JP2007088200A - Processing equipment and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radical processing equipment and method which can treat the surface of a processed substrate uniformly by preventing generation of uneven gas flow in the vicinity of the surface of the processed substrate even when gas is introduced at a high flow rate thereby equalizing spatial distribution of radical diffuse density. <P>SOLUTION: The processing equipment comprises a treatment chamber 101, a gas discharge means 106, a gas introduction means 105, a neutral radical generating means 108 for generating neutral radicals in an upper radical generation region 111 in the treatment chamber 101, and a means 103 installed in the upstream of gas flow as compared with the radical generation region 111 and supporting a processed substrate 102 wherein the gas introduction means 105 is provided between the radical generation region 111 and the processed substrate supporting means 103. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing apparatus and method such as an etching apparatus, an ashing apparatus, and a surface modification apparatus that can perform uniform processing on the surface of a substrate to be processed.

Generally, as a processing apparatus, an etching apparatus, an ashing apparatus, a surface modification apparatus, and the like are known.
Conventionally, a processing apparatus and method for precisely controlling a minute incident flux of radicals excited by microwave plasma to a substrate to be processed have been proposed in, for example, Japanese Patent Laid-Open No. 2005-142234 (Patent Document 1).
This conventional processing apparatus is shown in FIG. A processing chamber 501, a substrate to be processed 502 made of a semiconductor wafer, a support 503 for supporting the substrate to be processed 502, a temperature adjusting unit 504 for the substrate to be processed 502, an exhaust unit 506 for the processing chamber 501, a plasma processing gas introduction unit 505, power introduction means 508 for introducing power into the processing chamber 501, conductance control means 509, and the like.
In this conventional example, the inside of the processing chamber 501 is evacuated through the exhaust means 506, and the processing gas is introduced at a predetermined flow rate through the gas introducing means 505 provided in the lower portion of the processing chamber 501. . A conductance valve (not shown) provided in the exhaust unit 506 is adjusted to maintain the inside of the processing chamber 501 at a predetermined pressure. Desired power is introduced into the processing chamber 501 through the power introduction means 508, and plasma is generated in the plasma generation region 511.
The introduced processing gas is excited by the generated plasma, is ionized and activated, and processes the surface of the substrate to be processed 502 placed on the support 503.
At this time, most of the active species such as neutral radicals excited by the plasma are exhausted without reaching the substrate to be processed 502, and only some of the active species diffused to reach the substrate to be processed 502 are subjected to the plasma treatment. Contribute. By changing the flow rate by changing the gas flow rate and the exhaust conductance, the processing speed can be controlled with high accuracy, and an ultrathin film of several molecular layers can be formed.
JP 2005-142234 A

However, in the conventional example, a large flow of processing gas may be introduced in order to minimize the flux of radicals incident on the substrate to be processed, and at this time, a strong gas flow may be formed due to the introduced gas. was there.
For this reason, in the vicinity of the substrate support means to be processed, radical concentration unevenness due to the flow of the introduced gas occurs, and there is a possibility that uniform processing on the surface of the substrate to be processed cannot be performed.
Therefore, the present invention prevents a non-uniform gas flow from occurring near the surface of the substrate to be processed even when a large flow rate of gas is introduced, uniforms the spatial distribution of radical diffusion concentration, and improves the surface of the substrate to be processed. An object of the present invention is to provide a plasma processing apparatus and method capable of performing uniform processing.

In order to achieve the above object, a processing apparatus according to the present invention includes a processing chamber for storing a substrate to be processed,
Radical generating means for generating radicals in the processing chamber;
In a processing apparatus having a target substrate support means for supporting the target substrate in the processing chamber,
Gas introducing means for introducing a processing gas between the radical generation region and the substrate to be processed;
Gas exhaust means for exhausting the processing gas is provided between the radical generation region and the gas introduction means.
Furthermore, the processing apparatus according to the present invention further includes conductance adjusting means between the gas introducing means and the radical generating region.
Furthermore, the processing apparatus according to the present invention includes a flux uniformizing means between the gas introducing means and the substrate support means.
Furthermore, in the processing apparatus according to the present invention, the flux uniformizing means comprises a plate having a plurality of holes.
Furthermore, in the processing apparatus according to the present invention, the neutral radical is generated by microwaves.
Furthermore, in the processing apparatus according to the present invention, the neutral radical is generated by ultraviolet light.
Furthermore, in the processing apparatus according to the present invention, the conductance adjusting means and / or the flux uniformizing means is made of a material opaque to the ultraviolet light.
Furthermore, the treatment method according to the present invention is a treatment method for generating a neutral radical in a treatment chamber and radical-treating a substrate to be treated.
A processing gas is introduced between the substrate to be processed and the radical generation region, and the processing gas is discharged from between the radical generation region and the introduction portion of the processing gas.

