Comparison of properties between rapid thermally processed and conventional furnace pyrolyzed plzt thin films

Abstract

PLZT thin films of composition 2/55/45 (La/Zr/Ti) were spin coated from acetate precursors and crystallized by rapid thermal processing (RTP) and conventional furnace pyrolysis (CFP). One experiment isolating the effects of thermal processing from deposition technique involved a comparison of rapid thermally processed films, produced with a computer controlled automatic spin coat reactor/analyzer, with conventional furnace pyrolyzed films, fabricated manually using a photoresist spin technique. Heating rates of at least 70°C per second for RTP versus 35°C per second for CFP yielded differences in film properties with thermal processing technique. All of the films were spun on Pt-coated Si substrates and were fired at 700°C for 15 total minutes; however, different firing schedules were utilized with variable individual layer firing times and post-anneal times. These variable firing schedules also yielded noticeable differences in film properties. Film thickness, measured with a laser ellipsometer, ranged from 0.4 to 0.5 μm. RTP thin films exhibited improved crystallinity, smaller grain size and better saturated hysteresis loops than CFP films. Higher dielectric constants of 715-1700 and lower coercive fields of 34-64 kV/cm were also observed in the RTP films compared to 600-740 and 63-104 kV/cm, respectively, for CFP films. © 1994, Taylor & Francis Group, LLC