JP4539794B2 - Silica glass jig for semiconductor industry and manufacturing method thereof - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a silica glass jig for the semiconductor industry, and more particularly to a silica glass jig for the semiconductor industry in which small protrusions are uniformly distributed on the surface and a manufacturing method thereof.
[0002]
[Prior art]
Conventionally, a jig made of silica glass has been used for manufacturing a semiconductor element. For example, when a polysilicon film is grown on a semiconductor element by LPCVD (Low Pressure Chemical Vapor Deposition) method, many irregularities are formed on the quartz glass jig. It is effective that it is provided. Due to this unevenness, the generation of stress due to the difference in thermal expansion coefficient between the polysilicon film deposited on the surface of the quartz glass jig and the jig is reduced, and film peeling and cracking can be prevented. A mechanical process is used to form the unevenness. In this mechanical process, a layer having microcracks is formed below the uneven surface formed on the jig surface, and the depth may reach 100 μm. . When such a deep crack occurs, a substance that contaminates the semiconductor element may be taken into the crack, and may volatilize and contaminate the semiconductor element during heat treatment. Therefore, in the initial stage of processing of the semiconductor element, the process is performed after operating for a while without the semiconductor element. In addition, the crack becomes a crack starting crack of the jig, lowers the strength of the jig and shortens the service life, changes the unevenness of the jig during cleaning or cleaning of the jig, and changes the surface state, resulting in uniform There were drawbacks such as inability to perform a proper gas phase reaction. In order to solve this drawback, for example, in Japanese Patent Laid-Open No. 10-59744, a mechanically processed jig is etched with hydrofluoric acid containing 3 to 20% by mass of hydrogen fluoride to open microcracks. It has been proposed to make a microcrack-free surface, but the jig processed by this method has a large concavo-convex shape to form a mortar-shaped concave portion, which reduces the fine concavo-convex shape and is used as a semiconductor device processing jig. Was not satisfactory.
[0003]
Further, a method for forming irregularities on the surface of a silica glass jig by chemical treatment instead of mechanical processing is proposed in, for example, Japanese Patent Application Laid-Open No. 11-106225. In this chemical treatment, there is no microcrack in the jig, there is no contamination of the semiconductor element due to contaminants from inside the crack, and there is almost no change in unevenness when cleaning the jig, but a uniform chemical reaction can be performed, When the roughness is large, for example, Ra = 3 or more, a smooth portion exists on the convex slope or the bottom of the concave, and polysilicon adheres to the smooth portion, and the attached polysilicon film and jig Cracks were generated in the jig due to the difference in thermal expansion coefficient, resulting in particles that adversely affected the semiconductor element and reduced yield.
[0004]
[Problems to be solved by the invention]
In view of such a current situation, the present inventors have conducted extensive research, and as a result of treating the silica glass jig mechanically roughened with a specific aqueous solution, the microcracks are released and there is no uptake of contaminants. And by finding that a large number of small protrusions are uniformly distributed on the jig surface, it is found that a silica glass jig free from cracks due to a difference in thermal expansion coefficient between the jig and an adhesion film such as a polysilicon film can be obtained. The present invention has been completed. That is, [0005]
An object of the present invention is to provide a silica glass jig for the semiconductor industry that does not generate impurities that contaminate semiconductor elements during use and that does not generate cracks.
[0006]
Moreover, this invention aims at providing the manufacturing method of the said silica glass jig | tool for semiconductor industries.
[0007]
[Means for Solving the Problems]
In the silica glass jig for semiconductor industry, the present invention that achieves the above-mentioned object has a large number of concave parts having a width of 20 to 300 μm on the surface and grooves having a width of 0.5 to 50 μm at intervals of 20 to 300 μm. In addition, the present invention relates to a silica glass jig for semiconductor industry, characterized in that small protrusions having a width of 1 to 50 μm and a height of 0.1 to 10 μm are uniformly distributed between and within the grooves, and a method for manufacturing the same.
