JP4373487B2 - Corrosion resistant CVD-SiC coating material and jig for CVD equipment - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is excellent in corrosion resistance against metals and cleaning gases used as jigs for epitaxial growth apparatuses in semiconductor manufacturing processes and chemical vapor deposition (hereinafter referred to as CVD) apparatuses for in-line cleaning. The present invention relates to a corrosion-resistant CVD-SiC coating material whose surface is coated with a corrosion-resistant CVD-SiC and a jig for a CVD apparatus using the same.

  Conventionally, as a component or jig of various apparatuses in the semiconductor manufacturing process, SiC alone or a SiC coating material in which a substrate surface made of carbonaceous material such as graphite or ceramics is coated with SiC has been widely used. It's being used.

  For example, it is used as a jig for the silicon epitaxial growth apparatus 1 shown in FIG. The epitaxial growth apparatus 1 is an apparatus for growing crystals in the reaction chamber 4 so as to have a crystal orientation in the same direction on the surface of the silicon wafer 2 heated by the RF coil 5 or the like. Here, as the susceptor 3 on which the silicon wafer 2 is placed, a high purity isotropic graphite whose surface is coated with CVD-SiC is widely used.

  However, the SiC film may be unusable due to defects such as peeling or cracking of the SiC film due to repetitive thermal stress, or pinholes that are considered to be generated by reaction with metal that has intruded for some reason.

  Further, in the semiconductor manufacturing process, in addition to forming the above-described epitaxial growth film, a process of forming a polycrystalline Si film or the like on the wafer by various CVD apparatuses is one of the essential processes. At this time, the wafer is placed on a jig having at least a surface formed of SiC, similarly to the susceptor used in the above-described epitaxial growth apparatus. Therefore, a film having the same quality as the wafer is formed on the jig. Conventionally, the film formed on the jig has been washed and removed with an acid or alkali solution before the step of placing a new wafer and forming the film.

  However, in the conventional wet cleaning, each time cleaning is performed, the apparatus is temporarily stopped, these jigs are taken out of the apparatus, cleaned outside the apparatus, and after cleaning, the apparatus is loaded again. Due to external cleaning, there is a problem that impurities are attached to the jig when the apparatus is put in and out of the apparatus, which not only adversely affects the product quality but also shortens the life of the jig itself.

Recently, in order to improve the above problems, with the improvement of various CVD apparatuses and the development of cleaning techniques, after film formation, in the same reaction chamber of the CVD apparatus, that is, in-line with chlorine fluoride gas such as ClF ₃ Dry cleaning has been performed.

It has been found that in the dry cleaning with chlorine fluoride gas such as ClF ₃ , SiC on the surface of the jig which has not been etched so much in the conventional wet cleaning is etched. As a result, the SiC on the jig surface peels off and falls off, becomes particles, scatters in the chamber of the CVD apparatus, falls on the wafer, and becomes one of the causes of wafer defects. In addition, the service life of the jig has been shortened, and new problems have occurred that cause a reduction in yield and production efficiency.

  In addition, jigs used in these CVD apparatuses may react with metal that has intruded for some reason to generate pinholes and become unusable.

Therefore, in the present invention, β having corrosion resistance against various metals, particularly gases such as Al, Cr, Fe, Co, Ni, Cu or ClF, ClF ₃ , ClF ₅ , NF ₃ , HCl, Cl ₂ , and HF. It aims at providing the beta-SiC coating | covering material by which the base-material surface was coat | covered with -SiC, and the jig | tool for CVD apparatuses using the same.

When the ratio of the (111) plane of β-SiC formed on the surface to the main crystal plane formed is 0.5 or less, the present inventors have used ClF used for in-line cleaning. Etching resistance against gases such as ClF ₃ , ClF ₅ , NF ₃ , HCl, Cl ₂ , HF, etc., and one or more of metals such as Al, Cr, Fe, Co, Ni, Cu The present invention has been completed by finding out that it has corrosion resistance to an alloy composed of two or more.

  In the corrosion-resistant CVD-SiC coating material of the present invention, the proportion of the SiC (111) plane in the crystals constituting β-SiC formed by the CVD method is 0.5 or less, and SiC (111 in X-ray diffraction) ) The peak intensity of the SiC (200) plane with respect to the peak intensity of the plane is less than 1.0, and the ratio of the SiC (200) plane is the ratio of the SiC (220) plane and the SiC (311) plane CVD-SiC larger than the ratio and the ratio occupied by the SiC (222) plane is coated on a substrate made of SiC or a carbonaceous material.

