A Novel WaterWashable Coating for Avoiding Contamination During Dry Laser Dicing Operations

K.C. Su,a H.H. Lu,a S.H. Chen,a C.D. Tsai,Y.C. Chou,W.J. Wu,G.Q. Wu,and J.C. Moore,c aLee Chang Yung Chemical Industrial Corporation (LCY), 4F, No. 83, Sec. 4, Bade Road, Taipei, 105, Taiwan R.O.C. bOPTO Tech Corporation, No. 8, Innovation Rd. I, Hsinchu Science Park, Hsinchu, Taiwan, R.O.C. cDAETEC, LLC, 1227 Flynn Rd., Unit 310, Camarillo, CA 93012, USA a886 (2) 27631611, etech@lcy.com.tw, b886 (3) 5777481, 5418@opto.com.tw, c(805) 4845546, jmoore@daetec.com

Keywords: AqPCoatTM, ablation, protection, kerf, HAZ (heataffected zone), TTV, crosslinking.

Abstract

Laser micromachining has been used for years and is accepted as a common method to dice wafers [13]. The advantages of laser processing over sawing are well known to include a reduced kerf width and more flexibility in cutting irregularshaped die or throughcuts of fragile substrates below 50um [4]. It has been reported that protective coatings are required to eliminate particle contamination generated from material ablation in a dry laser [5]. A simple watersoluble coating is desired to offer engineers more flexibility to use dry lasers without contamination or serious impacts to manufacturing. A novel aqueoussoluble coating, AqPCoatTM , is available from Lee Chang Yung Chemical Industrial Corporation (LCY) [6]. Several coating chemistries have been developed by LCY to address a range of process demands, all offering a rapid water rinse. In one demonstration, LCY's AqPCoatTM chemistries were applied to wafers and laser scribed followed by subsequent water washing. The results suggest that certain polymers of a high molecular weight and inert chemical character (i.e. straightchain, high saturation, etc.) produced the best results with least residue and the smallest kerf. This report offers further details on our development of water washable coatings used to eliminate debris and improve laser processing of GaAs wafers.

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