Semiconductor heat treatment components

Abstract

To provide a semiconductor heat treatment component that allows for easy removal of polysilicon from a SiC film. [Solution] The semiconductor heat treatment member of the present invention is a semiconductor heat treatment member in which a CVD-SiC film is coated on the surface of a carbon substrate, wherein the surface of the CVD-SiC film is an unprocessed surface, the average particle diameter of the SiC particles of the CVD-SiC film is at least 60 μm, the surface roughness Sa of the CVD-SiC film is at least 3.5 μm, and at least 3600 μm 2 It contains SiC particles having a plane.

Description

[Technical Field]

[0001] The present invention relates to a semiconductor heat treatment component such as a susceptor that supports a wafer in an epitaxial film deposition apparatus, and a method for manufacturing the same. [Background technology]

[0002] One pretreatment step for forming semiconductor circuits on silicon (Si) wafers or silicon carbide (SiC) wafers is to form an epitaxial film on the wafer. Generally, in the process of forming an epitaxial film on a Si wafer, a susceptor (semiconductor heat treatment unit) made of a carbon substrate coated with SiC, as described in Patent Document 1, is used.

[0003] Generally, epitaxial film growth on Si wafers is performed at temperatures below 1250°C. When an epitaxial film grows on a Si wafer, polysilicon is also deposited on the susceptor. This polysilicon is periodically removed (cleaned) by reducing gases such as hydrogen chloride (HCl) and high-temperature treatment, resetting dimensional changes and particle generation caused by polysilicon deposition on the susceptor. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-157989 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, deposited polysilicon may not be completely removed and may remain at grain boundaries of the SiC film. This unremoved polysilicon could sometimes hinder Si epitaxial growth or impede wafer quality. Generally, the SiC film coating the surface of semiconductor heat-treated components is composed of polycrystalline materials of various sizes, making it difficult to control the desorption rate of polysilicon and to completely and efficiently remove polysilicon that has entered the grain boundaries.

[0006] On the other hand, if cleaning with reducing gases such as hydrogen chloride (HCl) is performed excessively in order to completely remove the deposited polysilicon, it can erode the SiC film coated on the carbon substrate, damaging the component and sometimes requiring its replacement.

[0007] In order to solve the above technical problems, the inventors have diligently researched semiconductor heat treatment components that can easily and more completely remove polysilicon deposited on semiconductor heat treatment components such as susceptors using processes that use Si, such as Si epitaxial processes, and a reducing gas such as hydrogen chloride (HCl), and have completed the present invention.

[0008] The present invention aims to provide a semiconductor heat treatment member that can easily remove polysilicon from a SiC film. [Means for solving the problem]

[0009] The semiconductor heat treatment member of the present invention is a semiconductor heat treatment member in which a CVD-SiC film is coated on the surface of a substrate made of carbon or silicon carbide, wherein the surface of the CVD-SiC film is an unprocessed surface, the average particle diameter of the SiC particles of the CVD-SiC film is at least 60 μm, the surface roughness Sa of the CVD-SiC film is at least 3.5 μm, and at least 3600 μm 2 It is characterized by containing SiC particles having a plane.

[0010] In semiconductor heat-treated members having such a CVD-SiC film, polysilicon can be easily removed from the SiC film.

[0011] In this case, it is preferable that the CVD-SiC film has SiC particles growing in a columnar shape from the surface of the substrate. [Effects of the Invention]

[0012] The present invention can provide a semiconductor heat treatment member enabled to easily remove polysilicon from on a CVD-SiC film.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a diagram showing the particulate state of the CVD-SiC film of the semiconductor heat treatment member according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of the CVD-SiC film of the semiconductor heat treatment member according to the present invention. [Figure 3] FIG. 3 is a diagram showing the particulate state of the CVD-SiC film of a conventional semiconductor heat treatment member.

Modes for Carrying Out the Invention

[0014] Hereinafter, an embodiment of the semiconductor heat treatment member of the present invention will be described. The present invention is a semiconductor heat treatment member in which a surface of a substrate made of carbon or silicon carbide is coated with a CVD-SiC film, and particularly, in a step of forming an epitaxial film on a wafer or the like, it is a semiconductor heat treatment member enabled to easily remove polysilicon deposited on the SiC film from on the SiC film. As a result, when the semiconductor heat treatment member of the present invention is used, a high-quality epitaxial layer can be obtained.

