Film forming method and film forming apparatus

Abstract

This disclosure provides a film-forming method and an apparatus, which are technologies capable of increasing the grain size of polycrystalline silicon films. One aspect of the film-forming method includes the following steps: preparing a substrate; forming an amorphous silicon film on the substrate; and crystallizing the amorphous silicon film. The step of forming the amorphous silicon film includes the following processes: supplying the substrate with a first processing gas comprising a silicon-containing gas and a phosphorus-containing gas; supplying the substrate with a second processing gas comprising a silicon-containing gas and a carbon-containing gas; and supplying the substrate with a third processing gas comprising the silicon-containing gas but not the phosphorus-containing gas or the carbon-containing gas. The supply of the first processing gas is performed at the beginning or midway through the step of forming the amorphous silicon film.

Description

Technical Field

[0001] This disclosure relates to a film-forming method and a film-forming apparatus. Background Technology

[0002] Patent document 1 discloses the following: After forming a multilayer film consisting of an interface layer, a main layer, and a surface layer in sequence on a substrate, a polycrystalline silicon film is formed by crystallizing the multilayer film.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-106217 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a technique for increasing the grain size of polycrystalline silicon films.

[0008] Solution for solving the problem

[0009] One aspect of the film formation method disclosed herein includes the following steps: preparing a substrate; forming an amorphous silicon film on the substrate; and crystallizing the amorphous silicon film, wherein the step of forming the amorphous silicon film includes the following processes: supplying the substrate with a first processing gas comprising a silicon-containing gas and a phosphorus-containing gas; supplying the substrate with a second processing gas comprising a silicon-containing gas and a carbon-containing gas; and supplying the substrate with a third processing gas comprising the silicon-containing gas but not the phosphorus-containing gas and the carbon-containing gas, wherein the process of supplying the first processing gas is performed at the beginning or in the middle of the step of forming the amorphous silicon film.

[0010] The effects of the invention

[0011] According to this disclosure, it is possible to increase the grain size of polycrystalline silicon films. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the film-forming method involved in the embodiment.

[0013] Figure 2 This is a cross-sectional view (1) showing the film-forming method involved in the embodiment.

[0014] Figure 3 This is a cross-sectional view (2) showing the film-forming method involved in the embodiment.

[0015] Figure 4 This is a cross-sectional view (3) showing the film-forming method involved in the embodiment.

[0016] Figure 5 This is a cross-sectional view (4) showing the film-forming method involved in the embodiment.

[0017] Figure 6 This is a cross-sectional view (5) showing the film-forming method involved in the embodiment.

[0018] Figure 7 Figure (1) shows the crystallization process of amorphous silicon films.

[0019] Figure 8 Figure (2) shows the crystallization process of amorphous silicon films.

[0020] Figure 9 This is a vertical cross-sectional view showing the film-forming apparatus involved in the embodiment.

[0021] Figure 10 This is a horizontal cross-sectional view showing the film-forming apparatus involved in the embodiment.

[0022] Figure 11 This is a schematic diagram showing the sample produced through experiments.

[0023] Figure 12 Figure (1) shows the grain size of the polycrystalline silicon film.

[0024] Figure 13 Figure (2) shows the grain size of the polycrystalline silicon film. Detailed Implementation

[0025] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding components or parts are labeled with the same or corresponding reference numerals, and repeated descriptions are omitted.

[0026] [Film Formation Method]

[0027] Figure 1 This is a flowchart illustrating the film-forming method involved in the embodiment. Figures 2 to 6 This is a cross-sectional view illustrating the film-forming method according to the embodiments. The film-forming method according to the embodiments includes... Figure 1 Steps S1 to S4 are shown.

[0028] In step S1, as Figure 2 As shown, a substrate 100 is prepared. The substrate 100 has a base substrate 110 and an insulating film 120. The base substrate 110 is, for example, a silicon substrate. The insulating film 120 is disposed on the surface of the substrate 100. The insulating film 120 is disposed on the base substrate 110. The insulating film 120 is, for example, a silicon oxide film. The insulating film 120 may also be a silicon nitride film or a silicon oxynitride film.

