CN117888192A - Film forming method and film forming apparatus - Google Patents
Film forming method and film forming apparatus Download PDFInfo
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- CN117888192A CN117888192A CN202311286795.2A CN202311286795A CN117888192A CN 117888192 A CN117888192 A CN 117888192A CN 202311286795 A CN202311286795 A CN 202311286795A CN 117888192 A CN117888192 A CN 117888192A
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- film
- amorphous silicon
- raw material
- nickel
- silicon film
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- 238000000034 method Methods 0.000 title claims abstract description 116
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 226
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 81
- 229910021417 amorphous silicon Inorganic materials 0.000 claims abstract description 78
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 70
- 239000002994 raw material Substances 0.000 claims abstract description 64
- 239000000758 substrate Substances 0.000 claims abstract description 57
- 238000002425 crystallisation Methods 0.000 claims abstract description 32
- 230000008025 crystallization Effects 0.000 claims abstract description 32
- 239000002184 metal Substances 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 230000001939 inductive effect Effects 0.000 claims abstract description 6
- 229920005591 polysilicon Polymers 0.000 claims description 73
- 238000009792 diffusion process Methods 0.000 claims description 25
- 238000012545 processing Methods 0.000 claims description 21
- 230000015572 biosynthetic process Effects 0.000 claims description 16
- 239000007788 liquid Substances 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 6
- 229910021334 nickel silicide Inorganic materials 0.000 abstract description 10
- RUFLMLWJRZAWLJ-UHFFFAOYSA-N nickel silicide Chemical compound [Ni]=[Si]=[Ni] RUFLMLWJRZAWLJ-UHFFFAOYSA-N 0.000 abstract description 10
- 230000002776 aggregation Effects 0.000 abstract description 6
- 238000005054 agglomeration Methods 0.000 abstract 1
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 68
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 45
- 229910052710 silicon Inorganic materials 0.000 description 45
- 239000010703 silicon Substances 0.000 description 45
- 238000002253 near-edge X-ray absorption fine structure spectrum Methods 0.000 description 25
- 239000002245 particle Substances 0.000 description 16
- 239000010410 layer Substances 0.000 description 15
- 239000002344 surface layer Substances 0.000 description 15
- 238000004458 analytical method Methods 0.000 description 8
- 239000012159 carrier gas Substances 0.000 description 8
- 238000001887 electron backscatter diffraction Methods 0.000 description 8
- 238000012986 modification Methods 0.000 description 8
- 230000004048 modification Effects 0.000 description 8
- 229910005881 NiSi 2 Inorganic materials 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 5
- 238000004220 aggregation Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000011144 upstream manufacturing Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000005247 gettering Methods 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 238000002003 electron diffraction Methods 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 238000013507 mapping Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000004998 X ray absorption near edge structure spectroscopy Methods 0.000 description 2
- 238000000833 X-ray absorption fine structure spectroscopy Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- BIVNKSDKIFWKFA-UHFFFAOYSA-N N-propan-2-yl-N-silylpropan-2-amine Chemical compound CC(C)N([SiH3])C(C)C BIVNKSDKIFWKFA-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000003028 elevating effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000011553 magnetic fluid Substances 0.000 description 1
- PEUPIGGLJVUNEU-UHFFFAOYSA-N nickel silicon Chemical compound [Si].[Ni] PEUPIGGLJVUNEU-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910021332 silicide Inorganic materials 0.000 description 1
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000000624 total reflection X-ray fluorescence spectroscopy Methods 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
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- Recrystallisation Techniques (AREA)
Abstract
Techniques are provided for inhibiting the agglomeration of nickel silicide. The film forming method according to one embodiment of the present disclosure includes the steps of: preparing a substrate having an amorphous silicon film on a surface thereof; supplying a nickel raw material gas to the amorphous silicon film, and diffusing nickel into the amorphous silicon film; and heating the amorphous silicon film, and crystallizing the amorphous silicon film by inducing lateral crystallization with a metal having the nickel as a nucleus diffused into the amorphous silicon film to form a polycrystalline silicon film.
Description
Technical Field
The present invention relates to a film forming method and a film forming apparatus.
Background
A technique of modifying an amorphous silicon film into a polysilicon film by adsorbing nickel particles on the surface of the amorphous silicon film and then annealing is known (for example, refer to patent document 1).
[ Prior Art literature ]
[ patent literature ]
Japanese patent application laid-open No. 2011-60908
Disclosure of Invention
[ problem ] to be solved by the invention
The present invention provides a technique for suppressing aggregation of nickel silicide.
[ means for solving the problems ]
The film forming method according to one embodiment of the present disclosure includes the steps of: preparing a substrate having an amorphous silicon film on a surface thereof; supplying a nickel raw material gas to the amorphous silicon film, and diffusing nickel into the amorphous silicon film; and heating the amorphous silicon film, and crystallizing the amorphous silicon film by inducing lateral crystallization with a metal having the nickel as a nucleus diffused into the amorphous silicon film to form a polycrystalline silicon film.
[ Effect of the invention ]
According to the present disclosure, aggregation of nickel silicide can be suppressed.
Drawings
Fig. 1 is a cross-sectional view showing a film forming method according to an embodiment.
