Back grinding adhesive sheet, and method for manufacturing semiconductor wafer
Provided is a back grinding adhesive sheet which can adequately protect protrusions provided to a semiconductor wafer, and with which back grinding can be adequately performed. The present invention provides a back grinding adhesive sheet for a semiconductor wafer having protrusions, the back grinding adhesive sheet comprising a non-adhesive cushion layer, and an adhesive layer provided on the cushion layer. The adhesive layer has an opening with a smaller diameter than the diameter of the semiconductor wafer, and the outer edge of the semiconductor wafer is adhered to the adhesive layer such that the protrusions on the semiconductor wafer are positioned inside the opening. The protrusions are protected by the cushion layer when the semiconductor wafer is in the state of being adhered to the adhesive layer. The adhesive sheet satisfies at least one of the following conditions (1)-(2). (1) When the cushion layer is cut out using the dumbbell from JISZ1702 and is stretched 25% at a gauge length of 40 mm and a tensile speed of 300 mm/min, the tensile stress is 2-30N/10 mm. (2) The cushion layer is formed from a thermoplastic resin that has a melt flow rate (JISK7210, 125° C./10.0 kg load) of 0.2-30 g/10 min, and a melting point of 60-110° C.
1. An adhesive sheet for back grinding of a semiconductor wafer having convex portions, comprising a non-adhesive cushion layer and an adhesive layer provided on the cushion layer,
wherein the adhesive layer comprises an opening with a diameter smaller than a diameter of the semiconductor wafer,
the adhesive layer is configured to be attached to an outer periphery of the semiconductor wafer so that the convex portions of the semiconductor wafer are placed in the opening, whereby the convex portions are protected by the cushion layer in a state where the semiconductor wafer is attached to the adhesive layer, and
at least one of the following conditions (1) and (2) is satisfied:
(1) tensile stress of the cushion layer punched out by using a dumbbell according to JISZ1702 is 2 to 30N/10 mm when the punched-out cushion layer is stretched by 25% at a distance between gauge lines of 40 mm and a tensile speed of 300 mm/min; and
(2) the cushion layer is composed of a thermoplastic resin with a melt flow rate of 0.2 to 30 g/10 min under 125° C./10.0 kg load according to JISK7210 and a melting point of 60 to 110° C.
2. The adhesive sheet according to claim 1 , wherein the convex portions are protected by being embedded in the cushion layer.
3. The adhesive sheet according to claim 1 , wherein the adhesive layer is attached the semiconductor wafer under reduced pressure.
4. The adhesive sheet according to claim 1 , wherein a thickness of the cushion layer is 50 to 300 μm and thickness of the adhesive layer is 1 to 100 μm.
5. The adhesive sheet according to claim 1 , further comprising a curable resin layer containing a curable resin and a support film,
wherein the curable resin and the support film are laminated onto the cushion layer side of the adhesive sheet.
6. The adhesive sheet according to claim 5 , wherein the curable resin has a viscosity of 100 to 3,000 mPa·s before curing and Shore D hardness of 5 to 72 after curing.
7. The adhesive sheet according to claim 5 , wherein when a height of the convex portions in μm is Td, a thickness of the curable resin is (Td+20) to (Td+200) μm.
8. The adhesive sheet according to claim 5 , wherein the curable resin layer is provided on an opposite side of a surface of the adhesive sheet provided with the adhesive layer and between the support film and a surface of the cushion layer.
9. The adhesive sheet according to claim 8 , further comprising a cured resin layer so as to surround the curable resin layer.
10. A method for manufacturing a semiconductor wafer using the adhesive sheet according to claim 1 , comprising
the adhesive sheet to a ring frame,
adhering the adhesive sheet to a surface of the semiconductor wafer having the convex portions on a periphery of the semiconductor wafer under reduced pressure,
cutting the adhesive sheet along the periphery of the semiconductor wafer,
curing a curable resin in a state where the cushion layer is in contact with the curable resin,
grinding a backside of the semiconductor wafer,
peeling off the adhesive sheet from the semiconductor wafer,
at least one of the following conditions (A) and (B) is satisfied:
(A) the above condition (1) is satisfied; and
(B) the above condition (2) is satisfied, and
the method further comprises heating the cushion layer to 60 to 150° C. when the condition (2) is satisfied.
11. The method for manufacturing the semiconductor wafer according to claim 10 , wherein tensile stress of the cushion layer punched out by using a dumbbell according to JISZ1702 is 2 to 30 N/10 mm when the punched-out cushion layer is stretched by 25% at a distance between gauge lines of 40 mm and a tensile speed of 300 mm/min.
12. The method for manufacturing the semiconductor wafer according to claim 10 , wherein the curable resin has a viscosity of 100 to 3,000 mPa·s before curing and Shore D hardness of 5 to 72 after curing.
13. The method for manufacturing the semiconductor wafer according to claim 10 further comprising, between the process of adhering the adhesive sheet to the surface of the semiconductor wafer and the process of curing the curable resin, pressing and spreading the curable resin by moving the adhesive sheet while the adhesive sheet faces the curable resin supplied on a support film.