[0029] In step S2, as Figure 3As shown, a seed layer 130 is formed on the insulating film 120. The seed layer 130 is a layer used to facilitate the formation of an amorphous silicon film on the insulating film 120 in step S3. The seed layer 130 is, for example, a laminated film in which a first seed layer and a second seed layer are sequentially stacked. For example, the first seed layer can be formed by chemical vapor deposition (CVD) using an aminosilane-based gas. The aminosilane-based gas is, for example, DIPAS (diisopropylaminosilane), 3DMAS (tris(dimethylamino)silane), BTBAS (bis(tert-butylamino)silane), or combinations thereof. For example, the second seed layer can be formed by chemical vapor deposition using a higher-order silane-based gas. A higher-order silane-based gas refers to a silane-based gas containing two or more silicon (Si) atoms in one molecule. Higher-order silane-based gases are, for example, diisosilane (Si2H6) gas, propane (Si3H8) gas, butane (Si4H6) gas, etc. 10 ( ) gas or combinations thereof. The seed layer 130 is not limited to the aforementioned laminated films. The seed layer 130 can be a single-layer film of the first seed layer. The seed layer 130 can also be a single-layer film of the second seed layer.

[0030] In step S3, an amorphous silicon film is formed on the seed layer 130. The amorphous silicon film can be as follows: Figure 4 As shown, a laminated film 140 is formed by sequentially stacking an amorphous silicon film 141 with added phosphorus (P), an amorphous silicon film 142 without added impurities, an amorphous silicon film 143 with added carbon, and an amorphous silicon film 144 without added impurities.

[0031] An amorphous silicon film 141 forms the lower surface of the laminated film 140. The amorphous silicon film 141 is in contact with the seed layer 130. The thickness of the amorphous silicon film 141 can be greater than 1 nm and less than 3 nm, for example, 2 nm. The amorphous silicon film 141 can be formed by chemical vapor deposition using a first processing gas containing silicon-containing gas and phosphorus-containing gas.

[0032] An amorphous silicon film 142 is disposed midway along the thickness direction of the laminated film 140. The amorphous silicon film 142 is in contact with the amorphous silicon film 141. The thickness of the amorphous silicon film 142 can be 3 nm or more and 8 nm or less, for example, 5.5 nm. The amorphous silicon film 142 can be formed by chemical vapor deposition using a third processing gas containing silicon gas but excluding phosphorus-containing gas and carbon-containing gas.

[0033] An amorphous silicon film 143 is disposed midway along the thickness direction of the laminated film 140. The amorphous silicon film 143 is in contact with the amorphous silicon film 142. The thickness of the amorphous silicon film 143 can be greater than 1 nm and less than 3 nm, for example, 2 nm. The amorphous silicon film 143 can be formed by chemical vapor deposition using a second processing gas containing a silicon-containing gas and a carbon-containing gas.

[0034] An amorphous silicon film 144 forms the upper surface of the laminated film 140. The amorphous silicon film 144 is in contact with the amorphous silicon film 143. The thickness of the amorphous silicon film 144 can be greater than 5 nm and less than 10 nm, for example, 7.5 nm. The amorphous silicon film 144 can be formed using the same method as the amorphous silicon film 142.

[0035] In this way, it is possible to form a chemical vapor deposition system by initially performing chemical vapor deposition using a first processing gas, then performing chemical vapor deposition using a second processing gas midway through the process, and finally performing chemical vapor deposition using a third processing gas. Figure 4 The laminated film 140 shown can be formed by sequentially performing chemical vapor deposition using a first processing gas, a third processing gas, a second processing gas, and a third processing gas. Figure 4 The laminated film 240 shown.

[0036] Amorphous silicon films can also be like... Figure 5 As shown, a laminated film 240 consists of an amorphous silicon film 241 without impurities, an amorphous silicon film 242 with added phosphorus and carbon, and an amorphous silicon film 243 without impurities, stacked sequentially.

[0037] An amorphous silicon film 241 forms the lower surface of the laminated film 240. The amorphous silicon film 241 is in contact with the seed layer 130. The thickness of the amorphous silicon film 241 can be 5 nm or more and 10 nm or less, for example, 7.5 nm. The amorphous silicon film 241 can be formed by chemical vapor deposition using a third processing gas containing silicon gas but not phosphorus gas or carbon gas.

[0038] An amorphous silicon film 242 is disposed midway along the thickness direction of the laminated film 240. The amorphous silicon film 242 is in contact with the amorphous silicon film 241. The thickness of the amorphous silicon film 242 can be greater than 1 nm and less than 3 nm, for example, 2 nm. The amorphous silicon film 242 can be formed by chemical vapor deposition using a fourth processing gas containing silicon-containing gas, phosphorus-containing gas, and carbon-containing gas.