Fig. 2 is a cross-sectional view showing a film formation method according to modification 1 of the embodiment.
Fig. 3 is a cross-sectional view showing a film formation method according to modification 2 of the embodiment.
Fig. 4 is a cross-sectional view showing a film forming apparatus according to an embodiment.
Fig. 5 is a comparative graph comparing grain patterns of polysilicon films.
Fig. 6 is a graph showing the results of measuring the relationship between the grain size of the polysilicon film and the Ni concentration.
Fig. 7 is a graph (1) showing the XANES spectrum of the polysilicon film formed by the condition 4A.
Fig. 8 is a graph (2) showing the XANES spectrum of the polysilicon film formed by the condition 4A.
Fig. 9 is a graph (3) showing the XANES spectrum of the polysilicon film formed by the condition 4A.
Fig. 10 is a graph (1) showing the XANES spectrum of the polysilicon film formed by the condition 4B.
Fig. 11 is a graph (2) showing the XANES spectrum of the polysilicon film formed by the condition 4B.
Fig. 12 is a graph (3) showing the XANES spectrum of the polysilicon film formed by the condition 4B.
Fig. 13 is a graph showing the measurement results of the TUNA method of the polysilicon film formed under conditions 5A and 5B.
Detailed Description
Non-limiting exemplary embodiments of the present invention are described below with reference to the accompanying drawings. In all the drawings, the same or corresponding reference numerals are used for the same or corresponding elements or components, and repetitive description will be omitted.
[ film Forming method ]
The film forming method according to the embodiment is a method of forming a polysilicon film on a substrate. For example, a polysilicon film may be used as a channel silicon film of a three-dimensional NAND flash memory.
A film forming method according to an embodiment will be described with reference to fig. 1. Fig. 1 is a cross-sectional view showing a film forming method according to an embodiment.
First, as shown in fig. 1 (a), a substrate 101 having an oxide film 102 on the surface thereof is prepared (preparation step). The substrate 101 is, for example, a silicon substrate. The oxide film 102 is, for example, a silicon oxide film. The substrate 101 may have a recess such as a hole or a groove on the surface.
Next, as shown in fig. 1b, an amorphous silicon film 103 is formed on the oxide film 102 by chemical vapor deposition (chemical vapor deposition: CVD) using a silicon source gas (film forming step). The silicon source gas is, for example, diisopropylaminosilane (DIPAS), disilane, monosilane, or a combination thereof. The substrate temperature is, for example, 350 ℃ to 500 ℃.
Next, as shown in fig. 1 (c), a nickel source gas is supplied to the substrate 101 to diffuse nickel (Ni) into the amorphous silicon film 103 (diffusion step). Thus, an amorphous silicon film (hereinafter referred to as "Ni-containing amorphous silicon film 103 a") in which Ni diffuses is formed in the film. The nickel raw material gas may be produced by, for example, gasifying a liquid nickel raw material. The liquid nickel raw material is, for example (EtCp) 2 Ni[Ni(C 2 H 5 C 5 H 4)2 ]、NiPF 3 [Ni(PF 3)4 ]、CpAllylNi[(C 3 H 5) (C 5 H 5) Ni]Or Ni (CO) 4 . The nickel raw material gas may be generated, for example, by sublimating a solid nickel raw material. The solid nickel starting material being, for example, (MeCp) 2 Ni[Ni(CH 3 C 5 H 4) ]. For example, in use (EtCp) 2 When Ni is used as a nickel raw material, the substrate temperature is 150 ℃ to 300 ℃. In the diffusion step, the amount of Ni diffused in the Ni-containing amorphous silicon film 103a can be adjusted by controlling the supply amount of the nickel source gas. The diffusion step is continuously performed in the same processing vessel as the film formation step, for example. However, the diffusion step may be performed in a process chamber different from the film formation step, for example.
Next, as shown in fig. 1d, the Ni-containing amorphous silicon film 103a is crystallized by metal-induced lateral crystallization (metal-inducedlateral crystallization: MILC), and a polysilicon film 105 is formed (crystallization process). Specifically, the substrate 101 is heated to a predetermined temperature in an inert gas atmosphere at normal pressure, and the Ni-containing amorphous silicon film 103a is crystallized by inducing lateral crystallization with a metal having Ni as a nucleus diffused in the Ni-containing amorphous silicon film 103a, thereby forming the polycrystalline silicon film 105. The predetermined temperature is, for example, 500 ℃ to 600 ℃. The crystallization step may be performed, for example, under reduced pressure. The crystallization step is continuously performed in the same processing vessel as the diffusion step, for example. However, the crystallization process may be performed in a process vessel different from the film formation process, for example.
Thereby, the polysilicon film 105 can be formed on the substrate 101. Ni remaining in the surface layer or film of the polysilicon film 105 may also be removed after the crystallization process, for example, by gettering.
As described above, by the film formation method according to the embodiment, ni is diffused into the amorphous silicon film 103 using the nickel source gas, and then the Ni-containing amorphous silicon film 103a is crystallized by metal-induced lateral crystallization, forming the polycrystalline silicon film 105. Therefore, the polysilicon film 105 can be formed by metal-induced lateral crystallization using Ni at a low concentration. As a result, aggregation of nickel silicide (NiSi) in the surface layer of the polysilicon film 105 can be suppressed. In addition, the polysilicon film 105 having small surface roughness and large grain size can be formed. In addition, ni remaining in the surface layer or film of the polysilicon film 105 can be easily removed by gettering.
