Substrate holding member

Abstract

To provide a substrate holding member capable of reducing the number of lift pin holes that may deteriorate the flatness of a substrate at a position near the center of the substrate to be sucked.SOLUTION: A substrate holding member 100 includes a flat substrate 10 having one or a plurality of air holes 14 and a plurality of lift pin holes 18 opening in an upper surface 12, a plurality of pin-shaped protrusions 22 formed to protrude upward from the upper surface 12 of the substrate 10, and an annular protrusion 24 projecting upward from the upper surface 12 of the substrate 10 and formed in an annular shape along the outer periphery of the upper surface 12, and at least one of the lift pin holes 18 is arranged outside the annular protrusion 24.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a substrate holding member.

Background Art

[0002] Conventionally, for the purpose of supporting a substrate such as a semiconductor wafer (silicon wafer) in semiconductor device manufacturing, a substrate holding member made of a ceramic sintered body has been used. In the semiconductor manufacturing process, a plurality of substrates are repeatedly adsorbed and desorbed by the substrate holding member, and the substrates are exchanged. For the substrate exchange, means such as lifting the substrate from the substrate holding member by protruding lift pins from a plurality of through holes formed in the substrate holding member toward the upper surface of the base body and transporting the substrate by a device such as a robot arm are used.

[0003] Patent Document 1 discloses a substrate holder including a plurality of protrusions for holding a substrate, a first partition wall surrounding the outer periphery, and a second partition wall surrounding the periphery of each of a plurality of through holes through which lift pins for substrate attachment and detachment can move up and down, wherein the upper surface of the first partition wall is located substantially on the same plane as the upper surface of the protrusions, the upper surface of the second partition wall is located 4 to 50 μm lower than the upper surface of the protrusions, and the surface roughness (Ra) of the upper surface of the first partition wall is 0.2 μm or less.

[0004] Further, Patent Document 2 discloses a substrate holding device including pin-shaped convex portions for supporting a wafer as a substrate, and adsorbing and holding the wafer supported on the convex portions by suction using a suction means, the substrate holding device including a plurality of lift pins for wafer transfer, and when the radius of the wafer is D and the distance from the center of the wafer at the position where the wafer is supported by the lift pins is R, each lift pin is provided at a position where R / D ≧ 0.7.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The inventors have confirmed that when a substrate is adsorbed using such a substrate holding member, the flatness of the substrate may deteriorate in the portion directly above the lift pin hole. They hypothesize that this is because the substrate is not placed in the portion directly above the lift pin hole, and the lift pin hole is a through-hole formed in the substrate and is open to the atmosphere, resulting in a portion where the adsorption force is weak and thus the flatness deteriorates.

[0007] In recent years, as semiconductor products have become smaller and more precise, there is a growing need to reduce even slight deteriorations in flatness in these small areas.

[0008] As described in Patent Document 1, when lift pin holes are positioned near the midpoint of the radius of the substrate on which they are placed, this area is a location where semiconductor elements are reliably formed on the substrate. Therefore, deterioration of flatness in this area leads to an increased risk of semiconductor element defects.

[0009] Furthermore, Patent Document 2 describes a means for attracting a substrate, in which the substrate is supported by adsorption through an adsorption hole opened in the center of a lift pin. In this case, it is necessary to increase the diameter of the lift pin, and proportionally the diameter of the lift pin hole formed in the substrate holding member for inserting the lift pin also increases. As a result, the area of ​​deterioration in flatness in that part also increases, which may affect the amount of semiconductor devices that can be manufactured.

[0010] This invention has been made in view of these circumstances, and aims to provide a substrate holding member that can reduce the number of lift pin holes, which may worsen the flatness of the substrate at positions close to the center of the substrate being held. [Means for solving the problem]

[0011] (1) To achieve the above objective, the substrate holding member of the present invention is a substrate holding member that adsorbs a substrate by vacuum suction, comprising: a flat plate-shaped base having one or more ventilation holes and a plurality of lift pin holes opening on its upper surface; a plurality of pin-shaped protrusions formed projecting upward from the upper surface of the base; and a ring-shaped projection formed on the outer circumference of the upper surface projecting upward from the upper surface of the base along the outer circumference , having an outer diameter smaller than the outer diameter of the substrate The substrate is provided with an annular protrusion, wherein at least one of the plurality of lift pin holes is located outside the annular protrusion, and the at least one lift pin hole located outside the annular protrusion is a hole for attaching and detaching the substrate from the base body.