[0008]
The silica glass jig for the semiconductor industry of the present invention is a jig used in the semiconductor industry such as a furnace core tube, a wafer mounting boat, and the like. There are a number of concave parts of 20 to 300 μm in width and there are grooves with a width of 0.5 to 50 μm at intervals of 20 to 300 μm. Between these grooves and within the grooves, a width of 1 to 50 μm and a height of 0.1 to A jig in which small protrusions of 10 μm are uniformly distributed. By having the said structure, the silica glass jig | tool for semiconductor industries of this invention has few generation | occurrence | production of a particle | grain and an impurity, can maintain the high cleanliness of the surface, and can fully exhibit the high purity performance as a bulk of silica glass. In the silica glass jig of the present invention, even if a polysilicon film, for example, is deposited on the surface thereof, the stress based on the difference in thermal expansion coefficient is relieved by the small protrusions, and the jig does not easily crack and has a long jig life. Become. The groove is a portion where a deep microcrack generated during mechanical processing is opened, and the width should be in the range of 0.5 to 50 μm. If the width is less than 0.5 μm, the microcrack spreads. However, the impurity element remains, and in the process where the groove width exceeds 50 μm, the amount of etching off of the surface is large and the dimensional accuracy is deviated. Moreover, although it changes with mechanical processing means between grooves, it is good to exist in the range of 20-300 micrometers. Between these grooves, there is a further concave portion in the shape of an elbow, and its width is in the range of 20 to 300 μm. The small protrusions are uniformly distributed between and within the grooves. Although the magnitude | size is based on the process liquid used for a process, it is good for a width | variety to exist in the range of 1-50 micrometers and height in 0.1-10 micrometers. If the small protrusion is less than the above range, the thermal stress of the deposited film is not sufficiently relaxed and cracks may occur. If the small protrusion is exceeded, a smooth portion remains. The treatment liquid contains 10 to 30% by mass of hydrogen fluoride, 5 to 30% by mass of ammonium fluoride, 45 to 70% by mass of organic carboxylic acid, and the remainder is preferably a treatment liquid of water . By containing this organic carboxylic acid, the small protrusions in the above range can be formed uniformly and easily. Examples of the organic carboxylic acid include water-soluble organic carboxylic acids such as formic acid, acetic acid, and propionic acid. Acetic acid is particularly preferable because it has high solubility in water and is inexpensive.
[0009]
As the production method of the present invention, the surface of the silica glass jig is first roughened by mechanical processing as described above. As the mechanical processing method, sand blasting method in which silicon dioxide fine particles, carbon fine particles, ceramic fine particles are sprayed, Examples thereof include a grinding method using diamond abrasive grains and a wet blasting method using slurry-like free abrasive grains. Sandblasting is preferable. In this sandblasting, the glass powder can be easily peeled off from the jig surface, and the coolant does not penetrate into the microcracks. Next, the particles adhered by washing after mechanical processing are removed, and 10 to 30% by mass of hydrogen fluoride and 5 to 30% by mass of ammonium fluoride are contained, and the balance is a treatment solution of water, preferably further organic carboxylic acid Is repeatedly dipped in a treatment solution containing 45 to 70% by mass to release a microcrack to form a large number of grooves with a width of 0.5 to 50 μm, and between the grooves, a concave portion with an exotic width of 20 to 300 μm. The small protrusions having a width of 1 to 50 μm and a height of 0.1 to 10 μm are uniformly distributed between and in the grooves. When the amount of the organic carboxylic acid contained in the treatment liquid is less than 45% by mass, the small protrusions become large and uniform distribution becomes difficult. When the amount of the organic carboxylic acid exceeds 70% by mass, the small protrusions become small and the effect is achieved. Can not. In addition, when the content of ammonium fluoride in the treatment liquid is less than 5% by mass, etching with hydrogen fluoride only occurs. Even when the amount of ammonium fluoride exceeds 30% by mass, the unevenness can be only about 30% by mass. It is expensive and not practical.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, examples of the present invention will be described, but the present invention is not limited thereto.