[0039] Amorphous silicon film 243 forms the upper surface of the laminated film 240. Amorphous silicon film 243 is in contact with amorphous silicon film 242. The thickness of amorphous silicon film 243 can be greater than 5 nm and less than 10 nm, for example, 7.5 nm. Amorphous silicon film 243 can be formed using the same method as amorphous silicon film 241.

[0040] In this way, it is possible to form a chemical vapor deposition system that initially uses a third processing gas, then uses a fourth processing gas midway through the process, and finally uses a third processing gas at the end. Figure 5The laminated film 240 shown can be formed by sequentially performing chemical vapor deposition using a third processing gas, chemical vapor deposition using a fourth processing gas, and chemical vapor deposition using the third processing gas again. Figure 5 The laminated film 240 shown.

[0041] Silicon-containing gases include, for example, silane. Other examples include silane, propane, and dichlorosilane. Phosphorus-containing gases include, for example, phosphine (PH3). Phosphorus-containing gases may also be phosphorus trichloride. Carbon-containing gases include, for example, ethylene (C2H4). Other examples include ethane, methane, acetylene, propane, propylene, butane, and butadiene.

[0042] In step S4, the amorphous silicon film (layered films 140, 240) formed in step S3 is crystallized by heat treatment of the substrate 100. Thus, as... Figure 6 As shown, a polycrystalline silicon film 150 is formed from a seed layer 130 and an amorphous silicon film (layered films 140, 240). The atmosphere at which the substrate 100 is heat-treated in step S4 is, for example, an inert gas atmosphere at atmospheric pressure. There is no particular limitation on the type of inert gas; for example, nitrogen (N2) gas. The atmosphere at which the substrate 100 is heat-treated can also be a reduced-pressure atmosphere.

[0043] Figure 7 and Figure 8 This is a diagram illustrating the crystallization process of an amorphous silicon film. In Figure 7 and Figure 8 The image shows a schematic representation of a grain CG.

[0044] like Figure 7 As shown, consider the case where a substrate on which a seed layer 130, an amorphous silicon film 142 without impurities, and a native oxide film 160 are sequentially stacked on an insulating film 120 undergoes heat treatment. In this case, crystal growth of the amorphous silicon film 142 from the seed layer 130 side is advantageous compared to crystal growth of the amorphous silicon film 142 from the native oxide film 160 side. However, crystal nuclei also form in the amorphous silicon film 142. The crystal nuclei formed in the amorphous silicon film 142 hinder crystal growth of the amorphous silicon film 142 from the seed layer 130 side.

[0045] like Figure 8As shown, consider the case where a substrate on which a seed layer 130, a phosphorus-added amorphous silicon film 141, an impurity-free amorphous silicon film 142, a carbon-added amorphous silicon film 143, an impurity-free amorphous silicon film 144, and a native oxide film 160 are sequentially stacked on an insulating film 120 undergoes heat treatment. The phosphorus-added amorphous silicon film 141 has properties that promote crystallization. Therefore, it promotes the crystallization of the stacked film 140 from the seed layer 130 side. Consequently, crystal growth of the stacked film 140 from the seed layer 130 side is more advantageous than crystal growth of the stacked film 140 from the native oxide film 160 side compared to the case without the amorphous silicon film 141. The carbon-added amorphous silicon film 143 has properties that suppress the formation of crystal nuclei. Therefore, the formation of crystal nuclei in the stacked film 140 is suppressed. Thus, it is difficult to hinder crystal growth of the stacked film 140 from the seed layer 130 side. As a result, compared to the absence of amorphous silicon film 141 and amorphous silicon film 143, the grain size of polycrystalline silicon film 150 can be increased.

[0046] As explained above, according to the film formation method of the embodiment, in step S3, a stacked film 140, 240 is formed on the seed layer 130, and then in step S4, the stacked films 140, 240 are heat-treated to crystallize them. The stacked films 140, 240 have phosphorus-added amorphous silicon films 141, 242, carbon-added amorphous silicon films 143, 242, and unadded amorphous silicon films 142, 144, 241, 243. The phosphorus-added amorphous silicon film 141 forms the lower surface of the stacked film 140. The phosphorus-added amorphous silicon film 242 is disposed in the middle of the stacked film 240. In this case, crystal growth of the stacked films 140, 240 from the seed layer 130 side is advantageous, and the formation of crystal nuclei in the films 140, 240 is suppressed. As a result, the grain size of the polycrystalline silicon film 150 can be increased.