[0012] In this way, by positioning at least one of the lift pin holes outside the annular protrusion, it is possible to reduce the number of lift pin holes that may worsen the flatness of the substrate near the center of the substrate being adsorbed.

[0013] (2) Furthermore, the substrate holding member of the present invention is characterized in that all of the lift pin holes are located on the outside of the annular protrusion.

[0014] Thus, by positioning all the lift pin holes on the outside of the annular protrusion, the deterioration of flatness near the center of the substrate caused by the lift pin holes can be sufficiently reduced. Furthermore, since the lift pin holes do not obstruct the suction channel during substrate adsorption, the substrate can be adsorbed with high uniformity.

[0015] (3) Furthermore, in the substrate holding member of the present invention, the annular protrusion is characterized in that a recess is formed in the substrate toward the center in the planar direction, and the lift pin hole, which is located on the outside of the annular protrusion, is located on the outside of the recess.

[0016] Thus, by forming a concave portion in the annular convex portion and forming a lift pin hole in this portion, the outermost diameter of the annular convex portion can be arranged closer to the outer edge of the substrate. As a result, the flatness of the outer edge portion of the substrate can be ensured, and the lift pin hole can be arranged at a position where the influence of semiconductor element manufacturing is less likely to occur.

[0017] (4) Further, in the substrate holding member of the present invention, the lift pin hole disposed outside the annular convex portion is characterized in that a part of the outer edge of the lift pin hole overlaps with a position corresponding to the outermost diameter of the annular convex portion.

[0018] As a result, since the lift pin hole disposed outside the annular convex portion does not move too far away from the annular convex portion, when a concave portion is formed in the annular convex portion and the outermost diameter of the annular convex portion is arranged near the outer edge of the substrate, the range in which the concave portion is formed can be limited, and the concave portion can be arranged at a position where the influence of semiconductor element manufacturing is less likely to occur.

[0019] (5) Further, in the substrate holding member of the present invention, the lift pin hole is characterized in that its diameter is 5 mm or less. <​​​​​​​​​​​​​​​​​​​​ [Figure 3] It is a schematic diagram showing a modification of the arrangement of lift pin holes of the substrate holding member according to the first embodiment. [Figure 4] It is a schematic diagram showing a modification of the arrangement of lift pin holes of the substrate holding member according to the first embodiment. [Figure 5] It is a schematic diagram showing an example of the upper surface of the substrate holding member according to the second embodiment of the present invention. [Figure 6] It is a partial cross-sectional view showing an example of the substrate holding member according to the second embodiment. [Figure 7] (a) to (d) are schematic diagrams showing the positional relationship between the concave portion of the annular convex portion and the lift pin holes, respectively. [Embodiments for Carrying out the Invention]

[0023] Next, embodiments of the present invention will be described with reference to the drawings. For ease of understanding the description, the same reference numerals are assigned to the same components in each drawing, and duplicate descriptions are omitted. In the configuration diagrams, the sizes of the respective components are conceptually represented and do not necessarily represent actual dimensional ratios.

[0024] [First Embodiment] The substrate holding member according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic diagram showing an example of the upper surface of the substrate holding member according to the first embodiment of the present invention. Further, FIG. 2 is a partial cross-sectional view showing an example of the substrate holding member according to the first embodiment. The substrate holding member 100 according to the present embodiment includes a base 10 for adsorbing and holding a substrate (wafer) W, a plurality of pin-shaped convex portions 22, and an annular convex portion 24. The base 10 is formed in a substantially flat plate shape by a ceramic sintered body. The base 10 may have various shapes such as a substantially disc shape, a polygonal plate shape, or an elliptical plate shape in addition to the substantially disc shape. As the ceramics constituting the base 10, silicon carbide, aluminum oxide, silicon nitride, aluminum nitride, etc. can be used.