By the film forming method according to the embodiment, ni is diffused into the amorphous silicon film 103 using the nickel source gas. Therefore, when Ni is diffused into the amorphous silicon film 103 formed on the inner surface of the concave portion, variation in the diffusion amount of Ni in the depth direction of the concave portion can be reduced. As a result, the polysilicon film 105 having small variations in the grain size in the depth direction of the recess can be formed.
In contrast, in the case where Ni is physically adsorbed on the surface layer of the amorphous silicon film 103 by sputtering or coating, if the polysilicon film 105 having a large grain size is to be formed, ni needs to be physically adsorbed on the surface layer of the amorphous silicon film 103 at a high concentration. Therefore, niSi tends to accumulate on the surface layer of the amorphous silicon film 103, and NiSi particles remain which deteriorate the surface roughness and are difficult to remove. In addition, it is difficult to physically adsorb Ni with good surface uniformity of the amorphous silicon film 103 in the depth direction of the concave portion.
A film formation method according to modification 1 of the embodiment will be described with reference to fig. 2. Fig. 2 is a cross-sectional view showing a film formation method according to modification 1 of the embodiment. The following description will focus on the point of difference from the film formation method shown in fig. 1.
First, as shown in fig. 2 (a), a substrate 201 having an oxide film 202 on the surface thereof is prepared (preparation step). The substrate 201 and the oxide film 202 may be the same as the substrate 101 and the oxide film 102, respectively.
Next, as shown in fig. 2 (b), an amorphous silicon film 203 is formed on the oxide film 202 by CVD using a silicon source gas (1 st film forming step). The thickness of the amorphous silicon film 203 may be, for example, a thickness thinner than the target film thickness of the polysilicon film 205. In this case, in a diffusion step described later, the amount of Ni diffused into the amorphous silicon film 203 can be reduced. The thickness of the amorphous silicon film 203 may be thinner than that of the amorphous silicon film 103, for example.
Next, as shown in fig. 2 (c), a nickel source gas is supplied to the substrate 201, and Ni is diffused into the amorphous silicon film 203 (diffusion step). Thus, an amorphous silicon film (hereinafter referred to as "Ni-containing amorphous silicon film 203 a") in which Ni diffuses is formed in the film.
Next, as shown in fig. 2 (d), an amorphous silicon film 204 is formed on the Ni-containing amorphous silicon film 203a by CVD using a silicon source gas (a 2 nd film forming step). The silicon source gas may be the same as that used in forming the amorphous silicon film 203, for example. However, the silicon source gas may be different from the silicon source gas used in forming the amorphous silicon film 203, for example.
Next, as shown in fig. 2 (e), the Ni-containing amorphous silicon film 203a and the amorphous silicon film 204 are crystallized by metal-induced lateral crystallization, thereby forming a polycrystalline silicon film 205 (crystallization process). In the crystallization step, the Ni-containing amorphous silicon film 203a and the amorphous silicon film 204 are crystallized by inducing lateral crystallization with a metal having Ni as a nucleus diffused in the Ni-containing amorphous silicon film 203 a.
Thereby, the polysilicon film 205 can be formed on the substrate 201. Ni remaining in the surface layer or film of the polysilicon film 205 may also be removed after the crystallization process, for example, by gettering.
As described above, according to the film forming method according to modification 1 of the embodiment, ni is diffused only in the amorphous silicon film 203. Thus, the polysilicon film 205 can be formed by metal-induced lateral crystallization with a lower concentration of Ni.
A film formation method according to modification 2 of the embodiment will be described with reference to fig. 3. Fig. 3 is a cross-sectional view showing a film formation method according to modification 2 of the embodiment. The following description will focus on the point of difference from the film formation method shown in fig. 1.
First, as shown in fig. 3 (a), a substrate 301 having an oxide film 302 on the surface thereof is prepared (preparation step). The substrate 301 and the oxide film 302 may be the same as the substrate 101 and the oxide film 102, respectively.
Next, as shown in fig. 3 (b), a silicon source gas is supplied to the substrate 301, and a seed layer 303 is formed on the oxide film 302 (seed layer forming step). The seed layer 303 is a layer in which silicon source gas is adsorbed in island form on the oxide film 302.
Next, as shown in fig. 3 (c), a nickel source gas is supplied to the substrate 301 to diffuse Ni into the seed layer 303 (diffusion step). Thereby, a Ni diffused seed layer (hereinafter referred to as "Ni-containing seed layer 303 a") is formed in the layer. The seed layer 303 is thinner than the amorphous silicon film 103, so that the amount of Ni diffused into the seed layer 303 can be reduced in the diffusion process.
Next, as shown in fig. 3 (d), an amorphous silicon film 304 is formed on the Ni-containing seed layer 303a by CVD using a silicon source gas (film formation step).
