JP2020177952A - Substrate holding member - Google Patents

Abstract

To provide a substrate holding member capable of avoiding false recognition of a negative pressure state in the vacuum suction of a substrate, while achieving a reduction in a contact area between multiple projecting portions and the substrate, a suppression in generation of particles, and an improvement in substrate flatness.SOLUTION: Each of a plurality of projecting portions 10 projecting from a first main surface 101 of a substrate 1 includes: first projecting elements 111, 121; and second projecting elements 112, 122 projecting from end surfaces 1110, 1210 of the respective first projecting elements 111, 121, respectively, the second projecting elements having respective end surfaces 1120, 1220 with a smaller area than the end surfaces. Some projecting portions of the plurality of projecting portions 10 are formed as a second projecting portion 12 that is an expanded projecting portion where the volume of the first projecting element is larger than that of each of first projecting portions 11 that are other projecting portions.SELECTED DRAWING: Figure 3

Description

The present invention relates to a substrate holding member used for vacuum suction holding a substrate such as a semiconductor wafer.

In a semiconductor manufacturing process or the like, a substrate holding member that has a large number of protrusions (pins) on the surface of a substrate to hold the substrate and holds the substrate by vacuum exhausting the space between the back surface of the substrate and the surface of the substrate. Are known.
The convex portion formed on the surface of the substrate is a portion that comes into direct contact with the substrate, and if particles intervene between the convex portion and the substrate, local swelling occurs on the substrate and the surface accuracy of the substrate is improved. It causes deterioration and occurrence of defocus error. In recent years, semiconductors have become finer and higher in density, and deterioration of the surface accuracy of the substrate directly affects the decrease in yield, so that high accuracy is required for the surface accuracy of the substrate.
Therefore, as a measure to minimize the generation of particles caused by the contact between the substrate and the substrate, the contact area between the convex portion and the substrate is reduced by reducing the number of convex portions or designing the tapered convex portion. It is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 10-242255

However, excessive reduction in the diameter of the convex portion reduces the strength of the convex portion, which may induce particle generation due to damage to the tip portion of the convex portion. Further, the volume of the space defined by the substrate holding member and the substrate mounted on the substrate holding member increases by the amount of the decrease in the number of the convex portions and the reduction in the diameter of the convex portions. Therefore, the expression of the negative pressure state in the space may be delayed, and it may be determined that an abnormality has occurred in the vacuum expression state in the space, and the operation of the vacuum suction device may be stopped.

Therefore, the present invention provides a substrate holding member capable of avoiding erroneous recognition of a vacuum development state during vacuum suction of a substrate while reducing the contact area between a plurality of convex portions and the substrate and suppressing the generation of particles. The purpose is to provide.

The substrate holding member of the present invention includes a substrate, a plurality of convex portions protruding from the main surface of the substrate, at least one ventilation path that passes through the inside of the substrate and has an opening in the main surface of the substrate, and the above-mentioned A substrate holding member including the plurality of convex portions and an annular convex portion surrounding the opening of the ventilation path, which protrudes from the main surface of the substrate, and each of the plurality of convex portions is from the main surface of the substrate. A first convex element that protrudes and a second convex element that protrudes from the end face of the first convex element and has an end face having a smaller area than the end face of the first convex element. A part of the convex portion is formed as an enlarged convex portion having a larger volume of the first convex element than the other convex portion.

According to the substrate holding member having this configuration, the substrate is placed on the main surface side of the substrate holding member, and the space defined by the main surface of the substrate and the back surface of the substrate is vacuum sucked through the ventilation path to create a negative pressure region. By being formed, the substrate is held by the substrate holding member in a state where the back surface of the substrate is in contact with each end surface of the plurality of convex portions. A first convex element in which each convex portion protrudes from the main surface of the substrate, and a second convex element that protrudes from the end surface of the first convex element and has an end surface having a smaller area than the end surface of the first convex element. , Consists of. Therefore, the strength of each convex portion is improved while reducing the contact area between the substrate and each convex portion.