[0025] The base body 10 has one or more ventilation holes 14 opening to the upper surface 12. If there are multiple ventilation holes 14, they may communicate with each other via a ventilation path that passes through the inside of the base body 10. The ventilation holes 14 are connected to a vacuum suction device (not shown). Figure 1 shows an example in which one ventilation hole 14 is located around the center 16 of the base body, but is not limited to this, and the position, shape, and size of the ventilation holes 14 will vary depending on the design of the substrate holding member 100, such as the shape of the suction surface determined by the annular protrusion 24 described later, the shape and type of the substrate W, and the suction force when vacuum suction is applied.

[0026] The base body 10 has a plurality of lift pin holes 18 that open on the upper surface 12. Lift pins (not shown) are inserted through the lift pin holes 18, and the lift pins lift up the substrate W.

[0027] At least one of the lift pin holes 18 is positioned outside the annular protrusion 24, which will be described later. By positioning at least one of the lift pin holes 18 outside the annular protrusion 24 in this way, the number of lift pin holes 18 that may worsen the flatness of the substrate W near the center of the substrate W to be adsorbed can be reduced.

[0028] The outer periphery of the substrate W may contain areas where semiconductor elements are not formed, or where they are formed but not used, due to potential warping in the substrate W, warping caused by the semiconductor manufacturing process, or material removal allowances. Therefore, even if a region with degraded flatness due to the lift pin holes 18 appears in this part of the substrate W, the impact of the amount of semiconductor elements manufactured can be minimized.

[0029] Figure 1 shows an example where the lift pin holes 18 are positioned at the vertices of an equilateral triangle centered on the base body's center 16, and all are located outside the annular protrusion 24. The number, position, shape, and size of the lift pin holes 18 are not limited to this and vary depending on the design of the substrate holding member 100, including the shape of the suction surface determined by the annular protrusion 24 (described later), the shape and type of the substrate W, and the suction force when vacuum suction is applied. Furthermore, they must be positioned so as not to come into contact with the robot arm used for substrate transport. There may be a gap between the outer edge of the lift pin holes 18 located outside the annular protrusion 24 and the outer circumference of the annular protrusion 24. The presence of this gap facilitates the formation of the lift pin holes 18.

[0030] Figures 3 and 4 are schematic diagrams showing modified arrangements of the lift pin holes 18 of the substrate holding member according to this embodiment. In Figures 3 and 4, the ventilation holes 14 and pin-shaped protrusions 22 are omitted. Figure 3 shows an example in which the lift pin holes 18 are located at the vertices of an equilateral triangle centered on the center 16 of the base body, and four holes are located at the center 16 of the base body, with three of them located outside the annular protrusions 24. Figure 4 shows an example in which the lift pin holes 18 are located at the vertices of a rectangle, and all of them are located outside the annular protrusions 24.

[0031] As shown in the example in Figure 3, the effects of the present invention are achieved even when there are lift pin holes 18 located inside the annular protrusion 24. This is because, by moving even one of the lift pin holes 18 that were located inside the annular protrusion 24 to the outside of the annular protrusion 24, the position where the flatness of the substrate W may deteriorate due to that lift pin hole 18 can be moved to a position closer to the outer edge of the substrate W, thereby ensuring the flatness of the central region of the substrate W.

[0032] Preferably, all lift pin holes 18 are positioned on the outside of the annular protrusion 24. By positioning all lift pin holes 18 on the outside of the annular protrusion 24 in this way, the deterioration of flatness near the center of the substrate W caused by the lift pin holes 18 can be sufficiently reduced. Furthermore, since the lift pin holes 18 do not obstruct the suction channel during the adsorption of the substrate W, the substrate W can be adsorbed with high uniformity.

[0033] The lift pin hole 18 preferably has a diameter of 5 mm or less. By making the diameter of the lift pin hole 18 5 mm or less, the area of ​​points where flatness is degraded due to the lift pin hole 18 can be reduced, thereby reducing the influence of the amount of semiconductor device manufactured. The lower limit of the diameter of the lift pin hole 18 varies depending on the size of the lift pin, but can be, for example, 2.5 mm or more. Ribs may be formed around the lift pin hole 18.

