Processing method and processing device
By forming a gettering layer of amorphous silicon and diffusing catalyst metal into it, the method addresses the challenge of element diffusion from the gettering layer into the polycrystalline silicon film, ensuring film quality and reduced particle size variation.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TOKYO ELECTRON LTD
- Filing Date
- 2025-12-12
- Publication Date
- 2026-07-02
AI Technical Summary
Existing methods for forming polycrystalline silicon films face challenges in reducing the diffusion of elements from the gettering layer into the silicon film, particularly when exposed to high temperatures.
A method involving the formation of a gettering layer made of amorphous silicon using organic aminosilane gas, followed by diffusing the catalyst metal into this layer and then etching it away, thereby minimizing the diffusion of carbon and nitrogen from the gettering layer into the polycrystalline silicon film.
This approach effectively reduces the diffusion of elements from the gettering layer into the polycrystalline silicon film, maintaining film quality even at high temperatures, and allows for consistent polycrystalline silicon film formation with reduced particle size variation.
Smart Images
Figure JP2025043479_02072026_PF_FP_ABST
Abstract
Description
Processing method and processing apparatus
[0001] This disclosure relates to a processing method and an apparatus.
[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.
[0003] Japanese Patent Application Publication No. 2011-60908
[0004] This disclosure provides a technology that can reduce the diffusion of elements originating from the gettering layer into the polycrystalline silicon film.
[0005] A processing method according to one aspect of the present disclosure comprises: preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface; forming a gettering layer made of amorphous silicon on the polycrystalline silicon film by chemical vapor deposition using organic aminosilane gas; and diffusing the catalyst metal contained in the polycrystalline silicon film into the gettering layer by annealing the substrate.
[0006] According to this disclosure, the diffusion of elements originating from the gettering layer into the polycrystalline silicon film can be reduced.
[0007] This is a flowchart showing the processing method according to the embodiment. This is a cross-sectional view (1) showing the processing method according to the embodiment. This is a cross-sectional view (2) showing the processing method according to the embodiment. This is a cross-sectional view (3) showing the processing method according to the embodiment. This is a cross-sectional view (4) showing the processing method according to the embodiment. This is a cross-sectional view (5) showing the processing method according to the embodiment. This is a cross-sectional view (6) showing the processing method according to the embodiment. This is a cross-sectional view showing the processing apparatus according to the embodiment. This is a diagram showing the measurement results of nickel concentration. This is a diagram showing the measurement results of carbon concentration. This is a diagram showing the measurement results of nitrogen concentration.
[0008] Hereinafter, exemplary embodiments of the present disclosure, not limited to those described herein, will be described with reference to the attached drawings. In all attached drawings, identical or corresponding members or components are denoted by the same or corresponding reference numerals, and redundant descriptions are omitted.
[0009] [Processing Method] Referring to FIGS. 1 to 7, the processing method according to the embodiment will be described. Hereinafter, the case of forming a polycrystalline silicon film on a substrate will be described as an example. The polycrystalline silicon film is used, for example, as a channel silicon film of a 3D NAND flash memory. FIG. 1 is a flowchart showing the processing method according to the embodiment. FIGS. 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 FIG. 1.
[0010] In step S1, as shown in FIG. 2, a substrate 100 is prepared. 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 FIG. 3, a nickel source 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. The nickel source gas can be generated, for example, by vaporizing a liquid nickel source or sublimating a solid nickel source. The nickel source may be an organic nickel source. The liquid nickel source is, for example, (EtCp) ２ Ni[Ni(C ２ H ５ C ５ H ４ ), or CpAllylNi[(C ２ H ３ H ５ )(C ５ H ５ )(C ２ H ３ C ５ H ４ )(C ２ H２ In the case of Ni, 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 with nickel as a nucleus in the amorphous silicon film 102 to form 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, a gettering layer 104 made of amorphous silicon is formed on the polycrystalline silicon film 103 by chemical vapor deposition using an organic aminosilane gas. In this case, amorphous silicon contains carbon (C) and nitrogen (N). The gettering layer 104 may be in contact with the polycrystalline silicon film 103. The organic aminosilane gas is, for example, diisopropylaminosilane gas. The organic aminosilane gas may also be 3DMAS (trisdimethylaminosilane) gas or BTBAS (bistarchal butylaminosilane) gas. For example, when the organic aminosilane gas is diisopropylaminosilane gas, the temperature of the substrate 100 when forming the gettering layer 104 (hereinafter referred to as the "gettering layer formation temperature") may be 400°C or higher and 500°C or lower.
[0014] In step S5, as shown in Figure 6, the substrate 100 is annealed to diffuse the nickel contained in the polycrystalline silicon film 103 into the gettering layer 104. The temperature of the substrate 100 when diffusing nickel into the gettering layer 104 (hereinafter referred to as the "annealing temperature") may be 500°C or more and 900°C or less.
