JP2011243710A - Film formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film formation apparatus which enables an improvement of a quality of a semiconductor wafer by reducing an amount of by-product falling onto a thin film during film formation by homoepitaxial growth.SOLUTION: A film formation apparatus 1 for homoepitaxial-growing a thin film on a silicon carbide substrate 2 includes: a susceptor 3 to put the silicon carbide substrate 2 on an upper surface thereof; and a reaction chamber 4 into which the susceptor 3 with the silicon carbide substrate 2 set thereon is loaded. The film formation apparatus has first and second liners 7 and 8 consisting of monocrystalline or polycrystalline 3C-SiC and provided on at least any one of an upper surface of the susceptor 3 and an inner surface of the reaction chamber 4.

Description

  The present invention relates to a film forming apparatus used in a semiconductor manufacturing process.

  In a thin film formation method such as chemical vapor deposition, a thin film containing a metal is formed on the substrate surface, and by-products are simultaneously generated and deposited on a wall surface inside the chamber. Since deposits such as by-products cause defects such as particles, measures are taken to prevent the deposits from dropping onto the surface of the substrate during the thin film formation process. For example, a method has been proposed in which the deposit once deposited is made difficult to peel off by increasing the surface roughness of the inner wall of the reactor (see, for example, Patent Document 1).

Japanese Patent No. 4401656 (Fig. 5)

  For example, when a 4H—SiC, 6H—SiC thin film is homoepitaxially grown on a 4H or 6H type silicon carbide (4H—SiC, 6H—SiC) substrate, the temperature of the substrate is set to 1500 to 1700 ° C. . However, since this 1500 to 1700 ° C. is a temperature range in which 3C-SiC as a by-product is likely to be generated, the inner surface of a film forming apparatus such as a reaction furnace or a chamber containing the substrate, and the substrate are mounted. 3C-SiC is deposited on the upper surface of the susceptor placed. Since 3C-SiC is granular, it is difficult to adhere to the surface, and it has been difficult to sufficiently prevent the deposits from being peeled off simply by roughing the inner surface of the film forming apparatus or the upper surface of the susceptor.

  Accordingly, an object of the present invention is to provide a film forming apparatus capable of preventing the adhesion of 3C-SiC on a thin film and improving the quality of the silicon carbide substrate during the film forming process by homoepitaxial growth of silicon carbide. And

  In order to solve the above-described problems, the present invention has the following features. A first feature of the present invention includes a susceptor (susceptor 3) on which a silicon carbide substrate (silicon carbide substrate 2) is placed, and a reaction vessel (reaction vessel 4) containing the silicon carbide substrate and the susceptor. A film forming apparatus (film forming apparatus 1) for homoepitaxially growing a silicon carbide thin film on the silicon carbide substrate, wherein at least part of the upper surface of the susceptor and at least part of the inner surface of the reaction vessel are The gist is to have liner members (first liner 7 and second liner 8) made of crystalline or polycrystalline 3C—SiC.

  When homoepitaxially growing a thin film on a silicon carbide substrate, a substrate made of 4H—SiC or 6H—SiC is used, and the same thin film made of 4H—SiC or 6H—SiC is formed on the substrate. In this case, the temperature of the substrate is generally 1500 to 1700 ° C. The temperature range of 1500 to 1700 ° C. is a temperature at which granular 3C—SiC, which is a byproduct, is likely to be generated, but the upper surface of the susceptor and the inner surface of the reaction vessel are made of single crystal or polycrystalline 3C—SiC. 3C-SiC grows from the surface of the liner member. For this reason, 3C-SiC as a by-product is not peeled off.

  As described above, since the by-product falls on the silicon carbide substrate or the thin film during the film formation, the quality of the semiconductor wafer can be improved. Along with this, it is possible to reduce the frequency of cleaning various members used for the film forming process of the reaction vessel and the like and the replacement frequency of the members themselves.

  The gist of the second feature of the present invention is that the liner member (the first liner 7 and the second liner 8) is subjected to a mirror surface treatment or a chemical etching treatment.

  The gist of the third feature of the present invention is that the arithmetic average roughness of the surface of the liner member (the first liner 7 and the second liner 8) is 300 nm or less.

  According to the film forming apparatus according to the present invention, a film forming apparatus capable of preventing the adhesion of 3C—SiC onto the thin film and improving the quality of the silicon carbide substrate during the film forming process by homoepitaxial growth of silicon carbide. Can be provided.

It is sectional drawing of the film-forming apparatus 1 of the thin film which concerns on embodiment of this invention.

  Hereinafter, details of a film forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) the overall configuration of the film forming apparatus according to the present embodiment, (2) the structure of the reaction vessel and the susceptor according to the present embodiment, (3) the procedure for producing a thin film, (4) examples, 5) Effects and (6) Other embodiments will be described. It should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Also included in the drawings are portions having different dimensional relationships and ratios.