[0015] This semiconductor heat treatment member is, for example, a susceptor and its peripheral members (lift pins, ring members, etc.), a vertical boat, a horizontal boat, and their peripheral members (pedestals, heat insulating plates, dummy wafers, etc.), which are ceramic members for supporting Si wafers or SiC wafers. The substrates used for this semiconductor heat treatment member are silicon, carbon such as graphite, and silicon carbide. Among these, substrates made of carbon are low in cost and low in processing difficulty, and are preferably used.

[0016] In the present embodiment, a susceptor made of carbon (carbon material) and having a SiC film on its surface will be described as a semiconductor heat treatment member used for growing an epitaxial layer on the surface of a wafer. For the carbon base material, an isotropic high-purity graphite (manufactured by Quartz Tech Co., Ltd.) carbon base material is used in the same manner as the conventional method. The carbon base material is preferably formed with a base material thickness of 1.0 to 20.0 mm and a diameter of Φ50 to 400 mm (for 4, 5, 6, 8, 12-inch Si wafers), and the content of each of the metal elements (Fe, Ni, Cr) is preferably 0.05 ppm or less. When the content of each of the metal elements (Fe, Ni, Cr) in the base material is 0.05 ppm or less, it is possible to prevent the reaction, erosion, and consumption between the CVD-SiC film coated on the surface of the base material and the metal impurities contained in the base material. Therefore, the function as a semiconductor heat treatment member can be maintained for a long time, and the occurrence of abnormal resistance and defects in the processed wafers can be suppressed.

[0017] On the surface of the carbon base material, there is a polymorphic crystal composed of 3C-SiC as a CVD-SiC film grown by crystal growth by the CVD method. Here, SiC has many polymorphs due to differences in the stacking order. Representative polymorphs include 3C-SiC, 2H-SiC, and 4H-SiC. 3C-SiC is cubic, and 2H-SiC and 4H-SiC are hexagonal.

[0018] The 3C-SiC cubic crystal has peaks corresponding to (111), (311), (200), (220), and (222) by X-ray diffraction. Having such peaks means that good crystals are formed by epitaxial growth of SiC. Note that X-ray diffraction is diffraction using X-rays (CuKα rays) with an energy of 40 keV.

[0019] For CVD-SiC film deposition, a binary raw material system is used, consisting of a Si source containing SiH4 and a C source containing C CH4. Keep coating is performed at a temperature of 1100°C to 1500°C and a furnace pressure of 0.10 to 0.40 Torr. Keep coating refers to the period during the deposition process when the coating is applied while maintaining a constant temperature. In addition, SiCl4 can be used as a Si source and C3H8 as a C source as raw materials. Furthermore, a vacuum pump capable of maintaining a vacuum level of 0.10 Torr or less is used during heating. At the start of film deposition, the furnace pressure is controlled to 0.30-0.40 Torr, and film deposition is carried out while reducing the pressure to 0.10-0.20 Torr through a keep coating process.

[0020] This film deposition process is repeated 1 to 7 times to obtain a total of 2 to 8 layers of CVD-SiC film. The surface roughness and particle size will differ depending on the number of layers, but two or more layers are preferred. Finally, the average particle size of the SiC particles is 60 μm or more, the SiC surface roughness Sa is 3.5 μm or more, and the total size is 3600 μm. 2 A susceptor is obtained in which SiC particles having the above-mentioned planes are included, and SiC is coated on the surface of the substrate, with the SiC particles growing columnarly from the substrate surface.

[0021] Thus, if the surface of the CVD-SiC film is an unprocessed surface, the average particle diameter of the SiC particles is 60 μm or more, the SiC surface roughness Sa is 3.5 μm or more, and the CVD-SiC film is formed by the SiC particles growing columnarly from the substrate surface as shown in Figure 2(a), then the polysilicon deposited on the SiC film can be easily removed. Figure 2(b) shows the case of a typical CVD-SiC film. Therefore, polysilicon, which can reduce the yield of the Si epitaxial process or degrade the quality of the epitaxial layer, can be easily removed from the CVD-SiC film, making it possible to obtain a high-quality epitaxial layer.

[0022] More specifically, it is preferable that the thickness of the CVD-SiC film in the susceptor having this CVD-SiC film is at least 80 μm. A CVD-SiC film thickness of 80 μm or more suppresses deformation of the susceptor when used at high temperatures, and also ensures a long lifespan without deformation of the susceptor or exposure of the substrate due to wear of the CVD-SiC film.