A part of the convex portions among the plurality of convex portions is selectively formed as an enlarged convex portion, that is, a convex portion having a larger volume of the first convex element as compared with the other convex portions. Therefore, while reducing the number of a plurality of convex portions in order to further reduce the contact area between the convex portions and the substrate, the increase in the volume of the space defined by the main surface of the substrate and the back surface of the substrate is suppressed. Alternatively, it is avoided, and the situation where it is erroneously recognized that an abnormality has occurred in the vacuum expression state of the space is avoided.

In the substrate holding member of the present invention, it is preferable that one or more of the enlarged convex portions are formed around the opening of the ventilation path on the main surface of the substrate. Here, the periphery of the opening of the ventilation path means, for example, a region within 4 mm from the opening edge of the opening.

According to the substrate holding member having this configuration, a plurality of enlarged convex portions arranged around the opening of the ventilation path, particularly the first convex element constituting the enlarged convex portion, causes the main surface of the substrate and the back surface of the substrate to be formed. In the space defined by, the fluid resistance in at least one directional range around the opening of the ventilation path is increased. Therefore, at the time of vacuum suction in the space, especially in the initial stage, it is possible to avoid a situation in which it is erroneously recognized that an abnormality has occurred in the vacuum expression state due to the insufficient fluid resistance in the space.

In the substrate holding member of the present invention, it is preferable that the plurality of enlarged convex portions are formed on the main surface of the substrate so as to surround the opening of the ventilation path.

According to the substrate holding member having the configuration, the main surface of the substrate and the back surface of the substrate are formed by a plurality of enlarged convex portions arranged so as to surround the opening of the ventilation path, particularly the first convex element constituting the enlarged convex portion. In the space defined by the above, the fluid resistance in a plurality of directional ranges around the opening of the ventilation path is increased. Therefore, at the time of vacuum suction in the space, especially in the initial stage, a situation in which it is erroneously recognized that an abnormality has occurred in the vacuum expression state due to the insufficient fluid resistance in the space can be more reliably avoided.

The substrate holding member of the present invention further includes an outer annular convex portion extending from the main surface of the substrate so as to surround the plurality of protrusions and the opening of the ventilation path and projecting from the main surface of the substrate. On the main surface of the substrate, the enlarged convex portion protrudes from the main surface of the substrate, and the first convex element as an inner annular convex portion that surrounds the opening of the ventilation path inside the outer annular convex portion and the first convex element. It is preferable to have a plurality of second convex elements protruding from the end surface of the first convex element.

According to the substrate holding member having this configuration, the substrate is provided with a plurality of enlarged convex portions arranged around the opening of the ventilation path, particularly an inner annular convex portion as a first convex element shared by the plurality of enlarged convex portions. In the space defined by the main surface and the back surface of the substrate, the fluid resistance in the omnidirectional range around the opening of the ventilation path is increased. Therefore, at the time of vacuum suction in the space, especially in the initial stage, a situation in which it is erroneously recognized that an abnormality has occurred in the vacuum expression state due to the insufficient fluid resistance in the space can be more reliably avoided.

Top view of the substrate holding member as one embodiment of the present invention. The vertical sectional view of the substrate holding member along the line II-II of FIG. Explanatory drawing about composition of enlarged convex part and other convex part. Explanatory drawing about arrangement mode of the enlarged convex part with respect to the opening of a ventilation path. Explanatory drawing about the deformation example of the enlarged convex part.

(First Embodiment)

(Constitution)
The substrate holding member as an embodiment of the present invention shown in FIGS. 1 and 2 includes a substrate 1, a plurality of convex portions 10 protruding from the first main surface 101 of the substrate 1, and the inside of the substrate 1. A ventilation path 2 having an opening 20 on the first main surface of the substrate 1, a plurality of convex portions 10 protruding from the first main surface 101 of the substrate 1, and an outer annular convex portion surrounding the opening 20 of the ventilation path 2. It is equipped with 14.

The substrate 1 is made of a substantially disk-shaped ceramic sintered body such as SiC, AlN or Al ₂ O ₃ . Each of the plurality of convex portions 10, the outer annular convex portion 14, and the ventilation path 2 is formed by grinding, blasting, milling, laser processing, or a combination thereof. Each of the first main surface 101 and the second main surface 102 of the substrate 1 is formed in a substantially planar shape.

