Processing method and processing apparatus

Abstract

This technology provides an efficient way to getter catalyst metals contained in polycrystalline silicon films. [Solution] A processing method according to one aspect of the present disclosure comprises the steps of: preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface; forming an amorphous silicon film on which carbon is added on the polycrystalline silicon film; and diffusing the catalyst metal contained in the polycrystalline silicon film into the amorphous silicon film by annealing the substrate.

Description

[Technical Field]

[0001] This disclosure relates to a processing method and an apparatus. [Background technology]

[0002] Patent Document 1 discloses a technique for forming a polycrystalline silicon film by a metal-induced crystallization method using nickel, and then removing the nickel remaining on the surface of the polycrystalline silicon film using oxygen radicals and hydrogen radicals. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-60908 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure provides a technology that can efficiently getter catalyst metals contained in polycrystalline silicon films. [Means for solving the problem]

[0005] A processing method according to one aspect of the present disclosure comprises the steps of: preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface; forming an amorphous silicon film on which carbon is added on the polycrystalline silicon film; and diffusing the catalyst metal contained in the polycrystalline silicon film into the amorphous silicon film by annealing the substrate. [Effects of the Invention]

[0006] According to this disclosure, catalyst metals contained in polycrystalline silicon films can be efficiently gettered. [Brief explanation of the drawing]

[0007] [Figure 1]This is a flowchart showing the processing method according to the embodiment. [Figure 2] This is a cross-sectional view (1) showing the processing method according to the embodiment. [Figure 3] This is a cross-sectional view (2) showing the processing method according to the embodiment. [Figure 4] This is a cross-sectional view (3) showing the processing method according to the embodiment. [Figure 5] This is a cross-sectional view (4) showing the processing method according to the embodiment. [Figure 6] This is a cross-sectional view (5) showing the processing method according to the embodiment. [Figure 7] This is a cross-sectional view (6) showing the processing method according to the embodiment. [Figure 8] This is a cross-sectional view showing the processing apparatus according to the embodiment. [Figure 9] This is a diagram (1) showing the measurement results of nickel concentration. [Figure 10] This is a diagram (2) showing the measurement results of nickel concentration. [Figure 11] This is a diagram (3) showing the measurement results of nickel concentration. [Figure 12] This is a diagram showing the measurement results of carbon concentration. DETAILED DESCRIPTION OF EMBODIMENTS

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. Throughout all the accompanying drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and duplicate descriptions thereof are omitted.

[0009] [Processing Method] The processing method according to the embodiment will be described with reference to Figures 1 to 7. In the following description, the case in which a polycrystalline silicon film is formed on a substrate will be used as an example. The polycrystalline silicon film is used, for example, as a channel silicon film in a 3D NAND flash memory. Figure 1 is a flowchart of the processing method according to the embodiment. Figures 2 to 7 are cross-sectional views showing the processing method according to the embodiment. The processing method according to the embodiment has steps S1 to S6 shown in Figure 1.

[0010] In step S1, the substrate 100 is prepared as shown in Figure 2. The substrate 100 has a silicon substrate 101 and an amorphous silicon film 102. The amorphous silicon film 102 is provided on the silicon substrate 101. The amorphous silicon film 102 can be formed, for example, by chemical vapor deposition (CVD) using a silicon-containing gas. The silicon-containing gas is, for example, diisopropylaminosilane (DIPAS) gas, disilane gas, monosilane gas, or a combination thereof.

[0011] In step S2, as shown in Figure 3, nickel raw material gas is supplied to the substrate 100 to diffuse nickel (Ni) into the amorphous silicon film 102. Nickel is an example of a catalytic metal. Nickel raw material gas can be produced, for example, by vaporizing a liquid nickel raw material or by sublimating a solid nickel raw material. The nickel raw material may be an organic nickel raw material. Examples of liquid nickel raw materials are (EtCp)2Ni[Ni(C2H5C5H4)2] or CpAllylNi[(C3H5)(C5H5)Ni]. Examples of solid nickel raw materials are (MeCp)2Ni[Ni(CH3C5H4)2]. For example, when the nickel raw material is (EtCp)2Ni, the temperature of the substrate 100 when diffusing nickel into the amorphous silicon film 102 (hereinafter referred to as the "diffusion temperature") may be 150°C or higher and 300°C or lower.

