Internal Stress of Sry Film Resist in Multilayer Structure

Multilayer resist process has been recognized as one candidate to realize high aspect ratio resist pattern. As one important control factor, strain and stress matching in multilayer structure should be taken into consideration. By using a strain gauge, the strain of dry film resist (DFR) in single, double and triple layer structure are measured as a function exposing time. The strain of DFR increases in proportion with the exposure dose but slightly decrease as number of multilayer. The stability of DFR multilayer structure is discussed.