[0023] Furthermore, in a susceptor having a CVD-SiC film, the average particle size of the SiC particles in the CVD-SiC film is at least 60 μm, thus reducing the number of SiC grain boundaries. If the average particle size of the SiC particles in the CVD-SiC film is less than 60 μm, the increase in SiC grain boundaries is undesirable because it can lead to the occasional incorporation of contaminants from metal components such as SUS or stainless steel when cleaning gas is transported into the reaction vessel from the outside. These contaminants can then adhere to the susceptor during cleaning, reducing resistance to chemical erosion caused by impurities. Furthermore, if the average particle size of the SiC particles in the CVD-SiC film is less than 60 μm, then 3600 μm 2 The above-mentioned planes are unlikely to exist, and there are many SiC grain boundaries, making it difficult to remove the polysilicon deposited on the SiC film. In this invention, the average particle diameter is calculated by measuring the maximum diameter of each particle (the diameter of the circumscribed circle of the particle) using image analysis software based on images acquired with a 20x laser microscope, and then taking the arithmetic mean of the measured values ​​of multiple particles.

[0024] Furthermore, in a susceptor having a CVD-SiC film, since the surface roughness Sa of the CVD-SiC film is at least 3.5 μm, it makes point contact with the wafer and is less likely to stick. If the surface roughness Sa of the CVD-SiC film is less than 3.5 μm, it is undesirable because the wafer may stick to it. Moreover, if the surface roughness Sa of the CVD-SiC film is too large, stress concentration is more likely to occur, which may induce defects such as slippage, so it is even more preferable that it be 10.0 μm or less. Furthermore, when polysilicon is deposited on a CVD-SiC film, if the surface roughness Sa of the CVD-SiC film exceeds 10 μm, the CVD-SiC film and the polysilicon film adhere closely together, making removal difficult. The surface roughness Sa of the aforementioned CVD-SiC film was calculated based on the shape data obtained by acquiring the three-dimensional shape of the surface to be measured using a non-contact optical surface shape measuring device. A commercially available laser scanning microscope was used for the measurement, but the type of device is not limited to this. Sa is the arithmetic mean height in accordance with ISO 25178.

[0025] Furthermore, in a susceptor having a CVD-SiC film, the CVD-SiC film has at least 3600 μm, as shown in Figure 1. 2 It contains SiC particles 1 having a plane. Thus, at least 3600 μm 2 Because it contains SiC particles with a flat surface, the surface energy is low and the reactivity is poor, making it easier for the polysilicon deposited on the susceptor to peel off. Furthermore, because the wafer is more likely to adhere to the contact surface of the susceptor, the SiC particles having a flat surface in the CVD-SiC film are 100,000 μm. 2 It is even more preferable that it has the following planes. Here, "at least 3600 μm" 2 "SiC particles having a plane" refers to SiC particles exposed on the surface of a CVD-SiC film that have a flat crystal plane, extracted using image analysis software based on three-dimensional shape data acquired by a laser microscope. The area of ​​the plane is the area when the flat plane is projected onto the XY plane, and is calculated as the average value of the projected areas measured using the same method for multiple SiC particles.

[0026] Here, it is preferable that the CVD-SiC film has SiC particles growing columnarly from the substrate surface, as shown in Figure 2(a). Figure 2(b) shows a typical CVD-SiC film. As described above, since the SiC particles of the CVD-SiC film grow columnarly from the substrate surface, a flat surface is more easily obtained on the surface of the CVD-SiC film. To grow the SiC particles of the CVD-SiC film in a columnar shape from the substrate surface, the raw material gas (SiH4 and CH4) and carrier gas can be introduced while increasing the temperature, thereby allowing the SiC particles to grow in a columnar shape from the substrate surface.

[0027] Here, it is preferable that the CVD-SiC film is an unprocessed surface. If the surface of the CVD-SiC film is processed by machining or other means to form the aforementioned flat surface, a fractured layer may be created or the crystal plane orientation may change, making it more susceptible to chemical erosion, and polysilicon may get into the irregularities of the processed surface, making it difficult to remove. The term "unprocessed surface" refers to a surface that has not undergone any machining processes such as polishing, grinding, or blasting.

