TW202031617A - Quartz glass dummy wafer - Google Patents

Abstract

The present invention provides a quartz glass dummy wafer with a clean textured surface by facilitating the cleaning and removal of metal impurities from the textured surface of the dummy wafer which is used for manufacturing semiconductor elements. Side surfaces of a texture formed on a surface of a quartz glass are made to be inclined surfaces and the inclined surfaces of the texture are made to be visible from the top surface side so that the effects of physically washing the wafer by scrubbing with a brush or by the flow of water from a shower, etc., is increased and the amount of metal impurities are reduced. Furthermore, the surface roughness Ra when forming the texture is made to be 1.6 [mu]m or less, so that washing efficiency is increased and residue of metal impurities can be prevented. Thus, by a process that combines photolithography and sandblasting, a quartz glass dummy wafer can be manufactured for which the side surfaces of the texture can be formed with desired inclinations and the texture can be formed to have a desired surface roughness.

Description

Dummy wafer made of quartz glass for semiconductor element manufacturing and manufacturing method thereof

The present invention relates to a dummy wafer made of quartz glass, which is used in a batch-type semiconductor device processing device, which is installed in the semiconductor device manufacturing device together with the silicon wafer of the semiconductor substrate for the product. The dummy wafer is used to reduce the unevenness of the formed film thickness by making the distribution of the film forming gas in the semiconductor device manufacturing apparatus uniform.

In semiconductor manufacturing, silicon wafers are subjected to film formation processes such as ALD (Atomic Layer Deposition) or CVD (Chemical Vapor Deposition). A batch-type vertical heat treatment device is used to process multiple silicon wafers at one time. As shown in Patent Document 1 and Patent Document 2, the following method is known: in order to reduce the uneven film thickness in a plurality of silicon wafers, a dummy wafer having the same surface area as the silicon wafer for forming semiconductor elements The circle is arranged in the device.

In addition, as dummy wafers, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 2015-173154) and Patent Document 2 (Japanese Patent Laid-Open No. 2017-22233), it is known to form rectangular irregularities on the surface. And expand the surface area. In addition, as shown in Patent Document 2, it is known to adjust the surface area by changing the number of grooves formed as rectangular concavities and convexities to have the same surface area as that of the silicon wafer forming the semiconductor element. As a method of forming a concave-convex pattern on the surface, laser processing or mechanical processing is known. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-173154 [Patent Document 2] Japanese Patent Laid-Open No. 2017-22233

[The problem to be solved by the invention]

With the miniaturization of semiconductor components, for dummy wafers, fewer metal impurities that cause defects in semiconductor components are required, and as metal impurities on the surface of the dummy wafer, each metal element is required to be less than 1×10 ¹⁰ atoms/cm ² .

When fabricating a dummy wafer with bumps formed on the surface to enlarge the surface area, when the sides of the bumps formed on the surface are vertical, even by subsequent washing, it is easy to leave processing dirt on the bumps and metals, and metal The problem of increased impurities. In addition, in the case where the height difference of the uneven shape is large, or the surface roughness of the processed surface when the unevenness is formed is large, the same problem is that it is likely to cause poor washing. The purpose of the present invention is to provide a clean dummy wafer for semiconductor device manufacturing with less metal impurities. [Means to Solve the Problem]

Dummy wafers for semiconductor device manufacturing use the concave and convex sides formed on the surface of the quartz glass substrate as inclined surfaces to improve the physical cleaning effect of brush scrubbing or water jets and reduce metal impurities after cleaning. And on at least one surface of the quartz glass substrate, there are periodically arranged protrusions with a flat top surface and an inclined surface. Furthermore, the period of the protrusions of the dummy wafer for semiconductor device manufacturing is 100 μm to 2500 μm, the width of the flat top surface of the protrusions is 50 μm to 2450 μm, the height difference of the unevenness is 50 μm to 700 μm, and the side surface of the protrusion is inclined The angle is 5°-25° with respect to the vertical, and the surface roughness Ra of the protrusion and the recess is 1.6 μm or less. [Effects of Invention]

By setting the side surface of the unevenness formed on the substrate surface of the dummy wafer for semiconductor device manufacturing of the present invention as an inclined surface, a high cleaning effect can be obtained. The metal impurities on the surface of the dummy wafer can be set to 1 for each element. ×10 ¹⁰ atoms/cm ² or less, it is a clean dummy wafer with less metal impurities, which can prevent the manufactured semiconductor device from becoming defective.