[0047] [Film-forming device]

[0048] Figure 9 This is a vertical cross-sectional view showing the film-forming apparatus 1 according to the embodiment. Figure 10 This is a horizontal cross-sectional view showing the film-forming apparatus 1 according to the embodiment.

[0049] Film deposition apparatus 1 is a batch processing apparatus that processes multiple substrates W at once. The substrates W are, for example, semiconductor wafers. Film deposition apparatus 1 includes a processing container 10, a gas supply unit 30, an exhaust unit 40, a heating unit 50, and a control unit 90.

[0050] The interior of the processing container 10 is capable of depressurization. The processing container 10 houses the substrate W. The processing container 10 has an inner tube 11 and an outer tube 12. The inner tube 11 has a topped cylindrical shape that is open at the lower end. The outer tube 12 has a topped cylindrical shape that is open at the lower end and covers the outside of the inner tube 11. The inner tube 11 and the outer tube 12 are formed of a heat-resistant material such as quartz. The inner tube 11 and the outer tube 12 have a double-tube structure arranged coaxially.

[0051] A receiving portion 13 for accommodating the gas supply pipe is formed on the side wall of the inner tube 11 along the long side direction (vertical direction). For example, a portion of the side wall of the inner tube 11 is made to protrude outward to form a protrusion 14, and the receiving portion 13 is formed inside the protrusion 14.

[0052] A rectangular opening 15 is formed on the side wall of the inner tube 11 along the long side. The opening 15 faces the receiving part 13.

[0053] The opening 15 is a gas exhaust port formed to exhaust gas from the inner tube 11. The length of the opening 15 is the same as the length of the wafer boat 16, or it is formed to be longer than the length of the wafer boat 16 and extends in the upward and downward directions respectively.

[0054] The lower end of the processing container 10 is supported by a cylindrical manifold 17. The manifold 17 is made of, for example, stainless steel. A flange 18 is formed at the upper end of the manifold 17. The flange 18 supports the lower end of the outer tube 12. A sealing member 19, such as an O-ring, is provided between the flange 18 and the lower end of the outer tube 12. Thus, the interior of the outer tube 12 is maintained airtight.

[0055] A ring-shaped support portion 20 is provided on the inner wall of the upper part of the manifold 17. The support portion 20 supports the lower end of the inner tube 11. The cover 21 is airtightly installed at the opening at the lower end of the manifold 17 via a sealing member 22 such as an O-ring. Thus, the opening at the lower end of the processing container 10, i.e., the opening of the manifold 17, is airtightly sealed. The cover 21 is, for example, made of stainless steel.

[0056] A rotating shaft 24 is provided through the center of the cover 21 via a magnetic fluid seal 23. The lower part of the rotating shaft 24 is supported by the arm 25A of the lifting mechanism 25, which is composed of a wafer boat lifting mechanism, in a rotatable manner.

[0057] A rotating plate 26 is provided at the upper end of the rotating shaft 24. A wafer boat 16 holding substrates W is placed on the rotating plate 26 via a quartz-made warming stage 27. The wafer boat 16 rotates by rotating the rotating shaft 24. The wafer boat 16 and the cover 21 move up and down together by lifting the lifting mechanism 25. Thus, the wafer boat 16 can be inserted and removed from the processing container 10. The wafer boat 16 can be housed in the processing container 10. The wafer boat 16 holds multiple (e.g., 50 to 150) substrates W in a shelf-like manner. The wafer boat 16 holds multiple substrates W approximately horizontally with spacing in the vertical direction.

[0058] The gas supply unit 30 is configured to introduce various processing gases into the inner tube 11. The gas supply unit 30 includes a silicon raw material supply unit 31, a phosphorus raw material supply unit 32, and a carbon raw material supply unit 33.

[0059] The silicon raw material supply unit 31 has a gas supply pipe 31a inside the processing container 10 and a supply flow path 31b outside the processing container 10. In the supply flow path 31b, a silicon raw material source 31c, a mass flow controller 31d, and a valve 31e are arranged sequentially from upstream to downstream in the gas flow direction. The valve 31e controls the timing of the supply of silicon-containing gas from the silicon raw material source 31c, and the mass flow controller 31d adjusts the flow rate of the silicon-containing gas from the silicon raw material source 31c to a predetermined flow rate. The silicon-containing gas flows from the supply flow path 31b into the gas supply pipe 31a and is ejected from the gas supply pipe 31a into the processing container 10.

