A Novel Low Wafer Stress i-Line Definable Polyimide.

To solve a recent technical problem relating to larger-size wafer production and thinner packaging technology, a new photodefinable polyimide, which can give smaller wafer bow (curvature) after curing and also can attain finer pattern performance, is designed based on xanthene-structure dianhydride. This paper describes synthesis of several polymers evaluation of their basic characters, and discussion on material design. On the basis of these results, a negative-working i-line-definable low-stress polyimide HD-LSXB was prepared as a trial, then its lithographic performance as well as wafer stress was evaluated. It was demonstrated that HD-LSXB gives a low stress (about 10MPa) and a high resolution(4μm line/space with 20μm thick after prebaking) with the i-line stepper.