(1) Overall Configuration of Film Forming Apparatus 1 The overall configuration of the film forming apparatus 1 according to this embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of a film forming apparatus 1 according to an embodiment of the present invention.

  A film forming apparatus 1 according to the present embodiment includes a susceptor 3 on which a silicon carbide (SiC) substrate 2 is mounted, a reaction vessel 4 that accommodates the silicon carbide substrate 2 and the susceptor 3, and a reaction vessel 4. And a heat insulating material 5 for housing. The film forming apparatus 1 is arranged in the order of the silicon carbide substrate 2, the susceptor 3, the reaction vessel 4, and the heat insulating material 5 from the inside to the outside.

  The susceptor 3 is formed in a plate shape and extends along the longitudinal direction. It has a function of holding the silicon carbide substrate 2 when a thin film is grown on the silicon carbide substrate 2 during the semiconductor manufacturing process.

  Moreover, the reaction container 4 is formed in the cylinder shape extended along a longitudinal direction, and the susceptor 3 is accommodated inside. Specifically, the reaction vessel 4 is a reaction furnace or a chamber.

  And the heat insulating material 5 is formed in the cylindrical shape extended along a longitudinal direction, and the reaction container 4 is accommodated inside.

(2) Structure of Reaction Container 4 and Susceptor 3 The structure of the reaction container 4 and the susceptor 3 according to this embodiment will be described with reference to FIG.

  Both ends of the film forming apparatus 1 are connected to quartz tubes 6 and 6 made of quartz. Inside the quartz tube 6, a deposition gas G <b> 1 flows from the left side to the right side in FIG. 1. The film forming gas G1 is used as a reaction for homoepitaxially growing a thin film on the silicon carbide substrate 2 in the film forming apparatus 1, and then discharged as an exhaust gas G2. Note that epitaxial growth is a growth method in which a single crystal film having the same crystal structure as the substrate is formed on the substrate, and homoepitaxial growth is a method in which a thin film made of the same material as the substrate is grown.

  The upper surface of the susceptor 3 and the inner surface of the reaction vessel 4 are provided with liner members that are mirror-finished or chemically etched. This liner member is a liner made of single crystal or polycrystalline 3C-SiC. Specifically, the first liner 7 is provided on the inner surface of the reaction vessel 4, and the second liner 8 is provided on the upper surface of the susceptor 3 except for the mounting surface 3 a on which the silicon carbide substrate 2 is mounted. Is provided. That is, the surface of these first liner 7 and second liner 8 is subjected to surface treatment such as mirror surface treatment or chemical etching treatment.

As the chemical etching treatment, for example, chemical polishing (CHP) or reactive gas etching using H ₂ , HCl, halogen-based gas or the like is preferable. By this surface treatment, the arithmetic average roughness (Ra) of the surfaces of the first liner 7 and the second liner 8 is formed to 300 nm or less.

  Conventionally, liners and susceptors used in film forming apparatuses are generally graphite, graphite coated with SiC, and graphite coated with TaC. However, since SiC in the SiC coating is considered to be 3C or a mixture of 3C and polymorphs such as 4H, 6H, and 15R, it does not become a mirror surface even by polishing.

(3) Thin Film Formation Procedure Next, a procedure for growing a thin film on the silicon carbide substrate 2 by flowing the film forming gas G1 into the film forming apparatus 1 according to this embodiment will be briefly described.

  First, as shown in FIG. 1, when a deposition gas G <b> 1 is flowed into the quartz tube 6, the deposition gas G <b> 1 enters the deposition apparatus 1. Since the silicon carbide substrate 2 is placed on the susceptor 3 of the film forming apparatus 1, a thin film is homoepitaxially grown on the silicon carbide substrate 2 by the film forming gas G1.

  Here, the silicon carbide forming the silicon carbide substrate 2 is 4H—SiC or 6H—SiC. In the case of a 4H—SiC substrate, the thin film is 4H—SiC of the same material as the substrate, and in the case of 6H—SiC, the thin film is also 6H—SiC. Therefore, the temperature of silicon carbide substrate 2 when the thin film is homoepitaxially grown is 1500 to 1700 ° C. However, in this temperature range of 1500 to 1700 ° C., 3C—SiC, which is a by-product, is likely to be generated, and most of the by-product becomes 3C—SiC.

  The first liner 7 disposed on the inner surface of the reaction vessel 4 and the second liner 8 disposed on the upper surface of the susceptor 3 are made of single crystal or polycrystalline 3C—SiC. The by-product 3C—SiC is deposited on the first liner 7 and the second liner 8, and is difficult to peel off from the first liner 7 and the second liner 8.

