Processing table of semiconductor device

Abstract

To provide a processing table for a semiconductor device which improves a quality of processing or the like when a substrate having a semiconductor element is warped.SOLUTION: A processing table 1 for a semiconductor device is a processing table for a semiconductor device on which a substrate 50 having semiconductor elements 55 is mounted and processed. The processing table includes: a base 10; a sheet-like elastic member 20 which is an elastic body and is disposed on the base 10; and a sheet-like covering member 30 which covers the elastic member 20 and has a lower friction than the elastic member 20. An upper surface of the covering member 30 is in contact with an entire lower surface of the substrate 50, and a lower surface of the covering member 30 is in contact with an entire surface of the elastic member 20.SELECTED DRAWING: Figure 2C

Description

[Technical Field]

[0001] The present invention relates to a processing table for semiconductor devices. [Background technology]

[0002] Semiconductor devices come in various forms, such as substrates on which semiconductor elements or semiconductor packages are mounted, and modules having multiple substrates, and processing and measurement in the manufacturing process are also performed in various forms. Therefore, a processing table on which work-in-progress products are placed during manufacturing is required to be able to accommodate the shape and characteristics of the work-in-progress products so that the desired processing and measurement can be performed stably. For example, Patent Document 1 describes a contact sheet that is disposed between a semiconductor package and a testing circuit board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-101410 Summary of the Invention [Problem to be solved by the invention]

[0004] The contact sheet in Patent Document 1 has a three-layer insulating sheet with protective films laminated on both sides of a rubber elastic layer, through which a conductive rubber elastic material penetrates, and both the insulating sheet and the rubber elastic material deform to accommodate variations in the flatness of the terminals of the semiconductor package. However, further consideration is required to process and measure a larger surface, for example, to accommodate warpage of a substrate having multiple semiconductor elements. The present invention has been made to solve the above problems, and aims to provide a processing table for semiconductor devices that improves the quality of processing when a substrate having semiconductor elements thereon is warped. [Means for solving the problem]

[0005] In order to solve such problems, the processing table for a semiconductor device according to the present invention is a processing table for a semiconductor device on which a substrate having a semiconductor element is placed and processed, and comprises a base, a sheet-like elastic member that is an elastic body and is placed on the base, and a sheet-like covering member that covers the elastic member and has lower friction than the elastic member. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a processing table for a semiconductor device that improves the quality of processing when a substrate having a semiconductor element thereon is warped. [Brief explanation of the drawings]

[0007] [Figure 1A] 1 is a perspective view illustrating an outline of a processing table for a semiconductor device according to an embodiment; [Figure 1B] 1 is a perspective view illustrating an outline of a state in which a substrate is placed on a processing table of a semiconductor device according to an embodiment; [Figure 2A] FIG. 1 is a cross-sectional view illustrating an outline of a warped substrate. [Figure 2B] FIG. 1B is a cross-sectional view taken along line IIB-IIB in FIG. 1A. [Figure 2C] FIG. 1C is a cross-sectional view taken along line IIC-IIC in FIG. 1B. [Figure 3A] 1 is a cross-sectional view illustrating an outline of a state in which ultrasonic waves and a load are applied in wire bonding; [Figure 3B] FIG. 10 is a cross-sectional view illustrating an outline of a state after wire bonding. [Figure 4A] 3 is an enlarged cross-sectional view illustrating an outline of the tip of the tool part and the wire as viewed from the extending direction of the wire. FIG. [Figure 4B] 3 is an enlarged cross-sectional view illustrating an outline of the tip of the tool part and the wire as viewed from the extending direction of the wire. FIG. [Figure 4C] FIG. 10 is an enlarged plan view illustrating an outline of the wire after bonding. [Figure 5] 10 is a graph illustrating an example of the variation in the relative value of the crushed width. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments and examples. In addition, in the drawings, some components may be omitted, and the size, shape, and positional relationship of each component may be exaggerated.