[0012] In step S3, as shown in Figure 4, the substrate 100 is heated, and the amorphous silicon film 102 is crystallized by metal-induced crystallization (MIC) with nickel in the amorphous silicon film 102 as the nucleation site, thereby forming a polycrystalline silicon film 103. The temperature of the substrate 100 when forming the polycrystalline silicon film 103 (hereinafter referred to as the "crystallization temperature") may be 500°C or higher and 600°C or lower. The atmosphere when heating the substrate 100 is, for example, an inert gas atmosphere at atmospheric pressure. The atmosphere when heating the substrate 100 may also be a reduced-pressure atmosphere.

[0013] In step S4, as shown in Figure 5, an amorphous silicon film 104 with carbon (C) added is formed on the polycrystalline silicon film 103. The amorphous silicon film 104 may be in contact with the polycrystalline silicon film 103. An amorphous silicon film (not shown) without added impurities may be formed between the polycrystalline silicon film 103 and the amorphous silicon film 104. In this case, it is easier to prevent the diffusion of carbon from the amorphous silicon film 104 to the polycrystalline silicon film 103.

[0014] The amorphous silicon film 104 can be formed, for example, by simultaneously supplying a silicon-containing gas and a carbon-containing gas to a substrate 100. The silicon-containing gas is, for example, monosilane (SiH4) gas. The silicon-containing gas may be monosilane gas, disilane (Si2H6) gas, trisilane (Si3H8) gas, higher-order silanes with four or more silicon (Si) atoms, or a combination thereof. The carbon-containing gas is, for example, C x H y It is a gas (x and y are integers greater than or equal to 1). C x H y Examples of gases include methane (CH4), ethane (C2H6), propane (C3H8), ethylene (C2H4), propylene (C3H6), and acetylene (C2H2). The amorphous silicon film formation temperature is, for example, between 455°C and 530°C.

[0015] The carbon concentration of amorphous silicon film 104 is 3.0 × 10⁻⁶.21 atoms / cm 3 The above is preferable. In this case, in step S5 described later, nickel contained in the polycrystalline silicon film 103 is likely to diffuse into the amorphous silicon film 104. In step S4, the carbon concentration of the amorphous silicon film 104 is 3.0 × 10 21 atoms / cm 3 The process conditions for forming the amorphous silicon film 104 may be determined in such a manner. The process conditions may include, for example, the flow rate ratio of silicon-containing gas to carbon-containing gas. The process conditions may also include the temperature of the substrate 100, the processing pressure, and so on.

[0016] In step S5, the substrate 100 is annealed. As a result, as shown in Figure 6, nickel contained in the polycrystalline silicon film 103 is gettered (captured) into the carbon-doped amorphous silicon film 104. Carbon suppresses the crystallization of the amorphous silicon film 104 due to heat. Therefore, the carbon-doped amorphous silicon film 104 is less likely to crystallize even after annealing compared to the amorphous silicon film without carbon. Nickel contained in the polycrystalline silicon film 103 diffuses more easily into the amorphous silicon film than into the crystallized silicon film. As a result, it is considered that using the carbon-doped amorphous silicon film 104 allows for better gettering of nickel contained in the polycrystalline silicon film 103 than using the amorphous silicon film without carbon. The temperature of the substrate 100 when annealing the substrate 100 (hereinafter referred to as the "annealing temperature") is, for example, 500°C or higher. In this case, nickel contained in the polycrystalline silicon film 103 diffuses easily into the amorphous silicon film 104. The annealing temperature is, for example, 900°C or lower. In this case, the carbon added to the amorphous silicon film 104 does not easily diffuse into the polycrystalline silicon film 103.

