JP4517935B2 - Shower plate and surface wave excitation plasma processing apparatus - Google Patents

Description

  The present invention relates to a shower plate for supplying various gases to a surface wave excited plasma processing chamber and a surface wave excited plasma processing apparatus using the shower plate.

  In a plasma processing apparatus using surface wave excitation plasma, a microwave propagating in a waveguide is introduced into a chamber through a dielectric window, and the catalyst gas in the chamber is excited by the surface wave generated on the surface of the dielectric window. Generate surface wave excitation plasma. A reactive main gas for processing an object to be processed is introduced into the chamber from one gas inlet provided on the side surface of the chamber (see, for example, Patent Document 1).

JP 2000-348898 (page 4, FIG. 1)

  In the apparatus disclosed in Patent Document 1, since gas is ejected from one gas inlet on the side of the chamber, there is a problem that the supply of gas to the object to be processed in the chamber becomes uneven.

(1) The invention of claim 1 is applied to a hollow flat shower plate that ejects a material gas into a chamber of a surface wave excitation plasma processing apparatus. The shower plate includes a multi-stage hollow chamber in which each stage chamber extends in a planar shape, a plurality of through-holes penetrating each hollow chamber, and a gas that introduces a material gas into the first-stage hollow chamber. A plurality of gas injection holes for injecting the introduced material gas from the hollow chamber in the final stage, and a plurality of walls for separating the adjacent hollow chambers, and allowing the material gas to flow from the upstream to the downstream hollow chamber The gas ejection holes and the communication holes are provided around the plurality of through holes , and the plurality of hollow chambers are provided with one or more independent exhaust ports, respectively. To do.
(2) The invention according to claim 2 is the shower plate according to claim 1, wherein the communication hole and the gas ejection hole as the gas inflow holes provided facing the final-stage hollow chamber or the intermediate-stage hollow chamber are provided. The communication hole as the gas inflow hole and the communication hole as the gas outflow hole provided so as to face each other are arranged so as not to face each other. (3) The invention of claim 3 is the invention according to claim 1. Alternatively, the shower plate according to 2 is characterized in that an adhesion preventing plate that covers a region excluding the gas ejection holes is disposed on the lower surface of the final-stage hollow chamber where the gas ejection holes are formed.
(4) The invention of claim 4 is the shower plate according to any one of claims 1 to 3, wherein two or more gas inlets are arranged in the first-stage hollow chamber. .
( 5 ) The invention of claim 5 is characterized in that the shower plate according to any one of claims 1 to 4 is provided with a temperature control means for adjusting the temperature of the material gas.
( 6 ) The surface wave excitation plasma processing apparatus according to the invention of claim 6 excites the surface wave excitation plasma in the upper space in the chamber to generate radical species from the process gas, and any one of claims 1 to 5 The material gas is introduced into the lower space by the shower plate according to any one of the above items, and various plasma treatments are performed by dissociating and reacting the material gas with radical species that pass through the through holes and flow down to the lower space. To do.

  According to the present invention, since the processing gas introduced into the first-stage hollow chamber is guided to the next-stage hollow chamber communicated via the communication hole and then ejected into the chamber from the gas ejection hole. The amount of gas ejected from each of the communication holes and the gas ejection holes becomes uniform, so that the processing gas can be uniformly supplied to the object to be processed in the chamber.

  Hereinafter, a surface wave plasma (SWP) processing apparatus (hereinafter abbreviated as SWP processing apparatus) using a shower plate according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a longitudinal sectional view schematically showing a configuration of a SWP processing apparatus according to an embodiment of the present invention. The SWP processing apparatus 100 is decomposed by a chamber 1, a microwave waveguide 2, a dielectric plate 3, a plurality of process gas introduction portions 4 for introducing a process gas for generating surface wave excited plasma, and surface wave excited plasma. And a plurality of shower plates 10 for introducing material gas (also referred to as processing gas in this specification). The chamber 1 is a sealed container having a chamber body 1a and a lid 1b, and performs plasma processing such as etching and film formation on the substrate S to be processed using plasma generated in the internal space thereof. The chamber body 1a is provided with a substrate holder 5 that holds the substrate S to be processed and a vacuum exhaust port 6 that is connected to a vacuum pump (not shown) and exhausts the inside of the chamber 1. The substrate holder 5 can move and rotate in the vertical direction in the figure, and has a heater 5a incorporated therein.