Next, as shown in fig. 3 (e), the Ni-containing seed layer 303a and the amorphous silicon film 304 are crystallized by metal-induced lateral crystallization, thereby forming a polysilicon film 305 (crystallization process). In the crystallization step, the Ni-containing seed layer 303a and the amorphous silicon film 304 are crystallized by inducing lateral crystallization with a metal having Ni as a nucleus diffused in the Ni-containing seed layer 303 a.
Thereby, the polysilicon film 305 can be formed on the substrate 301. Ni remaining in the surface layer or film of the polysilicon film 305 may also be removed after the crystallization process, for example, by gettering.
As described above, by the film forming method according to modification 2 of embodiment, ni is diffused only in the seed layer 303. Thus, the polysilicon film 305 can be formed by metal-induced lateral crystallization with a lower concentration of Ni.
[ film Forming apparatus ]
An example of a film forming apparatus capable of performing the film forming method according to the embodiment will be described with reference to fig. 4. Fig. 4 is a cross-sectional view showing a film forming apparatus according to an embodiment.
The film forming 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.
The processing container 10 has a double-pipe structure including an inner pipe 11 having a cylindrical shape and an outer pipe 12 having a ceiling concentrically placed outside the inner pipe 11. The inner tube 11 and the outer tube 12 are formed of quartz, for example. The process vessel 10 is configured to receive a hull 16.
A housing portion 13 is formed on one side of the inner tube 11 along the longitudinal direction (up-down direction) thereof. The housing portion 13 is a region in the convex portion 14 formed by projecting a part of the side wall of the inner tube 11 to the outside. The housing portion 13 houses a gas supply pipe.
The lower end of the process container 10 is supported by a cylindrical manifold 17 formed 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.
An annular support portion 20 is provided on an inner wall of an upper portion of the manifold 17. The support portion 20 supports the lower end of the inner tube 11. An exhaust port 21 is provided in the upper side wall of the manifold 17 above the support portion 20. The cover 22 is hermetically 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 formed of, for example, stainless steel.
A rotary shaft 25 is provided in a central portion of the cover 22 through a magnetic fluid seal 24. The lower end of the rotation shaft 25 is rotatably supported by an arm 26A of a lifting mechanism 26 constituted by a ship body lifter. A rotary plate 27 is provided at an upper end of the rotary shaft 25. The hull 16 is mounted on the rotary plate 27 by a thermal insulation cylinder 28 made of quartz.
The boat 16 holds a plurality of (e.g., 25 to 200) substrates W substantially horizontally with a space therebetween in the up-down direction. The substrate W is, for example, a semiconductor wafer. The hull 16 rotates integrally with the rotation shaft 25. The hull 16 moves up and down integrally with the cover 22 by lifting and lowering the arm 26A, and is inserted into and removed from the processing container 10.
The gas supply unit 30 is configured to be capable of introducing various gases used in the film forming method according to the embodiment into the inner tube 11. The gas supply section 30 includes a silicon raw material supply section 31 and a nickel raw material supply section 32.
The silicon raw material supply section 31 includes a silicon raw material supply pipe 31a in the processing container 10, and includes a silicon raw material supply path 31b outside the processing container 10. In the silicon raw material supply path 31b, a silicon raw material source 31c, a mass flow controller 31d, and a gate valve 31e are provided in this order from the upstream side to the downstream side in the gas flow direction. Thus, the supply timing of the silicon source gas from the silicon source 31c is controlled by the gate valve 31e, and the flow rate is adjusted to a predetermined flow rate by the mass flow controller 31 d. The silicon source gas flows into the silicon source supply pipe 31a from the silicon source supply path 31b, and is discharged into the processing container 10 from the silicon source supply pipe 31 a.
The nickel raw material supply section 32 includes a nickel raw material supply pipe 32a in the processing container 10, and a nickel raw material supply path 32b outside the processing container 10. In the nickel raw material supply path 32b, a raw material tank 32c, a regulating valve 32d, and a partition valve 32e are provided in this order from the upstream side toward the downstream side in the gas flow direction. The raw material tank 32c accommodates a nickel raw material. The nickel raw material is liquid raw material at normal temperature or solid raw material at normal temperature. A heater 32f is provided around the raw material tank 32 c. The heater 32f heats the nickel raw material in the raw material tank 32 c. Thereby, the liquid nickel raw material is gasified to generate a nickel raw material gas. Alternatively, the solid nickel feedstock sublimates to form a nickel feedstock gas.
The nickel raw material supply unit 32 has a carrier gas pipe 32g inserted into the raw material tank 32c from above. A carrier gas source 32h, a gate valve 32i, and a regulator valve 32j are provided in this order from the upstream side toward the downstream side in the gas flow direction in the carrier gas pipe 32g. Thus, the carrier gas of the carrier gas source 32h is supplied into the raw material tank 32c with the supply timing controlled by the gate valve 32i and the flow rate adjusted to a predetermined flow rate by the regulator valve 32j. The carrier gas, together with the nickel raw material gas in the raw material tank 32c, is controlled in supply timing by the gate valve 32e, and is adjusted to a predetermined flow rate by the regulator valve 32d, and flows into the nickel raw material supply pipe 32a from the nickel raw material supply path 32b. The nickel raw material gas and the carrier gas flowing into the nickel raw material supply pipe 32a are discharged from the nickel raw material supply pipe 32a into the process container 10. A bypass path 32k may be provided to connect the upstream side of the gate valve 32i in the carrier gas pipe 32g and the downstream side of the gate valve 32e in the nickel raw material supply path 32b, and a bypass valve 32l may be provided in the bypass path 32 k.
