Wafer machining adhesive tape, and its manufacturing method and using method

Abstract

An adhesive tape having an adhesive layer formed on one side of a substrate layer, which renders it possible to minimize the extent of development of chipping or fragmentation (nicks) or crack in chip when the silicon wafer, to which this tape is adhered, is cut into chips using a dicer. The adhesive layer of the tape has a storage modulus G′ of 1 MPa or more at a temperature of 15 to 35° C., and preferably tanδ as represented by the ratio of a loss modulus G″ to the storage modulus G′ is 0.05 or less. The adhesive layer is preferably constructed principally of an olefin polymer.

What we claim is:  
     
         1 . A wafer processing adhesive tape having an adhesive layer on one side of a substrate layer, which enables a silicon wafer of a 6-inch diameter adhered to said adhesive layer and ground on its backside to a 400 μm thickness to achieve production of chips having a maximum length of chipping or fragmentation (nicks) or crack of 30 μm or less by a ratio of 90% or higher as compared with a total number of chips obtained from a silicon wafer, when the silicon wafer is cut into 3 mm square size by full cutting using a dicer at a temperature of 15 to 35° C. and under conditions of a dicing speed of 70 mm/min. and cutting water maintained at a temperature of 20° C.  
     
     
         2 . A wafer processing adhesive tape according to  claim 1 , wherein the maximum length of said chipping or fragmentation (nicks) or crack of the chip is 10 μm or less.  
     
     
         3 . A wafer processing adhesive tape comprising an adhesive tape having an adhesive layer on one side of a substrate layer, wherein a storage modulus G′ of the adhesive layer at a temperature of 15 to 35° C. is 1 MPa or more.  
     
     
         4 . A wafer processing adhesive tape according to  claim 3 , wherein said adhesive layer has a tanδ of 0.05 or more as a ratio of a loss modulus G″ to the storage modulus G′ at a temperature of 15 to 35° C.  
     
     
         5 . A wafer processing adhesive tape according to either one of  claims 1  to  4 , wherein said adhesive layer comprises an olefin polymer as its principal component.  
     
     
         6 . A water processing adhesive tape according to either one of  claims 1  to  4 , wherein said adhesive layer comprises as its principal component one type or a mixture of two or more types of α-olefin copolymer comprising as its principal unit components at least two types of α-olefin selected from among α-olefins having from 2 to 12 carbon atoms.  
     
     
         7 . A wafer processing adhesive tape according to either one of  claims 1  to  4 , wherein said adhesive layer comprises of said α-olefin copolymer, a thermoplastic elastomer and a co-oligomer of ethylene with another α-olefin, and the α-olefin copolymer constitutes a continuous phase and the thermoplastic elastomer constitutes a dispersed phase.  
     
     
         8 . A wafer processing adhesive tape according to  claim 7 , wherein said thermoplastic elastomer is a block copolymer represented by the formula of A-B-A or A-B, wherein A is an aromatic vinyl compound polymer block or an olefin polymer block exhibiting crystallinity, B is a diene compound polymer block or an olefin polymer block derived by hydrogenating the diene compound polymer block.  
     
     
         9 . A wafer processing adhesive tape according to either one of  claims 6  to  8 , wherein one type of said α-olefin copolymer is an α-olefin copolymer derived by copolymerizing propylene, 1-butene and an α-olefin having from 5 to 12 carbon atoms.  
     
     
         10 . A wafer processing adhesive tape according to  claim 9 , wherein said α-olefin having from 5 to 12 carbon atoms is 4-methyl-1-pentene.  
     
     
         11 . A wafer processing adhesive tape according to either one of  claims 1  to  10 , wherein said substrate layer comprises of one or more layers and comprises as its principal component an olefin polymer.  
     
     
         12 . A wafer processing adhesive tape according to either one of  claims 1  to  11 , wherein said adhesive tape exhibits a probe tack in the range of 0.01 to 1 N/5 mm diam. as measured in a temperature range of 20 to 80° C. in accordance with the procedure stipulated in the reference column of JIS Z0237.  
     
     
         13 . A wafer processing adhesive tape according to either one of  claims 1  to  12 , wherein said adhesive tape has its substrate layer and adhesive layer formed according to a co-extrusion process.  
     
     
         14 . A method for manufacturing a wafer processing adhesive tape having a substrate layer comprising of one or more layers and an adhesive layer laminated over one side of such substrate layer according to either one of  claims 1  to  13 , comprising a co-extrusion process using a multilayer die, wherein melt flow rate (MFR) (ASTM D 1238, as determined at 230° C. under a load of 2.16 kg) of the polymer constituting the substrate layer and the adhesive layer is 5 to 40 g/10 min. and the difference in MFR between the adjoining layers is 10 g/10 min. or less, and operating conditions of which being such that melting temperature is 200 to 260° C. and the difference in the melting temperature between the adjoining layers is 30° C. or less.  
     
     
         15 . A method for using a wafer processing adhesive tape, comprising adhering the wafer processing adhesive tape according to either one of  claims 1  to  13  to a wafer under a load at a temperature of 20 to 80° C., cutting the wafer into chips at a temperature of 15 to 35° C., stretching said tape at a temperature of 40 to 80° C. and thereupon peeling the IC chips from the adhesive tape by picking up the same at room temperature.  
     
     
         16 . A method for using a wafer processing adhesive tape according to  claim 15 , wherein said wafer is a wafer on whose front surface has been formed circuit patterns and said cutting is performed by dicing.