  The microwave waveguide 2 is made of an aluminum alloy, a copper alloy, or the like, has a straight tube shape extending perpendicular to the paper surface, and is attached to the lid 1 b of the chamber 1. A plurality of slot antennas 2b are arranged on the bottom plate 2a of the microwave waveguide 2 at predetermined intervals along the axial direction of the tube. The slot antenna 2b is a long rectangular opening formed through the bottom plate 2a. The inner surface of the bottom plate 2a is called a magnetic field surface (H surface).

  The dielectric plate 3 is obtained by processing a dielectric material such as quartz, alumina, zirconia or the like into a flat plate shape, and has a through hole 3a for introducing a process gas in the plate thickness direction. The upper surface of the dielectric plate 3 is in contact with the bottom plate 2a of the microwave waveguide 2 and is attached to the lid 1b via the O-ring 1c, so that the airtightness in the chamber 1 is maintained. it can.

The process gas introduction unit 4 is fixed to the lid 1b of the chamber 1, and guides a process gas from a gas supply system (not shown) to the through hole 1d of the lid 1b. The process gas is introduced into the chamber 1 through the through hole 3 a of the dielectric plate 3. The process gas is a reactive gas such as N ₂ gas, O ₂ gas, or H ₂ gas, and a rare gas such as Ar gas, He gas, Ne gas, Kr gas, or Xe gas.

  The shower plate 10 will be described in detail with reference to FIG. 2A and 2B are diagrams schematically showing the shower plate 10, in which FIG. 2A is a cross-sectional view, and FIG. 2B is a partial bottom view. A cross section taken along line II in FIG. 2B corresponds to a region A in FIG. As shown in FIG. 3 to be described later, the shower plate 10 has a three-plate configuration and is disposed in the horizontal direction so that the chamber 1 is divided into two upper and lower chambers.

  Each of these shower plates 10 has a hollow flat plate shape as a whole, and includes a first chamber 11 and a second chamber 12 that form a two-stage upper and lower hollow structure, and a plate thickness direction of the two-stage hollow structure (FIG. 2 ( a) a plurality of through-holes 13 drilled in the vertical direction), a gas introduction port 14 for guiding a material gas from a gas supply system (not shown) to the first chamber 11, and an adhesion preventing plate 15. Here, the first chamber 11 is the first-stage hollow chamber, and the second chamber 12 is the last-stage hollow chamber. Since the first chamber 11 and the second chamber 12 are provided with a cylindrical side wall 10 a between the first chamber 11 and the second chamber 12, the first chamber 11 and the second chamber 12 are separated from the through hole 13. It has become. A partition plate between the first chamber 11 at the upper stage and the second chamber 12 at the lower stage, that is, the bottom plate of the first chamber 11 is the dispersion plate 11a, and the dispersion plate 11a has a plurality of gas ejection holes 11b having substantially the same opening diameter. It is installed. The gas ejection hole 11b is a communication hole that allows the first chamber 11 and the second chamber 12 to communicate with each other. The bottom plate of the lower second chamber 12 is the dispersion plate 12a, and the dispersion plate 12a is provided with a plurality of gas ejection holes 12b having substantially the same opening diameter. Further, a small hole 15a is formed in the deposition preventing plate 15 in accordance with the arrangement and opening diameter of the gas ejection holes 12b of the dispersion plate 12a. That is, the deposition preventing plate 15 is disposed so as to cover the area excluding the gas ejection holes 12b and the through holes 13.