[0017] In step S6, as shown in Figure 7, the amorphous silicon film 104 is selectively etched from the polycrystalline silicon film 103 by supplying an etching solution to the amorphous silicon film in which nickel has diffused. This removes the amorphous silicon film 104 from the polycrystalline silicon film 103. As a result, a polycrystalline silicon film 103 from which nickel has been removed can be formed. As the etching solution, a processing solution that can selectively etch the amorphous silicon film 104 from the polycrystalline silicon film 103 can be used. An example of the etching solution is DHF (dilute hydrofluoric acid).

[0018] Now, let's consider the case where an amorphous silicon film doped with phosphorus (P) is used instead of the amorphous silicon film doped with carbon 104. Nickel is easily gettered into regions where phosphorus is present. Therefore, when the substrate 100 is annealed, the nickel contained in the polycrystalline silicon film 103 is gettered into the amorphous silicon film doped with phosphorus. At this time, some of the phosphorus added to the amorphous silicon film may diffuse into the polycrystalline silicon film 103. In this case, some of the nickel contained in the polycrystalline silicon film 103 remains in the polycrystalline silicon film 103, or some of the nickel that was gettered into the amorphous silicon film may back-diffuse into the polycrystalline silicon film 103. For this reason, it is difficult to efficiently getter the nickel contained in the polycrystalline silicon film 103.

[0019] According to the processing method of the embodiment, an amorphous silicon film 104 with carbon added is formed on a polycrystalline silicon film 103 containing nickel, and then the nickel contained in the polycrystalline silicon film 103 is diffused into the amorphous silicon film 104 by annealing. The carbon suppresses the crystallization of the amorphous silicon film 104 due to heat. For this reason, the amorphous silicon film 104 with carbon added is less likely to crystallize even after annealing compared to an amorphous silicon film without carbon added. Nickel contained in the polycrystalline silicon film 103 diffuses more easily into the amorphous silicon film than into the crystallized silicon film. As a result, it is considered that by using an amorphous silicon film 104 with carbon added, nickel contained in the polycrystalline silicon film 103 can be gettered more effectively than by using an amorphous silicon film without carbon added.

[0020] The above embodiment describes the case in which a polycrystalline silicon film 103 is formed on a flat surface, but is not limited to this. For example, the processing method of this disclosure can also be applied when forming a polycrystalline silicon film 103 on the inner surface of a recess such as a hole or trench. In this case, by diffusing nickel into the amorphous silicon film 102 using a nickel source gas, the variation in the amount of nickel diffusion in the depth direction of the recess can be reduced. As a result, a polycrystalline silicon film 103 with small particle size variation in the depth direction of the recess can be formed.

[0021] [Processing device] Referring to Figure 8, an example of a processing apparatus 1 capable of executing steps S2 to S5 of the processing method according to the embodiment will be described. Figure 8 is a cross-sectional view showing the processing apparatus 1 according to the embodiment.

[0022] The processing apparatus 1 comprises a processing container 10, a gas supply unit 30, an exhaust unit 40, a heating unit 50, and a control unit 90.

[0023] The processing container 10 has a double-tube structure consisting of a cylindrical inner tube 11 and a ceiling-covered outer tube 12 concentrically placed outside the inner tube 11. The inner tube 11 and outer tube 12 are made of, for example, quartz. The processing container 10 is configured to accommodate a boat 16.

[0024] A housing section 13 is formed on one side of the inner pipe 11 along its longitudinal direction (vertical direction). The housing section 13 is a region within a protrusion 14 formed by making a part of the side wall of the inner pipe 11 protrude outward. The supply pipes 31a, 32a, and 33a, which will be described later, are housed in the housing section 13.