[0034] Multiple pin-shaped protrusions 22 are formed, projecting upward from the upper surface 12 of the base body 10. Pin-shaped protrusions 22 may also be formed on the outside of the annular protrusion 24. The shape of the pin-shaped protrusions 22 can be appropriately selected from shapes such as cylindrical, prismatic, conical, pyramidal, or truncated cone or truncated pyramidal shapes with the upper part cut off. The shape of the pin-shaped protrusions 22 may have a stepped shape such that the cross-sectional area of ​​the upper part is smaller than that of the lower part.

[0035] Multiple pin-shaped protrusions 22 support the substrate W. The upper ends 22a of the multiple pin-shaped protrusions are formed substantially flush with the surface. That is, a plane (reference plane) 30 formed by the upper ends 22a of the multiple pin-shaped protrusions is determined. As a result, the upper ends 22a of the multiple pin-shaped protrusions come into contact with the substrate W, and the substrate W is supported. However, some of the multiple pin-shaped protrusions 22 may not have their upper ends (upper ends 22a of the pin-shaped protrusions) in contact with the substrate W. This is because even if such pin-shaped protrusions 22 are present, the substrate W can still be supported depending on the arrangement of the surrounding pin-shaped protrusions 22.

[0036] The upper end 22a of the pin-shaped protrusion may be located further from the upper surface 12 of the base body 10 than the upper end 24a of the annular protrusion, which will be described later. In other words, the height of the pin-shaped protrusion 22 may be greater than the height of the annular protrusion 24. This ensures that air flows in from outside the base body 10 at all times during the substrate W adsorption operation, allowing the Bernoulli effect to be exerted near the annular protrusion 24 and suppressing the sinking of the edges of the substrate W. In addition, the contact area with the substrate W can be reduced, reducing the risk of particle generation. Although the annular protrusion 24 is formed a certain amount lower than the upper end 22a of the pin-shaped protrusion, so that outside air is always introduced from the outer periphery during substrate adsorption, this is not a problem as long as the gap is small enough to obtain a sufficient vacuum for the adsorption of the substrate W through the generation of a pressure gradient.

[0037] On the other hand, the distance from the upper surface 12 of the base body 10 to the upper end 22a of the pin-shaped protrusion may be equal to the distance from the upper surface 12 of the base body 10 to the upper end 24a of the annular protrusion. In other words, the height of the pin-shaped protrusion 22 may be equal to the height of the annular protrusion 24. This allows the substrate W to be attracted with strong force.

[0038] The height of the pin-shaped projection 22 is preferably 50 μm or more and 200 μm or less. The height of the pin-shaped projection 22 refers to the distance from the upper surface 12 of the base body 10 to the upper end 22a of the pin-shaped projection. If the upper surface 12 of the base body 10 is not a single plane, the distance is measured using a hypothetical plane that passes through the point that is the furthest distance from the reference plane 30 to the upper surface 12 of the base body 10.

[0039] The upper end 22a of the pin-shaped protrusion is preferably a flat surface of a predetermined size. In this case, the maximum diameter of the flat surface at the upper end 22a of the pin-shaped protrusion is preferably 100 μm or more and 500 μm or less. Furthermore, the surface roughness of the flat surface at the upper end 22a of the pin-shaped protrusion is preferably Ra 0.01 μm or more and 0.50 μm or less.

[0040] The arrangement of the pin-shaped protrusions 22 is not limited to a triangular lattice as shown in Figure 1; it may also be a regular arrangement such as a square lattice or concentric circles, or an irregular arrangement where localized density occurs. Furthermore, the distance between adjacent pin-shaped protrusions 22 is preferably 1.5 mm or more and 8 mm or less between their centers.

[0041] The annular projection 24 protrudes upward from the upper surface 12 of the base body 10 and is formed in an annular shape along the outer circumference of the upper surface 12. For example, if the base body 10 is formed in a disc shape, it is preferable that the annular projection 24 is formed in a continuous annular shape when viewed from above, either along the outer circumference of the upper surface 12 of the base body 10 or at a position a predetermined width away from the outer circumference and closer to the center.