  According to the processing apparatus and method of the present invention, the gas introduction means is provided between the radical generation region and the target substrate support means, so that there is no exhaust path from the space where the target substrate support means exists and the introduction is performed. A strong gas flow due to the treated gas is not formed. As a result, a gas retention state occurs in the vicinity of the substrate support means to be processed. Therefore, even when a large flow rate of gas is introduced, the surface of the substrate to be treated is uniformly treated with almost no radical diffusion unevenness due to the flow of the introduced gas in the vicinity of the substrate support means to be treated, so that the surface diffuses uniformly Is possible. Therefore, even when a large amount of gas is introduced, non-uniform gas flow is prevented from occurring near the surface of the substrate to be processed, the spatial distribution of radical diffusion concentration is made uniform, and the surface of the substrate to be processed is uniformly processed. It can be performed.

  Hereinafter, the present invention will be described with reference to the drawings based on the embodiments.

The processing apparatus of Example 1 of this invention is demonstrated using FIG.
The processing chamber 101 is a chamber for performing radical processing on a substrate 102 to be processed such as a semiconductor. The exhaust means 106 is an exhaust port for processing gas that exhausts the inside of the processing chamber 101. The gas introduction unit 105 is a unit that introduces a processing gas into the processing chamber 101. The neutral radical generating unit 108 is a unit that is provided on the upper surface of the processing chamber 101 and generates a neutral radical in the radical generation region 111 in the upper part of the processing chamber 101. The substrate supporting means 103 to be processed is a means for supporting the substrate to be processed 102 installed upstream of the gas flow from the radical generation region 111. Here, the gas introducing means 105 is provided between the radical generating region 111 and the substrate support means 103 to be processed, and this point is different from the conventional example shown in FIG. The temperature adjusting means 104 is a means for adjusting the temperature of the substrate 102 to be processed, and a conductance control means 109 is provided between the gas introduction means 105 and the radical generation region 111.
In the radical treatment, first, the inside of the processing chamber 101 is evacuated to a substantially vacuum state via a gas exhaust port serving as the exhaust means 106. Subsequently, a processing gas is introduced into the processing chamber 101 at a predetermined flow rate through a gas introducing means 105 provided in the processing chamber 101. Next, a conductance valve (not shown) provided in 106 is adjusted to maintain the inside of the processing chamber 101 at a predetermined pressure. Further, a desired power is supplied to the radical generating means 108 and the processing gas introduced into the processing chamber 101 is excited to generate radicals in the radical generating region 111. Most of the excited active radicals are exhausted without reaching the substrate to be processed 102, and only some radicals diffused to the substrate to be processed 102 contribute to the processing and are placed on the substrate to be processed supporting means 103. The surface of the processed substrate 102 is processed. Further, by controlling the gas flow rate by the gas introduction unit 105 and changing the flow rate by changing the exhaust conductance by the conductance control unit 109, the processing speed can be controlled with high accuracy.
In the first embodiment, the gas introduction unit 105 is provided between the radical generation region 111 and the target substrate support unit 103, and there is no exhaust path from the space where the target substrate support unit 103 is located. Therefore, a strong gas flow due to the introduced processing gas is not formed, and a gas retention state is generated in the vicinity of the target substrate support means 103. Therefore, even when a large flow rate of gas is introduced, in the vicinity of the substrate support means 103 to be processed, radical diffusion unevenness due to the flow of the introduced gas hardly occurs and the surface of the substrate to be processed 102 is uniformly distributed. Processing becomes possible. For this reason, even when a large amount of gas is introduced, a non-uniform gas flow is prevented from being generated in the vicinity of the surface of the substrate to be processed 102, the spatial distribution of radical diffusion concentration is made uniform, and the surface of the substrate to be processed 102 is made uniform. Can be processed.

