JP4437365B2 - 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 semiconductor industry, and more particularly to a silica glass jig for semiconductor industry in which protrusions are distributed on the surface and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, in the manufacture of semiconductor devices, a film made of a film material such as silicon oxide, silicon nitride, or polysilicon is formed on a substrate. However, the coating material stays on the substrate. It is also deposited on the surface of the reaction chamber for coating and the members disposed therein (hereinafter, the reaction chamber and members are simply referred to as jigs). When the jig is made of quartz glass, if the coating material exceeds a certain thickness, stress is generated due to the difference in thermal expansion coefficient between the jig and the coating material, and peeling or particles may contaminate the semiconductor element. . In particular, when a film is formed by a high-temperature CVD method, the tendency to peel off further increases. For this reason, cleaning is generally performed after the jig has been used for a certain period of time. However, cleaning takes time, and the number of steps increases, resulting in a high manufacturing cost. In view of this, a method for reducing the peeling of the film by providing irregularities on the jig surface has been proposed. For the formation of these irregularities, mechanical processing methods such as dry sand blasting method in which silicon dioxide fine particles, carbon fine particles, ceramic fine particles are sprayed, grinding method using diamond abrasive grains or wet blasting method using slurry-like free abrasive grains, etc. are specified. A chemical processing method or the like that is treated with the above processing solution is used, but in the mechanical processing method, a layer having microcracks is formed together with the unevenness formed on the surface of the jig, and the depth reaches 100 μm. There is. When such a deep microcrack occurs, a substance that contaminates the semiconductor element is taken into the microcrack, and the semiconductor element is contaminated, or the microcrack becomes a fracture start crack, reducing the strength of the jig and shortening the service life. There were drawbacks such as making things. Furthermore, the occurrence of the microcracks changes the unevenness of the jig surface during cleaning, making it impossible to perform a gas phase reaction under the same conditions, making it difficult to form a stable film. In order to solve this problem, for example, in Japanese Patent Application Laid-Open No. 10-59744, after machining, the microcracks are released by etching with hydrofluoric acid containing 3 to 20% by mass of hydrogen fluoride. In this method, smooth dimple-like irregularities are formed, and fine irregularities are eliminated, so that it is difficult to form a uniform coating film at a level required by recent advanced semiconductor elements.
[0003]
In addition, when the formation of irregularities on the surface of a silica glass jig is performed by a chemical processing method, the occurrence of microcracks certainly does not occur, the contamination of semiconductor elements due to contaminants is reduced, and the irregularities of the jig are also reduced. Uniform gas phase reaction is possible and a uniform film can be formed. However, when the unevenness of the jig surface becomes large, for example, when Ra = 3 or more, there is a smooth portion at the top of the convex or the bottom of the concave. Thus, there is a problem that the coating material adheres to the smooth portion, and a crack is generated in the jig due to a difference in thermal expansion coefficient between the attached coating material and the jig, which becomes a generation source of particles.
[0004]
[Problems to be solved by the invention]
In view of such a current situation, the present inventors have conducted intensive research, and as a result, the chemical processing method does not generate microcracks on the jig surface, and the unevenness of the jig is small. Based on the idea that an improved quartz glass jig can be obtained by improvement, a relatively large truncated pyramid-shaped protrusion was first formed by a chemical processing method, and further on that By forming small protrusions, the peeling of the film is further reduced, the occurrence of cracks due to the difference in thermal expansion coefficient between the jig and the coating material is extremely small, and the number of times the jig is cleaned can be reduced. And the present invention has been completed. That is, [0005]
The present invention provides a silica glass jig for the semiconductor industry with less peeling of the coating film, less contamination of the semiconductor element due to generation of particles and less frequency of cleaning, and less generation of cracks and longer service life. With the goal.
[0006]
Another object of the present invention is to provide a simple method for producing the silica glass jig for the semiconductor industry.