Since the dummy wafer is set on the wafer boat of the holding member of the silicon wafer for film formation, it is used as shown in Fig. 1, which has the same shape and diameter as the silicon wafer for film formation.的Quartz glass substrate 1.

In the case where irregularities are formed in the area near the outer periphery of the quartz glass substrate 1, when inserted into the wafer boat, which is the holding member of the dummy wafer, the irregularities contact the wafer boat, and the convex portions are removed or cracked and dust is generated The possibility. Therefore, although it also depends on the size of the quartz glass substrate 1 and the shape of the holding portion of the wafer boat, it is preferable to use the part outside the width of 4 mm to 12 mm from the outer periphery of the quartz glass substrate 1 toward the inner side. The protrusions with a flat top surface or the recesses with a flat bottom are provided, and the boundary is denoted by E.

As a manufacturing method for forming the uneven side surface of the inclined surface 4 on at least one of the surface of the quartz glass substrate 1 shown in FIG. 1 (refer to FIG. 2), the surface processing is performed by combining photolithography and sandblasting. To form the unevenness of the desired shape, the side surface of the unevenness can be set as an inclined surface, and the surface roughness can be adjusted. By changing the size of the unevenness formed on the surface of the quartz glass substrate 1, the surface area of the dummy wafer can be changed. By forming the unevenness, the area of the side surface portion of the unevenness is increased compared with the case where the surface of the quartz glass substrate is flat.

The example shown in FIG. 2 is a case where the protrusions 2 with a flat top surface and the side surfaces being inclined surfaces 4 are formed periodically. The size of each part is shown in FIG. ) To arrange, the flat top surface 2a of the protrusion 2 is quadrangular, the side surface is inclined to become the inclined surface 4, and the protrusion 2 is trapezoidal. By changing the width b of the flat top surface of the protrusion 2, the height c from the top surface 2a to the flat part of the recess 3, and the inclination angle θ of the concave and convex side surfaces, the area of the side surface of the protrusion 2 can be increased or decreased. The surface area of the dummy wafer is adjusted to the required value.

If the period a of the protrusion 2 is increased, the number of the protrusions 2 formed decreases, and the area of the side surface 4 of the protrusion 2 decreases. Therefore, the period (interval) a of the protrusion 2 is preferably 100 μm to 2500 μm, particularly preferably 100 μm to 1000 μm.

The width b of the flat top surface 2a of the protrusion 2 is preferably set to a value smaller than the period a of the protrusion 2. However, when the period a of the protrusion 2 is too small, the width of the side surface of the protrusion 2 becomes narrower and the protrusion The area of the side of 2 is reduced. Therefore, the width b of the flat top surface 2a of the protrusion 2 is preferably set to be 50 μm to 2450 μm, and is particularly preferably set to a value that is smaller than the period a of the protrusion 2 by about 50 μm to 500 μm.

If the height c from the top surface 2a of the protrusion 2 to the flat bottom 3a of the recess 3 is increased, foreign matter is likely to remain between the protrusions 2, that is, in the recess 3 during processing, and it is easy to cause subsequent washing failures. In addition, the protrusion 2 is prone to defects, which is not good. Therefore, the height c from the top surface 2a of the protrusion 2 to the flat bottom surface 3a of the recess 3 is preferably set to 50 μm to 700 μm.

In the example shown in FIG. 3, the irregularities of the convex and concave shapes periodically provided with the flat protrusions 2 on the top surface 2a are reversed, and the concave portions 3 on the flat bottom surface 3a are periodically provided to make the surface into the concave and convex shapes. In this case, the surface area of the dummy wafer can be adjusted in the same manner as in the case of periodically providing the flat protrusions 2 on the top surface 2a.