Further, in the processing apparatus of the first embodiment, in order to improve the uniformity of radical diffusion near the substrate support means 103 to be processed, a flux uniformizing means is provided between the gas introduction means 105 and the substrate support means 103 to be processed. 110 may be installed. The flux uniformizing means 110 is composed of a plate having a plurality of holes, and the shape of the flux uniforming means 110 is a flat plate if the flow of the introduced gas does not inhibit uniform radical diffusion to a certain region of the substrate support 103 to be processed. Or any other shape. The arrangement of the plurality of holes may be any arrangement such as an equidistant lattice arrangement or a concentric arrangement, and the diameters of the individual holes may be the same or different.
As the material of the flux uniformizing means 110, Si-based insulator materials such as quartz and silicon nitride are used when metal contamination becomes a problem. When metal contamination does not become a problem and it is desired to cut electromagnetic wave irradiation to the substrate to be processed 102, a metal such as aluminum may be used. When both metal contamination and electromagnetic wave irradiation are a problem, a Si-based insulator containing a metal may be used.
Further, when high energy ultraviolet light emitted during radical generation may adversely affect the substrate to be processed 102, the flux uniformizing means 110 may be formed of a material opaque to the ultraviolet light.
The radical generating means 108 used in the processing apparatus of the first embodiment can use either high-frequency plasma excitation or ultraviolet light excitation, and can be used in combination. As the high frequency plasma excitation, any plasma excitation means such as CCP, ICP, helicon, ECR, microwave, surface wave, surface wave interference type plasma source and the like can be applied.
As the ultraviolet light excitation means, any light source can be applied as long as it can emit light having energy that can be excited to a desired radical state. For example, a light source such as a xenon short arc lamp, a xenon flash lamp, a short arc type ultrahigh pressure mercury lamp, a capillary lamp, a long arc lamp, a low pressure mercury lamp, a deep UV lamp, a metal halide lamp, an excimer lamp, a nitrogen laser, and an excimer laser can be used. When an excimer lamp is used, the emission center wavelength differs depending on the sealing gas such as F ₂ , Cl ₂ , Br ₂ , I ₂ , ArBr, KrBr, XeBr, ArCl, KrCl, XeCl, ArF, KrF, XeF, and XeI. It is preferable to select one that can efficiently emit light having a wavelength most suitable for generating radicals.

In the processing method using the processing apparatus of the first embodiment, the pressure in the processing chamber is in the range of 0.1 mTorr to 10 Torr, and more preferably in the range of 10 mTorr to 5 Torr from the intermediate flow to the viscous flow side.
Formation of the deposited film by the processing method using the processing apparatus of the first embodiment is performed by appropriately selecting a gas to be used, and thereby Si ₃ N ₄ , SiO ₂ , SiOF, Ta ₂ O ₅ , TiO ₂ , TiN, and Al _2. Various deposited films such as insulating films such as O ₃ , AlN, and MgF ₂ , semiconductor films such as a-Si, poly-Si, SiC, and GaAs, and metal films such as Al, W, Mo, Ti, and Ta are efficiently used. It is possible to form.
The to-be-processed base | substrate 102 processed with the processing method using the processing apparatus of the present Example 1 may be a semiconductor, an electroconductive thing, or an electrically insulating thing.
Examples of the conductive substrate include metals such as Fe, Ni, Cr, Al, Mo, Au, Nb, Ta, V, Ti, Pt, and Pb, or alloys thereof, such as brass and stainless steel.
Examples of the insulating substrate include SiO ₂ -based quartz and various glasses, Si ₃ N ₄ , NaCl, KCl, LiF, CaF ₂ , BaF ₂ , Al ₂ O ₃ , AlN, MgO, and other inorganic materials, polyethylene, polyester, polycarbonate, Examples thereof include organic acetate films such as cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, and polyimide, and windows.
As a gas used when forming a thin film on a substrate by a CVD method, generally known gases can be used.
As source gases containing Si atoms introduced into the processing chamber 101 through the processing gas introducing means 105 when forming a Si-based semiconductor thin film such as a-Si, poly-Si, or SiC, SiH ₄ , Si ₂ Inorganic silanes such as H ₆ , organic silanes such as tetraethylsilane (TES), tetramethylsilane (TMS), dimethylsilane (DMS), dimethyldifluorosilane (DMDFS), dimethyldichlorosilane (DMDCS), SiF ₄ , Silane halides such as Si ₂ F ₆ , Si ₃ F ₈ , SiHF ₃ , SiH ₂ F ₂ , SiCl ₄ , Si ₂ Cl ₆ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₃ Cl, SiCl ₂ F ₂ , etc. Examples include those that are in a gas state at normal temperature and pressure, or those that can be easily gasified. In this case, H ₂ , He, Ne, Ar, Kr, Xe, and Rn are listed as additive gas or carrier gas that may be introduced by mixing with Si source gas.