[0015] In step S6, as shown in Figure 7, the gettering layer 104 in which nickel has diffused is supplied with an etching solution to selectively etch the gettering layer 104 from the polycrystalline silicon film 103. This removes the gettering layer 104 from the polycrystalline silicon film 103. As the etching solution, a processing solution that can selectively etch the gettering layer 104 from the polycrystalline silicon film 103 can be used. For example, the etching solution is DHF (dilute hydrofluoric acid).
[0016] As a result, a polycrystalline silicon film 103 can be formed on the silicon substrate 101.
[0017] According to the processing method of the embodiment, a gettering layer 104 formed of amorphous silicon is formed on the polycrystalline silicon film 103 by chemical vapor deposition using organic aminosilane gas. In this case, amorphous silicon contains carbon and nitrogen. The carbon and nitrogen contained in amorphous silicon do not easily diffuse into the polycrystalline silicon film 103 even when exposed to high temperatures. Therefore, even if the substrate 100 is annealed at the annealing temperature in step S5, they do not diffuse into the polycrystalline silicon film 103 or hardly diffuse at all. As a result, the diffusion of elements (carbon and nitrogen) originating from the gettering layer 104 into the polycrystalline silicon film 103 can be reduced.
[0018] 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 the present 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.
[0019] [Processing Apparatus] 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.
[0020] 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.
[0021] 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.
[0022] A housing portion 13 is formed on one side of the inner pipe 11 along its longitudinal direction (vertical direction). The housing portion 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 and 32a, which will be described later, are housed in the housing portion 13.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] The gas supply unit 30 is configured to allow various gases to be introduced into the inner pipe 11. The various gases include gases used in the processing method according to the embodiment. The gas supply unit 30 includes an organic aminosilane gas supply unit 31 and a nickel raw material gas supply unit 32.
[0028] The organic aminosilane gas 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, an organic aminosilane gas 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 organic aminosilane gas from the organic aminosilane gas 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 organic aminosilane 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.
[0029] The nickel raw material gas 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.
[0030] The nickel raw material gas 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, together 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.
[0031] A bypass route 32k may be provided to connect the upstream side of the on-off valve 32i in the carrier gas piping 32g and the downstream side of the on-off valve 32e in the supply route 32b. A bypass valve 32l may be provided in the bypass route 32k.
[0032] The supply pipes 31a and 32a are fixed to the manifold 17. The supply pipes 31a and 32a are made of, for example, quartz. The supply pipes 31a and 32a 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 and 32a are arranged side by side along the circumferential direction of the inner pipe 11 and are formed at the same height.
[0033] Multiple gas holes 31p and 32p are provided in the supply pipes 31a and 32a, respectively, at the locations within the inner pipe 11. The gas holes 31p and 32p are formed at predetermined intervals along the extending direction of each supply pipe 31a and 32a. The gas holes 31p and 32p release gas horizontally. The spacing between the gas holes 31p and 32p 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 and 32p is set to be at an intermediate position between adjacent substrates W in the vertical direction. In this case, the gas holes 31p and 32p can efficiently supply gas to the opposing surfaces between adjacent substrates W.
[0034] The gas supply unit 30 may mix a plurality of types of gases and discharge the mixed gas from one supply pipe. For example, the supply pipes 31a and 32a may be configured to discharge an inert gas. The supply pipes 31a and 32a may have different shapes and arrangements from each other. The gas supply unit 30 may further have a supply pipe for supplying another gas in addition to the nickel raw material gas and the organic aminosilane gas.
[0035] The exhaust unit 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 provided in the middle of the exhaust passage 41. The vacuum pump 43 is provided on the downstream side of the pressure regulating valve 42 in the gas flow direction. The gas in the processing vessel 10 is controlled in terms of the exhaust flow rate by the pressure regulating valve 42 and is discharged outside the processing vessel 10 by the vacuum pump 43.
[0036] The heating unit 50 has a cylindrical shape and is provided around the outer pipe 12. The heating unit 50 heats each substrate W in the processing vessel 10. The heating unit 50 includes, for example, a heater.
[0037] The control unit 90 is an electronic circuit such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit). The control unit 90 executes various control operations described in the present specification by executing instruction codes stored in a memory or by circuit design for special purposes.
[0038] [Operation of the processing apparatus] The operation when steps S2 to S5 of the processing method according to the embodiment are performed in the processing apparatus 1 will be described. Step S6 may be performed by an apparatus different from the processing apparatus 1.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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 at the gettering layer formation temperature. Next, the control unit 90 controls the gas supply unit 30 to supply organic aminosilane gas into the processing container 10. As a result, a gettering layer 104 is formed on the polycrystalline silicon film 103.
[0043] 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 gettering layer 104.
[0044] 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.
[0045] As described above, steps S2 to S5 of the processing method according to the embodiment are completed in the processing apparatus 1.
