Epitaxial wafer manufacturing method
By controlling the growth rate of gettering epitaxial films to 2.4 nm/sec or less, the method addresses cross-contamination and cost issues in metal gettering, enhancing productivity and quality of epitaxial wafers with controlled crystallinity and thickness.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SHIN ETSU HANDOTAI CO LTD
- Filing Date
- 2024-12-20
- Publication Date
- 2026-07-02
AI Technical Summary
Existing methods for fabricating metal gettering layers in semiconductor devices face issues such as cross-contamination and high costs, and lack specification of growth rate, which affects productivity and quality of epitaxial wafers.
A method for manufacturing epitaxial wafers by forming a gettering epitaxial film on a silicon substrate using a reduced-pressure CVD apparatus in a mixed gas atmosphere containing silicon and carbon, with a controlled growth rate of 2.4 nm/sec or less, to ensure single-crystalline formation and high-quality film production.
This method improves productivity and reduces costs by ensuring high-quality gettering epitaxial films with sufficient gettering ability and uniform film thickness, while maintaining excellent crystallinity and reducing unnecessary thickness.
Smart Images
Figure 2026110258000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for manufacturing epitaxial wafers. [Background technology]
[0002] Metal contamination is known to degrade the electrical properties of semiconductor devices. To minimize the effects of metal contamination, a widely used method involves trapping metals in a metal gettering layer to prevent contamination of the device region.
[0003] Conventionally, a metal gettering layer has been fabricated primarily by ion-implanting carbon into the surface of a silicon substrate and then performing epitaxial growth on top of it (Patent Document 1). However, methods using ion implantation equipment have problems such as cross-contamination and high costs.
[0004] As an alternative to methods using ion implantation devices, metal gettering layers have been fabricated by gas-doping with carbon (Patent Documents 2 and 3). However, Patent Documents 2 and 3 do not mention the growth rate, which is important for productivity. [Prior art documents] [Patent Documents]
[0005] [Patent Document 1] Japanese Patent Publication No. 2015-216327 [Patent Document 2] Japanese Patent Publication No. 2006-216934 [Patent Document 3] Patent No. 7487407 [Patent Document 4] Japanese Patent Application Publication No. 08-139027 [Patent Document 5] Japanese Patent Publication No. 2013-045805 [Overview of the Initiative] [Problems that the invention aims to solve]
[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a method for manufacturing an epitaxial wafer that defines the growth rate at which a gettering epitaxial film becomes single-crystalline.
Means for Solving the Problems
[0007] The present invention has been made to achieve the above object, and when forming a gettering epitaxial film made of silicon doped with carbon in a mixed gas atmosphere containing silicon and carbon on a silicon substrate using a reduced-pressure CVD apparatus, a method for manufacturing an epitaxial wafer is provided in which the growth rate of the gettering epitaxial film is set to 2.4 nm / sec or less.
[0008] According to such a method for manufacturing an epitaxial wafer, it is possible to set the growth rate at which the gettering epitaxial film becomes single-crystalline, and thereby improve the productivity in manufacturing an epitaxial wafer including a high-quality gettering epitaxial film.
[0009] At this time, the growth rate of the gettering epitaxial film can be set to 0.1 nm / sec or more.
[0010] Thereby, it is possible to set a realistic growth rate in manufacturing industrial products.
[0011] At this time, the growth rate of the gettering epitaxial film can be set to 1.2 nm / sec or more.
[0012] Thereby, it is possible to define a growth rate at which a higher-quality gettering epitaxial film can be grown with high productivity.
[0013] At this time, the carbon atom concentration of the gettering epitaxial film is 1.0×10 20 atoms / cm3 ~3.0×10 21 atoms / cm 3 can be in the range of
[0014] Thereby, sufficient gettering ability can be obtained, and when a silicon epitaxial film is formed on the gettering epitaxial film, the silicon epitaxial film can be made to have good crystallinity.
[0015] At this time, the carbon atom concentration of the gettering epitaxial film is 3.0×10 20 atoms / cm 3 ~1.0×10 21 atoms / cm 3 can be in the range of
[0016] Thereby, while sufficiently providing gettering ability, a silicon epitaxial film with more excellent crystallinity can be obtained.
[0017] At this time, the gettering epitaxial film can be formed under a pressure of 667 Pa to 10666 Pa.
[0018] Thereby, the film thickness and carbon atom concentration of the gettering epitaxial film can be made uniform easily.
[0019] At this time, the gettering epitaxial film can be formed under a pressure of 667 Pa to 2666 Pa.