[0042] The upper end 24a of the annular protrusion may be closer to the upper surface 12 of the base 10 than the upper end 22a of the pin-shaped protrusion. In other words, the height of the annular protrusion 24 may be lower than the height of the pin-shaped protrusion 22. The height of the annular protrusion 24 refers to the distance from the upper surface 12 of the base 10 to the upper end 24a of the annular protrusion. When the height of the annular protrusion 24 is formed to be lower than the height of the pin-shaped protrusion 22, it is preferable that the height of the annular protrusion 24 is 1 μm or more and 5 μm or less lower than the height of the pin-shaped protrusion 22. For example, when the height of the pin-shaped protrusion 22 is 100 μm, it is preferable that the height of the annular protrusion 24 is 95 μm or more and 99 μm or less.

[0043] The width of the annular projection 24 is preferably 0.05 mm or more and 8 mm or less. Furthermore, the width of the annular projection 24 is preferably less than or equal to the distance between the centers of adjacent pin-shaped projections 22. The annular projection 24 may have various cross-sectional shapes, such as rectangular, trapezoidal, or hemispherical, but the upper end 24a of the annular projection is preferably formed as a flat surface. In that case, the surface roughness of the flat surface (upper end face) of the upper end 24a of the annular projection is preferably Ra 0.20 μm or less.

[0044] [Second Embodiment] A substrate holding member according to a second embodiment of the present invention will be described with reference to Figures 5 to 7. Figure 5 is a schematic diagram showing an example of the upper surface of a substrate holding member according to a second embodiment of the present invention. Figure 6 is a partial cross-sectional view showing an example of a substrate holding member according to a second embodiment. Figures 7(a) to 7(d) are schematic diagrams showing the positional relationship between the recess 26 of the annular protrusion 24 and the lift pin hole 18, respectively. The substrate holding member 200 according to this embodiment has the same basic configuration as the substrate holding member 100 according to the first embodiment, so only the differences will be described below.

[0045] In the substrate holding member 200 according to this embodiment, the annular projection 24 has a recess 26 (notch portion) formed toward the center 16 in the planar direction of the base body 10. The lift pin hole 18, which is located on the outside of the annular projection 24, is located on the outside of the recess 26.

[0046] In this way, by forming a recess 26 in the annular protrusion 24 and arranging the lift pin hole 18 in that portion, it becomes possible to position the outermost diameter of the annular protrusion 24 closer to the outer edge of the substrate W. This ensures the flatness of the outer edge of the substrate and allows the lift pin hole 18 to be positioned in a location where it is less susceptible to the effects of semiconductor device manufacturing.

[0047] Figures 7(a) to 7(d) show an example in which the lift pin hole 18, located on the outside of the annular projection 24, is located on the outside of the recess 26. A gap 28a may be present between the outer edge of the lift pin hole 18 located on the outside of the annular projection 24 and the outer circumference of the recess 26 of the annular projection 24. This facilitates the formation of the lift pin hole 18. Figures 7(a) to 7(d) all show examples in which the gap 28a is present.

[0048] Furthermore, as shown in Figure 7(d), there may be a gap 28b between the outer edge of the lift pin hole 18 located outside the annular protrusion 24 and a position corresponding to the outermost diameter of the annular protrusion 24, which will be described later. By forming the lift pin hole 18 at the position shown in Figure 7(d), the reliability of the lift-up can be improved when the outermost diameter of the annular protrusion 24 is positioned closer to the outer edge of the substrate W. If both gaps 28a and 28b are present, it is preferable that their values ​​be equal.

[0049] Furthermore, in the substrate holding member 200, it is preferable that the lift pin hole 18, which is located on the outside of the annular projection 24, is positioned such that a part of the outer edge of the lift pin hole 18 coincides with a position corresponding to the outermost diameter of the annular projection 24. This prevents the lift pin hole 18, which is located on the outside of the annular projection 24, from being too far from the annular projection 24. When a recess 26 is formed in the annular projection 24 and the outermost diameter of the annular projection 24 is positioned near the outer edge of the substrate W, the range in which the recess 26 is formed can be limited, and the recess 26 can be positioned in a location where it is less affected by semiconductor device manufacturing.

