A comparison of planarization properties of TEOS and SiH/sub 4/ PECVD oxides

TEOS and SiH/sub 4/ PECVD films were deposited over patterned polysilicon in a parallel plate batch reactor. Both films were then etched using an etchback planarization process. Deposition and etch uniformity and quality were compared using optical thickness measurements and SEM (scanning electron microscope) cross sections. Electrical yield was also calculated for contact strings using each type of oxide. Nitrous oxide and oxygen were compared as reactants with TEOS. The use of O/sub 2/ gave the best TEOS product wafer deposition uniformity, 13.3% (3 sigma ). Overall uniformity for SiH/sub 4/ PECVD product wafers was 15.5% (3 sigma ). Etch uniformity was 5.0% (3 sigma ) for TEOS compared to 17.0% (3 sigma ) for SiH/sub 4/ films. TEOS step coverage before and after the etch was superior to SiH/sub 4/.<
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