| 摘要 |
PURPOSE:To make it possible to attach and remove a protective material to and from the rugged circuit-pattern forming surface of a semiconductor wafer easily and efficiently, by providing a pressure sensitive adhesive layer with composed structure whose adhesive strength is increased at the peripheral part. CONSTITUTION:A pressure sensitive adhesive layer 22, applied onto a waterproof sheet 21 for attaching a pattern-surface protective seal 2 to the circuit-pattern forming surface of a semiconductor wafer, is so formed that the adhesive strength of the peripheral part 23 to the semiconductor wafer may become stronger than that of the inside 24. The adhesive strength of the peripheral part 23 is 200 to 1000g/20mm, based on a 180degree peeling value to a stainless plate at normal temperature. The adhesive strength of the inside 24 is similarly 10 to 200g/20mm. Hereupon, 2 to 20mm is appropriate for the width of the peripheral part 23. Besides, 5 to 100mum is appropriate for the thickness of the pressure sensitive adhesive layer 22, and it is desirable that the layer 22 should have an elasticity modulus of 0.5 to 50kg/cm<2>. This prevents dirty water containing ground waste from permeating, and also makes it possible to expoliate a protective material smoothly without breaking a ground wafer.
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