[0050] When a lift pin hole 18 located on the outside of the annular projection 24 is said to be located on the outside of the recess 26, and with a portion of the outer edge of the lift pin hole 18 corresponding to the outermost diameter of the annular projection 24, it means that the lift pin hole 18 is located within the range shown in the examples of Figures 7(a) to (c). When a recess 26 is formed on the annular projection 24 toward the center of the base 10 in the planar direction (center 16 of the base), the smallest distance between the outer edge of the base 10 and the outer circumference of the annular projection 24 is taken, and the annular line drawn inward from the outer edge of the base 10 by that distance is called the virtual outer circumference of the annular projection 24. Therefore, when a recess 26 is formed on the annular projection 24, the virtual outer circumference of the annular projection 24 lies outside the recess 26. The position corresponding to the outermost diameter of the annular projection 24 is on the virtual outer circumference of the annular projection 24. For example, if the base 10 is disc-shaped, the virtual outer circumference of the annular projection 24 is the circumference. Note that the shape of the recess 26 is not limited to the shapes shown in Figures 5 and 7.

[0051] The range of the recess distance in the planar direction of the recess 26 (the minimum distance between a point on the virtual outer circumference of the annular protrusion 24 and the point on the outer circumference of the recess 26 that is furthest inside the base 10) also depends on the diameter of the lift pin hole 18 formed on the outside of the recess 26, but is preferably in the range of greater than 0 mm and less than or equal to 10 mm. 0 mm is the case when no recess 26 is formed.

[0052] [Manufacturing method for substrate holding member] A flat molded body is prepared from raw material powder using a well-known method, and a flat ceramic sintered body is obtained by firing this molded body. Although a disc-shaped substrate holder is shown in Figure 1, any shape is acceptable, such as polygonal or elliptical. Silicon carbide, aluminum oxide, silicon nitride, aluminum nitride, etc., can be used as the ceramic sintered body.

[0053] Next, ventilation holes, lift pin holes, pin-shaped protrusions, annular protrusions, etc., are formed on the upper surface of the ceramic sintered body. These can be formed by blasting, milling, laser processing, etc. Alternatively, after forming multiple protrusions, the upper end surfaces of each protrusion may be polished.

[0054] Multiple pin-shaped protrusions are formed. The shape of the pin-shaped protrusions is appropriately selected from shapes such as cylindrical, prismatic, conical, pyramidal, truncated cone, truncated pyramidal cone, and truncated pyramidal cone with the upper part cut off. The shape of the pin-shaped protrusions may also have a stepped shape such that the cross-sectional area of ​​the upper part is smaller than that of the lower part.

[0055] The upper ends of the multiple pin-shaped protrusions are formed to be substantially flush with the surface. The pin-shaped protrusions are preferably designed according to the conditions of the substrate to be adsorbed, for example, with a protrusion amount of 50 μm to 200 μm, a diameter of the upper end surface of 100 μm to 500 μm, and a spacing between the pin-shaped protrusions of 1.5 mm to 8 mm.

[0056] The arrangement of the pin-shaped protrusions is not particularly limited. Any known or similar form is acceptable. For example, the arrangement may be regular, such as on a triangular lattice, a square lattice, or concentric circles, or it may be an irregular arrangement where localized density occurs.

[0057] The annular projection is formed in an annular shape along the outer circumference of the upper surface of the base. Depending on the design, such as the shape, size, and arrangement of the lift pin holes, a recess toward the center in the planar direction of the base may be formed in the annular projection. The amount of the annular projection protruding from the upper surface of the base is preferably determined according to the amount of the pin-shaped projection protruding from the upper surface of the base. For example, it may be formed to be 1 μm to 5 μm lower than the height of the pin-shaped projection. The width of the annular projection is preferably formed in the range of 0.05 mm to 8 mm.

[0058] Ventilation holes and lift pin holes are drilled in predetermined shapes, sizes, and locations according to the design of the substrate holding member. Lift pin holes are preferably 5 mm or less in diameter.