  Moreover, the jig | tool for CVD apparatus of this invention has a preferable thing used for the dry cleaning for semiconductor manufacture using the above-mentioned corrosion-resistant CVD-SiC coating | covering material.

  According to the corrosion-resistant CVD-SiC coating material and the jig for a CVD apparatus according to the present invention, it exhibits etching resistance against various gases used at the time of in-line cleaning in an LPCVD apparatus, an RTPCVD apparatus, and an epitaxial growth CVD apparatus, Moreover, it comes to have corrosion resistance with respect to various metals, and can contribute to improvement of production efficiency and yield in semiconductor manufacturing.

It is an X-ray-diffraction result of SiC which performed CVD processing at 1400 degreeC. It is a X-ray-diffraction result of SiC which performed CVD processing at 1300 degreeC. It is the X-ray-diffraction result of SiC coat | covered on the surface by reaction of sublimation gas of Si and carbon dioxide gas. It is an X-ray-diffraction result of SiC which performed CVD processing at 1200 degreeC. It is the cross-sectional schematic of an epitaxial growth apparatus. 1 is a schematic cross-sectional view of an LPCVD apparatus. It is the cross-sectional schematic of an RTPCVD apparatus.

  The SiC in the present invention is obtained by coating a graphite substrate with SiC by a CVD method, and then removing the graphite mechanically or chemically to make only dense CVD-SiC. Any of the above-described SiC, sintered SiC, and the base material surface made of any one of the above-mentioned CVD-SiCs may be coated by the CVD method. Here, the SiC converted from the graphite material is so-called CVR-SiC in which the graphite material and silicic acid gas are reacted to convert the graphite material into SiC. The sintered SiC is sintered into SiC powder. A binder is added and sintered at a high temperature of 1600 ° C. or higher.

  Further, SiC formed by the CVD method is a very dense structure formed by SiC nuclei generated from the raw material gas during the CVD process being deposited on the surface of the base material and the deposited nuclei growing. It is a membrane. In addition, there are two types of SiC, α-type that is hexagonal and β-type that is cubic, but β-type SiC is generated by the CVD method according to the present invention.

  The ratio of the crystal showing the crystal orientation in the (111) plane direction among the crystals constituting the surface of β-SiC by this CVD method is 0.5 or less, preferably 0.4 or less. When the ratio is larger than 0.5, it is considered that the crystal orientation between the crystals or the crystal layers is likely to be eroded by increasing the orientation of the same plane, and corrosion resistance is not exhibited against various metals or cleaning gas. Here, the crystal planes that are the targets of this ratio are the (200) plane, (220) plane, and (311) plane that have different orientations from the (111) plane. This ratio is calculated by dividing the peak intensity of the (111) plane by the sum of the peak intensities (peak heights) representing the crystal planes with different orientations from the (111) plane from the X-ray diffraction results. ing.

The surface of β-SiC can be adjusted such that the ratio of crystals in the (111) plane direction of the constituent crystallites is 0.5 or less by adjusting the CVD processing conditions. The crystal orientation is messy. And compared to β-SiC formed of crystallites grown only in the (111) plane direction, it is for one or more of these metals such as Al, Cr, Fe, Co, Ni, Cu, etc. It will be excellent in corrosion resistance. Also, ClF, ClF ₃ , ClF ₅ , NF ₃ , HCl, Cl ₂ , or HF used for in-line cleaning in various CVD apparatuses, or a mixed gas obtained by diluting any of these with an inert gas On the other hand, it is estimated that etching resistance is exhibited. Among them, excellent etching resistance is exhibited by HCl and ClF ₃ gases.

  The (200), (220), and (311) planes, which are crystal planes different from the orientation of the (111) plane, are the base material, base material temperature, source gas, furnace pressure, source gas concentration, etc. during the CVD process. Among these control factors, it is particularly affected by the temperature, and becomes more noticeable as the substrate temperature during the CVD process increases. Therefore, in order to set the ratio of the (111) plane to 0.5 or less, preferably 0.4 or less, the substrate temperature during the CVD process is set to at least 1300 ° C., preferably 1400 ° C. or more.