[0007]
[Means for Solving the Problems]
The present invention that achieves the above object is a silica glass jig used in the semiconductor industry, having a truncated pyramid-shaped protruding structure on the surface of the jig, and a recess therebetween, and a small protrusion on them. The present invention relates to a silica glass jig for semiconductor industry, which is uniformly distributed, 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, etc., and a truncated pyramid-shaped protruding structure on the jig surface , A jig in which small protrusions are evenly distributed on the flat portion of the recess between them. The protruding structure may have a maximum width at the bottom of 70 to 1000 μm and a height from the bottom to the top of 10 to 100 μm. If the bottom maximum width of the protruding structure is less than 70 μm, the surface roughness is small, the effect at the time of forming a thick film is not sufficient, and it is technically difficult to form a structure having a maximum width exceeding 1000 μm. . Further, if the height of the protruding structure is less than 10 μm, the unevenness is shallow and the prevention of peeling is not sufficient, and it is difficult to form the protruding structure having a height exceeding 100 μm.
[0009]
The small protrusion formed on the protruding structure and the flat portion of the concave portion between the side surface and the protruding structure may have a maximum width of the bottom of 50 μm or less and a height from the bottom to the top of less than 10 μm. If the maximum width of the small protrusion exceeds 50 μm, a flat portion remains and cracks and particles are likely to occur. Since the silica glass jig for semiconductor industry of the present invention has the above-mentioned surface structure, it is possible to reduce the generation of cracks due to the difference in thermal expansion coefficient between the jig and the deposited film, and the coating deposited on the jig is less peeled and thick. The number of cleaning of the jig with the film attached can be reduced. In addition, since the irregularities are formed by chemical processing methods, there is no uptake of impurities due to the generation of microcrack layers, and there is no lack of strength due to microcracks, and there is no change in surface state due to cleaning, which stabilizes gas phase reactions. And a uniform film can be formed.
[0010]
In the method for producing a silica glass jig for semiconductor industry according to the present invention, the silica glass jig is first immersed in a first treatment liquid containing hydrogen fluoride, ammonium fluoride and an organic acid, and then an organic acid is added from the treatment liquid. Is immersed at least once in the second treatment liquid with a high ratio of the above, forming a truncated pyramid-shaped projecting structure on the jig surface and a recess therebetween, and uniformly distributing the small projections on them. To do. The content of hydrogen fluoride in the first treatment liquid to be used is 15 to 50% by mass, the content of ammonium fluoride is 6 to 30% by mass, and the content of organic acid is preferably 40 to 50% by mass. . Moreover, the content of hydrogen fluoride in the second treatment liquid is 5 to 20% by mass, the content of ammonium fluoride is 6 to 30% by mass, and the content of organic acid is in the range of 40 to 70% by mass. A range in which the content of the organic acid is higher than that of the first treatment liquid is selected.
[0011]
When the content of ammonium fluoride in the first treatment liquid is less than 6% by mass, etching with hydrogen fluoride occurs and no irregularities are formed. Even when ammonium fluoride exceeds 30% by mass, irregularities are formed. The effect is the same, it is expensive and not practical. Moreover, when the content of the organic acid is less than 20% by mass, the effect of containing the organic acid is small. When the content exceeds 50% by mass, the protruding structure becomes too small, and the effect at the time of forming the thick film is not sufficient. Furthermore, when the content of ammonium fluoride in the second treatment liquid is less than 6, etching with hydrogen fluoride occurs and no irregularities are formed, and when the content of organic acid is less than 40% by mass, protrusions are formed. Is too large, and it is difficult to prepare a treatment liquid exceeding 70% by mass. The organic acid is particularly preferably a water-soluble organic carboxylic acid, and specifically includes formic acid, acetic acid, propionic acid, etc. Among them, acetic acid having high solubility in water and being inexpensive is preferable.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, examples of the present invention will be described, but the present invention is not limited thereto.