  As shown in FIG. 2B, the gas ejection holes 11b and 12b and the through holes 13 are all regularly arranged. However, the gas ejection holes 11b and 12b are not aligned in a line in the vertical direction of FIG. 2A (perpendicular to the paper surface of FIG. 2B), that is, the gas ejection holes 11b and 12b are opposed to each other. It is arranged so as not to shift. Further, the gas ejection holes 11 b and 12 b are formed as holes having a cross-sectional area far smaller than the opening of the through hole 13 or the gas introduction port 14.

FIG. 3 is a plan view showing a schematic configuration of the SWP processing apparatus according to the embodiment, and shows a supply path of the material gas to the three shower plates 10. Each shower plate 10 is supplied with a gas G1 by a gas supply system 7 and a gas G2 different from the gas G1 by a gas supply system 8. In the gas supply system 7, a pipe 7 a connected to a gas supply source (not shown) is branched into three, and mass flow controllers 7 b, 7 c, and 7 d are arranged in each of the three pipes. Similarly, in the gas supply system 8, mass flow controllers 8b, 8c, and 8d are disposed in each of the three branch pipes. Since the outlet sides of the mass flow controllers 7b, 7c, and 7d and the outlet sides of the mass flow controllers 8b, 8c, and 8d are connected to each other, the gases G1 and G2 are mixed and supplied to the shower plates 10 as material gases. The material gas is a gas containing components of a silicon thin film or a silicon compound thin film such as SiH ₄ gas, Si ₂ H ₆ gas, NH ₃ gas, or the like.

  The plasma processing performed by the SWP processing apparatus 100 configured as described above will be described with reference to FIGS. 1 and 2 again. While the process gas is introduced through the vacuum exhaust port 6 while the process gas is introduced into the chamber 1 by the process gas introduction unit 4 and the material gas is introduced into the chamber 1 by the shower plate 10, the inside of the chamber 1 is maintained at a predetermined pressure.

  As shown in FIG. 2, the material gas is guided from the gas introduction port 14 to the first chamber 11 and transferred to the second chamber 12 through the plurality of gas ejection holes 11b. It is discharged to the outside of the shower plate 10, that is, into the chamber 1 through the hole 15 a. Since the opening cross-sectional area of the gas ejection holes 11b is very small, the material gas introduced into the first chamber 11 is uniformly ejected from the plurality of gas ejection holes 12b by the multistage arrangement of the gas ejection holes 11b and 12b. That is, the material gas is uniformly supplied toward the target substrate S in the chamber 1 by the shower plate 10.

  A microwave is introduced from a microwave generator (not shown) into the microwave waveguide 2, radiated to the dielectric plate 3 through the slot antenna 2 b, and introduced into the chamber 1 through the dielectric plate 3. The process gas in the chamber 1 is ionized and dissociated by the microwave energy to generate plasma. When the electron density of the plasma exceeds the critical density of surface wave generation, the microwave becomes a surface wave and propagates along the boundary surface between the plasma and the dielectric plate 3 and spreads over the entire area of the dielectric plate 3. As a result, high-density plasma, that is, surface wave excitation plasma is generated in a region corresponding to the area of the dielectric plate 3. The material gas is decomposed and caused to react by the surface wave excitation plasma, and plasma processing such as CVD film formation, etching, and ashing is performed on the substrate S to be processed disposed in the vicinity of the plasma.

A process for forming a CVD film on the substrate S to be processed using surface wave excitation plasma will be described with reference to FIG.
FIG. 4 is a schematic diagram showing a reaction process inside the chamber in the SWP processing apparatus according to the embodiment. Specifically, it is a process of forming a silicon nitride film, using N ₂ gas, H ₂ gas, Ar gas as process gas, SiH ₄ gas, NH ₃ gas as material gas, and adjusting the pressure in chamber 1. A predetermined pressure in the range of 1 to 100 Pa is set. The gas introduction ratio and the pressure in the chamber 1 are appropriately selected.