[0060] The phosphorus feedstock supply unit 32 includes a gas supply pipe 32a inside the processing container 10 and a supply flow path 32b outside the processing container 10. In the supply flow path 32b, a phosphorus feedstock source 32c, a mass flow controller 32d, and a valve 32e are arranged sequentially from upstream to downstream in the gas flow direction. The valve 32e controls the timing of the supply of phosphorus-containing gas from the phosphorus feedstock source 32c, and the mass flow controller 32d adjusts the flow rate of the phosphorus-containing gas from the phosphorus feedstock source 32c to a predetermined flow rate. The phosphorus-containing gas flows from the supply flow path 32b into the gas supply pipe 32a and is ejected from the gas supply pipe 32a into the processing container 10.

[0061] The carbon feedstock supply unit 33 has a gas supply pipe 33a inside the processing container 10 and a supply flow path 33b outside the processing container 10. In the supply flow path 33b, a carbon feedstock source 33c, a mass flow controller 33d, and a valve 33e are arranged sequentially from upstream to downstream in the gas flow direction. The valve 33e controls the timing of the supply of carbon-containing gas from the carbon feedstock source 33c, and the mass flow controller 33d adjusts the flow rate of the carbon-containing gas from the carbon feedstock source 33c to a predetermined flow rate. The carbon-containing gas flows from the supply flow path 33b into the gas supply pipe 33a and is ejected from the gas supply pipe 33a into the processing container 10.

[0062] Each gas supply pipe 31a, 32a, and 33a is fixed to the manifold 17. Each gas supply pipe 31a, 32a, and 33a is, for example, formed of quartz. Each gas supply pipe 31a, 32a, and 33a extends linearly in the vertical direction near the inner tube 11, and then bends in an L-shape within the manifold 17 and extends horizontally, thereby penetrating the manifold 17. The gas supply pipes 31a, 32a, and 33a are arranged circumferentially around the inner tube 11 and are formed at the same height position.

[0063] Multiple air holes 31f, 32f, and 33f are respectively provided in the portions of the gas supply pipes 31a, 32a, and 33a located within the inner pipe 11. Each air hole 31f, 32f, and 33f is formed at predetermined intervals along the extending direction of each gas supply pipe 31a, 32a, and 33a. Each air hole 31f, 32f, and 33f horizontally ejects gas from the outer side of the substrate W in the radial direction toward the substrate W. Each air hole 31f, 32f, and 33f ejects gas parallel to the main surface of the substrate W. The spacing between the air holes is, for example, set to be the same as the spacing between the substrates W held in the wafer boat 16. The position of each air hole in the height direction is, for example, set at the midpoint between adjacent substrates W in the vertical direction. In this case, each air hole can efficiently supply gas to the opposing surfaces between adjacent substrates W.

[0064] The gas supply unit 30 can also mix multiple gases and eject the mixed gas from a gas supply pipe. The gas supply pipes 31a, 32a, and 33a can also have different shapes and arrangements. The gas supply unit 30 may also include a gas supply pipe for supplying other gases, such as inactive gases.

[0065] The exhaust section 40 exhausts the gas that exits from the inner pipe 11 through the opening 15 and through the space P1 between the inner pipe 11 and the outer pipe 12, exiting through the gas outlet 41. The gas outlet 41 is formed on the upper side wall of the manifold 17 and above the support 20. An exhaust flow path 42 is connected to the gas outlet 41. A pressure regulating valve 43 and a vacuum pump 44 are sequentially arranged in the exhaust flow path 42 to exhaust gas from the processing container 10.

[0066] A heating element 50 is disposed around the outer tube 12. The heating element 50 is, for example, disposed on the base plate 28. The heating element 50 has a cylindrical shape to cover the outer tube 12. The heating element 50 includes, for example, a heating element to heat each substrate W within the processing container 10.

[0067] The control unit 90 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control unit 90 executes various control actions described in this application specification by executing instruction codes stored in memory or by designing circuits for specific applications.

[0068] [Operation of the film-forming device]

[0069] This section describes the operation of the film-forming apparatus 1 when the film-forming method described in the embodiment is implemented in the film-forming apparatus 1. The operation of the film-forming apparatus 1 shown below is performed under the control of the control unit 90.