Examples of raw materials containing Si atoms introduced through the processing gas introduction means 105 when forming Si compound thin films such as Si ₃ N ₄ and SiO ₂ include inorganic silanes such as SiH ₄ and Si ₂ H _6. , Organic silanes such as tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), octamethylcyclotetrasilane (OMCTS), dimethyldifluorosilane (DMDFS), dimethyldichlorosilane (DMDCS), SiF ₄ , Si ₂ F ₆ , halogenated silanes such as Si ₃ F ₈ , SiHF ₃ , SiH ₂ F ₂ , SiCl ₄ , Si ₂ Cl ₆ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₃ Cl, SiCl ₂ F _2, etc. And those which are in a gas state or can be easily gasified. In this case, the nitrogen source gas or the oxygen source gas introduced at the same time includes N ₂ , NH ₃ , N ₂ H ₄ , hexamethyldisilazane (HMDS), O ₂ , O ₃ , H ₂ O, NO, N ₂ O, NO _{2 and the} like can be mentioned.
As raw materials containing metal atoms introduced through the processing gas introduction means 105 when forming a metal thin film such as Al, W, Mo, Ti, Ta, etc., trimethylaluminum (TMAl), triethylaluminum (TEAl), Organic metals such as triisobutylaluminum (TIBAl), dimethylaluminum hydride (DMAlH), tungsten carbonyl (W (CO) ₆ ), molybdenum carbonyl (Mo (CO) ₆ ), trimethylgallium (TMGa), triethylgallium (TEGa), Examples thereof include metal halides such as AlCl ₃ , WF ₆ , TiCl ₃ , and TaCl ₅ . In this case, H ₂ , He, Ne, Ar, Kr, Xe, and Rn are listed as additive gas or carrier gas that may be introduced by mixing with Si source gas.
As a raw material containing a metal atom introduced through the processing gas introduction means 105 in the case of forming a metal compound thin film such as Al ₂ O ₃ , AlN, Ta ₂ O ₅ , TiO ₂ , TiN, WO ₃ , trimethyl is used. Aluminum (TMAl), triethylaluminum (TEAl), triisobutylaluminum (TIBAl), dimethylaluminum hydride (DMAlH), tungsten carbonyl (W (CO) ₆ ), molybdenum carbonyl (Mo (CO) ₆ ), trimethylgallium (TMGa) And organic metals such as triethylgallium (TEGa) and metal halides such as AlCl ₃ , WF ₆ , TiCl ₃ , and TaCl ₅ . Further, in this case, oxygen source gas or nitrogen source gas to be introduced at the same time includes O ₂ , O ₃ , H ₂ O, NO, N ₂ O, NO ₂ , N ₂ , NH ₃ , N ₂ H ₄ , hexamethyl A disilazane (HMDS) etc. are mentioned.
The etching gas introduced from the processing gas inlet 105 when etching the substrate surface is F ₂ , CF ₄ , CH ₂ F ₂ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , CF _2. Cl ₂ , SF ₆ , NF ₃ , Cl ₂ , CCl ₄ , CH ₂ Cl ₂ , C ₂ Cl _{6 and the} like can be mentioned.

Moreover, the processing method by the processing apparatus of Example 1 of the present invention can be applied to surface modification by appropriately selecting the gas to be used. For example, by using Si, Al, Ti, Zn, Ta or the like as a substrate or a surface layer, oxidation treatment or nitridation treatment of these substrates or surface layers, doping treatment of B, As, P or the like can be performed. Furthermore, the film forming technique employed in the present invention can also be applied to a cleaning method. In that case, it can also be used for cleaning oxides, organic substances, heavy metals, and the like.
Examples of the oxidizing gas introduced through the processing gas inlet 105 when the surface to be processed 102 is oxidized are O ₂ , O ₃ , H ₂ O, NO, N ₂ O, NO _{2 and the} like. . Further, N ₂ , NH ₃ , N ₂ H ₄ , hexamethyldisilazane (HMDS), and the like are introduced as the nitriding gas through the processing gas inlet 115 when the substrate to be processed 102 is nitrided. Can be mentioned.
The cleaning / ashing gas introduced from the processing gas inlet 105 when the organic substance on the surface of the substrate to be processed 102 is cleaned or when the organic component on the surface of the substrate such as a photoresist is removed by ashing includes O ₂ , O ₃ , H ₂ O, NO, N ₂ O, NO ₂ , H _{2 and the} like. The cleaning gas introduced from the processing gas inlet 105 when cleaning the inorganic substance on the surface of the substrate 102 is F ₂ , CF ₄ , CH ₂ F ₂ , C ₂ F ₆ , C ₄ F _8. , CF ₂ Cl ₂ , SF ₆ , NF _{3 and the} like.
Moreover, as an inert gas used for the processing method by the processing apparatus of Example 1 of this invention, noble gases, such as He, Ne, Ar, Kr, and Xe, N2, or those mixed gas is mentioned.

