left side surface of the dielectric plate block 4a, and the right side surface of the dielectric plate block 4d. It has been. The strip-shaped metal plate 9 is made of, for example, stainless steel, and the width (dimension in the z direction) is substantially equal to the thickness of the dielectric blocks 4b to 4d.

  Next, operations and effects of the SWP-CVD apparatus 100 will be described. The material gas G1 is introduced into the chamber 1 by the material gas introduction system 7, and the discharge gas G2 is introduced into the chamber 1 by the discharge gas introduction system 8, and a vacuum pump (not shown) is passed through the exhaust pipe 4 while introducing the gas. By evacuating, the pressure in the chamber 1 is maintained at a predetermined pressure of about 0.1 to 50 Pa.

  The microwave generators 3a to 3d output the microwaves M that are oscillated to the microwave waveguides 2a to 2d, respectively. Each microwave M spreads in the internal region of the microwave waveguides 2a to 2d while traveling in the + x direction inside the microwave waveguides 2a to 2d. As shown in FIG. Wave power zones 20A-20B are formed.

  Each microwave M enters the dielectric blocks 4a to 4d through the plurality of slot antennas 21 described above. Now, paying attention to the dielectric block 4a, the discharge gas G2 in the chamber 1 is ionized and dissociated by the microwave power from the single plasma source 10a, and the plasma P is generated. When the electron density of the plasma P exceeds the critical density of surface wave generation, the microwave M becomes a surface wave SW, propagates along the boundary surface between the plasma P and the dielectric block 4a, and spreads over the entire area of the dielectric block 4a. spread. As a result, plasma P is generated in a region corresponding to the area of the dielectric block 4a. The above phenomenon also occurs in the dielectric blocks 4b to 4d, and as shown in FIG. 3B, plasma discharge zones 40A to 40D are formed in regions corresponding to the four dielectric blocks 4a to 4d, respectively.

  Since the four dielectric blocks 4a to 4d are provided with the five strip-shaped metal plates 9 described above, the surface wave SW propagating on the surface of each dielectric block is reflected by the metal plate 9, Interference with adjacent surface waves SW can be prevented. As a result, an integrated plasma P is generated over the entire surface of the four dielectric blocks 4a to 4d. A practical thin film formation region is about the area of the plasma P. In the region of the plasma P, the material gas G1 decomposes or undergoes a chemical reaction, and the substrate S is held in contact with or close to the plasma P. A thin film is formed on the surface of the substrate S.

A case will be described in which a SiN thin film is formed on a large-area substrate S using the SWP-CVD apparatus 100 configured as described above.
SiH ₄ is introduced into the chamber 1 as the material gas G1 by the material gas introduction system 7, and N ₂ is introduced as the discharge gas G2 into the chamber 1 by the discharge gas introduction system 8, and the inside of the chamber 1 is held at 1 Pa. The microwave power of the microwave generators 3a and 3d located on the outer peripheral side of the upper surface of the chamber 1 is set to 2.25 kW, and the microwave power of the microwave generators 3b and 3c located near the center is set to 1.5 kW. To do. As described above, the material gas G1 is introduced from the outer peripheral side of the chamber 1 and the vicinity of the center, but the gas concentration is higher on the outer peripheral side of the chamber 1 than in the vicinity of the center. This is because more power is required on the outer peripheral side in order to promote the above.

  The film thickness distribution of the SiN thin film formed under the above conditions was ± 5%. On the other hand, when the microwave power of the microwave generators 3a to 3d was made uniform and the SiN thin film was formed without changing other conditions, the thickness distribution of the SiN thin film was ± 20%. In addition, the former was more uniform in film quality (crystallinity, refractive index, internal stress, etc.) than the latter.

  As described above, according to the SWP-CVD apparatus 100 of the present embodiment, the four plasma source units 10b to 10d are provided, and the microwave generators 3a to 3d are provided according to the gas concentration distribution of the material gas G1. Since the microwave power can be changed independently, a thin film having a uniform film thickness and quality can be formed on the substrate S having a large area. In other words, even if the gas concentration distribution of the material gas G1 is not uniform, a thin film having a uniform film thickness and quality can be formed by changing the microwave power accordingly.