[0020] Thereby, the film thickness and carbon atom concentration can be made more surely uniform.
[0021] At this time, the film thickness of the gettering epitaxial film can be 0.025 μm to 3 μm.
[0022] This allows for sufficient gettering capability without forming gettering epitaxial films of unnecessarily high thickness, thus enabling the manufacture of epitaxial wafers at a lower cost.
[0023] In this case, the thickness of the gettering epitaxial film can be set to 0.025 μm to 1 μm.
[0024] This makes it possible to manufacture epitaxial wafers with sufficient gettering capability at an even lower cost.
[0025] In this case, the gettering epitaxial film can be formed at a temperature of 700°C to 800°C.
[0026] This allows for efficient formation of gettering epitaxial films and carbon doping.
[0027] In this case, SiH4, SiH2Cl2, SiHCl3, Si2H6, or SiCl4 can be used as the silicon source in the mixed gas atmosphere containing silicon and carbon.
[0028] Such silicon source gases are suitable for obtaining gettering epitaxial films containing silicon and carbon.
[0029] In this case, SiH(CH3)3, CH3SiH3, or C3H8 can be used as the carbon source in the mixed gas atmosphere containing silicon and carbon.
[0030] Such carbon source gases are suitable for obtaining gettering epitaxial films containing silicon and carbon. [Effects of the Invention]
[0031] As described above, the epitaxial wafer manufacturing method of the present invention allows for a growth rate at which the gettering epitaxial film becomes a single crystal, thereby improving productivity in the manufacturing of epitaxial wafers containing high-quality gettering epitaxial films. [Brief explanation of the drawing]
[0032] [Figure 1] The conditions for single-crystallization or polycrystalline formation in XRD (X-Ray Diffraction) measurements of epitaxial wafers manufactured in the examples and comparative examples are shown. [Modes for carrying out the invention]
[0033] The present invention will be described in detail below, but the present invention is not limited to these descriptions.
[0034] As mentioned above, there was a need for a method of manufacturing epitaxial wafers that specified the growth rate at which the gettering epitaxial film would become a single crystal.
[0035] To solve the above problems, the inventors fabricated gettering epitaxial films containing silicon and carbon on a silicon substrate using a vacuum CVD apparatus under reduced pressure, while varying the growth rate. The crystallinity of each gettering epitaxial film was then evaluated by XRD measurement, and the correlation between the growth rate and crystallinity was investigated to determine the growth rate at which the gettering epitaxial film becomes a single crystal.
[0036] As a result of the above investigations, the present inventors have found that when forming a gettering epitaxial film made of carbon-doped silicon on a silicon substrate using a reduced-pressure CVD apparatus under a mixed gas atmosphere containing silicon and carbon (hereinafter also referred to as "epitaxial growth"), a growth rate of 2.4 nm / sec or less for the gettering epitaxial film can be set to a growth rate that causes the gettering epitaxial film to become a single crystal, thereby improving productivity in the manufacture of epitaxial wafers containing high-quality gettering epitaxial films, and thus completing the present invention.
[0037] The method for manufacturing an epitaxial wafer according to the present invention will be described below.
[0038] The vacuum CVD (RP-CVD) apparatus that can be suitably used in the method for manufacturing epitaxial wafers of the present invention is not particularly limited, and for example, conventional vacuum CVD apparatus can be used.
[0039] The silicon substrate is not particularly limited; for example, it can be obtained by slicing an ingot manufactured by the Czochralski method or the floating zone method, and can have a diameter of, for example, 200-300 mm or even larger. Other conditions are not particularly limited; it may be doped, the conductivity type may be p-type or n-type, and it may have low or high resistivity.
[0040] Using the vacuum CVD apparatus described above, a gettering epitaxial film made of carbon-doped silicon is formed on the silicon substrate described above in a mixed gas atmosphere containing silicon and carbon.
[0041] In the manufacturing method of the present invention, when forming a gettering epitaxial film, the growth rate of the gettering epitaxial film is set to 2.4 nm / sec or less.
[0042] The growth rate of the silicon epitaxial film is usually 1.0 μm / min (= 16.7 nm / sec) (paragraph
[0001] of Patent Document 4) or 3.6 μm / min (= 60 nm / sec) (paragraph
[0016] of Patent Document 5), etc. The growth rate in the manufacturing method of the present invention is a considerably lower growth rate compared to these.