The gas supply pipes (silicon raw material supply pipe 31a, nickel raw material supply pipe 32 a) are fixed to the manifold 17. Each gas supply tube is formed of, for example, quartz. Each gas supply pipe extends linearly in the vertical direction at a position near the inner pipe 11, and extends horizontally by being bent in an L-shape in the manifold 17, so as to penetrate the manifold 17. The gas supply pipes are arranged side by side along the circumferential direction of the inner pipe 11 and are formed to have the same height as each other.
A plurality of air holes 31p are provided in the silicon raw material supply pipe 31a at positions located in the inner pipe 11. A plurality of air holes 32p are provided in the nickel raw material supply pipe 32a at positions located in the inner pipe 11. The air holes (air holes 31p, 32 p) are formed at predetermined intervals along the extending direction of the respective gas supply pipes. Each vent releases gas in a horizontal direction. The interval between the air holes is set to be the same as the interval between the substrates W held by the boat 16, for example. The position of each air hole in the height direction is set to be an intermediate position between the substrates W adjacent in the vertical direction. Thus, each gas hole can efficiently supply gas to the opposing surface between the adjacent substrates W.
The gas supply unit 30 may mix a plurality of gases and discharge the mixed gases from 1 supply pipe. For example, the silicon raw material supply pipe 31a and the nickel raw material supply pipe 32a may be configured to be capable of ejecting an inert gas. The gas supply pipes (the silicon raw material supply pipe 31a and the nickel raw material supply pipe 32 a) may be formed or arranged in different shapes from each other. The gas supply unit 30 may have a gas supply pipe for supplying other gases in addition to the silicon source gas and the nickel source gas.
The exhaust portion 40 has an exhaust passage 41 connected to the exhaust port 21. In the exhaust passage 41, a pressure adjustment valve 42 and a vacuum pump 43 are provided in this order from the upstream side to the downstream side in the flow direction of the gas. Thus, the gas in the process container 10 is discharged outside the process container 10 by the vacuum pump 43 while the flow rate of the gas is controlled by the pressure regulating valve 42.
The heating portion 50 has a cylindrical shape and is provided around the outer tube 12. The heating unit 50 includes, for example, a heater, and heats the substrates W in the process container 10.
The control unit 90 performs the film forming method according to the embodiment by controlling the operations of the respective units of the film forming apparatus 1, for example. For example, the control section 90 may be a computer. A program of a computer that performs operations of each section of the film forming apparatus 1 is stored in a storage medium. The storage medium may be, for example, a floppy disk, CD, hard disk, flash memory, DVD, etc.
[ operation of film Forming apparatus ]
The operation of the film forming apparatus 1 when the film forming method according to the embodiment is performed will be described.
First, the control unit 90 controls the lifting mechanism 26 to carry the boat 16 holding the plurality of substrates W into the process container 10, and the opening at the lower end of the process container 10 is hermetically closed by the lid 22. Each substrate W is, for example, a substrate 101 having an oxide film 102 on a surface thereof.
Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to perform the film forming process described above. Specifically, first, the control unit 90 controls the evacuation unit 40 to reduce the pressure in the process container 10 to a predetermined pressure, and controls the heating unit 50 to adjust the temperature of the substrate W to a predetermined temperature and maintain the temperature. Next, the control unit 90 controls the silicon raw material supply unit 31 to supply the silicon raw material gas into the process container 10. Thereby, the amorphous silicon film 103 is formed on the oxide film 102.
Next, the control unit 90 controls the gas supply unit 30, the gas discharge unit 40, and the heating unit 50 to perform the diffusion process. Specifically, first, the control unit 90 controls the evacuation unit 40 to reduce the pressure in the process container 10 to a predetermined pressure, and controls the heating unit 50 to adjust the temperature of the substrate W to a predetermined temperature and maintain the temperature. Next, the control unit 90 controls the nickel raw material supply unit 32 to supply the nickel raw material gas into the process container 10. Thereby, nickel diffuses into the amorphous silicon film 103, forming a Ni-containing amorphous silicon film 103a.
Next, the control unit 90 controls the gas supply unit 30, the exhaust unit 40, and the heating unit 50 to perform the crystallization process. Specifically, first, the control unit 90 controls the gas supply unit 30 to supply an inert gas into the process container 10, controls the exhaust unit 40 to adjust the pressure in the process container 10 to a predetermined pressure, and controls the heating unit 50 to adjust the temperature of the substrate W to a predetermined temperature and maintain the temperature. Thus, the Ni-containing amorphous silicon film 103a is crystallized by metal-induced lateral crystallization, thereby forming the polysilicon film 105.
Next, the control unit 90 increases the pressure in the process container 10 to the atmospheric pressure, lowers the temperature in the process container 10 to the carry-out temperature, and then controls the elevating mechanism 26 to carry the hull 16 out of the process container 10.