[0009] [Semiconductor device processing table] A processing table (hereinafter referred to as processing table) 1 for a semiconductor device according to an embodiment will be described with reference to Figures 1A to 2C. The processing table 1 is a table on which a substrate having semiconductor elements is placed when processing, measuring, etc., the substrate. As illustrated in Figures 1A and 1B, a substrate 50 is placed on the upper surface of the processing table 1. 2A, it is assumed that the substrate 50 has warpage. The height difference G1 that occurs on the underside of the substrate 50 due to the warpage of the substrate 50 is the height difference on the underside of the conductive pattern 52B, which is the underside of the substrate 50. The warpage may be curved not only downwardly convex as shown in FIG. 2A, but also upwardly convex.

[0010] The processing table 1 is a processing table for a semiconductor device on which a substrate 50 having a semiconductor element 55 is placed and processed, and includes a base 10, a sheet-like elastic member 20 that is an elastic body and is placed on the base 10, and a sheet-like covering member 30 that covers the elastic member 20 and has lower friction than the elastic member 20. Each component of the processing table 1 will be described below.

[0011] (Base) The base 10 is a member that serves as a base for supporting the substrate 50 during processing, measurement, etc. Here, the base 10 has a substantially rectangular parallelepiped shape, and the elastic member 20 and the covering member 30 are provided on the upper surface. The upper surface of the base 10 may have grooves, recesses, etc. in some parts, but the areas where the elastic member 20 and the covering member 30 are provided are formed flat. It is preferable that the material of the base 10 has a high elastic modulus. A high elastic modulus can suppress deformation of the upper surface and fluctuations in position, improving the accuracy of processing, measurement, etc. The material of the base 10 can be, for example, a metal, and in this case, stainless steel. The base 10 may have a pair of walls 12 on its upper surface. For example, when the substrate 50 is transported horizontally, the walls 12 can be provided along the direction D1 of transport of the substrate 50. The walls 12 face each other at a distance that allows the substrate 50 to pass through.

[0012] (elastic member) The elastic member 20 is a member that changes its thickness to match the curved shape of the substrate 50. The elastic member 20 is a sheet-like member that is an elastic body and is placed on the base 10. Here, the elastic member 20 is rectangular and encompasses the substrate 50 in a plan view. As shown in Fig. 2B, when the substrate 50 is not placed on the elastic member 20, the elastic member 20 has a uniform thickness T1. Then, as shown in Fig. 2C, when the substrate 50 is placed on the elastic member 20, the elastic member 20 becomes thinner as the position of the lower surface of the substrate 50 decreases, and assumes a shape that matches the curvature of the lower surface of the substrate 50. This makes it possible to prevent the occurrence of gaps between the processing table 1 and the substrate 50, even if the substrate 50 is warped.

[0013] The smaller the elastic modulus of the elastic member 20, the easier it is to deform to match the warpage of the substrate 50. Therefore, from the viewpoint of suppressing the occurrence of voids, a smaller elastic modulus is preferable. The elastic modulus of the elastic member 20 can be set to 0.1 MPa or more and 10 MPa or less. On the other hand, if the elastic modulus is low, positional deviation is likely to occur. For this reason, the elastic modulus of the elastic member 20 is preferably 1 MPa or more and 7 MPa or less, and more preferably 2 MPa or more and 5 MPa or less. The elastic modulus is Young's modulus.

[0014] The thickness T1 of the elastic member 20 is set to be thicker than the height difference G1 that occurs on the underside of the substrate 50 due to warping of the substrate 50. This allows the elastic member 20 to deform so that no gap occurs between the processing table 1 and the substrate 50. On the other hand, the thicker the elastic member 20, the more likely it is that the position will be displaced. The thickness of the elastic member 20 can be set to be 1 to 3 times the height difference G1, and preferably 1 to 2 times the height difference G1. The degree of warpage of the substrate varies depending on the size of the substrate and the process performed. For example, if a warpage with a height difference G1 of 0.1 mm is allowed, the thickness T1 of the elastic member 20 can be set to 0.1 mm or more and 0.3 mm or less, and preferably 0.1 mm or more and 0.2 mm or less. The material of the elastic member 20 can be natural rubber or synthetic rubber, with natural rubber being preferred due to its suitable elastic modulus.