Further, by providing the strip-shaped metal plate 9 to the dielectric blocks 4a to 4d, it is possible to prevent the surface waves SW propagating through the surfaces of the respective dielectric blocks from interfering with each other, and therefore the microwave generators 3a to 3d. It is possible to accurately reflect the change in microwave power due to the formation of the surface wave SW.
Furthermore, since four plasma source units 10b to 10d are provided and used simultaneously, small microwave generators 3a to 3d having a small maximum output can be used.

According to the SWP-CVD apparatus 100 according to the present embodiment described above, a thin film having a uniform film thickness and quality can be formed on the substrate S having a large area of 1 m × 1 m, for example. Using the SWP-CVD apparatus 100, it is possible to form an organic EL protective film (SiN _x , SiO _x , SiON) and an antireflection film (SiN) for solar cells, which have recently been required to have a large area, Further, a gate oxide film and an interlayer insulating film (SiO ₂ ) of the TFT can be formed.

  The present invention is not limited to the above-described embodiment as long as the characteristics are not impaired. For example, in the present embodiment, the SWP-CVD apparatus 100 includes four plasma source units 10a to 10d. Three may be sufficient and five or more may be sufficient. When the number is increased, a large-area plasma discharge area corresponding to a large-area substrate can be secured. Alternatively, each of the dielectric blocks 4a to 4d can be cut at right angles to the traveling direction of the microwave M, and one dielectric block can be further divided into small blocks.

1 is an overall configuration diagram schematically showing an outline of an SWP-CVD apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view explaining the detail of the SWP-CVD apparatus which concerns on embodiment of this invention. FIG. 3A shows a cross section taken along the line II in FIG. 2, and is a view in which the microwave waveguides 2a to 2d are cut along the xy plane. FIG. 3B is a cross-sectional view taken along the line II-II in FIG. 2, and is a diagram in which the dielectric blocks 4a to 4d are cut along the xy plane.

Explanation of symbols

1: Chamber 2a-2d: Microwave waveguide 3a-3d: Microwave generator 4a-4d: Dielectric block 7: Material gas introduction system 7a: Shower head 8: Discharge gas introduction system 8a: Gas outlet 9: Metal Plate 10: Plasma source 10a to 10d: Plasma source alone 20A to 20D: Microwave power zone 40A to 40D: Plasma discharge zone 100: SWP-CVD apparatus G1: Material gas G2: Discharge gas M: Microwave P: Plasma S: Substrate SW: Surface wave

Claims (4)

A plurality of microwave waveguides arranged in parallel along the direction of propagation of microwaves;
A plurality of microwave generators provided for each of the plurality of microwave waveguides and outputting microwaves to the respective microwave waveguides;
The plasma source, wherein the microwave generators are capable of independently changing the power of the microwaves. A plasma source according to claim 1;
A dielectric member that introduces the microwave from the plasma source to form a surface wave, and generates plasma in the film forming chamber by the surface wave energy;
A material gas introducing means for introducing a material gas into the film forming chamber;
A surface wave excitation plasma CVD apparatus comprising discharge gas introduction means for introducing a discharge gas into the film forming chamber. In the surface wave excitation plasma CVD apparatus according to claim 2,
The dielectric member is a dielectric block divided into a plurality of parts corresponding to the plurality of microwave waveguides, and reflects the surface wave formed in each of the dielectric blocks at the boundary of the dielectric block A surface wave excitation plasma CVD apparatus characterized in that a metal plate is provided. A method of forming a film using the surface wave excitation plasma CVD apparatus according to claim 2 or 3,
Depending on the concentration distribution of the material gas in the film forming chamber, the microwave power is increased in a region where the concentration of the material gas is high, and the microwave power is decreased in a region where the concentration of the material gas is low. A film forming method characterized by forming a film.

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