[0011]
【Example】
Example 1
A silicon carbide abrasive (No. 320) was used for sandblasting by blowing an abrasive with compressed air onto the inner surface of the LPCVD furnace core tube. The surface roughness Ra was 3 μm. This furnace core tube was immersed in a treatment liquid bath of 15% by mass of hydrogen fluoride, 15% by mass of ammonium fluoride and 50% by mass of acetic acid for 1 hour, and the furnace core tube after treatment was viewed with a scanning electron microscope, as shown in FIG. There were many small protrusions. Also, microcracks were opened and many grooves with a width of about 1 μm were observed. A CVD process for forming a polysilicon film on a silicon wafer was performed using this furnace core tube. It was used until the polysilicon film adhered to the furnace core tube, but the generation of particles was small and the yield rate of silicon wafers was high. Moreover, there was no crack in the furnace core tube with a polysilicon film after use, and no film was peeled off.
[0012]
Comparative Example 1
A CVD process for forming a polysilicon film on a silicon wafer was performed in the same manner as in Example 1 using a furnace core tube that had been sandblasted in the same manner as in Example 1. Many particles were generated after the start of the CVD process, and the wafer could not be processed for a while. Then, when it was used until the polysilicon film adhered to the furnace core tube, some cracks were generated, but the film was not peeled off.
[0013]
Comparative Example 2
The furnace core tube subjected to sandblasting in Example 1 was etched with 20% by mass of hydrogen fluoride for 1 hour. The surface roughness Ra of the obtained jig was 7 μm. When the surface was observed with a scanning electron microscope, a number of smooth, concave (slip-like) concave portions were seen as shown in FIG. Using this furnace core tube, a CVD process was performed in the same manner as in Example 1. When the polysilicon film adhered to the jig at 15 μm, the amount of particles generated increased and the treatment became difficult. Moreover, many cracks were seen in the jig after use, and peeling was also seen in a part of the polysilicon film.
[0014]
【The invention's effect】
The semiconductor silica glass jig of the present invention has a large number of concave parts having a width of 20 to 300 μm on its surface, and grooves having a width of 0.5 to 50 μm at intervals of 20 to 300 μm. Small protrusions with a width of 1 to 50 μm and a height of 0.1 to 10 μm are evenly distributed inside, reducing the generation of particles such as polysilicon film during use, and reducing the generation of cracks, resulting in a long tool life. Can be used for a long time. The silica glass jig can be manufactured by a simple method of treating with a treatment liquid containing a specific concentration of hydrogen fluoride or ammonium fluoride, followed by roughening by mechanical processing that has been conventionally used. Some industrial values are high.
[Brief description of the drawings]
FIG. 1 is a 100 × photograph of the surface of a silica glass jig according to the present invention, taken with a scanning electron microscope.
FIG. 2 is a 100 × photograph taken by a scanning electron microscope of the surface of a silica glass jig obtained by subjecting conventional sandblasting to hydrogen fluoride etching.

Claims (4)

In the silica glass jig for semiconductor industry, there are a large number of excavated recesses with a width of 20 to 300 μm on the surface, and grooves with a width of 0.5 to 50 μm at intervals of 20 to 300 μm, and between these grooves and in the grooves A silica glass jig for semiconductor industry, wherein small protrusions having a width of 1 to 50 μm and a height of 0.1 to 10 μm are uniformly distributed. After machining the surface of the silica glass jig to form irregularities, it contains 10-30 mass% hydrogen fluoride, 5-30 mass% ammonium fluoride, 45-70 mass% organic carboxylic acid, 2. The method for producing a silica glass jig for semiconductor industry according to claim 1 , wherein the remainder is treated with a treatment liquid which is water . 3. The method for producing a silica glass jig for semiconductor industry according to claim 2, wherein the machining is sandblasting. The method for producing a silica glass jig for semiconductor industry according to claim 2, wherein the organic carboxylic acid is acetic acid.

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