[0015] (adhesive material) The adhesive member 40 is a member that adheres and fixes the elastic member 20 to the base 10. The adhesive member 40 can be a member that is made by applying and curing an adhesive that can bond metal and rubber, or a double-sided tape that has adhesiveness on both sides, and here it is double-sided tape. Increasing the thickness of the adhesive member 40 can easily cause positional deviation. The thickness T3 of the adhesive member 40 can be set to, for example, 0.3 mm or less, and is preferably 0.15 mm or less.

[0016] (Covering material) The covering member 30 forms the upper surface of the processing table 1 and is a member that comes into contact with the substrate 50. The covering member 30 is a sheet-like member that has lower friction than the elastic member 20, and covers the elastic member 20. As illustrated in FIG. 2C , the upper surface of the covering member 30 comes into contact with the substrate 50 along the surface thereof, and the lower surface of the covering member 30 comes into contact with the elastic member 20 along the surface thereof. This allows the processing table 1 to support the substrate 50 without any gap between the upper surface of the base 10 and the substrate 50. The covering member 30 has lower friction than the elastic member 20. This makes it easier for the shape of the warp of the substrate 50 to be transmitted to the elastic member 20, and makes it easier for the warp of the substrate 50 to be reflected in the deformation of the elastic member 20. It is also preferable that the covering member 30 has lower friction. The low friction of the covering member 30 makes it easier for the covering member 30 to bend to match the warp, and also allows the substrate 50 to be slid smoothly during transportation.

[0017] The covering member 30 is preferably thin enough to ensure strength. A thin covering member 30 allows it to flex flexibly to conform to the warp of the substrate 50. The thickness T2 of the covering member 30 can be 0.1 mm or less, and is preferably 0.05 mm or less. By providing the low-friction covering member 30 on the elastic member 20, the processing table 1 can flexibly deform the upper surface to conform to the warp of the substrate 50, thereby preventing the occurrence of gaps between the processing table 1 and the substrate 50. The covering member 30 can be a film made of polyimide, polypropylene, or the like. In this example, a polyimide tape is used, one side of which is adhesive. The covering member 30 may also be adhered to the elastic member 20 with an adhesive.

[0018] The processing table 1 having the above-described configuration is placed on the base 10 and is equipped with a sheet-like elastic member 20 which is an elastic body, and a sheet-like covering member 30 which covers the elastic member 20 and has lower friction than the elastic member 20, thereby enabling the processing table 1 to deform in accordance with the warping of the substrate 50 and suppress the occurrence of voids between the substrate 50. Furthermore, the upper surface of the covering member 30 contacts the substrate 50 along its length, and the lower surface of the covering member 30 contacts the elastic member 20 along its length. This allows the substrate 50 to be supported without any gap between the upper surface of the base 10 and the substrate 50, improving the accuracy and quality of processing, measurement, etc., of the substrate 50. The processing table 1 has a low-friction covering member 30 and an elastic member 20 having an appropriate thickness and elastic modulus provided on the base 10, which allows them to deform appropriately and effectively eliminate the gap between the base 10 and the substrate 50.

[0019] The substrate 50 may be fixed by a chuck 60 that extends from an external device to the upper surface of the processing table 1. The chuck 60 can fix the substrate 50 so that the magnitude of the warp does not change. The chuck 60 fixes the substrate 50 during processing, etc., and releases the fixation after processing, etc. Then, for example, the substrate 50 is transported in direction D1, and the next substrate 50 is placed on the processing table 1. This process can be repeated sequentially to proceed with processing, etc. The covering member 30 forming the upper surface of the processing table 1 has low friction, which allows the substrate 50 to be transported smoothly and is suitable for automatic transport. In addition, damage to the substrate 50 due to snagging or the like can be prevented.