[0025] The lower end of the processing container 10 is supported by a cylindrical manifold 17, which 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 pipe 12. A sealing member 19, such as an O-ring, is provided between the flange 18 and the lower end of the outer pipe 12.

[0026] An annular support portion 20 is provided on the upper inner wall of the manifold 17. The support portion 20 supports the lower end of the inner pipe 11. An exhaust port 21 is provided on the upper side wall of the manifold 17, above the support portion 20. A cover 22 is airtightly attached to the opening at the lower end of the manifold 17 via a sealing member 23 such as an O-ring. The cover 22 is made of, for example, stainless steel.

[0027] A rotating shaft 25 is provided through the center of the lid 22 via a magnetic fluid seal 24. The lower end of the rotating shaft 25 is rotatably supported by an arm 26A of a lifting mechanism 26 consisting of a boat elevator. A rotating plate 27 is provided at the upper end of the rotating shaft 25. The boat 16 is placed on the rotating plate 27 via a quartz insulation cylinder 28.

[0028] The boat 16 holds multiple substrates W (for example, 25 to 200) in a substantially horizontal position with vertical spacing between them. The substrates W are, for example, semiconductor wafers. The boat 16 rotates integrally with the rotation axis 25. The boat 16 moves up and down integrally with the lid 22 by raising and lowering the arm 26A, and is inserted into and removed from the processing container 10.

[0029] The gas supply unit 30 is configured to allow various gases to be introduced into the inner pipe 11. These various gases include gases used in the processing method according to the embodiment. The gas supply unit 30 includes a silicon raw material supply unit 31, a nickel raw material supply unit 32, and a carbon raw material supply unit 33.

[0030] The silicon raw material supply unit 31 includes a supply pipe 31a inside the processing container 10 and a supply path 31b outside the processing container 10. In the supply path 31b, a silicon raw material source 31c, a mass flow controller 31d, and an on-off valve 31e are provided in order from the upstream side to the downstream side in the direction of gas flow. The supply timing of the silicon-containing gas from the silicon raw material source 31c is controlled by the on-off valve 31e, and the flow rate is adjusted to a predetermined level by the mass flow controller 31d. The silicon-containing gas flows from the supply path 31b into the supply pipe 31a and is discharged from the supply pipe 31a into the processing container 10.

[0031] The nickel raw material supply unit 32 is equipped with a supply pipe 32a inside the processing container 10 and a supply path 32b outside the processing container 10. In the supply path 32b, a raw material tank 32c, a control valve 32d, and an on / off valve 32e are provided in order from the upstream side to the downstream side in the direction of gas flow. The raw material tank 32c contains nickel raw material. The nickel raw material is either a liquid or solid material at room temperature. A heater 32f is provided around the raw material tank 32c. The heater 32f heats the nickel raw material inside the raw material tank 32c. As a result, the liquid nickel raw material vaporizes or the solid nickel raw material sublimes, generating nickel raw material gas.

[0032] The nickel raw material supply unit 32 has a carrier gas pipe 32g inserted into the raw material tank 32c from above. The carrier gas pipe 32g is equipped with a carrier gas source 32h, an on-off valve 32i, and a control valve 32j in order from the upstream side to the downstream side in the direction of gas flow. As a result, the carrier gas from the carrier gas source 32h is supplied to the raw material tank 32c, with the supply timing controlled by the on-off valve 32i and the flow rate adjusted to a predetermined level by the control valve 32j. The carrier gas, along with the nickel raw material gas in the raw material tank 32c, is supplied to the raw material tank 32c, with the supply timing controlled by the on-off valve 32e and the flow rate adjusted to a predetermined level by the control valve 32d, and flows from the supply path 32b into the supply pipe 32a. The nickel raw material gas and carrier gas that have flowed into the supply pipe 32a are discharged into the processing container 10 from the supply pipe 32a.

[0033] A bypass path 32k may be provided to connect the upstream side of the on-off valve 32i in the carrier gas piping 32g to the downstream side of the on-off valve 32e in the supply path 32b. A bypass valve 32l may be provided in the bypass path 32k.

