Stress in chemical-vapor-deposited SiO2 and plasma-SiN<i>x</i> films on GaAs and Si

Abstract

Stress was measured in films of chemical-vapor-deposited SiO2 and plasma-deposited SiNx on GaAs, in the temperature range 20–300 °C, using the laser beam deflection method to measure curvature of the substrate. Film thickness was in the range 1000–7500 Å. SiO2 films with and without P doping were deposited at 425 °C in a silox reactor. Stress in these films is independent of film thickness. The intrinsic stress σi is tensile with σi=5.1×109 dyne/cm2 and dσ/dT =12.6×106 dyne/cm2 °C for undoped films. P doping decreases the value of each of these parameters. Films of SiNx were deposited at 500 °C in a plasma-reactor. Both σi and dσ/dT decrease with film thickness, with values on the order of 5–15×109 dyne/cm2 and 15–35×106 dyne/cm2 °C, respectively. Annealing of films, deposited on Si, at temperatures in the range 500–700 °C does not affect stress in SiNx. However, stress relief is observed in both undoped and P-doped films of SiO2.