Robust PECVD SiC membrane made for stencil lithography

Abstract

Stencil lithography (SL) is a shadow mask technique which allows parallel, resistless, micro- and nano-patterning of material through apertures created in a membrane (stencil) onto a substrate. The stencils are usually made of LPCVD low-stress SiN due to its outstanding physical and chemical stability. However, limitations are found for some specific design cases, where membranes can be distorted because of the deformations induced by stress from the deposited materials. Here we present a recently developed PECVD SiC shadow mask for applications in SL. The SiC has higher Young’s modulus than SiN, which transfers to a better performance for SiC stencil than the shadow mask made of SiN in terms of robustness to the stress-induced deformation. We show direct local etching of SiO2 through SiC stencil, otherwise impossible with SiN masks. SiC stencils with both compressive and tensile stresses were fabricated and compared to the SiN stencils. The higher robustness to deformation and better resistance to etching of the SiC membranes allow for a wider choice of the deposited materials, leading themselves to a more precise pattern duplication and less complicated resistless dry etching applications.