[0034] The carbon raw material supply unit 33 is equipped with a supply pipe 33a inside the processing container 10 and a supply path 33b outside the processing container 10. In the supply path 33b, a carbon raw material source 33c, a mass flow controller 33d, and an on-off valve 33e are provided in order from the upstream side to the downstream side in the direction of gas flow. The carbon-containing gas of the carbon raw material source 33c is supplied at a timing controlled by the on-off valve 33e and adjusted to a predetermined flow rate by the mass flow controller 33d. The carbon-containing gas flows from the supply path 33b into the supply pipe 33a and is discharged from the supply pipe 33a into the processing container 10.

[0035] The supply pipes 31a, 32a, and 33a are fixed to the manifold 17. The supply pipes 31a, 32a, and 33a are made of, for example, quartz. The supply pipes 31a, 32a, and 33a extend linearly along the vertical direction near the inner pipe 11 and then bend in an L-shape within the manifold 17 to extend horizontally, thereby penetrating the manifold 17. The supply pipes 31a, 32a, and 33a are arranged side by side along the circumferential direction of the inner pipe 11 and are formed at the same height.

[0036] Multiple gas holes 31p, 32p, and 33p are provided in the supply pipes 31a, 32a, and 33a, respectively, at the locations within the inner pipe 11. The gas holes 31p, 32p, and 33p are formed at predetermined intervals along the extending direction of each supply pipe 31a, 32a, and 33a. The gas holes 31p, 32p, and 33p release gas horizontally. The spacing between the gas holes 31p, 32p, and 33p is set to be the same as, for example, the spacing between the substrates W held in the boat 16. The height position of the gas holes 31p, 32p, and 33p is set to be at an intermediate position between adjacent substrates W in the vertical direction. In this case, the gas holes 31p, 32p, and 33p can efficiently supply gas to the opposing surfaces between adjacent substrates W.

[0037] The gas supply unit 30 may mix multiple types of gases and discharge the mixed gas from a single supply pipe. For example, the supply pipes 31a, 32a, and 33a may be configured to discharge inert gas. The supply pipes 31a, 32a, and 33a may have different shapes and arrangements from each other. In addition to silicon-containing gas, nickel raw material gas, and carbon-containing gas, the gas supply unit 30 may further have supply pipes for supplying other gases.

[0038] The exhaust section 40 includes an exhaust passage 41, a pressure regulating valve 42, and a vacuum pump 43. The exhaust passage 41 is connected to the exhaust port 21. The pressure regulating valve 42 and the vacuum pump 43 are located in the middle of the exhaust passage 41. The vacuum pump 43 is located downstream of the pressure regulating valve 42 in the gas flow direction. The gas inside the processing container 10 is discharged outside the processing container 10 by the vacuum pump 43, with the exhaust flow rate controlled by the pressure regulating valve 42.

[0039] The heating section 50 has a cylindrical shape and is provided around the outer tube 12. The heating section 50 heats each substrate W inside the processing container 10. The heating section 50 includes, for example, a heater.

[0040] 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 performs the various control operations described in this specification by executing instruction codes stored in memory or by circuit design for special applications.

[0041] [Processing device operation] The operation when steps S2 to S5 of the processing method according to the embodiment are performed in the processing device 1 will be described. Step S6 may be performed in a device other than the processing device 1.

[0042] First, the control unit 90 controls the lifting mechanism 26 to move the boat 16 holding the multiple substrates W into the processing container 10, and then seals the opening at the lower end of the processing container 10 airtight with the lid 22. Each substrate W is, for example, a substrate 100 prepared in step S1.

[0043] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute step S2. Specifically, first, the control unit 90 controls the exhaust unit 40 to adjust the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W at the diffusion temperature. Then, the control unit 90 controls the gas supply unit 30 to supply nickel raw material gas into the processing container 10. This causes nickel to diffuse into the amorphous silicon film 102.