Each of the plurality of convex portions 10 has a shape in which a small-diameter cylinder is concentrically overlapped on a large-diameter cylinder. The plurality of convex portions 10 are arranged so as to form lattice points of a lattice such as a triangular lattice or a square lattice on the first main surface 101 of the substrate 1, and are arranged along each of the plurality of concentric circles, or It may be arranged regularly, such as being arranged regularly along each of a plurality of radiations extending from the center, or may be arranged irregularly. Of the plurality of convex portions 10, the arrangement mode or regularity of the convex portions 10 (for example, the plurality of convex portions 10 arranged close to the periphery of the opening 20 of the ventilation path 2) constituting one convex portion group. And the arrangement mode or rule of the convex portion 10 constituting another convex portion group different from the one group (for example, a plurality of convex portions 10 arranged apart from the periphery of the opening 20 of the ventilation path 2). Gender may be different.

Each of the plurality of convex portions 10 is divided into a first convex portion 11 and a second convex portion 12 (see FIG. 3). The first convex portion 11 protrudes from the substantially columnar first convex element 111 protruding from the first main surface 101 of the substrate 1 and the end surface 1110 of the first convex element 111, and the end surface 1110 of the first convex element 111. It includes a substantially columnar second convex element 112 having a smaller area end face 1120. The second convex portion 12 protrudes from the substantially columnar first convex element 121 protruding from the first main surface 101 of the substrate 1 and the end surface 1210 of the first convex element 121, and the end surface 1210 of the first convex element 121. It includes a substantially columnar second convex element 122 having a smaller area end face 1220.

The height H111 of the first convex element 111 of the first convex portion 11 and the height H112 of the second convex element 112, and the height H121 and the second convex element 122 of the first convex element 121 of the second convex portion 12, respectively. Are equal to each of the heights H122 of. That is, the height H11 of the first convex portion 11 (the amount of protrusion from the first main surface 101) and the height H12 of the second convex portion 12 are equal.

The diameter W112 of the second convex element 112 of the first convex portion 11 and the diameter W122 of the second convex element 122 of the second convex portion 12 are equal. On the other hand, the diameter W111 of the first convex element 111 of the first convex portion 11 is smaller than the diameter W121 of the first convex element 121 of the second convex portion 12. As a result, the volume of the first convex element 121 of the second convex portion 12 as the enlarged convex portion (= π (W121) ² × (H121)) becomes the first convex of the first convex portion 11 as the other convex portion. It is larger than the volume of element 111 (= π (W111) ² × (H111)).

In addition to the relationship of "W111 <W121 and H111 = H121", "W111 = W121 and H111 <H121", "W111 <W121 and H111 <H121", "W111 <W121 and H111> H121" or "W111> W121 and H111" According to the relationship <H121 ", the volume of the first convex element 121 of the second convex portion 12 may be larger than the volume of the first convex element 111 of the first convex portion 11.

In each of the first convex portion 11 and the second convex portion 12, it seems that a small diameter cylinder (second convex elements 112, 122) is concentrically superposed on a large diameter cylinder (first convex elements 111, 121). It may have various shapes such as a cylinder, a prism, a truncated cone, and another shape in which a truncated cone is arbitrarily combined and stacked. The upper end surface of the first convex element 111 of the first convex portion 11 and the lower end surface of the substantially frustum-shaped second convex element 112 are the same, and the continuous portion of the first convex element 111 and the second convex element 112. The first convex portion 11 does not have to have a step. The upper end surface of the first convex element 121 of the second convex portion 12 and the lower end surface of the second convex element 122 having a substantially frustum shape are the same, and the continuous portion of the first convex element 121 and the second convex element 122. The second convex portion 12 does not have to have a step.

As shown in FIG. 4, a plurality (for example, 6 pieces) included in the substantially circular first region S1 extending with reference to the opening 20 of the ventilation path 2 on the first main surface 101 of the substrate 1. At least one of the convex portions 10 is formed as the second convex portion 12. On the first main surface 101 of the substrate 1, a plurality of (18) convex portions included in the second region S2 having a diameter larger than that of the first region S1 extending with reference to the opening 20 of the ventilation path 2. At least one of 10 may be formed as the second convex portion 12.