Next, as a second embodiment of the processing apparatus of the present invention, a microwave-excited surface wave interference type plasma apparatus using a slotted endless annular waveguide will be described with reference to FIG.
The processing chamber 201 is a chamber that performs radical processing on a substrate to be processed 202 such as a semiconductor wafer. The exhaust unit 206 is an exhaust port for processing gas that exhausts the inside of the processing chamber 201. The gas introduction unit 205 is a unit that introduces a processing gas into the processing chamber 201. The slotted endless annular waveguide 208 is provided on the upper surface of the processing chamber 201 and is a means for generating neutral radicals in the radical generation region 211 in the upper portion of the processing chamber 201.
The slotted endless annular waveguide 208 introduces microwaves into the processing chamber 201 through the dielectric window 207. The target substrate support unit 203 is a unit that is installed upstream of the gas flow from the radical generation region 211 and supports the target substrate 202. Here, the gas introduction means 205 is provided between the radical generation region 211 and the substrate support means 203 to be processed, and this point is different from the conventional example shown in FIG. The temperature adjusting unit 204 is a unit that adjusts the temperature of the substrate 202 to be processed, and a conductance control unit 209 is provided between the gas introduction unit 205 and the radical generation region 211. Further, a flux uniformizing means 210 may be installed between the gas introducing means 205 and the substrate support means 203 to be processed.
The conductance control means 209 has a flat plate shape, and φ1 to φ3 holes are formed at a pitch of 20 mm. The flux uniformizing means 210 is also plate-shaped, and holes of φ5 to φ10 are formed at a pitch of 20 mm so that the radical flux is uniform.
The slotted endless annular waveguide 208 is TE10 mode, has an inner wall cross-sectional dimension of 27 mm × 96 mm (inner wavelength 158.8 mm), and a waveguide center diameter of 151.6 mm (one round length is three times the inner wavelength). ) Was used. The slotted endless annular waveguide 208 is made of Al alloy in order to suppress microwave propagation loss. A slot for introducing a microwave into the plasma processing chamber 201 is formed on the H surface of the slotted endless annular waveguide 208. The slot is a rectangle having a length of 40 mm and a width of 4 mm, and six slots are radially formed at intervals of 60 ° at a center diameter of 151.6 mm. To the slotted endless annular waveguide 208, a 4E tuner, a directional coupler, an isolator, and a microwave power source (not shown) having a frequency of 2.45 GHz are sequentially connected.
In the plasma processing, first, the inside of the processing chamber 201 is evacuated to a substantially vacuum state via the exhaust means 206. Subsequently, the processing gas is introduced into the processing chamber 201 at a predetermined flow rate through the gas introduction means 205 provided in the processing chamber 201. Next, a conductance valve (not shown) provided in the exhaust unit 206 is adjusted to maintain the inside of the processing chamber 201 at a predetermined pressure. A desired power is supplied from a microwave power source (not shown) through the dielectric window 207 through the slotted endless annular waveguide 208 and supplied into the processing chamber 201.
The processing gas introduced from the periphery is excited by the generated plasma, is ionized and activated, and processes the surface of the substrate to be processed 202 placed on the substrate support 203 to be processed at low speed and high quality.
At this time, many active species such as neutral radicals excited by plasma are exhausted without reaching the substrate 202 to be processed. Only some of the active species that have flowed back through the holes of the conductance control means 201 and the flux uniformizing means 210 and have diffused to the substrate 202 to be treated contribute to the treatment. By changing the gas flow rate and the exhaust conductance and changing the flow rate, the processing speed can be controlled with high accuracy. For example, if oxygen is selected as the introduced gas and a silicon substrate is selected as the substrate to be processed 202, a uniform ultrathin silicon oxide film of several molecular layers Can also be formed.

Here, the ultra-thin gate oxide film of the semiconductor element was formed using the microwave plasma processing apparatus of Example 2 of the present invention shown in FIG.
As the substrate to be processed 202, a φ8 ″ P-type single crystal silicon substrate (plane orientation <100>, resistivity 10 Ωcm) from which the natural oxide film on the surface was removed by cleaning was used. First, the silicon substrate as the substrate to be processed 202 Then, the inside of the processing chamber 201 is evacuated to a value of 10 ⁻⁷ Torr through the exhaust means 206. Subsequently, the heater as the temperature adjusting means 204 is energized. Then, the silicon substrate as the substrate to be processed 202 was heated to 280 ° C., and the substrate to be processed 202 was held at this temperature, and oxygen gas was supplied into the processing chamber 201 through the plasma processing gas inlet 205 at a flow rate of 2000 sccm. Next, a conductance valve (not shown) provided in the exhaust means 206 was adjusted to keep the inside of the processing chamber 201 at 3 Torr, and then 2.4. The power of 1.0kW than GHz microwave power source (not shown) was supplied through the slotted endless annular waveguide 208. Thus, plasma is generated in the processing chamber 201 was subjected to 60 seconds treatment.
At this time, the oxygen gas introduced through the plasma processing gas inlet 205 is excited and decomposed in the processing chamber 201 to become active species such as O ⁺ ions and O radicals. Some of the active species flow back into the gas flow by diffusion, pass through the holes of the conductance control plate 209, and pass through the flux uniformizing plate 210 to be uniform over the entire surface of the silicon substrate as the substrate 202 to be processed. A very small amount of flux is reached.
After the treatment, the film quality such as oxide film thickness, uniformity, and pressure resistance was evaluated. The oxide film thickness was 0.9 nm, the film thickness uniformity was ± 1.5%, and the withstand voltage was 12.5 MV / cm.

