JP2006335787A - Pressure-sensitive adhesive sheet and method for producing electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that the follow-up to bumps cannot be made and dimples (recessed parts of the back surface ground parts) corresponding to the bumps or cracks are formed to cause deterioration of thickness accuracy of a pressure-sensitive adhesive sheet or blocking during molding of a substrate of the pressure-sensitive adhesive sheet even if the follow-up can be made when an electronic member such as a semiconductor wafer having the bumps such as a circuit surface having unevennesses of ≥25 μm or solder balls is ground, etc. <P>SOLUTION: The pressure-sensitive adhesive sheet is obtained by laminating a reinforcing layer, a flexible layer, an intermediate layer and a pressure-sensitive adhesive layer in the order mentioned. The reinforcing layer has 40-90 Shore D hardness and 5-1,000 μm thickness and the flexible layer has 20-80 Shore A hardness and 50-1,000 μm thickness. The intermediate layer has 40-90 Shore D hardness and 5-100 μm thickness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an adhesive sheet and an electronic component manufacturing method, and more particularly, to an adhesive sheet and an electronic component manufacturing method used for manufacturing a semiconductor wafer having a circuit surface of 25 μm or more and bumps such as solder balls and electronic components.

  There are silicon wafers, gallium arsenide, and the like as wafers used for manufacturing semiconductor chips, and among these, silicon wafers are frequently used. Silicon wafers are manufactured by slicing high-purity single crystal silicon thinly to a thickness of about 500 to 1000 μm. Recently, a packaged 100 to 100 typified by a wafer with a circuit of about 50 μm or a wafer level CSP is used. There is an increasing demand for wafers having bumps of 500 μm (unevenness such as solder balls).

  As in Patent Document 1, the pressure-sensitive adhesive sheet in which the hardness and thickness of the sheet are specified, when used for a semiconductor wafer having irregularities exceeding 25 μm, can not withstand followability to irregularities and stress relaxation, and dimples corresponding to bumps ( A dent in the back grinding part) or a crack occurred.

In the means for laminating a substrate having a Shore D hardness of 30 to 50 on a soft substrate having a JIS-A hardness of 10 to 55 in Patent Document 2, even if the irregularities of 25 μm or more can be absorbed, the adhesive sheet is soft because the substrate is soft The thickness accuracy was poor, and blocking occurred during the molding of the substrate.
Japanese Patent Publication No. 6-18190 JP 2000-8010 A

  An object of the present invention is that when an electronic member such as a semiconductor wafer having bumps such as a circuit surface of 25 μm or more and a solder ball is ground, dimples corresponding to the bumps (dents on the back surface grinding portion) are generated. Even if cracks occur and follow-up, the thickness accuracy of the pressure-sensitive adhesive sheet is lowered, and blocking is performed when the base material of the pressure-sensitive adhesive sheet is formed.

  The invention of claim 1 of the present application is a pressure-sensitive adhesive sheet that is laminated in the order of a reinforcing layer, a soft layer, an intermediate layer, and a pressure-sensitive adhesive layer, wherein the reinforcing layer has a Shore D hardness of 40 to 90 and a thickness of 5 to 1000 μm. The pressure-sensitive adhesive sheet has a layer having a Shore A hardness of 20 to 80 and a thickness of 50 to 1000 μm, and an intermediate layer having a Shore D hardness of 40 to 90 and a thickness of 5 to 100 μm.

  Invention of Claim 2 of this application is the adhesive sheet of Claim 1 whose thickness of an adhesive layer is 3-100 micrometers.

  The invention according to claim 3 of the present application is the pressure-sensitive adhesive sheet according to claim 1 or 2 for electronic parts.

  Invention of Claim 4 of this application is an electronic component manufacturing method which manufactures an electronic component by grinding the back surface of the electronic component which has a protrusion of 25-500 micrometers on the surface, Comprising: The protrusion formation surface of an electronic component and Claim 1 or 2. An electronic component manufacturing method in which the adhesive layer of the adhesive sheet according to 2 is bonded and the back surface of the electronic component is ground.