[0028] Furthermore, the surface of the CVD-SiC film is an unprocessed surface, the average particle size of the SiC particles in the CVD-SiC film is at least 80 μm, the surface roughness Sa of the CVD-SiC film is at least 4.0 μm, and at least 5000 μm 2 It is even more preferable to include SiC particles having a plane. This makes it possible to easily and completely remove polysilicon deposited on the SiC film from the SiC film during processes such as forming an epitaxial film on a wafer. Furthermore, when using the susceptor of the present invention, a high-quality epitaxial layer can be obtained.

[0029] Furthermore, it is preferable that the CVD-SiC film is formed at least on the outer surface of the substrate on which the wafer is placed, and more preferably on the entire outer surface of the substrate. Furthermore, although a susceptor was described as an example of a heat treatment member for semiconductors in the above embodiment, the present invention is not limited to that form and can be broadly applied to heat treatment members for semiconductors having a SiC coating on the surface of a carbon or silicon carbide substrate. [Examples]

[0030] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited by the examples shown below.

[0031] [Example 1] Isotropic high-purity graphite (manufactured by Kuraray Techno Co., Ltd.) was purified to reduce the impurity concentration (metal elements of Fe, Ni, and Cr) in the carbon base material to 0.05 ppm or less to obtain a base material.

[0032] Using a CVD apparatus, SiC was deposited on the carbon base material. In the CVD apparatus, the carbon base material was placed in the chamber, and after reducing the pressure to 0.1 Torr or less using a vacuum pump, a carrier gas (H2) was introduced. Next, the temperature was raised to 1200 °C in the chamber. When the temperature in the chamber was raised from 1200 °C to 1300 °C, the raw material gases (SiH4 and CH4) and the carrier gas were introduced for 25 minutes. Then, a keep coating was performed for 11 hours at 1300 °C and 0.20 Torr. After the keep coating, only N2 was introduced to lower the temperature.

[0033] By the above procedure, a CVD-SiC film was deposited on the carbon base material. This was repeated 5 times to obtain a CVD-SiC film with a SiC film thickness of 144 μm, an average SiC particle diameter of 80 μm, a SiC surface roughness (Sa) of 5.0 μm, and a plane area of SiC particles having a plane of 5500 μm 2 was obtained. In addition, the SiC film thickness was measured non-contact using an eddy current type film thickness measuring machine. The average SiC particle diameter was determined by measuring the particle diameter using a laser microscope. The SiC surface roughness (Sa) was measured using a laser microscope. The plane area of SiC particles having a plane was measured using a laser microscope. The state of the particles on the surface of this SiC film is shown in Fig. 1. Fig. 1 is a photograph taken by SEM, where reference numeral 1 indicates SiC particles and reference numeral 2 indicates grain boundaries between SiC particles.

[0034] Then, polysilicon was deposited and removed under the following conditions. For the polysilicon deposition, the temperature of the semiconductor heat-treated material was set to 1150°C, and a silicon raw material gas such as trichlorosilane (SiHCl3:Trichlorosilane) was passed through it for 120 seconds. For the polysilicon removal conditions, the semiconductor heat-treated material was heated to 1200°C and flowed through a hydrogen chloride and hydrogen gas atmosphere for 60 seconds.

[0035] The degree of polysilicon removal in semiconductor processed materials was evaluated. The degree of polysilicon removal was evaluated using SEM and EPMA to assess the presence or absence of polysilicon. The results are shown in Table 1.

[0036] [Example 2] The same substrate as in Example 1 was used. Next, the heating conditions up to 1100°C were the same as in Example 1. When the chamber temperature rose from 1100°C to 1200°C, the raw material gases (SiH4 and CH4) and carrier gas were introduced for 25 minutes. Keep coating was performed at 1200°C under 0.20 Torr for 11 hours. The cooling conditions were also the same as in Example 1. A CVD-SiC film was deposited on a carbon substrate using the procedure described above. This was repeated four times, resulting in a SiC film thickness of 137 μm, four SiC layers, an average SiC particle diameter of 60 μm, a SiC surface roughness (Sa) of 3.5 μm, and a planar area of ​​3600 μm for SiC particles with flat surfaces. 2 A CVD-SiC film was obtained. Then, polysilicon was deposited and removed in the same manner as in Example 1. Then, the degree to which polysilicon was removed from the semiconductor processed material was evaluated. The degree of polysilicon removal was evaluated using SEM and EPMA to assess the presence or absence of polysilicon. The results are shown in Table 1.