[0070] First, the lifting mechanism 25 moves the wafer boat 16, which holds multiple substrates W, into the processing container 10, and the cover 21 seals the lower opening of the processing container 10 airtightly. Next, the exhaust unit 40 depressurizes the pressure inside the processing container 10, and the heating unit 50 adjusts the temperature of the substrates W to a predetermined temperature. Each substrate W can be the substrate 100 described above.

[0071] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to sequentially execute steps S2, S3, and S4 of the film-forming method according to the embodiment.

[0072] Next, the control unit 90 pressurizes the processing container 10 to atmospheric pressure and cools the processing container 10 to the removal temperature, and then controls the lifting mechanism 25 to remove the wafer boat 16 from the processing container 10.

[0073] [Experimental Results]

[0074] Figure 11 This is a schematic diagram showing the sample produced through experiments. Figure 11 In this document, silicon oxide film, as an example of an insulating film, is referred to as "SiO2," and the seed layer is referred to as "Seed." Furthermore, amorphous silicon film with added phosphorus is referred to as "P-doped Si," amorphous silicon film with added carbon is referred to as "C-doped Si," and amorphous silicon film with both added phosphorus and carbon is referred to as "C&P-doped Si." Additionally, amorphous silicon film without added impurities is referred to as "Non-doped Si."

[0075] In the experiment, firstly, a... Figure 11 The samples shown are X, A, and B.

[0076] Sample X has a stacked structure consisting of a silicon oxide film, a seed layer, and an amorphous silicon film without added impurities, stacked sequentially. The seed layer has a thickness of 2 nm. The amorphous silicon film without added impurities has a thickness of 17 nm.

[0077] Sample A has a stacked structure consisting of a silicon oxide film, a seed layer, an amorphous silicon film without impurities, an amorphous silicon film with phosphorus and carbon, and another amorphous silicon film without impurities, stacked sequentially. The seed layer has a thickness of 2 nm. The amorphous silicon films without impurities all have a thickness of 7.5 nm. The amorphous silicon films with phosphorus and carbon have a thickness of 2 nm. The peak phosphorus concentration of the amorphous silicon films with phosphorus and carbon is 1 × 10⁻⁶. 21 cm -3 The peak carbon concentration of the amorphous silicon film with added phosphorus and carbon was 8 × 10⁻⁶. 20 cm -3 .

[0078] Sample B has a stacked structure consisting of a silicon oxide film, a seed layer, a phosphorus-added amorphous silicon film, an unadded amorphous silicon film, a carbon-added amorphous silicon film, and another unadded amorphous silicon film. The seed layer has a thickness of 2 nm. The phosphorus-added amorphous silicon film has a thickness of 2 nm. The unadded amorphous silicon film, located between the phosphorus-added and carbon-added amorphous silicon films, has a thickness of 5.5 nm. The carbon-added amorphous silicon film has a thickness of 2 nm. The unadded amorphous silicon film, located on top of the carbon-added amorphous silicon film, has a thickness of 7.5 nm. The peak phosphorus concentration of the phosphorus-added amorphous silicon film is 1 × 10⁻⁶. 21 cm -3 The peak carbon concentration of the carbon-added amorphous silicon film was 8 × 10⁻⁶. 20 cm -3 .

[0079] Next, for samples X, A, and B, the amorphous silicon film was crystallized to form a polycrystalline silicon film by heat treatment at 620°C for 36 hours under a nitrogen atmosphere at atmospheric pressure. Then, the grain size distribution of the polycrystalline silicon film of each sample (X, A, and B) was obtained by electron backscatter diffraction (EBSD). Furthermore, the weighted average and average grain size were calculated based on the grain size distribution maps.

[0080] Figure 12 and Figure 13 This is a diagram showing the grain size of a polycrystalline silicon film. Figure 12 The relative values ​​of the weighted average values ​​of the polycrystalline silicon of sample A and sample B are shown when the weighted average value of the grain size of the polycrystalline silicon film of sample X is set to 1. Figure 13 The relative values ​​of the average values ​​of the polycrystalline silicon in samples A and B are shown when the average grain size of the polycrystalline silicon film of sample X is set to 1.