  The invention according to claim 5 of the present application is an electronic component manufacturing method for individually dicing a plate-like body having a plurality of electronic components each having a projection of 25 to 500 μm on the surface, wherein the projection forming surface of the electronic component and claim 1 are provided. Or it is the electronic component manufacturing method which bonds together the adhesive layer of the adhesive sheet of 2, and dices an electronic component individually.

  The present invention maintains the thickness accuracy of the pressure-sensitive adhesive sheet by the above-described configuration, does not cause blocking during molding of the base material of the pressure-sensitive adhesive sheet, and has an electronic member such as a semiconductor wafer having a circuit surface of 25 μm or more and a bump such as a solder ball. Even after grinding, the bumps follow the bumps, and dimples corresponding to the bumps (recessed portion dents) and cracks do not occur.

  In the present invention, a pressure-sensitive adhesive sheet is laminated in the order of a reinforcing layer, a soft layer, an intermediate layer, and a pressure-sensitive adhesive layer, the reinforcing layer has a Shore D hardness of 40 to 90 and a thickness of 5 to 1000 μm, and the soft layer has a Shore A hardness. The pressure-sensitive adhesive sheet having a thickness of 20 to 80 and a thickness of 50 to 1000 μm and an intermediate layer having a Shore D hardness of 40 to 90 and a thickness of 5 to 100 μm is simply a sheet obtained by laminating a low hardness substrate and a high substrate. The problem of the present invention cannot be solved. By stacking a relatively thin substrate (intermediate layer of the present application) on the other soft substrate side, it becomes possible to follow the bump, and the wafer having a bump of 25 μm or more is obtained. The inventors have found that good results can be obtained even when used for back surface grinding and dicing, and have reached the present invention.

  The reason why the Shore D hardness of the reinforcing layer is 40 to 90 is that if it is too hard, winding in a roll shape becomes difficult, and if it is too soft, distortion occurs during grinding and the wafer is damaged or the yield is affected by blocking. This is because of a decrease. The Shore D hardness is a value using a D-type Shore hardness meter according to ASTM D-2240.

  The reason why the thickness of the reinforcing layer is 5 to 1000 μm is that if the layer is too thin, the effect of laminating the reinforcing layer cannot be exhibited. If the layer is too thick, the film is distorted by stress applied during grinding and cracks occur in the wafer.

  As a material for forming the reinforcing layer and the intermediate layer described later, a conventionally known synthetic resin can be appropriately selected as long as the Shore D hardness is within the above range, specifically, a polyolefin represented by polyethylene or polypropylene, Examples include polyvinyl chloride, polybutene, polybutadiene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, and polyimide.

  The reason why the shore A hardness of the soft layer is 20-80 is that if it is too low, the base material will be distorted by the pressure during grinding, causing the wafer surface to deteriorate and causing damage. If it is too high, the bump stress cannot be absorbed or alleviated. It is because it causes damage, and 15 to 50 is more preferable. The Shore A hardness is a value using an A-type Shore hardness meter defined in ASTM D-2240.

  The reason why the thickness of the soft layer is set to 10 to 1000 μm is that if it is too thin, bump irregularities cannot be absorbed, and if it is too thick, the entire pressure-sensitive adhesive sheet is distorted by the stress applied during grinding and causes cracks in the wafer. The thickness is preferably 100 to 500 μm.

  As the material employed as the soft layer, a conventionally known synthetic resin can be appropriately selected as long as the Shore A hardness is the above value. Specifically, polyolefins represented by polyethylene and polypropylene, polyvinyl chloride, polybutene, polybutadiene, There are ethylene-vinyl acetate copolymer and ethylene-ethyl acrylate copolymer.

  The reason why the thickness of the intermediate layer is 5 to 100 μm is that if it is too thin, pinholes are generated in the film, which makes it difficult to manufacture, and if it is too thick, bump followability of the entire adhesive sheet is lost and cracks occur in the wafer. .

  When the adhesive layer described later is an ultraviolet curable adhesive, the sheet formed of the reinforcing layer, the soft layer, and the intermediate layer needs to allow the ultraviolet rays to reach the adhesive layer through the sheet itself. Must be UV transmissive. In the case where the pressure-sensitive adhesive layer described later is a thermosetting pressure-sensitive adhesive or a heat-foaming pressure-sensitive adhesive, the sheet itself must have a melting point that is higher than the temperature used during heating.