If the inclination angle θ of the inclined side surface 4 of the protrusion 2 and the recessed portion is increased, the washing property of the inclined side surface 4 is improved, but when it is too large, the flat portion of the groove 3 decreases, so the surface area cannot be increased too much. Also, on the contrary, when it is small, it is difficult to obtain a high washing effect on the inclined side surface 4 of the protrusion 2. Therefore, the inclination angle θ of the inclined side surface 4 of the protrusion 2 is preferably 5 degrees to 25 degrees, and more preferably 6 degrees to 10 degrees.

When the surface roughness Ra of the protrusions 2 and the recesses 3 is large, dirt remains on the fine irregularities on the surface, which is likely to cause poor washing. Therefore, the surface roughness Ra is preferably 1.6 μm or less. When the projections 2 with flat top surfaces are periodically provided by photolithography and sandblasting, the inclined side surface 4 and the bottom 3a of the recess 3 are processed by sandblasting to have the same surface roughness, but the photoresist The top surface 2a of the protrusion 2 that is the non-processed part protected by the etching film maintains the surface roughness before sandblasting. Therefore, the surface roughness of the sandblasted part and the non-processed part may be different, but any part only needs the surface The roughness Ra should be 1.6 μm or less. In the case of reversing the irregularities of the protrusions 2 periodically provided with the flat top surface 2a, the surface roughness of the sandblasted part and the non-processed part are also different, but any part only needs the surface roughness Ra It is only 1.6 μm or less.

If the values of the surface roughness Ra of the protrusions 2 and the recesses 3 are different, it may be difficult to distinguish foreign matter during surface inspection. Therefore, it is preferable to perform sandblasting on the entire surface of the substrate after the unevenness is formed by sandblasting. Set the entire surface to a uniform surface roughness.

For dummy wafers, fewer metal impurities are required to cause defects in semiconductor devices. Therefore, as metal impurities on the surface of the component, it is preferable that each element is less than 1×10 ¹⁰ atoms/cm ² .

When unevenness is formed on the surface of the quartz glass substrate, adhesion of metal impurities occurs on the surface, especially the side and bottom surfaces of the unevenness. Therefore, washing must be carried out after processing. In order to remove metal ions or particles, detergents, brushes and water jets are used for washing, and then washing and rinsing with ultrapure water and drying are carried out in a clean room. When washing, it is preferable to combine etching with hydrofluoric acid. The front end of microcracks or microchips generated in the sandblasting process and the micronized quartz are dissolved by etching, thereby preventing particles from being generated from the surface.

If a defect occurs in the peripheral portion 3b of the protrusion 2 or the recess 3 formed on the surface of the substrate, the front end of the defect may be damaged and dust may be generated. Therefore, the peripheral edge of the protrusion 2 or recess 3 formed on the surface The defect of the part 3b is preferably set to 0.02% or less.

In order to form periodic irregularities on the quartz glass substrate, it is preferable to perform processing by photolithography and sandblasting. Using the photolithography method, a photoresist film is formed on the portion corresponding to the convex portion of the uneven shape (the portion that becomes the flat top surface 2a), and the photoresist film is not formed on the portion that becomes the concave portion. After the photoresist film is formed, by sandblasting the entire surface of the quartz glass substrate 1, the part where there is no photoresist film is selectively removed to form recesses, so the photoresist film is removed to obtain The established bump shape. Since the surface of the quartz glass substrate 1 is scraped off by sandblasting, the amount of cutting on the lower side by sandblasting is small. Therefore, the side surface of the protrusion 2 or the recess 3 is formed as an inclined surface 4.

The inclination angle θ of the inclined surface 4 of the protrusion 2 or the inclined surface 4 of the side surface of the recess 3 can be changed by adjusting the pattern of the photoresist film, the abrasive particle spray pressure of sandblasting, and the abrasive particle spray nozzle angle. Moreover, by adjusting the processing time of sandblasting, the height c of the uneven shape can be changed. In addition, by changing the size of abrasive grains used for sandblasting, the surface roughness of the processed surface can be changed.