[0081] like Figure 12 As shown, the weighted average grain size of the polycrystalline silicon film in sample A is approximately 2.4 times that of the weighted average grain size of the polycrystalline silicon film in sample X. Figure 13 As shown, the average grain size of the polycrystalline silicon film in sample A is approximately 1.06 times the average grain size of the polycrystalline silicon film in sample X. Based on these results, it can be concluded that by placing an amorphous silicon film with added phosphorus and carbon at a midpoint in the thickness direction of the laminated structure, the grain size of the polycrystalline silicon film can be increased compared to the case where an amorphous silicon film without added phosphorus and carbon is not present.

[0082] like Figure 12 As shown, the weighted average grain size of the polycrystalline silicon film in sample B is approximately 4.4 times that of the weighted average grain size of the polycrystalline silicon film in sample X. Figure 13 As shown, the average grain size of the polycrystalline silicon film in sample B is approximately 1.14 times the average grain size of the polycrystalline silicon film in sample X. Based on these results, it can be concluded that by placing an amorphous silicon film with phosphorus added at the contact position with the seed layer and placing an amorphous silicon film with carbon added at the midpoint of the thickness direction of the laminated structure, the grain size of the polycrystalline silicon film can be significantly increased.

[0083] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The above embodiments may also be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0084] In the above embodiments, the film-forming apparatus is described as a batch-type apparatus that processes multiple substrates at once, but this disclosure is not limited to this. For example, the film-forming apparatus may also be a single-sheet-type apparatus that processes substrates one by one. For example, the film-forming apparatus may also be a semi-batch-type apparatus that processes substrates by rotating a rotary table on which multiple substrates are placed, causing each substrate to revolve, and repeatedly passing the substrates through a supply area of ​​processing gas arranged along the radial direction of the rotary table.

[0085] Explanation of reference numerals in the attached figures

[0086] 100: Substrate; 140, 240: Laminated films.

Claims

1. A film-forming method, comprising the following steps: Prepare the substrate; An amorphous silicon film is formed on the substrate; and Crystallize the amorphous silicon film. in, The process of forming the amorphous silicon film includes the following steps: A first processing gas comprising silicon-containing gas and phosphorus-containing gas is supplied to the substrate; A second processing gas comprising silicon-containing gas and carbon-containing gas is supplied to the substrate; and A third processing gas comprising the silicon-containing gas but excluding the phosphorus-containing gas and the carbon-containing gas is supplied to the substrate. The processing of the first processing gas is carried out at the beginning or in the middle of the process of forming the amorphous silicon film.

2. The film-forming method according to claim 1, wherein, The processing of the second processing gas is carried out midway through the process of forming the amorphous silicon film.

3. The film-forming method according to claim 1, wherein, The processing of the second processing gas is performed after the processing of the first processing gas.

4. The film-forming method according to claim 1, wherein, The processing of the second processing gas and the processing of the first processing gas are performed simultaneously.

5. The film-forming method according to claim 1, wherein, The treatment of the third processing gas is performed at the end of the process of forming the amorphous silicon film.

6. The film-forming method according to claim 1, wherein, The processes of supplying the first processing gas, the third processing gas, the second processing gas, and the third processing gas are performed sequentially.

7. The film-forming method according to claim 1, wherein, The process of supplying the third processing gas, the process of simultaneously supplying the first processing gas and the second processing gas, and the process of supplying the third processing gas are performed sequentially.

8. The film-forming method according to any one of claims 1 to 7, wherein, The process of forming a seed layer on the substrate is included before the process of forming the amorphous silicon film.

9. The film-forming method according to any one of claims 1 to 7, wherein, The silicon-containing gas is silane gas. The phosphorus-containing gas is phosphine gas. The carbon-containing gas is ethylene gas.

10. The film-forming method according to any one of claims 1 to 7, wherein, The substrate has a silicon oxide film on its surface.

11. A film-forming apparatus comprising a processing unit and a control unit, wherein in the film-forming apparatus, The control unit is configured to control the processing unit to perform the following steps: Prepare the substrate; An amorphous silicon film is formed on the substrate; and Crystallize the amorphous silicon film. in, The process of forming the amorphous silicon film includes the following steps: A first processing gas comprising silicon-containing gas and phosphorus-containing gas is supplied to the substrate; A second processing gas comprising silicon-containing gas and carbon-containing gas is supplied to the substrate; and A third processing gas comprising the silicon-containing gas but excluding the phosphorus-containing gas and the carbon-containing gas is supplied to the substrate. The processing of the first processing gas is carried out at the beginning or in the middle of the process of forming the amorphous silicon film.

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