[0059] In this way, the substrate holding member of the present invention can be manufactured.

[0060] [Examples and Comparative Examples] (Example 1) The substrate holding member of Example 1 is a substrate holding member that has an annular projection formed with a recess that is directed toward the center in the planar direction of the substrate, as shown in Figure 5, and all lift pin holes are located outside the recess, and a part of the outer edge of the lift pin holes is positioned to coincide with a position corresponding to the outermost diameter of the annular projection. First, a roughly disc-shaped substrate with a diameter of φ200 mm and a thickness of t1.5 mm made of a sintered silicon carbide body was prepared, and ventilation holes, lift pin holes, a plurality of pin-shaped projections, and an annular projection were formed using known processing methods such as blasting.

[0061] A single ventilation hole with a diameter of φ3 mm was formed in the center of the base. Multiple pin-shaped protrusions were formed with a height of 150 μm and an upper end face diameter of φ300 μm, forming a triangular grid with a 3 mm spacing between the centers of each pin-shaped protrusion. An annular protrusion was formed to surround the ventilation hole and the multiple pin-shaped protrusions, with an outermost diameter of φ195 mm and a width of 200 μm, and was formed by additional processing to be 3 μm lower than the multiple pin-shaped protrusions. Three lift pin holes with a diameter of φ3 mm were formed at 120° intervals, with the distance between the center of the lift pin hole and the center of the base being 193.5 mm. As a result, the lift pin holes were formed so that the outer edge of the lift pin hole closest to the outer circumference of the base contacts the outermost diameter of the annular protrusion (circumference of φ195 mm). Furthermore, recesses were formed in the annular protrusion so that the lift pin holes are located on the outside of the annular protrusion. Specifically, the positional relationship between the recess of the annular projection and the lift pin hole was as shown in Figure 7(c). The recess was positioned and shaped to create a 2 mm gap between the outer edge of the lift pin hole and the outer circumference of the recess of the annular projection.

[0062] (Example 2) Example 2 is a substrate holding member, as shown in Figure 1, which has an annular projection and all lift pin holes are located on the outside of the annular projection. The outermost diameter of the annular projection is φ188 mm and the width is 200 μm, and it was formed by additional processing so that it is 3 μm lower than the other projections. Three lift pin holes are formed at 120° intervals with a diameter of φ3 mm, at a distance of 0.5 mm between the outer edge of the lift pin hole and the outermost diameter of the annular projection. A substrate holding member was manufactured that was the same as in Example 1 except for the above configuration.

[0063] (Example 3) Example 3 is a substrate holding member similar to that of Example 1, except that the diameter of the lift pin hole was changed to φ8 mm, the center was moved to a position where the distance between the center of the lift pin hole and the center of the base was 191 mm, and the recess of the annular protrusion was formed further inward on the substrate holding member according to the diameter of the lift pin hole. In other words, in Example 3 as well, the positional relationship between the recess of the annular protrusion and the lift pin hole was as shown in Figure 7(c). The recess was positioned and shaped so that there was a 2 mm gap between the outer edge of the lift pin hole and the outer circumference of the recess of the annular protrusion.

[0064] (Example 4) Example 4 is a substrate holding member similar to that of Example 1, except that the annular protrusion is made to be the same height as the multiple pin-shaped protrusions.

[0065] (Comparative Example 1) Comparative Example 1 is a substrate holding member similar to Example 2, except that the outermost diameter of the annular protrusion is formed at φ195 mm, the lift pin holes are located inside the annular protrusion, and three lift pin holes are formed at φ7 mm intervals of 120°, with a distance of 50 mm between the center of the lift pin hole and the center of the base.

[0066] (Evaluation method) A φ195mm silicon wafer was adsorbed onto the fabricated substrate holder, and the flatness of the substrate was confirmed using a non-contact laser interferometer. The PV value was measured for an arbitrary 20mm square region of the held wafer.

[0067] (Evaluation results) In Comparative Example 1, the maximum PV value in the region including the lift pin hole was 0.25 μm. Since such a region with poor flatness occurs near the center of the substrate, when semiconductor devices are manufactured using the substrate holding member of Comparative Example 1, the semiconductor devices formed in that region of the substrate are likely to be defective, resulting in a low yield.

