Low-temperatue PECVD SiO_2 on Si and SiC

摘要

The deposition of SiO_2 films by plasma-enhanced-chemical-vapor-deposition (PECVD) using tetraetylorthosilicate (TEOS) was studied. MOS capacitors were fabricated on both Si and SiC for this study. Several different sets of experiments were conducted for PECVD deposition according to different growth parameters and the results compared. For Si samples with SiO_2 deposited at a substrate temperature 300 deg C, the C approx V curve gave a flat-band voltage of 1V and a transition slope of 112 pF/V. The dielectric constant of te depositied SiO_2 film was 4.2 and the si/SiO_2 interface trap density was calculated to be 1.8x10~(10) cm~(-2). The I-V curve showed a leakage current density of 1.210~(-9) a/cm~2 and dielectric breakdown field strength of 9.2 MV/cm. For SiC samples, the PECVD deposition gave a uniform SiO_2 film with a controllable deposition rate of 0.3nm/sec. The refractive index and dielectric constant of the as-deposited SiO_2 film were 1.46 and 3.84 respectively. The I approx V curve showed a leakage current density of 2x10~(-9) a/cm~2 and a breakdown field of 4.7 MV/cm.