INTRINSICALLY ABSORBING POLYMERS FOR ANTIREFLECTIVE COATING APPLICATIONS

DEEP UV AND I-LINE LITHOGRAPHY WILL BE USED EXTENSIVELY THROUGHOUT THE 1990'S TO BUILD SUBMICRON INTEGRATED CIRCUITS. RECENT STUDIES WITH COMMERCIAL DEEP UV AND I-LINEPHOTORESISTS HAVE SHOWN THAT THEIR PERFORMANCE FALLS DRAMATICALLY WHEN PRINTING OVER REFLECTIVE SUBSTRATES SUCH AS POLYSILICON AND ALUMINUM. THE FORMATION OF STANDING WAVES AND STRAY REFLECTIONS CAUSES A SEVERE LOSS OF RESOLUTION AND CD CONTROL. THE SIMPLEST APPROACH FOR CONTROLLING REFLECTIVITY PROBLEMS IS TO APPLY A LIGHT ABSORBING POLYMER FILM, OR ANTIREFLECTIVE COATING (ARC), BENEATH THE RESIST. ARCS HAVEBEEN USED SUCCESSFULLY FOR THE PAST DECADE BY CHIP MAKERS WORKING AT G-LINE. THE HIGH ABSORPTIVITY OF THE ANTIREFLECTIVE COATING IS OBTAINED BY THE ADDITION OF DYES TO THE POLYMER COATING. TO BE COMPATIBLE WITH SUBMICRON PROCESSING, ANTIREFLECTIVE COATINGS FOR I-LINE AND DEEP UV LITHOGRAPHY MUST BE EXTREMELY THIN ( 0.1 MUM) AND PLASMA ETCHABLE. OBTAINING ADEQUATE ABSORPTIVITY WITH SUCH THIN FILMS IS DIFFICULT USING A CONVENTIONAL DYE-FILLED POLYMER COATING. THE SOLUTION TO THIS PROBLEM IS TO DEVELOP POLYMER COATINGS WHICH ARE INTRINSICALLY ABSORBING AT THE EXPOSURE WAVELENGTH. THIS INNOVATION ELIMINATES THE NEED FOR DYES AND ALLOWS THE OPTICAL DENSITY OF THE ARC TO BE INCREASED. DURING PHASE I WE WILL INVESTIGATE THE PREPARATION OF NOVEL INTRINSICALLY ABSORBING POLYMERS FOR I-LINE AND DEEP UV ARC APPLICATIONS. THE POLYMER STRUCTURES WILL BE DEVELOPED USING RESULTS FROM PHYSICAL PROPERTY DETERMINATIONS AND REALLIFE LITHOGRAPHIC TESTING.