  As described above, β-SiC formed on the surface of a CVD-SiC coating material in which SiC is coated on the surface of a CVD-SiC, or a carbonaceous material such as graphite, or a ceramic substrate such as SiC is formed. When the ratio of the (111) plane in the crystal to be set is 0.5 or less, the metal has corrosion resistance. Thereby, it can be used as a jig for various semiconductor manufacturing CVD apparatus. That is, by forming CVD-SiC according to the present invention on the jig surface, the occurrence of pinholes and the like can be suppressed and the service life can be extended.

  As the CVD apparatus for semiconductor manufacturing, for example, an epitaxial growth apparatus, or dry cleaning using chlorine fluoride gas or the like, in-line cleaning is performed to improve yield and production efficiency. For example, an LPCVD apparatus, an RTPCVD apparatus, etc. is there. It can be applied as a jig such as a susceptor for mounting these Si wafers. Each of these has one or more reaction chambers, and in-line cleaning is performed in the same reaction chamber.

  FIG. 6 shows a schematic cross-sectional view of the reaction chamber of the LPCVD apparatus. The LPCVD apparatus is an abbreviation of Low Pressure CVD apparatus, and as shown in the figure, is composed of a SiC boat 13 on which a wafer 14 is placed and a SiC soaking tube 12, and CVD under reduced pressure. Processing is performed, and the wafer 14 is used for forming or diffusing a polycrystalline silicon film, a silicon nitride film, or the like. Here, the jigs according to the present invention are the boat 13 and the soaking tube 12.

  FIG. 7 shows a schematic cross-sectional view of the reaction chamber of the RTPCVD apparatus. The RTPCVD apparatus is an abbreviation for a Rapid Thermal Processing CVD apparatus, and includes an SiC susceptor 22 on which a wafer 23 is placed and an SiC jig 24 on which the susceptor 22 is placed, as shown in the figure. It is a device that can be heated and heated by a halogen lamp and locally oxidize and CVD, and is used to form a polycrystalline silicon film and a silicon nitride film. Here, the jig according to the present invention is a susceptor 22 and a SiC jig 24 on which the susceptor 22 is placed.

  As described above, the CVD-SiC or the CVD-SiC coating material in the present invention can be applied as a jig for a CVD apparatus for semiconductor manufacturing. Moreover, it can also be used as a jig for a single crystal pulling apparatus using its excellent corrosion resistance other than a jig for a semiconductor manufacturing CVD apparatus.

  The present invention will be specifically described with reference to examples.

Example 1
An isotropic graphite material (manufactured by Toyo Tanso Co., Ltd.) having a bulk density of 1.85 g / cm ³ was used as a base material and processed into 20 × 20 × 5 mm. Next, these were installed in a CVD apparatus, SiCl ₄ + C ₃ H ₈ was used as a source gas, a CVD process was performed at a furnace pressure of 250 Torr and a substrate temperature of 1400 ° C., and SiC was coated on the entire surface.

After coating with CVD-SiC, the surface was subjected to X-ray diffraction analysis using a Cu tube. FIG. 1 shows the analysis result. In the figure, β-SiC (111) and the like represent each crystal plane. Next, in the crystal constituting the surface, the ratio of the (111) plane is the intensity ratio of each crystal plane having a crystal orientation different from that of the (111) plane (the peak height representing each crystal plane). And calculated by the following formula. That is,
Ratio = (111) / ((111) + (200) + (220) + (311))
It is. The ratio of the (111) plane in the constituent crystallites of SiC covering the surface was 0.32.

(Example 2)
After processing a base material of the same quality as in Example 1 into the same shape, using the same CVD apparatus as in Example 1, using SiCl ₄ + C ₃ H ₈ as the source gas, with a furnace pressure of 250 Torr and a base material temperature of 1300 ° C. A CVD process was performed to coat the entire surface with SiC. Thereafter, in the same manner as in Example 1, X-ray diffraction analysis of the surface coated with SiC was performed. FIG. 2 shows the result of X-ray diffraction. From this result, in the same manner as in Example 1, the ratio of the (111) plane in the constituent crystallites of SiC covering the surface was determined to be 0.50.

