LITHOGRAPHY USING CONVENTIONAL, COMMERCIAL RESIST SYSTEMS

BY OPTIMIZING CONDITIONS, CONVENTIONAL ELECTRON BEAM BY OPTIMIZING CONDITIONS, CONVENTIONAL ELECTRON BEAM RESISTS, SUCH AS PBS, CAN BE USED TO PRODUCE GEOMETRIES IN THE 0.3 TO 0.5 MICRON RANGE IN A CONTROLLED MANNER, USING RASTER SCAN WRITING TECHNIQUES IN A LIMITED PRODUCTION ENVIRONMENT. IN ORDER FOR THESE PATTERNING TECHNIQUES TO BE USEFUL, THE DEFECT DENSITY OF THE FINAL PRODUCT MUST BE VERY TIGHTLY CONTROLLED AND EXTREMELY LOW (LESS THAN 0.5 PER SQ.IN). TO ACCOMPLISH THIS, SEVERAL APPROACHES WILL BE INVESTIGATED. THEY ARE: 1. PLASMA ASSISTED DEVELOPMENT OF THICK RESIST MATERIALS. IN THIS STEP RESIST FILMS WILL BE USED IN THE 6,000 TO 8,000 A RANGE, WET DEVELOPED AND THE PLASMA CLEANED TO REMOVE THE REMAINING RESIST MATERIAL. THE SOLVENT CHEMISTRY IS USED TO FORM A PARTIAL RELIEF IMAGE WHICH WILL THEN BE ENHANCED BY PLASMA TREATMENT. 2. VARIATIONS IN ACCELERATING VOLTAGE WILL BE INVESTIGATED TO PRODUCE HIGHER CONTRAST EXPOSURE. THESE PARAMETERS WILL BE FIRST MODELED THROUGH COMPUTER SIMULATION AND THEN PRODUCED IN RESIST AND CHECKED BY SCANNING ELECTRON MICROSCOPY ANALYSIS. 3. PRESENT SOLVENT CHEMISTRIES WILL BE MODIFIED TO BE MORE SELECTIVE TO LOWER MOLECULAR WEIGHT SPECIES, THEREBY PRODUCING HIGHER CONTRAST. CARE MUST BE TAKEN TO REDUCE SWELLING AS MUCH AS POSSIBLE, WHILE MAINTAINING REASONABLE PROCESS TIMES. 4. EXISTING PROCESS EQUIPMENT WILL BE MODIFIED TO PRODUCE GREATER UNIFORMITY, BOTH IN DEVELOP AND ETCHING STEPS.