Examples (example)
In example 1, a silicon substrate having an oxide film on the surface thereof was prepared, and the prepared silicon substrate was stored in the processing container 10 of the film forming apparatus 1, and a polysilicon film was formed on the oxide film under the following conditions 1A to 1C. Then, the grain size and Ni concentration of the polysilicon film were measured. The grain size was measured by TEM electron diffraction mapping (TEM Electron Diffraction Mapping: TEMED-Map). Ni concentration was measured by total reflection fluorescent X-ray analysis (total reflection X-ray fluorescence: TXRF).
(condition 1A)
In condition 1A, the film forming step, the diffusion step, and the crystallization step according to the film forming method of the above embodiment are sequentially and continuously performed to form a polysilicon film. In the film forming step, an amorphous silicon film having a thickness of 19nm was formed. In the diffusion step, a nickel source gas (EtCp) is supplied at a low concentration 2 Ni gasified gas. In the crystallization process, the silicon substrate is heated to 550 ℃.
(condition 1B)
In condition 1B, the nickel source gas is supplied at a higher concentration than in condition 1A in the diffusion step. Other conditions were the same as in condition 1A.
(condition 1C)
Under condition 1C, the diffusion step was not performed. Other conditions were the same as in condition 1A.
Fig. 5 is a graph comparing grain patterns of polysilicon films. As shown in FIG. 5, under condition 1A, the arithmetic average particle diameter was 1.23. Mu.m, the weighted average particle diameter was 6.80. Mu.m, and the Ni concentration in the film was 4.7X10 @ 12 atoms/cm 2 . Under condition 1B, the arithmetic average particle diameter was 1.07. Mu.m, the weighted average particle diameter was 2.26. Mu.m, and the Ni concentration in the film was 1.3X10 14 atoms/cm 2 。 Under condition 1C, the arithmetic average particle diameter was 0.66. Mu.m, and the weighted average particle diameter was 0.76. Mu.m. The results indicate that by performing the diffusion process, a polysilicon film having a large grain size can be formed. In addition, when the diffusion step is performed, a polysilicon film having a large crystal grain size can be formed by reducing the Ni concentration in the film.
In example 2, a silicon substrate having an oxide film on the surface thereof was prepared, and the prepared silicon substrate was stored in the processing container 10 of the film forming apparatus 1, and a polysilicon film was formed on the oxide film under the following conditions 2A to 2C. Then, the grain size and Ni concentration of the polysilicon film were measured. The grain size was measured by TEM electron diffraction mapping. The Ni concentration was measured by total reflection fluorescent X-ray analysis.
(condition 2A)
Condition 2A is the same as condition 1A.
(condition 2B)
Under condition 2B, instead of the diffusion step, ni is physically adsorbed on the surface layer of the amorphous silicon film by applying a Ni-containing liquid. Other conditions were the same as in condition 1A.
(condition 2C)
Under condition 2C, ni was physically adsorbed to the surface layer of the amorphous silicon film by sputtering using a Ni target instead of the diffusion step. Other conditions were the same as in condition 1A.
Fig. 6 is a graph showing the results of measuring the relationship between the grain size of the polysilicon film and the Ni concentration. In FIG. 6, the vertical axis represents the grain size [ μm ] of the polysilicon film]The horizontal axis represents the Ni concentration [ atoms/cm ] of the polysilicon film 2 ]. In FIG. 6, the results contained in region A indicate formation by condition 2AThe results contained in the region B represent the results of the polysilicon film formed by the condition 2B, and the results contained in the region C represent the results of the polysilicon film formed by the condition 2C. In fig. 6, the circle marks represent EBSD weighted average particle diameters, and the triangle marks represent EBSD arithmetic average particle diameters.
As shown in FIG. 6, under condition 2A, the Ni concentration was 1.0X10 12 atoms/cm 2 ～1.0×10 13 atoms/cm 2 About, the EBSD weighted average particle diameter is about 7 μm, and the EBSD arithmetic average particle diameter is about 1 μm. Under condition 2B, ni concentration was 1.0X10 14 atoms/cm 2 About, the EBSD weighted average particle diameter is about 2 μm to 3 μm, and the EBSD arithmetic average particle diameter is about 1 μm. Ni concentration under condition 2C was 1.0X10 16 atoms/cm 2 About, the EBSD weighted average particle diameter and the EBSD arithmetic average particle diameter are about 1 μm or less and more than 0 μm. From the results, it is clear that by diffusing Ni into the amorphous silicon film using the nickel source gas, a polycrystalline silicon film having a low Ni concentration and a large grain size can be formed as compared with the case where Ni is physically adsorbed on the surface layer of the amorphous silicon film.
In example 3, a silicon substrate having an oxide film on the surface thereof was prepared, and the prepared silicon substrate was stored in the processing container 10 of the film forming apparatus 1, and a polysilicon film was formed on the oxide film under the following conditions 3A to 3B. The polysilicon film was then observed with a transmission electron microscope (Transmission Electron Microscope: TEM).
(condition 3A)
The same as in condition 1A.
(condition 3B)
The same as in condition 1B.
(condition 3C)
The same as in condition 2C.