[0020] Next, as an example of processing a substrate having semiconductor elements, a case where a substrate 50 is placed on the processing table 1 and wire bonding is performed will be described with reference to FIGS. 3A to 4C. (substrate) As illustrated in FIGS. 1B and 2A, the substrate 50 has a semiconductor element 55. For example, the substrate 50 has a conductor pattern 52A on the upper surface of a rectangular, plate-like insulating base material 51 and a conductor pattern 52B on the lower surface. The semiconductor element 55 is, for example, an IGBT (Insulated Gate Bipolar Transistor), and has electrodes on both the upper and lower surfaces. The electrode on the lower surface of the semiconductor element 55 is joined to the conductor pattern 52A on the upper surface of the substrate 50 via a joining member 53. During the joining of the semiconductor element 55 to the conductor pattern 52A, the substrate 50 may warp. The conductor patterns 52A and 52B are made of, for example, copper, and the joining member 53 is, for example, solder. The conductor pattern 52B on the lower surface is rectangular and slightly smaller than the insulating base material 51, and is formed to have a uniform thickness.

[0021] (wire bonding) As shown in FIG. 3A, wire bonding is performed by unwinding wire 75 from guide portion 72, pressing wire 75 against an electrode or the like with the tip of tool portion 71, and applying load F1 and ultrasonic vibration. The ultrasonic vibration vibrates tool portion 71 in direction D2, which is the extension direction of wire 75, at a constant frequency corresponding to ultrasonic waves. Bonds 75A are formed by load F1 and ultrasonic vibration from tool portion 71. As shown in FIG. 3B, three bonds 75A may be formed with one wire 75. The material of the wire 75 can be gold, silver, copper, aluminum, etc., and here it is aluminum.

[0022] As shown in Fig. 4A, tool part 71 has a groove 73 at its tip. When a load and ultrasonic vibration are applied with the direction of groove 73 aligned with the extension direction of wire 75, wire 75 enters groove 73, deforms, and is bonded, as shown in Fig. 4B. In this case, wire 75 is bonded to electrode 56 on the top surface of semiconductor element 55. Note that Figs. 4A and 4B illustrate cross sections seen from the extension direction of wire 75. As shown in the plan view of FIG. 4C, the diameter W2 of the deformed portion of the wire 75 after bonding is larger than the original diameter W1. The diameter W2 is called the crushed width of the wire. The relative value of the crushed width, i.e., the ratio W2 / W1 of the diameter W2 to the diameter W1, can be used as an indicator of the quality of the bond. The shear strength of the wire 75 is also an indicator of the bond strength. The shear strength is measured by breaking the bonded portion in a direction D3 perpendicular to the wire and measuring the force required to break it.

[0023] Conventionally, wire bonding has been susceptible to the effects of substrate warpage. This is thought to be because when warpage creates a gap between the base and the substrate, it causes abnormalities in the transmission of load and ultrasonic vibration, affecting the formation of the bond. Therefore, to confirm the improvement in the quality of wire bonding using the processing table 1, the shear strength and crush width were measured by changing the elastic modulus of the rubber sheet placed on the base. Note that gaps below the tool portion can be a problem when forming a bond, but on the substrate 50, a conductor pattern 52B is provided below the position where the tool portion applies load and ultrasonic vibration. [Example]

[0024] The following working tables for the example and three comparative examples were created, and substrates having warpage with a height difference G1 of 0.1 mm as shown in FIG. 2A were placed on them. Multiple wire bonding was performed on each of them, and the relative values of shear strength and crushed width were measured. In Example E1, a 0.1 mm thick natural rubber sheet was fixed to a base with 0.1 mm thick double-sided tape as an elastic member, and a 0.05 mm thick Kapton (registered trademark) tape was attached to the natural rubber sheet as a covering member. The Kapton tape is a polyimide tape with one adhesive side.