If the space region from the dielectric plate 3 to the substrate S to be processed is divided into five, the surface wave-excited plasma is generated in the region 1, and many active nitrogen radicals are generated. In addition to radicals, ions and electrons are generated.
Region 2 is a diffusion region of generated nitrogen radicals. The generated radical species diffuse in the direction of the substrate S to be processed, that is, in the downward direction in FIG. 4, and are sufficiently uniformly distributed until reaching the shower plate 10. Nitrogen radicals pass through the plurality of uniformly arranged through holes 13 of the shower plate 10 and further diffuse downward. In this region, the SiH ₄ gas and the NH ₃ gas are uniformly released from the shower plate 10 as described above.

In region 3, the dissociation reaction of SiH ₄ gas and NH ₃ gas by nitrogen radicals is promoted, and a precursor of silicon nitride is uniformly generated at each point in the region and diffuses downward.
The region 4 is a region where a silicon nitride film can be formed.
In the region 5, the silicon nitride molecules that have reached the target substrate S are deposited on the substrate surface. Silicon nitride molecules undergo migration due to the surface temperature of the substrate to be processed S heated by the heater 5a incorporated in the substrate holder 5, and finally the film quality (crystallinity, refractive index, internal stress, etc.) of the thin film is determined. Is done.

  In the surface wave excitation plasma processing apparatus described above, various types of plasma processing are performed on the substrate S as follows. That is, surface wave excitation plasma is excited in the upper space in the chamber 1 to generate radical species from the process gas, the material gas is introduced into the lower space by the shower plate 10, passes through the through hole 13, and is lowered to the lower space. The material gas is dissociated and reacted by the flowing radical species.

The shower plate 10 and the SWP processing apparatus 100 of the present embodiment described above have the following operational effects.
(1) When the material gas is delivered in the order of the first chamber 11 and the second chamber 12 of the shower plate 10, the material gas is uniformly ejected from the plurality of gas ejection holes 12b by the multi-stage arrangement of the gas ejection holes 11b and 12b. , The substrate S can be supplied uniformly.
(2) By arranging the gas ejection holes 11b and 12b of the shower plate 10 so as not to line up in a line in the vertical direction of FIG. 2A, the uniformity of the gas pressure distribution in the second chamber 12 is further increased. This improves the uniformity of the supply of the material gas to the substrate S to be processed.
(3) Since the plurality of through holes 13 are arranged in the shower plate 10, radical species generated by the surface wave excitation plasma flow down to the lower space through the through holes 13 and diffuse, so that the material gas is decomposed. It is performed spatially uniformly.
(4) By providing the adhesion preventing plate 15 on the lower surface of the dispersion plate 12a, the maintenance frequency of the dispersion plate 12a can be reduced. That is, only the replacement of the deposition preventing plate 15 is required, and the number of cleaning and replacement of the dispersion plate 12a is reduced.
(5) Due to the effects (1) to (3), the SWP processing apparatus 100 can perform uniform CVD film formation, and a thin film with uniform film thickness and film quality can be obtained.
(6) A plurality of shower plates 10 are arranged in parallel, and a mass flow controller is provided for each shower plate 10 to finely control the gas supply amount and the mixing ratio of the gases G1 and G2. As a result, the uniformity of the gas concentration distribution in the vicinity of the substrate to be processed S in the chamber 1 is improved.

  Although the case where the SWP processing apparatus 100 forms a film on the substrate S has been described above, the SWP processing apparatus according to the present invention can also perform an etching process or an ashing process. In this case, a process gas (gas species 1) that contributes to plasma generation is jetted into the upper space of the chamber, and a processing gas (gas species 2) that contributes to the etching process or the ashing process is transferred from the shower plate 10 to the bottom of the chamber. What is necessary is just to erupt into space.