Based on the observation result of TEM, niSi aggregation was not seen on the surface of the polysilicon film under the conditions 3A and 3B, whereas NiSi aggregation was seen on the surface of the polysilicon film under the condition 3C. The results indicate that Ni can be suppressed from aggregating by diffusing Ni into the amorphous silicon film using the nickel source gas.
In example 4, a silicon substrate having an oxide film on the surface thereof was prepared, and the prepared silicon substrate was stored in the processing container 10 of the film forming apparatus 1, and a polysilicon film was formed on the oxide film under the following conditions 4A and 4B. Next, the polysilicon film was analyzed by using an X-ray absorption microstructure (X-ray Absorption Fine Structure: XAFS).
(condition 4A)
Under condition 4A, the film forming step, the diffusion step, and the crystallization step according to the film forming method of the above embodiment are sequentially and continuously performed to form a polysilicon film. In the film forming step, an amorphous silicon film having a thickness of 19nm was formed. In the diffusion step, a supply control (EtCp) 2 The Ni vaporized gas serves as a nickel raw material gas, and Ni is diffused into the amorphous silicon film, thereby forming a Ni-containing amorphous silicon film. Ni concentration in the Ni-containing amorphous silicon film was 7.7X10 14 atoms/cm 2 。 In the crystallization step, the crystal is crystallized by nitrogen (N) at 700Pa 2 ) The silicon substrate was heated at 575 ℃ in a gas atmosphere for 240 minutes to crystallize the Ni-containing amorphous silicon film and form a polycrystalline silicon film.
(condition 4B)
Under condition 4B, after the film forming process and before the diffusion process, a process of removing the oxide film on the surface of the amorphous silicon film is performed. Other conditions were the same as in condition 4A.
Based on XAFS analysis, L3 absorption end XANES (X-ray Absorption Near Edge Structure) spectra of Ni were measured using a partial electron yield (Partial Electron Yield: PEY) method, a total electron yield (Total Electron Yield: TEY) method, and a fluorescence yield (Fluorescence Yield: FLY) method. By adopting the PEY method, the TEY method and the FLY method, information of different depth ranges can be obtained. The detection depth of the PEY method is about several nm, the detection depth of the TEY method is about several tens of nm, and the detection depth of the FLY method is about several hundred nm.
Fig. 7 to 9 are graphs showing XANES spectra of the polysilicon film formed by the condition 4A. Fig. 7 is a XANES spectrum measured by PEY method. Fig. 8 is a XANES spectrum measured using the TEY method. Fig. 9 is a XANES spectrum measured by the FLY method. In fig. 7 to 9, the upper graph shows the measured value of XANES spectrum of the polysilicon film, and the lower graph shows the obtained value from the databaseTaken Ni, niO, niSi 2 Is a XANES spectrum of (c). In fig. 7 to 9, the horizontal axis represents the energy of X-rays [ eV]The vertical axis represents the X-ray absorption [ a.u ].]。
As shown in the upper diagrams of fig. 7 to 9, it is clear that the XANES spectrum of the polysilicon film is different between the case of using the PEY method, the case of using the TEY method, and the case of using the FLY method. As shown in the upper diagrams of fig. 7 and 8, a peak near 854eV can be seen when the PEY method or the TEY method is used, whereas a peak near 854eV cannot be seen when the FLY method is used. The peak value near 854eV in the PEY method is higher than the peak value near 854eV in the FEY method. As shown in the lower diagrams of fig. 7 to 9, the peak around 854eV is derived from NiO. From the results, it is presumed that NiO is present in a depth range of several tens of nm, and particularly, is present in a depth range of several nm.
As shown in the upper diagrams of fig. 7 to 9, when any of the PEY method, the TEY method, and the FLY method is used, a peak around 856eV can be seen. The peak value near 856eV is higher when the FLY method is used than when the PEY method and the TEY method are used. As shown in the lower graphs of fig. 7 to 9, the peak around 856eV comes from NiSi 2 . The results show that the silicide composition in the deep portion of the surface of the polysilicon film is almost entirely changed to NiSi 2 It is presumed that the formation efficiency of the polysilicon film based on the metal-induced lateral crystallization can be effectively improved.
As a result of analysis of XANES spectra obtained by the PEY method, the abundance of Ni was 17%, the abundance of NiO was 32%, and the abundance of NiSi was found 2 The abundance of (2) was 51%. As a result of analysis of XANES spectra by the TEY method, the abundance of Ni was 22%, the abundance of NiO was 15%, and the abundance of NiSi was 15% 2 The abundance of (2) is 62%. As a result of analysis of XANES spectrum by FLY method, the abundance of Ni was 9%, and NiSi 2 The abundance of (2) is 91%.