(4) Examples Next, the present invention will be described more specifically through examples. A liner made of polycrystalline 3C-SiC is attached to the entire inner surface of the reaction vessel (that is, the upper surface, the lower surface, and the left and right side surfaces) as in the film forming apparatus having the configuration described in FIG. Were used in the examples of the present invention. On the other hand, a film forming apparatus that does not attach a liner to the inner surface of the reaction vessel as in the prior art was used as a comparative example. A film forming gas was supplied to each film forming apparatus to grow a thin film on the silicon carbide substrate for 200 hours, and then cleaning by hydrogen etching was performed for the same time (200 hours).

(4-1) Adhesion of by-products to the liner After 200 hours as the total film formation time, the liner was taken out of the reaction container according to the present invention and the surface of the liner was confirmed. -SiC was not seen. However, a portion where 3C-SiC was crystallized and deposited and a portion where the liner itself was scraped by hydrogen etching were confirmed. On the other hand, in the film forming apparatus according to the comparative example, a large number of granular 3C—SiC as a by-product was observed to adhere to the inner surface of the reaction vessel.

(4-2) Epitaxial Defect Density After the elapse of 200 hours, the density of epitaxial defects in the thin film due to 3C-SiC particles was confirmed. When the film forming apparatus according to the example of the present invention was used, the density of epitaxial defects in the thin film was 0.2 / cm ² . On the other hand, when the film forming apparatus according to the comparative example was used, the density of epitaxial defects in the thin film was 5.0 / cm ² .

(4-3) Number of particles dropped onto silicon (Si) substrate by manual conveyance After preparing a Si substrate instead of the SiC substrate described above and performing a film forming process for 200 hours on the Si substrate, by manual conveyance The number of 3C-SiC particles dropped on the silicon substrate was confirmed.

  When the film forming apparatus according to the example of the present invention was used, the number of particles dropped on the silicon substrate was 30 on the 4-inch substrate. On the other hand, when the film forming apparatus according to the comparative example was used, the number was 3000 for a 4-inch substrate.

(5) Effects The film forming apparatus 1 includes a liner member (first liner) made of single crystal or polycrystalline 3C—SiC on at least a part of the upper surface of the susceptor 3 and at least a part of the inner surface of the reaction vessel 4. 7. A second liner 8) is provided, and when the thin film is homoepitaxially grown on the silicon carbide substrate, the substrate temperature is generally set to 1500 to 1700 ° C.

  This temperature range of 1500 to 1700 ° C. is a temperature at which granular 3C—SiC, which is a by-product, is likely to be generated. On the upper surface of the susceptor 3 and the inner surface of the reaction vessel 4 of the film forming apparatus 1, Since the first liner 7 and the second liner 8 made of polycrystalline 3C—SiC are provided, the by-product 3C—SiC is separated from the surfaces of the first liner 7 and the second liner 8. Grows as crystals.

  Thereby, 3C-SiC which is a by-product can be prevented from falling on the silicon carbide substrate, and the quality of the silicon carbide substrate can be improved. As a result, it is possible to reduce the frequency of cleaning various members used in the film forming process of the reaction vessel or the like and the replacement frequency of the members themselves.

  Further, the surface of the liner members 7 and 8 is mirror-finished or chemically etched, so that crystals of 3C—SiC as a by-product can be efficiently grown on the surfaces of the liner members 7 and 8.

  Even when a large amount of 3C-SiC, which is a by-product, is deposited on the inner surface of the reaction vessel 4, it reacts with hydrogen and is gasified and scraped by thermal cleaning by hydrogen etching. The 3C-SiC granulated at the time of the thermal cleaning by is not dropped on the substrate.

  When the arithmetic average roughness of the surfaces of the liner members 7 and 8 is 300 nm, 3C-SiC as a by-product is likely to grow, and the by-product is difficult to peel off.

(6) Other Embodiments It should not be understood that the description and drawings that constitute part of the disclosure of the above-described embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In this embodiment, liners 7 and 8 made of single crystal or polycrystalline 3C—SiC are provided on both the entire inner surface of the reaction vessel 4 and the upper surface of the susceptor 3. However, a liner may be provided on one of the entire inner surface of the reaction vessel 4 and the upper surface of the susceptor 3.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus, 2 ... Silicon carbide substrate, 3 ... Susceptor, 4 ... Reaction container, 7 ... 1st liner (liner member), 8 ... 2nd liner (liner member)

Claims (3)

A film forming apparatus, comprising: a susceptor on which a silicon carbide substrate is placed; and a reaction vessel that accommodates the silicon carbide substrate and the susceptor, wherein the silicon carbide thin film is homoepitaxially grown on the silicon carbide substrate,
A film forming apparatus having a liner member made of single crystal or polycrystalline 3C-SiC on at least a part of the upper surface of the susceptor and at least a part of the inner surface of the reaction vessel.   The film forming apparatus according to claim 1, wherein the liner member is subjected to mirror surface treatment or chemical etching treatment.   The film forming apparatus according to claim 1, wherein an arithmetic average roughness of the surface of the liner member is 300 nm or less.

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