Next, the modification of the shower plate 10 of the said embodiment is demonstrated.
FIG. 5 is a diagram schematically showing a first modification of the shower plate 10, and is a schematic plan view of an SWP processing apparatus in which the shower plate of the first modification is arranged. As shown in the figure, four shower plates 20 </ b> A to 20 </ b> D are juxtaposed in the chamber 1. These shower plates 20A to 20D are basically the same type as the shower plate 10 of the embodiment, but the shower plates 20A to 20D are different in that two gas introduction ports are provided. For example, two gas introduction ports 21a and 22a are disposed on the shower plate 20A substantially diagonally.

  The gas line L1 connected to the gas supply unit 70 is branched into two at the branch portion 21, and one is connected to the gas introduction ports 21a and 21b, and the other is connected to the gas introduction ports 21c and 21d. Similarly, the gas line L2 is branched into two at the branch portion 22, and one is connected to the gas introduction ports 22a and 22c, and the other is connected to the gas introduction ports 22b and 22d. As described above, the first stage chambers of the shower plates 20A to 20D have a structure in which gas can be introduced from two locations on the diagonal line, so that the gas pressure distribution in the first stage chamber becomes more uniform, and the final stage chambers have the same structure. The uniformity of the gas pressure distribution in the chamber is improved, and the supply of the material gas to the substrate to be processed S can be made uniform.

  6A and 6B are diagrams schematically showing a second modification of the shower plate 10, where FIG. 6A is a cross-sectional view showing a state at the time of gas introduction, and FIG. c) is a plan view. The shower plate 30 of the second modified example is basically the same type as the shower plate 10 described above, and the 10th code is replaced with the 30th code. The difference is that two gas introduction ports 34 and 35 are provided, and exhaust ports 36 and 37 are added to the second chamber 32. As shown in FIG. 6C, the gas introduction ports 34 and 35 are arranged on the diagonal line of the shower plate 30, and the exhaust ports 36 and 37 are also arranged on the diagonal line.

  At the time of gas introduction shown in FIG. 6A, the exhaust ports 36 and 37 are closed, the material gas introduced into the first chamber 31 is transferred to the second chamber, and is discharged into the chamber through the plurality of gas ejection holes 32b. During the evacuation shown in FIG. 6B, the first chamber 31 and the second chamber 32 are evacuated using the gas introduction ports 34 and 35 and the exhaust ports 36 and 37, respectively. Thus, by providing the exhaust ports 36 and 37 and diverting the gas introduction ports 34 and 35 to exhaust gas, the residual gas in the first chamber 31 and the second chamber 32 can be quickly removed. The time can be shortened when it is desired to perform the process continuously with the change.

  FIG. 7 is a cross-sectional view schematically showing a third modification of the shower plate 10. The shower plate 30 </ b> A of the third modification is basically the same type as the shower plate 30 of the second modification, except that a temperature control plate 38 is added to the upper side of the first chamber 31.

  A flow path 38a for flowing a fluid medium is formed inside the temperature control plate 38, and the temperature of the shower plate 30A is adjusted by controlling the temperature of the fluid medium. The fluid medium may be liquid or gas. For example, water, oil, ethylene glycol, air, nitrogen gas, helium gas, or the like can be used. By controlling the temperature of the material gas with the temperature control plate 38, a substance that is difficult to vaporize at room temperature, for example, TEOS, is heated to about 130 ° C., thereby preventing adhesion on the surface and inside of the shower plate 30A. .

  FIG. 8 is a diagram schematically illustrating a fourth modification of the shower plate 10. 8A is a cross-sectional view, FIG. 8B is a partial bottom view, and a cross section taken along line II-II in FIG. 8B corresponds to a region B in FIG. 8A. The plurality of through holes 43 are arranged in a honeycomb shape, and when the pitch in the arrangement direction of the through holes 43 (X direction in the figure) is P, the interval in the direction orthogonal to the arrangement direction (Y direction) is P√3. . This arrangement can increase the ratio of the opening area of the through-holes 43 in the shower plate, and thus is effective in minimizing the reduction of radical species, and at the same time, increases the processing speed and further increases the processing speed. Uniformity can be achieved.