When forming the uneven shape by photolithography and wet etching using hydrofluoric acid, the etching is performed isotropically. Therefore, the side surface of the formed uneven shape is curved and the predetermined inclination angle cannot be obtained. When the uneven shape is formed by cutting and grinding using a grinding stone, the uneven side surface becomes approximately vertical, and the tool tip shakes due to the influence of tool precision and mechanical accuracy, so it is difficult to tilt the uneven side surface The angle is processed at a predetermined angle. In the case of forming uneven shapes by CO ₂ laser processing, when the suction and removal of the quartz glass dust dissolved by the CO ₂ laser is incomplete, the remaining dust will block the laser light, and the uneven shape will be easily formed The part where the inclination of the inclined plane does not reach the predetermined angle.

The thickness of the photoresist film used in the photolithography method is preferably 50 μm-100 μm. If it is thinner, the resistance to sandblasting is insufficient, and it is difficult to obtain the set uneven shape. In the case of thick, high resolution cannot be obtained, so it is difficult to form the uneven shape with a fine period of 100 μm or less. The developer of the photosensitive material used in the photolithography method is preferably an alkaline aqueous solution. The photosensitive material has little swelling or dissolution, and high adhesion to the surface of the component is obtained.

The abrasive particles used for sandblasting are preferably alumina-based abrasive particles, silicon carbide-based abrasive particles, silicon nitride-based abrasive particles, and diamond-based abrasive particles. Alumina-based abrasive grains have high specific gravity, so they have high processing ability and can be formed into uneven shapes in a short time. Silicon carbide abrasive particles are formed of carbon and silicon, so the composition does not contain impurities that can become metal impurities, and can be cleaned. Silicon nitride-based abrasive grains and diamond-based abrasive grains also contain no impurities that can become metallic impurities in the composition, and can be cleaned.

The model of abrasive particles used for sandblasting is preferably #400～#2000. When it is thicker than #400, it is difficult to obtain the surface roughness Ra 1.6 μm or less of the processed surface. When it is thinner than #2000, the surface roughness of the processed surface is no problem, but the processing time is greatly increased, and the productivity is reduced, so it is not good. Sandblasting can be done with one type of abrasive grains for all processing, and it is also possible to switch abrasive grains in the middle of processing and use two or more types in combination.

Hereinafter, the present invention will be described in detail through examples, but the present invention is not limited to the examples. Example 1 Prepare a disc-shaped quartz glass substrate with a thickness of 1.5 mm and a diameter of 300 mm that is mirror-polished on both sides. Laminate a photosensitive material with a thickness of 100 μm with a dry film resist for sandblasting (MS7100 manufactured by Mitsubishi Paper Manufacturing) on one side of the substrate, and then use a film mask to perform UV exposure. The alkaline aqueous solution is developed to form a photoresist film with periodic patterns.

Then, on the surface of the quartz glass substrate, #800 alumina-based abrasive grains were sprayed from the nozzle from the vertical direction to scan the entire surface, thereby performing sandblasting. After that, the quartz glass substrate was immersed in a resist stripping solution, and the remaining photoresist film was stripped and removed to obtain a dummy wafer, which was 7 mm from the outer periphery of the one side surface of the quartz glass substrate , The protrusions on the flat surface are periodically arranged in a grid pattern.

The period a of the protrusion 2 is 500 μm, the width b of the flat portion of the protrusion is 370 μm, and the height c from the flat surface 2a of the protrusion 2 to the bottom surface 3a of the recess 3 is 350 μm. The average inclination angle θ of the uneven side surface 4 is 6.5 degrees.

After sandblasting, use neutral lotion (Mamalemon manufactured by Lion King), brushes and water jets for washing and rinsing, and then use hydrofluoric acid for etching to remove the microcracks or microchips generated during the sandblasting process The front end and the micronized quartz glass dissolve. Furthermore, use a lotion (Cleanthrough KS-3030 manufactured by Kao Co., Ltd.), brushes and water jets for washing and rinsing, and then washing and rinsing with ultrapure water in a clean room to dry. The defects of the trapezoidal protrusions 2 formed on the surface after drying were visually inspected. As a result, there were 6 defects.