  For the pressure-sensitive adhesive layer, a general pressure-sensitive pressure-sensitive adhesive, an ultraviolet curable pressure-sensitive adhesive, a heat-curable pressure-sensitive adhesive, or the like can be used. Conventional pressure-sensitive adhesives include conventionally known pressure-sensitive adhesives such as acrylic, rubber, and silicon. The ultraviolet curable pressure-sensitive adhesive is obtained by blending a curable compound and an ultraviolet curing initiator with a general pressure-sensitive pressure-sensitive adhesive, and the adhesive strength thereof can be adjusted by irradiation with ultraviolet rays. The heat-curable pressure-sensitive adhesive is a general pressure-sensitive pressure-sensitive adhesive blended with a curable compound and a heat-curing initiator, and the adhesive strength can be adjusted by heating.

  The thickness of the pressure-sensitive adhesive layer is preferably in the range of 3 to 100 μm in view of coating property and workability.

  The pressure-sensitive adhesive sheet according to the present invention can be stored by bringing a release paper or a release sheet such as polyethylene laminated paper or a release-treated plastic film into close contact with the pressure-sensitive adhesive surface of the wafer pressure-sensitive adhesive layer as necessary.

  The sheet manufacturing method according to the present invention may be formed by a conventionally known T-die coextrusion method, inflation coextrusion method, calender extrusion method, or the like, and various methods such as a method of applying an adhesive to a single layer film and laminating it. The method can be used.

  The sheet according to the present invention can be produced by various methods such as a conventionally known T-die coextrusion method, inflation coextrusion method, calender extrusion method, etc., as well as a method of applying an adhesive to a single layer film and laminating it. Can be used.

  The pressure-sensitive adhesive layer surface of the above-mentioned pressure-sensitive adhesive sheet is bonded to the protrusion-forming surface of an electronic component having a protrusion of 25 to 500 μm on the surface, and the back surface (surface without the protrusion) of the electronic component is ground by a grinding machine. Parts can be manufactured.

  The above-mentioned pressure-sensitive adhesive sheet surface of the pressure-sensitive adhesive sheet is bonded to the protrusion-forming surface of an electronic component having a protrusion of 25 to 500 μm on the surface, and the electronic component is individually chipped, diced, chip-shaped, with a protrusion Parts can be manufactured.

Examples according to the present invention will be described in detail with reference to Table 1 and in comparison with comparative examples.

  Evaluation in Examples and Comparative Examples was performed as follows.

  “Evaluation of film formability” in Table 1 indicates that there are fine holes such as pinholes on the adhesive sheet of each example and each comparative example, or the adhesive sheet is too hard to be wound. Was “impossible” and the others were “good”.

  “Evaluation of grindability” in Table 1 shows that a semiconductor wafer having a diameter of 5 inches, a thickness of 650 μm, and a bump (solder ball) of a circuit surface of 150 μm is mounted on a pressure-sensitive adhesive sheet of each example and each comparative example. After mounting the semiconductor wafer backside grinding sheet using a mounter ATM-1100), the backside of the wafer is ground to 150 μm using a grinding machine (Dogco's back grinder DFG-841). Then, the state of occurrence of dimples and cracks on the surface of the semiconductor wafer after grinding was visually evaluated, and “not acceptable” was given to those in which cracks and dimples were generated even in one of the 10 wafers, and “good” was designated otherwise.

  The pressure-sensitive adhesive sheet according to Example 1 will be described. The pressure-sensitive adhesive sheet according to Example 1 is a pressure-sensitive adhesive sheet formed in the order of a reinforcing layer, a soft layer, an intermediate layer, and a pressure-sensitive adhesive layer. The reinforcing layer and the intermediate layer are made of an ethylene-ethyl acrylate copolymer (Mitsui DuPont). A-701 made by Polychemical Co., Shore D hardness 50, thickness 25 μm), and the soft layer is an ethylene-vinyl acetate copolymer (EV150, Mitsui-Dupont Polychemical Co., Shore A hardness 68, thickness 200 μm) It was formed by.

  This three-layer sheet is formed by molding each of the above synthetic resins by a T-die coextrusion method.