[0025] In Comparative Example C1, nothing was provided on the base, and the upper surface was stainless steel. In Comparative Example C2, a 0.1 mm thick ISODAMP (registered trademark) vibration-damping rubber sheet was attached to the base with 0.1 mm thick double-sided tape. In Comparative Example C3, a 0.1 mm thick silicone rubber sheet was attached to the base with 0.1 mm thick double-sided tape. Note that no Kapton tape was attached to the Comparative Example. The bases were made of stainless steel and had the same shape in both the Examples and Comparative Examples. The elastic modulus of the rubber sheet is 4.80 MPa for Example E1, 200 GPa for Comparative Example C1, 114 MPa for Comparative Example C2, and 1.88 MPa for Comparative Example C3.

[0026] As a result of the measurements, the shear strength was equivalent for the example and the three comparative examples. On the other hand, although there was no significant difference in the average value of the relative value of the crushed width, there was a difference in the variation. Figure 5 shows the variation in the relative value of the crushed width against the elastic modulus of the rubber sheet. Note that the solid line in Figure 5 is simply a straight line connecting the measurement points. A high elastic modulus tends to result in a large variation in the relative value of the crush width. In particular, in Comparative Examples C1 and C2, where the elastic modulus exceeds 100 MPa, it appears that the gap between the base and the substrate is not sufficiently eliminated. On the other hand, when the elastic modulus is reduced from 100 MPa, the variation in the relative value of the crush width decreases, and when reduced further, it tends to increase. This is thought to be because, although the gap is eliminated, it is disadvantageous for fixing the position of the substrate, resulting in positional deviation. From these results, it can be said that a low elastic modulus is not necessarily better for processing or measurement, such as wire bonding, where positional deviation is a problem. The elastic modulus of the elastic member 20 is particularly preferably 2 MPa or more and 5 MPa or less. It is also estimated that good results can be obtained even with a value of 1 MPa or more and 7 MPa or less.

[0027] The base 10 is not limited to a substantially rectangular parallelepiped shape as long as it has a flat upper surface. [Explanation of symbols]

[0028] 1. Semiconductor device processing table 10 Foundations 12 Wall 20 Elastic member 30 Covering material 40 Adhesive material 50 boards 51 Insulating substrate 52A Conductor pattern (top surface) 53 Joint materials 55 Semiconductor elements 60 Chuck part 71 Tools section 75 wire

Claims

1. A processing table for a semiconductor device on which a substrate having a semiconductor element is placed and processed, The base and a sheet-like elastic member that is an elastic body and is disposed on the base; a sheet-like covering member that covers the elastic member and has lower friction than the elastic member;

2. 2. The processing table for semiconductor devices according to claim 1, wherein an upper surface of said covering member contacts said substrate along its length, and a lower surface of said covering member contacts said elastic member along its length.

3. 2. The processing table for semiconductor devices according to claim 1, wherein the material of said elastic member is natural rubber.

4. 2. The processing table for semiconductor devices according to claim 1, wherein the elastic member has a modulus of elasticity of 0.1 MPa or more and 10 MPa or less.

5. 2. The processing table for semiconductor devices according to claim 1, wherein the elastic member is thicker than a height difference that occurs on the lower surface of the substrate due to warping of the substrate.

6. 2. The processing table for semiconductor devices according to claim 1, wherein the elastic member has a thickness that is one to three times the height difference that occurs on the lower surface of the substrate due to warping of the substrate.

7. 2. The processing table for semiconductor devices according to claim 1, wherein the thickness of said elastic member is 0.1 mm or more and 0.3 mm or less.

8. 2. The processing table for semiconductor devices according to claim 1, wherein the material of said covering member is polyimide.

9. 2. The processing table for semiconductor devices according to claim 1, wherein the thickness of said covering member is 0.1 mm or less.

10. 10. The processing table for semiconductor devices according to claim 1, wherein the material of the base is a metal.

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