In the vertical cross-sectional view of the substrate holding member, the outer annular convex portion 14 has a substantially rectangular shape, a substantially trapezoidal shape, a semi-elliptical shape, a semicircular shape, or a rectangular shape and a semicircular shape having one side of the rectangular shape as a diameter. It may have various shapes such as a combined shape. The outer annular convex portion 14 may be omitted. The height position of the upper end surface 140 of the outer annular convex portion 14 with respect to the first main surface 101 of the substrate 1 (the amount of protrusion from the first main surface 101) is the upper end surface 1120 and the second of the first convex portion 11. It is designed to be lower or the same as the height position of the upper end surface 1220 of the convex portion 12.

The substrate 1 has an opening 20 of one ventilation path 2 arranged in the center and an opening 20 of six ventilation paths 2 arranged so as to have six-fold symmetry with respect to the center on the outside thereof. And are formed. The ventilation path 20 is composed of substantially columnar holes penetrating the substrate 1 from the first main surface 101 to the second main surface 102 of the substrate 1. The number, arrangement, and extension of the ventilation paths 2 may be arbitrarily redesigned. For example, the ventilation path 2 may be arranged so as to have mirror image symmetry with respect to a plane perpendicular to the first main surface 101 of the substrate 1, and is asymmetric so as not to have rotational symmetry or mirror image symmetry. May be placed in.

In the drawings, the substrate holding members are schematically shown, and the aspect ratio, spacing, number, and the like of the components of the substrate holding member are in principle different from the actual design values. This is the same in all embodiments.

(function)
According to the substrate holding member as one embodiment of the present invention, the substrate W is placed on the side of the first main surface 101 of the substrate holding member, and is defined by the first main surface 101 of the substrate 1 and the back surface of the substrate W. The space to be formed is vacuum-sucked through the ventilation path 2 to form a negative pressure region, so that the substrate W is held by the substrate holding member in a state where the back surface of the substrate W is in contact with each end surface of the plurality of convex portions 10. (See FIGS. 1 and 2). The first convex portion 11 protrudes from the first convex element 111 protruding from the first main surface 101 of the substrate 1 and the end surface 1110 of the first convex element 111, and has a smaller area than the end surface 1110 of the first convex element 111. It is composed of a second convex element 112 having an end face 1120 (see FIG. 3). The second convex portion 12 protrudes from the first convex element 121 projecting from the first main surface 101 of the substrate 1 and the end surface 1210 of the first convex element 121, and has a smaller area than the end surface 1210 of the first convex element 121. It is composed of a second convex element 122 having an end face 1220 (see FIG. 3). Therefore, the strength of the convex portions 11 and 12 is improved while reducing the contact area between the substrate W and the convex portions 11 and 12. The substrate W can be uniformly brought into contact with the upper end surface of the convex portion 10, and the flatness of the substrate W when it is attracted and held by the substrate holding member can be improved. Then, on the surface (upper surface) of the substrate W, a predetermined process such as an exposure process for forming a circuit of a desired pattern can be performed.

The volume of the first convex element 121 of the second convex portion 12 (enlarged convex portion) which is a partial convex portion of the plurality of convex portions 10 is the volume of the first convex element of the first convex portion 11 which is another convex portion. It is larger than the volume of 111. Therefore, while reducing the number of the plurality of convex portions 10 in order to further reduce the contact area between the convex portions 10 and the substrate W, the first main surface 101 of the substrate 1 and the back surface of the substrate W are defined. The increase in the volume of the space is suppressed or avoided, and the situation in which it is erroneously recognized that an abnormality has occurred in the vacuum development state of the space is avoided. In particular, a plurality of second convex portions 12 (see FIG. 4) arranged around the opening 20 of the ventilation path 2, particularly the first convex element 121 constituting the second convex portion 12, causes the first of the substrate 1. In the space defined by the main surface 101 and the back surface of the substrate W, the fluid resistance in one or more directional ranges around the opening 20 of the ventilation path 2 is increased. Therefore, at the time of vacuum suction in the space, especially in the initial stage, it is possible to avoid a situation in which it is erroneously recognized that an abnormality has occurred in the vacuum expression state due to the insufficient fluid resistance in the space.