(Example 3)
An isotropic graphite material (manufactured by Toyo Tanso Co., Ltd.) having a bulk density of 1.85 g / cm ³ was used as a substrate, and the substrate was processed into 20 × 20 × 5 mm having the same shape as in Example 1. These are placed in a CVD apparatus together with metal Si, the furnace temperature is heated to 1800 ° C., carbon dioxide gas is introduced into the furnace, metal sublimation gas and carbon dioxide gas are reacted, and SiC is deposited on the substrate surface. Precipitated. Thereafter, in the same manner as in Example 1, X-ray diffraction analysis of the surface coated with SiC was performed. FIG. 3 shows the result of X-ray diffraction. From this result, in the same manner as in Example 1, the ratio of the (111) plane in the constituent crystallites of SiC covering the surface was determined to be 0.36.

(Comparative Example 1)
After processing a base material of the same quality as in Example 1 into the same shape, using the same CVD apparatus as in Example 1, using SiCl ₄ + C ₃ H ₈ as the source gas, with a furnace pressure of 250 Torr and a base material temperature of 1200 ° C. A CVD process was performed to coat the entire surface with SiC. Thereafter, in the same manner as in Example 1, X-ray diffraction analysis of the surface coated with SiC was performed. FIG. 4 shows the result of X-ray diffraction. From this result, in the same manner as in Example 1, the ratio of the (111) plane in the constituent crystallites of SiC covering the surface was 1.0.

  Examples 1 and 2 and Comparative Example 1 differ only in the substrate temperature during the CVD process, and all other processing conditions are the same, but the substrate temperature during the CVD process is shown in FIGS. By increasing the ratio, the proportion of the (111) plane in the crystals constituting the surface decreases. In other words, it can be said that as the substrate temperature increases, the direction of SiC precipitation and growth becomes multi-directional, and the crystals constituting the surface become messy.

In order to examine the etching resistance against the gas used for in-line cleaning of the samples of Examples 1 to 3 and Comparative Example 1, each sample was exposed to 800 ° C. ClF ₃ and 1000 ° C. HCl for 60 minutes, respectively, to be etched resistant. I examined the sex.

  Table 1 shows the etching resistance of each sample to each gas.

  Moreover, in order to investigate the reactivity with a metal about the sample of Example 1 and the comparative example 1, each sample is film thickness so that film thickness and surface roughness may not influence the reaction with various metals, respectively. Was 105 μm, and the surface of each sample was polished under the same conditions. A metal powder having a purity of 99% or more and a particle size of 40 μm was placed on the polished surface and heated to 1000 ° C. to 1300 ° C., respectively, and the reactivity with the metal was examined. The reactivity was observed by an electron microscope, and the cross section of each sample was evaluated by performing a line analysis by X-ray from the outer surface side to the inside.

  Table 2 shows the degree of reaction with each metal at each temperature of the sample of Example 1 and Table 3 of the sample of Comparative Example 1. The degree of reaction was evaluated in three stages. In the table, ○ indicates that the reaction was observed only in the surface layer, Δ indicates that the reaction was observed up to the film, and × indicates that the intense reaction reaching the substrate was observed.

  From Table 1, it is used for in-line cleaning by increasing the substrate temperature during the CVD process so that the growth direction of the deposited SiC grows not only in the (111) plane direction but also in other planes. It can be seen that the resistance to the etching gas is improved.

  Further, from Tables 2 and 3, it can be seen that in Example 1, the reaction start temperature with each metal is shifted to the high temperature side as compared with the sample of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 Epitaxial growth apparatus 2 Silicon wafer 3 Susceptor 4 Reaction chamber 5 RF coil 11 LPCVD apparatus reaction chamber 12 Soaking tube 13 Board 14 Wafer 21 RTPCVD apparatus reaction chamber 22 Susceptor 23 Wafer 24 Jig

Claims (2)

Of the crystals constituting β-SiC formed by the CVD method,
The proportion of the SiC (111) plane is 0.5 or less,
The peak intensity of the SiC (200) plane relative to the peak intensity of the SiC (111) plane in X-ray diffraction is less than 1.0, and
CVD-SiC in which the proportion of the SiC (200) plane is larger than the proportion of the SiC (220) plane, the proportion of the SiC (311) plane, and the proportion of the SiC (222) plane is SiC or a carbonaceous material. Corrosion-resistant CVD-SiC coating material coated on a substrate comprising A jig for a CVD apparatus, which is used for dry cleaning for semiconductor production, using the corrosion-resistant CVD-SiC coating material according to claim 1.

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