Fig. 10 to 12 are graphs showing XANES spectra of the polysilicon film formed by the condition 4B. Fig. 10 is a XANES spectrum measured using the PEY method. Fig. 11 is a XANES spectrum measured using the TEY method. Fig. 12 is a XANES spectrum measured using the FLY method. In FIGS. 10 to 12The upper graph shows the measured value of XANES spectrum of the polysilicon film, and the lower graph shows Ni, niO, niSi obtained from the database 2 Is a XANES spectrum of (c). In fig. 10 to 12, the horizontal axis represents the energy of X-rays [ eV]The vertical axis represents the X-ray absorption [ a.u ].]。
As shown in the upper diagrams of fig. 10 to 12, when any of the PEY method, the TEY method, and the FLY method is used, a peak around 856eV is seen. As shown in the lower graphs of fig. 10 to 12, the peak around 856eV comes from NiSi 2 . From the result, niSi was estimated 2 Exist in all depth ranges. That is, it is estimated that NiSi can be formed in all depth ranges of the polysilicon film by removing the oxide film on the surface of the amorphous silicon film after the film forming process and before the diffusion process 2 。
As a result of analysis of XANES spectra obtained by the PEY method, the abundance of Ni was 3%, and NiSi 2 The abundance of (2) is 97%. As a result of analysis of XANES spectrum in the case of using the TEY method, the abundance of Ni was 1%, and NiSi 2 The abundance of (2) is 99%. As a result of analysis of XANES spectrum by FLY method, the abundance of Ni was 10%, and NiSi 2 The abundance of (2) is 90%. From this result, it is assumed that NiO is not present in the polysilicon film. NiO creates a surface trap state that reduces electron mobility. For example, in the case where a polysilicon film is used as a channel silicon film of a three-dimensional NAND flash memory, the absence of NiO is advantageous from the viewpoint of obtaining high electron mobility.
In example 5, a silicon substrate having an oxide film on the surface thereof was prepared, and the prepared silicon substrate was stored in the processing container 10 of the film forming apparatus 1, and a polysilicon film was formed on the oxide film under the following conditions 5A and 5B. The polysilicon film was then analyzed by a tunnel AFM (TUNA) method.
(condition 5A)
Condition 5A is the same as condition 4A.
(condition 5B)
Condition 5B is the same as condition 4B.
In the analysis by the TUNA method, ni contained in the surface layer of the polysilicon film increases the minute leakage current,in contrast, niSi contained in the surface layer of the polysilicon film 2 Little contribution to the increase in minute leakage current. Therefore, by comparing the minute leakage current between different polysilicon films, ni and NiSi in the surface layer of the polysilicon film can be reduced between the different polysilicon films 2 Is compared relatively.
Fig. 13 is a graph showing the measurement results of the TUNA method of the polysilicon film formed under conditions 5A and 5B. In fig. 13, the horizontal axis represents the distance [ μm ] in the direction along the main surface of the silicon substrate, and the vertical axis represents the minute leakage current [ pA ] measured when the polysilicon film is biased.
As shown in fig. 13, it is seen that the minute leakage current of the polysilicon film formed by the condition 5B becomes smaller than the minute leakage current of the polysilicon film formed by the condition 5A. From the results, it is assumed that NiSi can be formed on the surface layer of the polysilicon film by performing a treatment for removing the oxide film on the surface of the amorphous silicon film after the film forming process and before the diffusion process 2 Is increased.
It should be understood that the presently disclosed embodiments are illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted or altered in various ways without departing from the scope of the appended claims and their spirit.
In the above embodiment, the case where the film forming apparatus is a batch apparatus that processes a plurality of substrates at a time has been described, but the present disclosure is not limited thereto. For example, the film forming apparatus may be a single-wafer apparatus for processing substrates one by one.
Claims (7)
1. A film forming method comprising the steps of:
preparing a substrate having an amorphous silicon film on a surface thereof;
supplying a nickel raw material gas to the amorphous silicon film, and diffusing nickel into the amorphous silicon film; and
and heating the amorphous silicon film, and crystallizing the amorphous silicon film by inducing lateral crystallization with a metal having the nickel as a nucleus diffused into the amorphous silicon film to form a polycrystalline silicon film.
2. The film forming method according to claim 1, wherein,
the step of diffusing the nickel includes gasifying a liquid nickel raw material or sublimating a solid nickel raw material to generate the nickel raw material gas.
3. The film forming method according to claim 2, wherein,
the nickel raw material is Ni (C) 2 H 5 C 5 H 4 ) 2 ]、Ni(PF 3 ) 4 、(C 3 H 5 )(C 5 H 5 )Ni、Ni(CO) 4 Or Ni (CH) 3 C 5 H 4 ) 2 。
4. A film forming method according to any one of claim 1 to 3, wherein,
a recess is formed in the surface of the substrate,
the step of preparing the substrate includes forming the amorphous silicon film on the inner surface of the concave portion.
5. The film forming method according to claim 1, wherein,
the step of preparing the substrate includes forming the amorphous silicon film on the surface of the substrate in the same processing container as the step of diffusing the nickel.
6. The film forming method according to claim 1, wherein,
the nickel diffusion step and the polysilicon film formation step are performed in the same processing container.
7. A film forming apparatus includes:
a processing container for accommodating a substrate;
a nickel raw material supply unit that gasifies a liquid nickel raw material or sublimates a solid nickel raw material to generate a nickel raw material gas and supplies the nickel raw material gas into the processing container; the method comprises the steps of,
and a heating unit configured to heat the substrate stored in the processing container.
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| JP2023135969A JP2024058582A (en) | 2022-10-13 | 2023-08-24 | Film forming method and film forming apparatus |
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