  The present invention is not limited to the embodiments described above as long as the characteristics are not impaired. For example, the hollow structure of the shower plate is not limited to two stages, and may be a multistage of three or more stages. When three or more stages of hollow chambers are provided, the positional relationship between the gas inflow holes and the gas outflow holes of the hollow chamber located in the middle is preferably shifted without being opposed to each other. Moreover, various deformation | transformation can be considered regarding the dimension of the through-hole of a shower plate, a shape, arrangement | positioning.

It is a longitudinal cross-sectional view which shows typically the structure of the SWP processing apparatus which concerns on embodiment of this invention. It is a figure which shows typically the structure of the shower plate by embodiment, (a) is sectional drawing, (b) is a partial bottom view. It is a top view which shows typically the supply path | route of the material gas to three shower plates. It is a schematic diagram which shows the reaction process inside the chamber in the SWP processing apparatus by embodiment. It is a figure which shows typically the shower plate of a 1st modification. It is a figure which shows typically the shower plate of a 2nd modification, (a) is sectional drawing which shows the state at the time of gas introduction, (b) is sectional drawing which shows the state at the time of exhaustion, (c) is a bottom view. It is. It is sectional drawing which shows typically the shower plate of a 3rd modification. It is a figure which shows typically the structure of the shower plate of a 4th modification, (a) is sectional drawing, (b) is a partial bottom view.

Explanation of symbols

1: Chamber 2: Microwave waveguide 3: Dielectric plate 4: Process gas introduction part 10, 20A to 20D, 30, 30A: Shower plate 11, 31: First chamber 11a, 31a: Dispersion plate 11b, 31b: Gas Ejection holes 12, 32: Second chambers 12a, 32a: Dispersion plates 12b, 32b: Gas ejection holes 13, 13A, 33: Through holes 14, 34, 35: Gas introduction ports 15: Deposition plates 36, 37: Exhaust ports 38: Temperature control plate 100: SWP processing device S: Substrate to be processed

Claims (6)

A hollow flat shower plate that ejects a material gas into a chamber of a surface wave excitation plasma processing apparatus,
A multi-stage hollow chamber in which each stage chamber spreads in a plane,
A plurality of through holes penetrating the hollow chambers of the respective stages;
A gas inlet for introducing the material gas into the first-stage hollow chamber;
A plurality of gas ejection holes for ejecting the introduced material gas from the final-stage hollow chamber;
A plurality of communication holes provided on a wall separating adjacent hollow chambers and allowing the material gas to flow from upstream to downstream hollow chambers;
The gas ejection hole and the communication hole are provided around the plurality of through holes,
The plurality of hollow chambers are provided with one or more independent exhaust ports, respectively. The shower plate according to claim 1,
As the communication hole and the gas ejection hole as the gas inflow hole provided facing the hollow chamber of the final stage, or as the communication hole and the gas outflow hole as the gas inflow hole provided to face the hollow chamber of the intermediate stage The shower plate is arranged so as not to be opposed to each other. The shower plate according to claim 1 or 2,
A shower plate, characterized in that an adhesion preventing plate that covers a region excluding the gas ejection holes is disposed on a lower surface of the final-stage hollow chamber where the gas ejection holes are formed. In the shower plate as described in any one of Claims 1-3,
The shower plate according to claim 1, wherein two or more gas inlets are disposed in the first hollow chamber. In the shower plate as described in any one of Claims 1-4 ,
A shower plate, characterized in that temperature control means for adjusting the temperature of the material gas is provided. The surface wave excitation plasma is excited in the upper space in the chamber to generate radical species from the process gas, and the material gas is introduced into the lower space by the shower plate according to any one of claims 1 to 5. A surface wave-excited plasma processing apparatus that performs various plasma processing by dissociating and reacting the material gas with the radical species that flow down to the lower space through the through hole.

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