(Example)

(Example 1)
As the substrate 1, a substrate made of a substantially disk-shaped silicon carbide sintered body having a diameter of φ300 mm and a thickness of 5 mm was prepared. On the first main surface 101 of the substrate 1, 19900 convex portions 10 are arranged in a triangular lattice pattern with an interval of 2.0 mm so as to have a uniform density over the entire first main surface 101 of the substrate 1. The first convex portion 11 is formed on a substantially cylindrical first convex element 111 having a diameter of φ0.5 mm and a height of 0.25 mm, and a substantially cylindrical second convex element having a diameter of φ0.2 mm and a height of 0.05 mm. It was formed in a stepped columnar shape in which 112 were concentrically stacked. The second convex portion 12 is a substantially cylindrical second convex element 121 having a diameter of φ0.2 mm and a height of 0.05 mm on a substantially cylindrical first convex element 121 having a diameter of φ1.0 mm and a height of 0.25 mm. The 122 was formed in a stepped columnar shape as if they were concentrically stacked.

On the first main surface 101 of the substrate 1, an outer annular convex portion 14 having an inner diameter of φ299 mm, a width of 0.5 mm, and a height of 0.3 mm was formed so as to surround the plurality of convex portions 10. On the first main surface 101 of the substrate 1, 18 ventilation paths having a diameter of φ1.0 mm arranged so as to have 6-fold symmetry with respect to the center along each of three annular rings having different distances from the center. The opening 20 of 2 was formed. Here, six pieces (see FIG. 4) included in a substantially circular first region S1 (see FIG. 4) with reference to the opening 20 of each ventilation path 2 and arranged concentrically so as to surround the opening 20 (see FIG. 4). Only the convex portions 10 (108 in total) were formed as the second convex portions 12.
As a result, the substrate holding device of Example 1 was manufactured. In this case, the contact area ratio, which is the ratio of the area of the upper end surfaces of the plurality of convex portions 10 to the area of the back surface of the disk-shaped substrate W having a diameter of φ300 mm, was 0.90%. By operating the vacuum pump and vacuum-sucking the space between the first main surface 101 of the substrate holding member and the substrate W, the substrate W is a high flat surface without damaging the tips of the plurality of convex portions 10. It was adsorbed and held by the substrate holding member. Even if 0.3 seconds have passed from the start of operation of the vacuum pump, it is detected that an abnormality has occurred in the vacuum development state when the pressure is higher than -50 kPa, but in Example 1, an abnormality is detected during vacuum suction. It never happened.

(Example 2)
6 on three concentric circles that are included in the substantially circular second region S2 (see FIG. 4) with respect to the opening 20 of each ventilation path 2 and have different distances from the center so as to surround the opening 20. Only 18 convex portions 10 (324 in total) arranged one by one were formed as the second convex portions 12. Of the 18 second convex portions 12 arranged so as to surround the opening 20 of each suction path 2, 6 arranged on the circle closest to the opening 20 (included in the first region S1). The second convex portion 12 has a substantially cylindrical second convex element 121 having a diameter of φ0.2 mm and a height of 0.05 mm on the first convex element 121 having a diameter of φ1.0 mm and a height of 0.25 mm. The convex elements 122 were formed in a stepped columnar shape as if they were concentrically stacked. The six second convex portions 12 arranged on the circle second closest to the opening 20 have a diameter on the substantially cylindrical first convex element 121 having a diameter of 0.9 mm and a height of 0.25 mm. A substantially cylindrical second convex element 122 having a diameter of 0.2 mm and a height of 0.05 mm was formed into a stepped columnar shape as if they were concentrically overlapped. The six second convex portions 12 arranged on the circle farthest from the opening 20 have a diameter of φ0. On a substantially cylindrical first convex element 121 having a diameter of φ0.8 mm and a height of 0.25 mm. A substantially cylindrical second convex element 122 having a height of 2 mm and a height of 0.05 mm was formed into a stepped columnar shape as if they were concentrically overlapped.

Other than that, the substrate holding member 2 of Example 2 was produced under the same conditions as in Example 1. Similar to the first embodiment, the vacuum pump is operated and the space between the first main surface 101 of the substrate holding member and the substrate W is vacuum-sucked, so that the tips of the plurality of convex portions 10 are damaged. The substrate W was attracted and held by the substrate holding member with high flatness. Moreover, in Example 2, no abnormality was detected during vacuum suction.