Next, using the microwave plasma processing apparatus of Example 2 of the present invention shown in FIG. 2, an ultra-thin gate nitride film of a semiconductor element was formed.
As the substrate to be processed 202, a φ8 ″ P-type single crystal silicon substrate (plane orientation <100>, resistivity 10 Ωcm) from which the natural oxide film on the surface was removed by cleaning was used. First, the silicon substrate as the substrate to be processed 202 Then, the inside of the processing chamber 201 is evacuated to a value of 10 ⁻⁷ Torr through the exhaust means 206. Subsequently, the heater as the temperature adjusting means 204 is energized. Then, the silicon substrate serving as the substrate to be processed 202 was heated to 380 ° C., and the silicon substrate serving as the substrate to be processed 202 was held at this temperature, and nitrogen gas was processed at a flow rate of 700 sccm through the gas inlet for plasma processing 205. Next, the conductance valve (not shown) provided in the exhaust means 206 is adjusted to maintain the inside of the processing chamber 201 at 0.1 Torr. Next, 1.5 kW of electric power was supplied from a 2.45 GHz microwave power source (not shown) through the slotted endless annular waveguide 208. Thus, plasma was generated in the processing chamber 201, and The treatment was performed for 100 seconds.
At this time, the nitrogen gas introduced through the plasma processing gas inlet 205 is excited and decomposed in the processing chamber 201 to become active species such as N2 ⁺ ions and N radicals. Some of the active species flowed back through the holes of the conductance control means 209 and reached the surface of the silicon substrate as the substrate to be processed 202, and the surface of the silicon substrate as the substrate to be processed 202 was nitrided.
After processing, the film quality such as nitride film thickness, uniformity, breakdown voltage, and leakage current was evaluated. The nitride film thickness was 1.3 nm, the film thickness uniformity was ± 1.5%, the withstand voltage was 12.5 MV / cm, and the leakage current was 0.1 mA / cm ² @ 1V, which was good.

Next, surface nitridation of the ultra-thin gate oxide film of the semiconductor element was performed using the microwave plasma processing apparatus of Example 2 of the present invention shown in FIG.
As the substrate to be processed 202, a φ8 ″ P-type single crystal silicon substrate (plane orientation <100>, resistivity 10 Ωcm) with an oxide film having a thickness of 1.2 nm was used. First, the silicon substrate as the substrate to be processed 202 was covered. After being placed on the processing substrate support 203, the inside of the processing chamber 201 was evacuated through the exhaust means 206, and the pressure was reduced to a value of 10 ⁻⁷ Torr. A silicon substrate was heated to 350 ° C., and the silicon substrate as the substrate to be processed 202 was held at this temperature, and nitrogen gas was introduced into the processing chamber 201 through the plasma processing gas inlet 205 at a flow rate of 200 sccm. Next, a conductance valve (not shown) provided in the exhaust unit 206 was adjusted, and the inside of the processing chamber 201 was held at 0.2 Torr. A 1.5 kW electric power was supplied from a chromowave power source (not shown) through the slotted endless annular waveguide 208. Thus, plasma was generated in the radical generation region 211 in the processing chamber 201, and the processing was performed for 30 seconds. went.
At this time, the nitrogen gas introduced through the plasma processing gas inlet 205 is excited and decomposed in the processing chamber 201 to become active species such as N2 ⁺ ions and N radicals. Some of the active species flowed back through the holes of the conductance control means 209 to reach the surface of the silicon substrate as the substrate to be processed 202, and nitrided the oxide film on the surface of the silicon substrate as the substrate to be processed 202.
After the treatment, the film quality such as oxynitride film thickness, uniformity, breakdown voltage, and leakage current was evaluated. The oxide film equivalent film thickness was 1.0 nm, the film thickness uniformity was ± 1.9%, the withstand voltage was 13.9 MV / cm, and the leakage current was 0.2 mA / cm ² @ 1V.