The completed dummy wafer made of quartz glass is immersed in aqua regia which is mixed with hydrochloric acid and nitric acid in a volume ratio of 3:1, the recovered aqua regia is evaporated to dryness, the residue is dissolved with acid, and then induction Coupled plasma mass spectrometry to determine the amount of metal impurities. The value obtained by dividing the obtained amount of metallic impurities by the surface area of the component is regarded as the amount of metallic impurities on the surface of the component.

Example 2 In the same procedure as in Example 1, the #400 silicon carbide abrasive grains were used for sandblasting, and the part 7 mm from the outer periphery of the one side surface of the quartz glass substrate was formed in a grid pattern with periodic arrangement Concave-convex shape with flat protrusions. The period a of the protrusion 2 is 500 μm, the width b of the flat top surface 2a of the protrusion 2 is 370 μm, and the height c from the flat top surface 2a of the protrusion to the flat bottom surface 3a of the recess 3 is 350 μm. The average tilt angle θ is 7.3 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the protrusions 2 formed on the surface after drying were inspected visually, and the result was 11 places.

Example 3 In the same procedure as in Example 1, the part of the single side surface of the quartz glass substrate 6 mm from the outer periphery was formed into a concave-convex shape periodically provided with flat projections in a lattice pattern. The period a of the protrusion 2 is 2500 μm, the width b of the flat top surface 2a of the protrusion 2 is 2320 μm, and the height c from the flat top surface 2a of the protrusion 2 to the flat bottom surface 3a of the recess 3 is 700 μm. The average tilt angle θ is 6.9 degrees. Washing was performed in the same procedure as in Example 1, and the defects of trapezoidal protrusions formed on the surface after drying were inspected visually. As a result, there were 2 defects.

Example 4 In the same procedure as in Example 1, the remaining resist film was stripped and removed, and the entire surface was sandblasted again to obtain a dummy wafer, which was 7 mm from the outer periphery of the quartz glass substrate 1 on one side of the wafer The other part is formed with a concave-convex shape in which protrusions 2 with flat top surfaces are periodically provided in a grid pattern.

The period a of the protrusion 2 is 500 μm, the width of the flat top surface 2a of the protrusion 2 is 200 μm, and the height c from the flat top surface 2a of the protrusion 2 to the flat bottom surface 3a of the recess 3 is 350 μm. The average tilt angle θ is 23.2 degrees. Washing was performed in the same procedure as in Example 1, and the defects of trapezoidal protrusions formed on the surface after drying were inspected visually. As a result, there were 2 defects.

Example 5 In the same procedure as in Example 1, a portion of the one-side surface of the quartz glass substrate 1 outside of 7 mm from the outer periphery was formed into a concave-convex shape periodically provided with flat protrusions in a lattice pattern. The period a of the protrusion 2 is 500 μm, the width b of the flat top surface 2a of the protrusion 2 is 390 μm, the height c from the flat top surface 2a of the protrusion 2 to the flat bottom surface 3a of the recess is 200 μm, and the average slope of the uneven side surface The angle θ is 9.9 degrees. Washing was performed in the same procedure as in Example 1, and the defects of trapezoidal protrusions formed on the surface after drying were visually inspected. As a result, there were 5 defects.

Example 6 In the same procedure as in Example 1, a portion of the one-side surface of the quartz glass substrate 1 outside of 7 mm from the outer periphery was formed into a concave-convex shape periodically provided with flat protrusions in a lattice pattern. The period a of the protrusion 2 is 200 μm, the width b of the flat top surface 2a of the protrusion 2 is 70 μm, the height c from the flat top surface 2a of the protrusion to the flat bottom surface 3a of the recess is 500 μm, and the average inclination angle of the uneven side surface θ is 5.7 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the protrusions 2 formed on the surface after drying were inspected visually. As a result, there were 23 defects.