[0043] According to such a method for manufacturing an epitaxial wafer, the growth rate at which the gettering epitaxial film becomes single-crystalline can be set. Thereby, since there is no need to lower the growth rate more than necessary, the productivity in the manufacture of an epitaxial wafer including a high-quality gettering epitaxial film can be improved.
[0044] Before forming the gettering epitaxial film, it is preferable to perform DHF cleaning or hydrogen baking on the silicon substrate to remove the native oxide film of the silicon substrate. Thereby, a gettering epitaxial film can be grown directly on the surface of the silicon substrate.
[0045] The growth rate of the gettering epitaxial film is preferably 0.1 nm / sec or more, and more preferably 1.2 nm / sec or more. Thereby, a realistic growth rate can be achieved in manufacturing industrial products, and a growth rate at which a higher-quality gettering epitaxial film can be grown can be defined. <E000201> [[ID=K00020]]As a silicon source in a mixed gas atmosphere containing silicon and carbon, SiH4, SiH2Cl2, SiHCl3, Si2H6 or SiClA can be used, and as a carbon source, SiH(CH3)3, CH3SiH3 or C3H8 can be used. Such gases are suitable for obtaining a gettering epitaxial film containing silicon and carbon.
[0047] The carbon atom concentration of the gettering epitaxial film is 1.0×10 20atoms / cm 3 ~3.0×10 21 atoms / cm 3 It is preferable to set the range to 3.0 × 10 20 atoms / cm 3 ~1.0×10 21 atoms / cm 3 It is more preferable to define it within that range. This allows for sufficient gettering capability, and when forming a silicon epitaxial film on top of a gettering epitaxial film, it enables the silicon epitaxial film to have good crystallinity.
[0048] Furthermore, the thickness of the gettering epitaxial film can preferably be 0.025 μm to 3 μm, and more preferably 0.025 μm to 1 μm. This allows for sufficient gettering capability without forming gettering epitaxial films of unnecessarily high thickness, thus enabling the manufacture of epitaxial wafers at a lower cost.
[0049] Epitaxial growth is preferably carried out under a pressure of 667 Pa to 10666 Pa, more preferably 667 Pa to 2666 Pa. This makes it possible to easily achieve uniform thickness and carbon atom concentration in the gettering epitaxial film.
[0050] Furthermore, epitaxial growth is preferably carried out at a temperature of 700°C to 800°C. This allows for efficient formation of gettering epitaxial films and carbon doping. [Examples]
[0051] The present invention will be described in detail below with reference to examples, but this is not intended to limit the present invention.
[0052] (Examples) On a 300mm diameter silicon substrate, a gettering epitaxial film containing silicon and carbon was created using an RP-CVD apparatus at 740°C, 667 Pa (5 Torr) under reduced pressure, and in a mixed gas atmosphere containing SiH4 and SiH3 (CH3). (Carbon dioxide concentration: 1 × 10⁻¹⁶) 20 , 3 x 10 20 , 6×10 20 , 1 x 10 21 , 2×10 21 , 3 x 10 21 atoms / cm 3 Epitaxial wafers were manufactured by forming 0.3 μm layers (measured using SIMS) at growth rates of 1.2 nm / sec and 2.4 nm / sec, respectively.
[0053] XRD measurements were performed to evaluate the crystallinity of the formed epitaxial film. Based on the XRD results, it was determined whether the gettering epitaxial film was single-crystal or polycrystalline.
[0054] Figure 1 shows the conditions for single crystallization and polycrystallization of the manufactured epitaxial wafers during XRD measurement. As shown in Figure 1, single crystallization was achieved at growth rates of 1.2 nm / sec and 2.4 nm / sec for both carbon atom concentrations.
[0055] (Comparative example) Epitaxial wafers were manufactured under the same conditions as in the examples, except that the growth rates of the gettering epitaxial film were set to 4.8 nm / sec and 6.4 nm / sec.
[0056] To evaluate the crystallinity of the formed epitaxial film, XRD measurements and evaluations were performed in the same manner as in the examples.
[0057] The evaluation results are shown in Figure 1. As shown in Figure 1, polycrystalline formation occurred at growth rates of 4.8 nm / sec and 6.4 nm / sec at all carbon atom concentrations.
[0058] As described above, according to the embodiments of the present invention, single crystallization of the gettering epitaxial film was possible by setting the growth rate to 2.4 nm / sec or less. Furthermore, since a low growth rate is not practical when manufacturing industrial products, the lower limit of the growth rate can be set to 0.1 nm / sec. From the above, the growth rate of the gettering epitaxial film can be defined as 0.1 to 2.4 nm / sec.