[0013]
【Example】
Example 1
The furnace core tube for CVD is immersed in a treatment liquid bath of 30% by mass of hydrogen fluoride, 10% by mass of ammonium fluoride and 35% by mass of acetic acid for 1 hour, the maximum width at the bottom is 300 μm, and the height from the bottom to the top is A 30 μm truncated pyramid-shaped projecting structure and a furnace core tube having a flat portion between the concave portions therebetween were obtained. As for the dimensions of the protruding structure, the scanning electron micrograph of the processed furnace core tube is taken as shown in FIG. 1, the maximum width of the bottom of each protruding structure, the height from the bottom to the top, and the average value. It is a representation. When this treated furnace core tube was measured with a roughness meter, the average roughness Ra was 3 μm. The furnace core tube was further immersed in a treatment solution of 15% by mass of hydrofluoric acid, 15% by mass of ammonium fluoride, and 50% by mass of acetic acid. When the surface of the obtained furnace core tube was observed with a scanning electron microscope, as shown in FIG. 2, small protrusions having a maximum width of 15 μm at the bottom and a height of 2 μm from the bottom to the top were uniformly distributed. The average roughness Ra of the furnace core tube was 3.5 μm and the whole was opaque. The polysilicon film of the silicon wafer was formed by the CVD method using the furnace core tube. Although it was used until the polysilicon film adhered to the furnace core tube to a thickness of 30 μm, there was no generation of particles and the silicon wafer could be processed with a high yield. Further, the furnace core tube with a polysilicon film after use had no cracks and the film was not peeled off.
[0014]
Comparative Example 1
In Example 1, the chemical processing of the furnace core tube was limited to the processing of the first treatment liquid, and the furnace core tube was used to perform a process of applying a polysilicon film to a silicon wafer by 25 μm by the CVD method. Many cracks were found in the furnace core tube, and film peeling was observed in part.
[0015]
Comparative Example 2
The furnace core tube of Example 1 was chemically processed using the second treatment liquid. The average roughness Ra of the surface was 1 μm. Using this furnace core tube, a process of attaching a polysilicon film of a silicon wafer to 30 μm by the CVD method was carried out. If the polysilicon film adhered to the furnace core pipe exceeded 25 μm, the generation of particles increased, Later furnace core tubes had cracks.
[0016]
【The invention's effect】
The semiconductor silica glass jig of the present invention has a structure in which the surface thereof has a truncated pyramid-shaped protruding structure and a structure in which small protrusions are uniformly distributed in the recesses between them. The generation of cracks and the generation of particles due to peeling of the coating are small, and the semiconductor element is not contaminated even if the cleaning interval is increased. The silica glass jig can be easily manufactured by treating at least twice with a treatment liquid containing hydrogen fluoride, ammonium fluoride and an organic acid having specific concentrations, and has a high industrial value.
[Brief description of the drawings]
FIG. 1 is a 100 × photograph of a surface of a silica glass jig treated with a first treatment liquid, taken with a scanning electron microscope.
FIG. 2 is a 100 × photograph of the surface of a silica glass jig treated with first and second treatment liquids, taken with a scanning electron microscope.

Claims (5)

In a silica glass jig used in the semiconductor industry having a truncated pyramid-shaped protruding structure on the surface and concave portions therebetween, and small protrusions uniformly distributed thereon, the truncated pyramid-shaped protruding structure The maximum width of the bottom of the body is 70 to 1000 μm, the height from the bottom to the top of the protruding structure is 10 to 100 μm, and the maximum width of the bottom of the small protrusions uniformly distributed in the protruding structure and the recesses between them 1 to 50 μm, and the height from the bottom to the top is 0.1 to 10 μm. 2. The silica glass jig for semiconductor industry according to claim 1, wherein the average roughness Ra of the surface of the silica glass jig for semiconductor industry is in the range of 1 to 10 [mu] m. After immersing the silica glass jig in the first treatment liquid containing hydrogen fluoride, ammonium fluoride, and organic acid, at least one second treatment liquid having a higher content of organic acid than the first treatment liquid is used. The method for producing a silica glass jig for semiconductor industry according to claim 1 or 2, wherein the method is immersed once. The first treatment liquid is an aqueous solution containing 15 to 50% by mass of hydrogen fluoride, 6 to 30% by mass of ammonium fluoride, and 30 to 50% by mass of an organic acid, and the second treatment liquid is 5 to 5% of hydrogen fluoride. 4. The process for producing a silica glass jig for semiconductor industry according to claim 3, wherein the treatment liquid contains 20% by mass, ammonium fluoride 6-30% by mass and organic acid 40-70% by mass. The method for producing a silica glass jig for semiconductor industry according to claim 3 or 4, wherein the organic acid is acetic acid.

Images