Research Of Lithography Process With Polyimide As Photo Resist

Polyimide material has been applied in Semiconductor field for about30years. In view of its significant chemical characteristic, it’s used as thepassivation layer on the semiconductor device.This paper mainly works on Polyimide Litho process setup and thesolution of some process issues. Polyimide material takes the place ofphoto resist in Litho process, but it brings up many difficulties in Lithoprocess setup, due to its special chemical characteristic which is quitedifferent from normal photo resist, for example, the high viscosity. Themain problem can be summarized as Polyimide resist residue and resistedge peeling up. This paper not only finishes the work of PolyimideLitho process setup which make it starts mass production smoothly, butalso solve the two main process issue, polyimide resist residue and resistpeeling up, through a lots of experiments and researches.In chapter1of this paper, firstly, it simply introduces the specialproperties of Polyimide and Polyimide’s application in semiconductordevices, Litho process flow and resist properties, and also combines withthe special properties of polyimide and polyimide Litho process, illustratesthe difficulty and particularity of Polyimide Litho process. And also theresearch background of this paper.In Chapter2, sooner or later, it introduces Litho process flow in detail,especially about Polyimide Litho process, introduces Track and Stepperworking principal, mainly illustrates the process parameter setting basis ofeach Litho step, tool recipe adjustment methods and experiment methods. From Chapter3, the paper focuses on studying the Polyimide resistresidue problem possibly caused by coating system and coating process;the affect on resist residue and resist edge peeling issue from Litho bakingprocess, especially soft bake process; optimization on Litho develop recipestep by step through several times of parameter adjustment in developrecipe, and finally solve the problems of Polyimide resist residue and resistedge peeling. Except for process parameter adjustment, there are alsoimprovements on hardware, for example, changes on coating arm toprevent wafer drop and on resist dispense system to prevent resistcrystallization.In addition, in Chapter6, the paper introduced Polyimide processflow optimization and polyimide resist batch control, and finally decreasethe Polyimide Litho defect.