Next, an ultraviolet light excited radical processing apparatus according to Example 3 of the present invention will be described with reference to FIG.
The processing chamber 301 is a chamber for performing radical processing on a substrate to be processed 302 such as a semiconductor wafer. The exhaust means 306 is an exhaust port for processing gas that exhausts the inside of the processing chamber 301. The gas introduction unit 305 is a unit that introduces a processing gas into the processing chamber 301. An ultraviolet light source 308 that is a neutral radical generating unit is a unit that is provided in the upper part of the processing chamber 301 and generates neutral radicals in the radical generation region 311 in the upper part of the processing chamber 301.
The ultraviolet light source 308 emits ultraviolet light when power is applied. The processing gas is excited by the ultraviolet light to generate radicals. The target substrate support unit 303 is a unit that is installed upstream of the gas flow with respect to the radical generation region 311 and supports the target substrate 302. Here, the gas introducing means 305 is provided between the radical generation region 311 and the substrate support means 303 to be processed, and this point is different from the conventional example shown in FIG. The temperature adjusting means 304 is a means for adjusting the temperature of the substrate 302 to be processed, and a conductance control means 309 is provided between the gas introduction means 305 and the radical generation region 311. Further, a flux uniformizing means 310 may be installed between the gas introducing means 305 and the substrate support means 303 to be processed.
The conductance control means 309 has an aluminum plate shape, and φ3 to φ5 holes are formed at a pitch of 20 mm. The flux uniformizing means 210 is also plate-shaped, and holes of φ5 to φ10 are formed at a pitch of 20 mm so that the radical flux is uniform.
As the ultraviolet light source 308 which is an ultraviolet light excitation means, any light source can be applied as long as it can emit light having energy that can be excited to a desired radical state. For example, a light source such as a xenon short arc lamp, a xenon flash lamp, a short arc type ultrahigh pressure mercury lamp, a capillary lamp, a long arc lamp, a low pressure mercury lamp, a deep UV lamp, a metal halide lamp, an excimer lamp, a nitrogen laser, and an excimer laser can be used. When an excimer lamp is used, the emission center wavelength varies depending on the sealing gas such as F ₂ , Cl ₂ , Br ₂ , I ₂ , ArBr, KrBr, XeBr, ArCl, KrCl, XeCl, ArF, KrF, XeF, and XeI. Among them, it is preferable to select one that can efficiently emit light having a wavelength most suitable for generating radicals.
In the radical treatment, first, the inside of the processing chamber 301 is evacuated to a substantially vacuum state via the exhaust means 306. Subsequently, the processing gas is introduced into the processing chamber 301 at a predetermined flow rate through the gas introduction means 305 provided around the processing chamber 301. Next, a conductance valve (not shown) provided in the exhaust unit 306 is adjusted to maintain the inside of the processing chamber 301 at a predetermined pressure. A desired power is input to the ultraviolet light source 308 to emit ultraviolet light.
The processing gas introduced from the periphery is excited by the emitted ultraviolet light and processes the surface of the substrate 302 to be processed placed on the substrate support 303 to be processed at a low speed and with high quality.
At this time, most of the neutral radicals excited by the ultraviolet light are exhausted without reaching the substrate to be processed 302. Only some of the active species that have flowed back through the holes of the conductance control means 309 and the flux uniformization means 310 and have diffused to the substrate to be treated 302 contribute to the treatment. By changing the flow rate by changing the gas flow rate and the exhaust conductance, for example, if oxygen is selected as the introduced gas and a silicon substrate is selected as the substrate to be processed 302, a uniform ultrathin silicon oxide film of several molecular layers can be formed.

Here, the ultra-thin gate oxide film formation of a semiconductor element was performed using the ultraviolet light excitation radical processing apparatus of Example 3 of this invention shown in FIG.
A φ8 ″ P-type single crystal silicon substrate (plane orientation <100>, resistivity 10 Ωcm) was used as the substrate 302 to be processed. First, a silicon substrate as the substrate 302 to be processed was placed on the substrate support 303 to be processed. The inside of the processing chamber 301 was evacuated through the exhaust unit 306 and the pressure was reduced to a value of 10 ⁻⁷ Torr, and then the heater serving as the temperature adjusting unit 304 was energized, and the silicon substrate serving as the substrate 302 was processed. The substrate was heated to 450 ° C., and the silicon substrate serving as the substrate to be processed 302 was held at this temperature, and oxygen gas was introduced into the treatment chamber 301 through the radical treatment gas inlet 305 at a flow rate of 1000 sccm. A conductance valve (not shown) provided in 306 was adjusted to maintain the inside of the processing chamber 301 at 1 Torr. The silver lamp was supplied with 300 W of power to emit ultraviolet light, and 254 nm of the ultraviolet light emitted from the low-pressure mercury lamp, which is the ultraviolet light source 308, dissociated oxygen gas into active singlet oxygen atoms. Thus, atomic oxygen radicals were generated in the radical generation region 311 in the processing chamber 301. A part of the radical oxygen radicals was transported toward the silicon substrate as the substrate 302 to be processed against the flow of the introduced gas. As a result, the surface of the silicon substrate as the substrate to be processed 302 was oxidized by about 0.8 nm.
After processing, the uniformity, breakdown voltage, and leakage current were evaluated. The uniformity was as good as ± 1.3%, the withstand voltage was 10.9 MV / cm, and the leakage current was 1.3 mA / cm ² @ 1V.