[0044] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute step S3. Specifically, first, the control unit 90 controls the gas supply unit 30 to supply an inert gas such as nitrogen gas into the processing container 10, controls the exhaust unit 40 to adjust the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W at the crystallization temperature. As a result, the amorphous silicon film 102 crystallizes due to metal-induced crystallization, forming a polycrystalline silicon film 103.

[0045] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute step S4. Specifically, first, the control unit 90 controls the exhaust unit 40 to adjust the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W to the amorphous silicon film formation temperature. Then, the control unit 90 controls the gas supply unit 30 to simultaneously supply silicon-containing gas and carbon-containing gas into the processing container 10. As a result, an amorphous silicon film 104 with carbon added is formed on top of the polycrystalline silicon film 103.

[0046] Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to execute step S5. Specifically, first, the control unit 90 controls the gas supply unit 30 to supply an inert gas such as nitrogen gas into the processing container 10, controls the exhaust unit 40 to adjust the pressure inside the processing container 10 to a predetermined level, and controls the heating unit 50 to adjust and maintain the temperature of the substrate W at the annealing temperature. As a result, nickel contained in the polycrystalline silicon film 103 diffuses into the amorphous silicon film 104.

[0047] Next, the control unit 90 increases the pressure inside the processing container 10 to atmospheric pressure, then lowers the temperature inside the processing container 10 to the discharge temperature, and then controls the lifting mechanism 26 to discharge the boat 16 from inside the processing container 10.

[0048] As a result, steps S2 to S5 of the processing method according to the embodiment are completed in the processing apparatus 1.

[0049] [Experimental results] In the experiment, Sample A, Sample B, and Sample C shown below were produced.

[0050] Sample A has a stacked structure in which a silicon oxide film, a polycrystalline silicon film, and a carbon-added amorphous silicon film are stacked in this order. The polycrystalline silicon film has a thickness of 100 nm. The carbon-added amorphous silicon film has a thickness of 100 nm and a carbon concentration of 1.6×10 21 atoms / cm 3 . The carbon-added amorphous silicon film was formed by supplying monosilane gas and ethylene gas to the substrate at a flow rate ratio of 12.5:1.

[0051] Sample B is a sample in which the carbon concentration of the carbon-added amorphous silicon film is changed to 3.0×10 with respect to Sample A 21 atoms / cm 3 . The carbon-added amorphous silicon film was formed by supplying monosilane gas and ethylene gas to the substrate at a flow rate ratio of 5:1. The other configurations are the same as those of Sample A.

[0052] Sample C is a sample in which the carbon concentration of the carbon-added amorphous silicon film is changed to 5.9×10 with respect to Sample A 21 atoms / cm 3 . The carbon-added amorphous silicon film was formed by supplying monosilane gas and ethylene gas to the substrate at a flow rate ratio of 1.9:1. The other configurations are the same as those of Sample A.

[0053] Next, in the processing apparatus 1, the pressure inside the processing container 10 was set to atmospheric pressure, and samples A, B, and C were annealed for 60 minutes while nitrogen gas was supplied into the processing container 10 at a flow rate of 20 slm. The annealing temperature was set to 700°C or 800°C. Next, the nickel concentration of each layer in samples A, B, and C was measured by secondary ion mass spectrometry (SIMS), and the carbon concentration of each layer in sample C was measured. For comparison, the nickel concentration of each layer in samples A, B, and C was measured by SIMS without annealing, and the carbon concentration of each layer in sample C was also measured. For nickel concentration measurement, SIMS analysis was performed from the surface side (amorphous silicon film with added carbon) of each sample. For carbon concentration measurement, SIMS analysis (backside SIMS analysis) was performed from the back side (silicon oxide film) of the sample.