  The method for laminating the pressure-sensitive adhesive layer on the three-layer sheet was performed by the following method. By using a comma coater, N-3330 (100 parts by mass) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. and Coronate L-45 (5 parts by mass) manufactured by Nippon Polyurethane Industry Co., Ltd. were stirred and homogenized with a stirrer for 1 hour. A polyethylene terephthalate film (thickness: 38 μm) as a release film was applied to the release treatment surface, and the applied adhesive layer was pressed and transferred to the intermediate layer side of the above three-layer sheet for lamination.

  In the pressure-sensitive adhesive sheets of Examples 2 and 3, the thickness of the pressure-sensitive adhesive of Example 1 was set to the value described in Table 1. Except for this thickness, it was constructed in the same manner as in Example 1 and manufactured. It is a thing.

  The pressure-sensitive adhesive sheets of Comparative Examples 1 to 12 were produced in the same manner as in Example 1 except that the hardness and thickness of each layer were the values described in Table 1.

  As shown in Table 1, in Example 1, the occurrence of dimples and cracks was not observed in the evaluation of grindability, the film formability was good, and the usable grade was satisfactory. In Examples 2 and 3, the surface condition of the wafer was slightly bad in the evaluation of grindability, but it was usable.

  In Comparative Example 1 in which the soft layer had a low Shore A hardness and Comparative Example 2 in which the Shore A hardness was high, cracks were observed during grinding and the grindability was poor. In Comparative Example 3 in which the soft layer was thin, pinholes were generated during film formation, and the film formability was poor and the bump following ability was not obtained, so cracks occurred and the grindability was also poor. In Comparative Example 4 where the soft layer was thick, cracks occurred and the grindability was poor. In Comparative Example 5 where the Shore D hardness of the intermediate layer was low, cracks occurred and the grindability was poor, and in Comparative Example 6 where the Shore D hardness of the intermediate layer was high, film formability was poor, cracks were generated during grinding and the grindability was also poor. . In Comparative Example 7 in which the intermediate layer was thin, the film formability was poor, cracks were generated during grinding and the grindability was poor, and in Comparative Example 8 in which the intermediate layer was thick, cracks were generated during grinding and the grindability was poor. In Comparative Example 9 where the Shore D hardness of the reinforcing layer was low, cracks occurred during grinding and the grindability was poor, and in Comparative Example 10 where the Shore D hardness of the reinforcing layer was high, the grindability was good but the film formability was poor. In Comparative Example 11 in which the reinforcing layer was thin, the film formability was poor and cracks were generated during grinding and the grindability was also poor. In Comparative Example 12 in which the reinforcing layer was thick, cracks were generated during grinding and the grindability was poor.

The present invention relates to an adhesive sheet and an electronic component manufacturing method, and more particularly, to an adhesive sheet and an electronic component manufacturing method used for manufacturing a semiconductor wafer having a circuit surface of 25 μm or more and bumps such as solder balls and electronic components.

Claims (5)

  A pressure-sensitive adhesive sheet laminated in the order of a reinforcing layer, a soft layer, an intermediate layer, and a pressure-sensitive adhesive layer, wherein the reinforcing layer has a Shore D hardness of 40 to 90 and a thickness of 5 to 1000 μm, and the soft layer has a Shore A hardness of 20 to 80 and A pressure-sensitive adhesive sheet having a thickness of 50 to 1000 μm and an intermediate layer having a Shore D hardness of 40 to 90 and a thickness of 5 to 100 μm.   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 3 to 100 µm.   The pressure-sensitive adhesive sheet according to claim 1 or 2, which is used for electronic parts.   An electronic component manufacturing method for manufacturing an electronic component by grinding a back surface of an electronic component having a projection of 25 to 500 μm on the surface, wherein the protrusion forming surface of the electronic component and the adhesive layer of the adhesive sheet according to claim 1 or 2 are provided. An electronic component manufacturing method for bonding and grinding the back surface of an electronic component.   3. An electronic component manufacturing method for individually dicing a plate-like body having a plurality of electronic components having a projection of 25 to 500 [mu] m on the surface, wherein the projection forming surface of the electronic component and the adhesive layer of the adhesive sheet according to claim 1 or 2 An electronic component manufacturing method in which the electronic components are individually diced together.