Next, a radical processing apparatus according to a fourth embodiment of the present invention that does not use flux uniformizing means will be described with reference to FIG.
2 differs from the second embodiment of the present invention shown in FIG. 2 only in that the flux uniformizing means 210 is not provided, and the radical treatment method is the same as that of the first embodiment of the present invention shown in FIG.
At this time, the processing gas introduced from the gas introduction unit 405 passes through the through hole of the conductance control unit 409 and is exhausted from the exhaust unit. In the vicinity of the substrate to be processed 402, the influence of the gas flow caused by the introduced gas is small, and the radicals that have flowed back due to diffusion reach the substrate with a uniform in-plane distribution. Of course, the processing speed can be controlled by changing the flow rate by changing the gas flow rate and the exhaust conductance.

Here, a radical processing apparatus which is a microwave plasma processing apparatus of Example 4 of the present invention which does not use the flux uniformizing means shown in FIG. 4 was used to form a titanium oxide film for semiconductor element capacitor insulation.
A φ8 ″ P-type single crystal silicon substrate (plane orientation <100>, resistivity 10 Ωcm) was used as the substrate to be processed 402. First, a silicon substrate as the substrate to be processed 402 was placed on the substrate support 403 to be processed. The inside of the processing chamber 401 was evacuated through the exhaust unit 406, and the pressure was reduced to a value of 10 ⁻⁷ Torr, and then the heater serving as the temperature adjusting unit 404 was energized, and the silicon substrate serving as the substrate to be processed 402 was removed. The silicon substrate as the substrate to be processed 402 was held at this temperature by heating to 300 ° C. TiCl ₄ vapor was supplied at a flow rate of 200 sccm through the gas inlet for plasma processing 405 and Ar carrier gas. It was introduced into the processing chamber 401 at a flow rate of 10 sccm, and then a conductance valve (not shown) provided in the exhaust means 406 was adjusted to The inside of 401 was kept at 50 mTorr, and then 2.0 kW of electric power was supplied from a 2.45 GHz microwave power source into the processing chamber 401 through the annular waveguide 403. Thus, the radical generation region in the processing chamber 401 Radicals were generated in 411. The source gas introduced through the plasma processing gas inlet 405 was excited and decomposed in the processing chamber 401 and transported in the direction of the silicon substrate, which is the substrate to be processed 402, to form titanium oxide. A film was formed with a thickness of 5 nm on a silicon substrate which is the substrate to be processed 402.
After the treatment, the uniformity and pressure resistance were evaluated. The uniformity was as good as ± 2.7% and the breakdown voltage was good at 8.2 MV / cm.

It is sectional drawing of the radical processing apparatus of Example 1 of this invention. It is sectional drawing of the radical processing apparatus of Example 2 of this invention. It is sectional drawing of the radical processing apparatus of Example 3 of this invention. It is sectional drawing of the radical processing apparatus of Example 4 of this invention. It is sectional drawing of the radical processing apparatus of a prior art example.

Explanation of symbols

101, 201, 301, 401, 501 Processing chambers 102, 202, 302, 402, 502 Substrate to be processed 103, 203, 303, 403, 503 Substrate support 104, 204, 304, 404, 504 Substrate temperature adjusting means 105, 205, 305, 405, 505 Processing gas introduction means 106, 206, 306, 406, 506 Exhaust means 207, 407 Dielectric windows 108, 208, 308, 408, 508 Radical generation means 109, 209, 309, 409, 509 Conductance control means 110, 210, 310 Flux equalization means

Claims (8)

A processing chamber for storing a substrate to be processed;
Radical generating means for generating neutral radicals in the processing chamber;
In a processing apparatus having a target substrate support means for supporting the target substrate in the processing chamber,
Gas introducing means for introducing a processing gas between the radical generation region and the substrate to be processed;
A processing apparatus comprising: a gas discharge unit configured to discharge the processing gas between the radical generation region and the gas introduction unit.   The processing apparatus according to claim 1, further comprising a conductance adjusting unit between the gas introducing unit and the plasma generation region.   The processing apparatus according to claim 1, further comprising a flux uniformizing unit between the gas introducing unit and the substrate support unit.   4. A processing apparatus according to claim 3, wherein said flux uniformizing means comprises a plate having a plurality of holes.   The processing apparatus according to claim 1, wherein the plasma is generated by microwaves.   The processing apparatus according to claim 1, wherein the plasma is generated by ultraviolet light.   The processing apparatus according to claim 6, wherein the conductance adjusting unit and / or the flux uniformizing unit is made of a material opaque to the ultraviolet light. In a treatment method for generating a neutral radical in a treatment chamber and radical-treating a substrate to be treated,
A processing gas is introduced between the substrate to be processed and the radical generation region, and the processing gas is discharged from between the radical generation region and the introduction portion of the processing gas. Method.

Images