Example 7 In the same procedure as in Example 1, use a photosensitive material with a thickness of 50 μm dry film resist for sandblasting (MS7050 manufactured by Mitsubishi Paper) on one side surface of the quartz glass substrate 7 mm from the outer periphery In part, a concave-convex shape in which protrusions with a flat surface are periodically provided in a lattice pattern is formed. The period a of the protrusion 2 is 200 μm, the width b of the flat top surface 2a of the protrusion is 140 μm, the height c from the flat top surface of the protrusion to the flat bottom surface of the recess is 200 μm, and the average inclination angle θ of the uneven side surface is 7.1 degree. Washing was performed in the same procedure as in Example 1, and the defects of the trapezoidal protrusions formed on the surface after drying were visually inspected. As a result, there were 11 defects.

Example 8 In the same procedure as in Example 1, a portion of the single side surface of the quartz glass substrate 1 other than 7 mm from the outer periphery is formed into a concave-convex shape in which concave portions 3 with a flat bottom surface 3a are periodically provided in a lattice pattern. The period a of the concave portion 3 is 500 μm, the width d of the flat bottom surface 3a of the concave portion 3 is 390 μm, the height c from the flat top surface 2a of the convex portion 2 to the flat bottom surface 3a of the concave portion is 200 μm, and the average slope of the concave-convex side The angle θ is 9.8 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the flat part except the recesses formed on the surface after drying were inspected visually. As a result, there were 3 defects.

Comparative example 1 In the same procedure as in Example 1, protrusions 2 with a flat top surface 2a are periodically provided in a grid pattern at a portion 7 mm from the outer periphery of the one side surface of the quartz glass substrate 1 to form an uneven surface. The period a of the protrusion 2 is 500 μm, the width b of the flat top 2a of the protrusion 2 is 370 μm, the height c from the flat top 2a of the protrusion 2 to the flat bottom surface 3a of the recess 3 is 350 μm, and the average inclination angle of the uneven side surface θ is 3.3 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the protrusions 2 formed on the surface after drying were inspected visually. As a result, there were 10 defects.

Comparative example 2 Prepare a quartz glass substrate with a thickness of 1.5 mm and a diameter of 150 mm that will be mirror-polished on both sides. The quartz glass substrate 1 is set on a microtome, and a #800 diamond grinding stone is used on one side of the quartz glass substrate to periodically arrange flat protrusions 2 on the top surface in a grid pattern to form an uneven shape. The period a of the protrusion 2 is 500 μm, the width b of the flat top surface 2a of the protrusion 2 is 350 μm, and the height c from the flat top surface 2a of the protrusion 2 to the flat bottom surface 3a of the recess 3 is 800 μm. The average tilt angle θ is 1.1 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the protrusions 2 formed on the surface after drying were inspected visually. As a result, there were 8 defects other than the outer periphery.

Comparative example 3 In the same procedure as in Example 1, the #320 alumina-based abrasive grains were used for sandblasting, and the part of the single side surface of the wafer beyond 7 mm from the outer periphery of the wafer was formed in a grid pattern to be periodically arranged Concave-convex shape of protrusion 2 with flat top surface. The period a of the protrusion is 500 μm, the width b of the flat top 2a of the protrusion 2 is 370 μm, the height c from the flat top 2a of the protrusion to the flat bottom surface 3a of the recess 3 is 350 μm, and the average inclination angle θ of the uneven side surface is 8.1 degrees. Washing was performed in the same procedure as in Example 1, and the defects of the protrusions formed on the surface after drying were inspected visually. As a result, there were 19 defects. Table 1 shows the various elements of the concavity and convexity of the dummy wafer made of quartz glass of the Examples and Comparative Examples, and the measurement results of the amount of metal impurities and the surface roughness.