(Comparison example)
Regardless of the first convex portion 11 and the second convex portion 12, all the convex portions 10 have a diameter of φ0.2 mm on the substantially cylindrical first convex element 111 having a diameter of φ0.5 mm and a height of 0.25 mm. The second convex element 112 having a height of 0.05 mm and having a substantially cylindrical shape was formed into a stepped columnar shape in which the second convex elements 112 were concentrically overlapped. Other than that, the substrate holding member 2 of Comparative Example 1 was produced under the same conditions as in Example 1. When the vacuum pump is operated and the space between the first main surface 101 of the substrate holding member and the substrate W is evacuated, an abnormality presumed to be caused by a delay in the formation of negative pressure is detected, and the vacuum pump is operated. Was stopped.

(Other Embodiments of the present invention)
As shown in FIG. 5, it protrudes from the first main surface 101 of the base 1 and surrounds the opening 20 of the ventilation path 2 inside the outer annular convex portion 14 on the first main surface 101 of the base 1. An extending inner annular convex portion 120 is formed, and a plurality of enlarged convex portions projecting from a first convex element which is the inner annular convex portion 120 and an end surface of the inner annular convex portion 120 (first convex element). The second convex element 122 of the above may be provided.

According to the substrate holding member having the above configuration, the space defined by the first main surface 101 of the substrate 1 and the back surface of the substrate W by the inner annular convex portion 120 arranged around the opening 20 of the ventilation path 2. Among them, the fluid resistance in the omnidirectional range around the opening 20 of the ventilation path 2 is increased. Therefore, at the time of vacuum suction in the space, especially in the initial stage, a situation in which it is erroneously recognized that an abnormality has occurred in the vacuum expression state due to the insufficient fluid resistance in the space can be more reliably avoided.

1 ... Base, 2 ... Ventilation path, 10 ... Convex part, 11 ... 1st convex part, 12 ... 2nd convex part (enlarged convex part), 14 ... Outer annular convex part, 20 ... Ventilation path opening, 101 ... 1st main surface (upper surface), 102 ... 2nd main surface (lower surface), 111 ... 1st convex element of 1st convex part, 112 ... 2nd convex element of 1st convex part, 120 ... inner annular convex part, 121 First convex element of the second convex part, 122 Second convex element of the second convex part 1200 End face of the inner annular convex part 1110 End face of the first convex element of the first convex part 1120 First The end face of the second convex element of the convex portion, 1210 ... the end face of the first convex element of the second convex portion, 1220 ... the end face of the second convex element of the second convex portion, W ... substrate (wafer).

Claims (4)

With the base
A plurality of convex portions protruding from the main surface of the substrate,
At least one ventilation path that passes through the interior of the substrate and has an opening on the main surface of the substrate.
A substrate holding member comprising a plurality of protrusions protruding from the main surface of the substrate and an annular protrusion surrounding the opening of the ventilation path.
Each of the plurality of convex portions has a first convex element projecting from the main surface of the substrate and an end surface having a smaller area than the end surface of the first convex element projecting from the end surface of the first convex element. With a second convex element,
A substrate holding member, characterized in that some of the plurality of convex portions are formed as enlarged convex portions having a larger volume of the first convex element than the other convex portions. In the substrate holding member according to claim 1,
A substrate holding member characterized in that one or a plurality of the enlarged convex portions are formed on the main surface of the substrate around the opening of the ventilation path. In the substrate holding member according to claim 2,
A substrate holding member characterized in that, on the main surface of the substrate, the plurality of enlarged convex portions are formed so as to surround the opening of the ventilation path. In the substrate holding member according to claim 3,
An outer annular convex portion extending on the main surface of the substrate so as to surround the plurality of protrusions and an opening of the ventilation path and projecting from the main surface of the substrate is further provided.
On the main surface of the substrate, the enlarged convex portion protrudes from the main surface of the substrate, and the first convex element as an inner annular convex portion that surrounds the opening of the ventilation path inside the outer annular convex portion and the first convex element. A substrate holding member having a plurality of second convex elements protruding from the end faces of the first convex element.

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