[0054] Figures 9 to 11 show the results of nickel concentration measurements. Figure 9 shows the nickel concentration measurement results for sample A. Figure 10 shows the nickel concentration measurement results for sample B. Figure 11 shows the nickel concentration measurement results for sample C. In Figures 9 to 11, the horizontal axis represents the depth from the surface of the layered structure [nm], and the vertical axis represents the nickel concentration [atoms / cm³]. 3 This shows the results. In Figures 9 to 11, the solid line shows the results when no annealing treatment is performed, the dashed line shows the results when the annealing temperature is 700°C, and the dotted line shows the results when the annealing temperature is 800°C.

[0055] As shown in Figure 9, in sample A, when the annealing temperature is 800°C, the nickel concentration of the amorphous silicon film with added carbon is higher compared to the case without annealing, but there is almost no change in the carbon concentration of the polycrystalline silicon film. From this result, the carbon concentration of the amorphous silicon film is 1.6 × 10⁻⁶. 21 atoms / cm 3In this case, even after annealing at a temperature of 800°C, it is thought that the nickel contained in the polycrystalline silicon film does not sufficiently diffuse into the amorphous silicon film and remains in the polycrystalline silicon film. In sample A, when the annealing temperature is 700°C, the nickel concentration in the carbon-doped amorphous silicon film is higher and the carbon concentration in the polycrystalline silicon film is lower compared to the case where no annealing treatment was performed. From these results, it can be concluded that the carbon concentration of the amorphous silicon film is 1.6 × 10⁻⁶. 21 atoms / cm 3 In this case, it was shown that annealing at a temperature of 700°C resulted in the nickel contained in the polycrystalline silicon film being gettered by the amorphous silicon film.

[0056] As shown in Figure 10, in sample B, when the annealing temperature was 700°C and 800°C, the nickel concentration of the amorphous silicon film with added carbon was higher and the carbon concentration of the polycrystalline silicon film was lower compared to the case without annealing. From these results, the carbon concentration of the amorphous silicon film is 3.0 × 10⁻⁶. 21 atoms / cm 3 In this case, it was shown that annealing at temperatures of 700°C and 800°C resulted in gettering of nickel contained in the polycrystalline silicon film by the amorphous silicon film. In particular, when the annealing temperature was 800°C, the decrease in the carbon concentration of the polycrystalline silicon film was greater than when the annealing temperature was 700°C. From these results, it was found that the carbon concentration of the amorphous silicon film was 3.0 × 10⁻⁶. 21 atoms / cm 3 In this case, it is thought that by setting the annealing temperature to 800°C or higher, the nickel contained in the polycrystalline silicon film is efficiently gettered by the amorphous silicon film.

[0057] As shown in Figure 11, the same trend as in sample B is observed in sample C. From this result, the carbon concentration of the amorphous silicon film is 5.9 × 10⁻⁶. 21 atoms / cm 3In this case, it was shown that annealing at temperatures of 700°C and 800°C resulted in nickel in the polycrystalline silicon film being gettered by the amorphous silicon film. Furthermore, when the carbon concentration of the amorphous silicon film was 5.9 × 10⁻⁶ 21 atoms / cm 3 In this case, it is thought that by setting the annealing temperature to 800°C or higher, the nickel contained in the polycrystalline silicon film is efficiently gettered by the amorphous silicon film.

[0058] Figure 12 shows the results of carbon concentration measurement. Figure 12 shows the carbon concentration measurement results for sample C. In Figure 12, the horizontal axis represents depth [nm] and the vertical axis represents carbon concentration [atoms / cm³]. 3 This shows the results when no annealing treatment is performed. In Figure 12, the solid line shows the results when the annealing temperature is 800°C, and the dashed line shows the results when the annealing temperature is 800°C.

