Global optimization of process parameters for low-temperature SiNx based on orthogonal experiments

Low-temperature silicon nitride (SiN_x) films deposited by plasma-enhanced chemical vapor deposition (PECVD) have huge application potential in the flexible display. However, the applicability of SiN_x largely depends on the film’s general properties, including flexibility, deposition rate, residual stress, elastic modulus, fracture strain, dielectric constant, refraction index, etc. Process optimization towards specific application by conventional experiment design needs lots of work due to the interaction of muti quality and process parameters. Therefore, an efficient global optimization approach for the process technology was proposed based on the Taguchi orthogonal experiment method considering muti-factor muti-responses. First of all, the Taguchi orthogonal experiment design and analysis was used to rank the influences of main process parameters on the quality characteristics, including radio frequency (RF) power, pressure, silane flow rate, ammonia flow rate and nitrogen flow rate. Then, the global optimization approach was carried out utilizing the multi-response optimizer considering the combination target of film formation rate, residual stress, dielectric constant, elastic modulus, fracture strain, refractive index. Finally, the optimal solution of the SiN_x film was finally obtained and verified.