[Table 1] Concave-convex pattern (μm) Average inclination angle of uneven side surface (degrees) The amount of metal impurities (×10 ¹⁰ atoms/cm ² ) Surface roughness Ra (μm) a b c Cu Fe Al Na Example 1 500 370 350 6.5 ND 0.60 0.65 ND 0.85 Example 2 500 370 350 7.3 ND 0.90 0.74 ND 1.6 Example 3 2500 2320 700 6.9 ND 0.52 0.57 ND 0.85 Example 4 500 200 350 23.2 ND 0.81 0.92 ND 0.85 Example 5 500 390 200 9.9 ND 0.44 0.61 ND 0.85 Example 6 200 70 500 5.7 ND 0.78 0.64 ND 0.85 Example 7 200 140 200 7.1 ND 0.43 0.85 ND 0.85 Example 8 Use the same pattern as in Example 5 to reverse the unevenness ND 0.74 0.50 ND 0.85 Comparative example 1 500 370 350 3.3 0.22 1.94 7.72 1.33 0.85 Comparative example 2 500 350 800 1.1 0.40 8.31 3.66 2.79 1.5 Comparative example 3 500 370 350 8.1 0.47 5.56 15.21 1.54 1.8 Lower detection limit 0.05 0.06 0.12 0.15

1: Quartz glass substrate 2: protrusion 2a: flat top surface of protrusion 3: recess (groove) 3a: The bottom of the recess E: indicates the line forming the boundary of the bump 4: Inclined surface (side) a: Period of protrusion (interval) b: The width of the flat top of the protrusion c: The height difference between the protrusion and the recess d: The width of the recess θ: Angle of inclined plane

FIG. 1 is a plan view showing the shape of the quartz glass substrate of the dummy wafer of the present invention. 2 is a perspective view and a cross-sectional view of an embodiment of the concave-convex pattern of the present invention. Fig. 3 is a perspective view and a cross-sectional view of another embodiment of the concave-convex pattern of the present invention. 4 is a detailed cross-sectional view of an embodiment of the concave-convex pattern of the present invention.

1: Quartz glass substrate

E: indicates the line forming the boundary of the bump

Claims (5)

A dummy wafer for the manufacture of semiconductor elements, which is a dummy wafer made of quartz glass for the purpose of adsorbing reactive gases in the manufacture of semiconductor elements, characterized in that: on at least one side of a quartz glass substrate, there are periodically arranged A protrusion with a flat top surface and an inclined side surface, and the period of the protrusion is 100 μm～2500 μm, the width of the flat top surface is 50 μm～2450 μm, and the height from the top surface to the flat part of the groove is 50 μm to 700 μm, the inclination angle θ of the side surface of the protrusion is 5°-25° with respect to the vertical, and the surface roughness Ra of the protrusion and recess is 1.6 μm or less. A dummy wafer for the manufacture of semiconductor elements, which is a dummy wafer made of quartz glass for the purpose of adsorbing reactive gases in the manufacture of semiconductor elements, characterized in that: on at least one side of a quartz glass substrate, there are periodically arranged A concave portion with a flat bottom surface and an inclined side surface, and the period of the concave portion is 100 μm～2500 μm, the width of the bottom surface of the concave portion is 50 μm～2450 μm, the depth of the concave portion is 50 μm～700 μm, and the side surface of the concave portion is inclined The angle θ is 5 to 25 degrees with respect to the vertical, and the surface roughness Ra is 1.6 μm or less. A manufacturing method of a dummy wafer for manufacturing a semiconductor device is to form a photoresist film forming a pattern of irregularities arranged periodically on the surface of a quartz glass substrate, and to form irregularities with inclined surfaces by sandblasting. The method of manufacturing a dummy wafer for semiconductor device manufacturing according to claim 3, wherein The thickness of the photoresist film is 50 μm-100 μm, the developer is an alkaline aqueous solution, and the abrasive grains used for sandblasting are alumina-based abrasives, silicon carbide-based abrasives, silicon nitride-based abrasives, and diamond-based abrasives. Any one of the grains or a mixture of them. The method of manufacturing a dummy wafer for manufacturing a semiconductor element according to claim 4, wherein The model of abrasive grain used for sandblasting is in the range of #400～#2000.

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