[0037] [Comparative Example 1] The same substrate as in Example 1 was used. Next, the heating conditions were also the same as in Example 1. Keep coating was performed at 1300°C under 0.20 Torr for 11 hours. The cooling conditions were also the same as in Example 1. A CVD-SiC film was deposited on a carbon substrate using the procedure described above. This was repeated five times. After that, the SiC surface was planarized by machining. The SiC film thickness is 120 μm, the number of SiC layers is 5, the average SiC particle diameter is 80 μm, the SiC surface roughness (Sa) is 0.9 μm, and the area of ​​the planar surface of the planar SiC particles is 100,000 m². 2 This was obtained. Furthermore, it is believed that the surface area of ​​the flat surface increased even under the same conditions as in Example 1 because the surface of the SiC film was flattened by machining. Then, polysilicon was deposited and removed in the same manner as in Example 1. Then, the degree to which polysilicon was removed from the semiconductor processed material was evaluated. The degree of polysilicon removal was evaluated using SEM and EPMA to assess the presence or absence of polysilicon. The results are shown in Table 1.

[0038] [Comparative Example 2] The same substrate as in Example 1 was used. Next, the heating conditions were also the same as in Example 1. Keep coating was performed at 1200°C under 0.20 Torr for 11 hours. The cooling conditions were also the same as in Example 1. Following the procedure described above, a CVD-SiC film was deposited on a carbon substrate. This was repeated twice, resulting in a SiC film thickness of 102 μm, 2 SiC layers, an average SiC particle diameter of 40 μm, a SiC surface roughness (Sa) of 2.2 μm, and a planar area of ​​SiC particles with planar surfaces of 900 μm. 2 A CVD-SiC film was obtained. Then, polysilicon was deposited and removed in the same manner as in Example 1. Then, the degree to which polysilicon was removed from the semiconductor processed material was evaluated. The degree of polysilicon removal was evaluated using SEM and EPMA to assess the presence or absence of polysilicon. The results are shown in Table 1. Furthermore, compared to Example 1, the lower keep-coating temperature and fewer coating repetitions resulted in a smaller average particle size, which in turn reduced the surface area and surface roughness of the plane.

[0039] [Comparative Example 3] The same substrate as in Example 1 was used. Next, the heating conditions were also the same as in Example 1. Keep coating was performed at 1100°C under 0.20 Torr for 11 hours. The cooling conditions were also the same as in Example 1. A CVD-SiC film was deposited on a carbon substrate using the procedure described above (single coat only). Furthermore, the SiC film thickness is 122 μm, the average SiC particle diameter is 10 μm, the SiC surface roughness (Sa) is 1.2 μm, and the planar area of ​​the SiC particles with a flat surface is 30 μm. 2 A CVD-SiC film was obtained. Then, polysilicon was deposited and removed in the same manner as in Example 1. Then, the degree to which polysilicon was removed from the semiconductor processed material was evaluated. The degree of polysilicon removal was evaluated using SEM and EPMA to assess the presence or absence of polysilicon. The results are shown in Table 1. Furthermore, compared to Example 1, the lower keep-coating temperature and fewer coating repetitions resulted in a smaller average particle size, which in turn reduced the surface area and surface roughness of the plane.

[0040] [Table 1]

[0041] The present invention makes it possible to easily remove deposited polysilicon from a SiC film, which can reduce the yield of the Si epitaxial process or degrade the quality of the epitaxial layer. This will significantly reduce semiconductor manufacturing costs and enable the production of high-quality Si wafers, contributing to further improvements in the performance of semiconductor devices. [Explanation of symbols]

[0042] 1 SiC particles 2 Grain boundaries between SiC particles 3. Grain boundaries between SiC particles

Claims

1. A semiconductor heat-treated member comprising a substrate made of carbon or silicon carbide coated with a CVD-SiC film, The surface of the CVD-SiC film is an unprocessed surface. The average particle size of the SiC particles in the CVD-SiC film is at least 60 μm. The surface roughness Sa of the CVD-SiC film is at least 3.5 μm and at least 3600 μm. 2 A semiconductor heat treatment member characterized by containing SiC particles having a plane.

2. The semiconductor heat treatment member according to claim 1, characterized in that the CVD-SiC film has SiC particles growing columnarly from the surface of the substrate.

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