Low stress PECVD - SiNx layers at high deposition rates using high power and high frequency for MEMS applications

Abstract

The paper reports a new fabrication method for low stress SiNx layers at high deposition rates in a PECVD reactor using high power and high frequency (13.56 MHz) and their MEMS applications. By increasing the deposition power at 600 W in high frequency mode, a decrease of the tensile residual stress to values between 0 and 20 MPa was noticed. Meanwhile, the high power, which promotes a high dissociation of gases, generates a high deposition rate (in the range 250 to 350 nm min-1). In addition, the paper presents the influence of other important parameters that affect the residual stress and deposition rate such as pressure and SiH4, NH3 and N 2 flow rates. SiNx layers fabricated at high power in high frequency mode were successfully used in two classical MEMS applications: fabrication of the masking layer for anisotropic wet etching in KOH solution and fabrication of a low stress cantilever. © 2006 IOP Publishing Ltd.