[0068] In Examples 1 to 4, the maximum PV values ​​in the region including the lift pin hole locations were 0.1 μm, 0.1 μm, 0.3 μm, and 0.1 μm, respectively. In each of the examples, the region with the maximum PV value is the location where the lift pin hole is formed, and since it occurs close to the outer edge of the substrate, when manufacturing semiconductor devices by holding the substrate with the substrate holding members of Examples 1 to 4, it is easy to make that region of the substrate a region where no semiconductor device is formed, thus reducing the impact of production volume and other factors in semiconductor device manufacturing. Therefore, the risk of defective products being manufactured can be reduced, and it is considered that the yield will be improved compared to Comparative Example 1.

[0069] In Example 1, the maximum PV value in the outer peripheral region, excluding the area containing the lift pin holes, was better compared to Example 2. This is thought to be because, in Example 1, a recess was formed in the annular protrusion, and the lift pin holes were placed outside of it, allowing the annular protrusion to be formed closer to the outermost edge of the substrate. From this, it was found that it is preferable for the annular protrusion to be formed near the outermost edge of the substrate, and it is even more preferable for the lift pin holes to be placed outside the annular protrusion where the recess is formed.

[0070] Furthermore, in Example 1, the maximum PV value in the region including the lift pin hole on the outer periphery was better compared to Example 3 and Comparative Example 1. This is thought to be because the diameter of the lift pin hole was reduced to 3 mm in Example 1, compared to 8 mm in Example 3 and 7 mm in Comparative Example 1. From this, it was found that a smaller diameter for the lift pin hole is preferable, for example, φ5 mm or less is preferable.

[0071] Examples 1 and 4, which differ only in the height of the annular protrusion, yielded similarly good results. This demonstrates that the effects of the present invention can be achieved with both Bernoulli-type substrate holders and conventional substrate holders.

[0072] Based on the above, it has been confirmed that the substrate holding member of the present invention can reduce the number of lift pin holes, which may worsen the flatness of the substrate at a position close to the center of the substrate being held.

[0073] The present invention is not limited to the embodiments described above, and it goes without saying that it extends to various modifications and equivalents that fall within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc., of the components shown in each drawing are for illustrative purposes only and may be modified as appropriate. [Explanation of Symbols]

[0074] 10 Base 12 Top side 14 Ventilation holes 16 Center of the substrate 18 lift pin holes 22 Pin-shaped protrusion 22a Upper end of pin-shaped protrusion 24 Annular protrusion 24a Upper end of the annular protrusion 26 recesses 28a, 28b gap 30 Reference plane 100, 200 substrate holding member W board

Claims

1. A substrate holding member that adsorbs a substrate by vacuum suction, A flat plate-shaped base having one or more ventilation holes and multiple lift pin holes opening on its upper surface, Multiple pin-shaped protrusions are formed projecting upward from the upper surface of the base, The substrate comprises an annular projection that protrudes upward from the upper surface of the substrate and is formed in an annular shape along the outer circumference of the outer surface of the upper surface, having an outer diameter smaller than the outer diameter of the substrate, Of the plurality of lift pin holes, at least one lift pin hole is located on the outside of the annular protrusion. A substrate holding member characterized in that the at least one lift pin hole located on the outside of the annular protrusion is a hole for attaching and detaching the substrate from the base body.

2. The substrate holding member according to claim 1, characterized in that all of the lift pin holes are located on the outside of the annular protrusion.

3. The annular protrusion has a recess formed toward the center in the planar direction of the base body. The substrate holding member according to claim 1 or 2, characterized in that the lift pin hole, which is located on the outside of the annular protrusion, is located on the outside of the recess.

4. The substrate holding member according to claim 3, characterized in that the lift pin hole, which is located on the outside of the annular projection, is positioned such that a part of the outer edge of the lift pin hole coincides with a position corresponding to the outermost diameter of the annular projection.

5. The substrate holding member according to any one of claims 1 to 4, characterized in that the lift pin hole has a diameter of 5 mm or less.

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