[0059] As shown in Figure 12, in sample C, the carbon concentration of the polycrystalline silicon film is almost the same when the annealing temperature is 800°C and when no annealing treatment is performed. From this result, the carbon concentration of the amorphous silicon film is 5.9 × 10⁻⁶. 21 atoms / cm 3 In this case, it can be said that, with a thermal history of at least 800°C for 60 minutes, the carbon added to the amorphous silicon film does not diffuse into the polycrystalline silicon film, or diffuses very little. Furthermore, even with a thermal history of 700°C for 60 minutes, which is lower than 800°C, it is considered that the carbon added to the amorphous silicon film does not diffuse into the polycrystalline silicon film, or diffuses very little. In addition, even in samples A and B, where the carbon concentration of the amorphous silicon film is lower than that of sample C, it is considered that, with a thermal history of at least 800°C for 60 minutes, the carbon added to the amorphous silicon film does not diffuse into the polycrystalline silicon film, or diffuses very little.

[0060] The experimental results above demonstrate that by using an amorphous silicon film with added carbon, nickel contained in the polycrystalline silicon film can be efficiently gettered without significantly diffusing the carbon contained in the amorphous silicon film into the polycrystalline silicon film.

[0061] The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The above embodiments may be omitted, replaced, or modified in various ways without departing from the scope and spirit of the appended claims.

[0062] Although the above embodiments describe the case where the catalyst metal is nickel, the disclosure is not limited thereto. For example, the catalyst metal may be iron (Fe), copper (Cu), chromium (Cr), cobalt (Co), or silver (Ag).

[0063] In the embodiments described above, the processing apparatus is a batch-type apparatus that processes multiple substrates at once, but the disclosure is not limited thereto. For example, the processing apparatus may be a single-wafer apparatus that processes substrates one at a time. [Explanation of Symbols]

[0064] 100 circuit boards 103 Polycrystalline silicon film 104 Amorphous silicon film

Claims

1. A step of preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface, A step of forming an amorphous silicon film on the polycrystalline silicon film, The process involves annealing the substrate to diffuse the catalyst metal contained in the polycrystalline silicon film into the amorphous silicon film, A processing method having the following characteristics.

2. In the process of forming the amorphous silicon film, the amorphous silicon film is formed by simultaneously supplying a silicon-containing gas and a carbon-containing gas to the substrate. The processing method according to claim 1.

3. The carbon concentration of the amorphous silicon film is 3.0 × 10⁻⁶ ２１ atoms / cm ３ That's all. The processing method according to claim 2.

4. In the process of forming the amorphous silicon film, the carbon concentration of the amorphous silicon film is 3.0 × 10 ２１ atoms / cm ３ The process conditions for forming the amorphous silicon film are determined as described above. The processing method according to claim 2.

5. The process conditions include the flow rate ratio of the silicon-containing gas and the carbon-containing gas. The processing method according to claim 4.

6. In the step of preparing the substrate, the polycrystalline silicon film is formed by metal-induced crystallization with the catalyst metal as a nucleus. The processing method according to any one of claims 1 to 3.

7. The method further comprises a step of removing the amorphous silicon film by supplying an etching solution to the substrate after the step of diffusing the solution into the amorphous silicon film. The processing method according to any one of claims 1 to 3.

8. The process of forming the amorphous silicon film and the process of diffusing into the amorphous silicon film are carried out in the same processing container. The processing method according to any one of claims 1 to 3.

9. The catalyst metal is nickel. The processing method according to any one of claims 1 to 3.

10. A recess is formed on the surface of the substrate, The polycrystalline silicon film is formed on the inner surface of the recess. The processing method according to any one of claims 1 to 3.

11. A processing container for housing the substrate, A gas supply unit that supplies gas into the processing container, The substrate housed in the processing container is heated by the heating unit, Control unit and Equipped with, The control unit, A step of preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface, A step of forming an amorphous silicon film on the polycrystalline silicon film, The process involves annealing the substrate to diffuse the catalyst metal contained in the polycrystalline silicon film into the amorphous silicon film, The gas supply unit and the heating unit are configured to be controlled to perform the following actions: Processing device.

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