[0046] [Example] In this example, first, a substrate was prepared in which a polycrystalline silicon film containing nickel was formed on a silicon oxide film. Next, in the processing apparatus 1, while maintaining the substrate temperature at 450°C, a gettering layer formed of amorphous silicon containing carbon and nitrogen was formed on the polycrystalline silicon film by chemical vapor deposition using organic aminosilane gas. Next, in the processing apparatus 1, the substrate was annealed in a nitrogen atmosphere at 800°C. Next, the nickel concentration, carbon concentration, and nitrogen concentration in the polycrystalline silicon film and the gettering layer were measured by secondary ion mass spectrometry (SIMS).
[0047] In the comparative example, a substrate was first prepared in which a polycrystalline silicon film containing nickel was formed on a silicon oxide film. Next, without forming a gettering layer on the polycrystalline silicon film, the substrate was annealed in a nitrogen atmosphere at 800°C in the processing apparatus 1. Then, the nickel concentration, carbon concentration, and nitrogen concentration in the polycrystalline silicon film were measured by secondary ion mass spectrometry.
[0048] Figure 9 shows the results of nickel concentration measurement. Figure 10 shows the results of carbon concentration measurement. Figure 11 shows the results of nitrogen concentration measurement. In Figures 9, 10, and 11, the horizontal axis represents the depth from the surface of the gettering layer [nm]. In Figure 9, the vertical axis represents nickel (Ni) concentration [atoms / cm³]. ３ The vertical axis in Figure 10 represents the carbon (C) concentration [atoms / cm³]. ３ In Figure 11, the vertical axis represents nitrogen (N) concentration [atoms / cm³]. ３ This indicates [...].
[0049] As shown in Figure 9, in this embodiment, the nickel concentration in the polycrystalline silicon film is lower than in the comparative example, and the nickel concentration in the gettering layer is higher than in the polycrystalline silicon film. This result indicates that by using a gettering layer formed from amorphous silicon containing carbon and nitrogen, nickel contained in the polycrystalline silicon film can be diffused into the gettering layer.
[0050] As shown in Figure 10, there is almost no difference in carbon concentration in the polycrystalline silicon film between the example and the comparative example. This result indicates that the carbon contained in the gettering layer does not diffuse into the polycrystalline silicon film, or diffuses very little, even when exposed to a high temperature of 800°C.
[0051] As shown in Figure 11, there is almost no difference in carbon concentration in the polycrystalline silicon film between the example and the comparative example. This result indicates that nitrogen contained in the gettering layer does not diffuse into the polycrystalline silicon film, or diffuses very little, even when exposed to a high temperature of 800°C.
[0052] The embodiments disclosed herein should be considered in all respects to be 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.
[0053] The above embodiments describe the case where the catalyst metal is nickel, but the disclosure is not limited thereto. For example, the catalyst metal may be iron (Fe), copper (Cu), chromium (Cr), cobalt (Co), or silver (Ag).
[0054] 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.
[0055] This international application claims priority based on Japanese Patent Application No. 2024-227745, filed on 24 December 2024, and the entire contents of said application are incorporated herein by reference.
[0056] 100 Substrate 103 Polycrystalline silicon film 104 Gettering layer
Claims
1. A processing method comprising: preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface; forming a gettering layer made of amorphous silicon on the polycrystalline silicon film by chemical vapor deposition using organic aminosilane gas; and diffusing the catalyst metal contained in the polycrystalline silicon film into the gettering layer by annealing the substrate.
2. The treatment method according to claim 1, wherein the organic aminosilane gas is diisopropylaminosilane gas.
3. The processing method according to claim 1, wherein the polycrystalline silicon film is formed by crystallizing an amorphous silicon film by metal-induced crystallization with the catalyst metal as a nucleus.
4. The processing method according to claim 1, further comprising supplying an etching solution to the gettering layer in which the catalyst metal has diffused to remove it.
5. The processing method according to any one of claims 1 to 4, wherein the formation of the gettering layer and the diffusion of the catalyst metal into the gettering layer are performed in the same processing vessel.
6. The treatment method according to any one of claims 1 to 4, wherein the catalyst metal is nickel.
7. The processing method according to any one of claims 1 to 4, wherein a recess is formed on the surface of the substrate, and the polycrystalline silicon film is formed on the inner surface of the recess.
8. A processing apparatus comprising: a processing container for housing a substrate; a gas supply unit for supplying gas into the processing container; a heating unit for the substrate housed in the processing container; and a control unit, wherein the control unit is configured to control the gas supply unit and the heating unit to perform the following: preparing a substrate having a polycrystalline silicon film containing a catalyst metal on its surface; forming a gettering layer made of amorphous silicon on the polycrystalline silicon film by chemical vapor deposition using organic aminosilane gas; and diffusing the catalyst metal contained in the polycrystalline silicon film into the gettering layer by annealing the substrate.