[0059] This specification includes the following embodiments: [1]: A method for manufacturing an epitaxial wafer, wherein a gettering epitaxial film made of carbon-doped silicon is formed on a silicon substrate using a reduced-pressure CVD apparatus in a mixed gas atmosphere containing silicon and carbon, and the growth rate of the gettering epitaxial film is 2.4 nm / sec or less. [2]: A method for manufacturing the epitaxial wafer according to [1], comprising setting the growth rate of the gettering epitaxial film to 0.1 nm / sec or more. [3]: A method for manufacturing an epitaxial wafer according to [1] or [2], comprising setting the growth rate of the gettering epitaxial film to 1.2 nm / sec or more. [4]: The carbon atom concentration of the gettering epitaxial film is 1.0 × 10 20 atoms / cm 3 ~3.0×10 21 atoms / cm 3 A method for manufacturing an epitaxial wafer according to [1], [2], or [3] above, including the range of [1], [2], or [3]. [5]: The carbon atom concentration of the gettering epitaxial film is 3.0 × 10 20 atoms / cm 3 ~1.0×10 21 atoms / cm 3 A method for manufacturing an epitaxial wafer according to [1], [2], [3], or [4] above, including the range of [1], [2], [3], or [4] above. [6]: A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], or [5], comprising forming the gettering epitaxial film under a pressure of 667 Pa to 10666 Pa. [7]: A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5] or [6], comprising forming the gettering epitaxial film under a pressure of 667 Pa to 2666 Pa. [8]: A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5], [6] or [7], comprising setting the thickness of the gettering epitaxial film to 0.025 μm to 3 μm. [9]: A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5], [6], [7] or [8], comprising setting the thickness of the gettering epitaxial film to 0.025 μm to 1 μm.
[10] : A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5], [6], [7], [8] or [9], comprising forming the gettering epitaxial film at a temperature of 700°C to 800°C.
[11] : A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5], [6], [7], [8], [9], or
[10] , comprising using SiH4, SiH2Cl2, SiHCl3, Si2H6, or SiCl4 as the silicon source in a mixed gas atmosphere containing silicon and carbon.
[12] : A method for manufacturing an epitaxial wafer according to [1], [2], [3], [4], [5], [6], [7], [8], [9],
[10] , or
[11] , comprising using SiH(CH3)3, CH3SiH3, or C3H8 as the carbon source in the mixed gas atmosphere containing silicon and carbon.
[0060] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.
Claims
1. When forming a gettering epitaxial film made of carbon-doped silicon on a silicon substrate using a reduced-pressure CVD apparatus under a mixed gas atmosphere containing silicon and carbon, A method for manufacturing an epitaxial wafer, characterized in that the growth rate of the gettering epitaxial film is 2.4 nm / sec or less.
2. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the growth rate of the gettering epitaxial film is 0.1 nm / sec or more.
3. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the growth rate of the gettering epitaxial film is 1.2 nm / sec or more.
4. The carbon atom concentration of the gettering epitaxial film is 1.0 × 10 ２０ atoms / cm ３ ~3.0 x 10 ２１ atoms / cm ３ A method for manufacturing an epitaxial wafer according to claim 1, characterized in that the range is specified as follows.
5. The carbon atom concentration of the gettering epitaxial film is 3.0 × 10 ２０ atoms / cm ３ ~1.0 x 10 ２１ atoms / cm ３ A method for manufacturing an epitaxial wafer according to claim 1, characterized in that the range is specified as follows.
6. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the gettering epitaxial film is formed under a pressure of 667 Pa to 10666 Pa.
7. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the gettering epitaxial film is formed under a pressure of 667 Pa to 2666 Pa.
8. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the thickness of the gettering epitaxial film is 0.025 μm to 3 μm.
9. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the thickness of the gettering epitaxial film is 0.025 μm to 1 μm.
10. The method for manufacturing an epitaxial wafer according to claim 1, characterized in that the gettering epitaxial film is formed at a temperature of 700°C to 800°C.
11. As the silicon source in the mixed gas atmosphere containing silicon and carbon, SiH ４ , SiH ２ Cl ２ , SiHCl ３ , Si ２ H ６ or SiCl ４ is used, and the method for manufacturing an epitaxial wafer according to claim 1 is characterized by this.
12. As the carbon source of the mixed gas atmosphere containing silicon and carbon, SiH(CH) ３ ) ３ ,CH ３ SiH ３ or C ３ H ８ A method for manufacturing an epitaxial wafer according to any one of claims 1 to 11, characterized by using [a specific product / method].