Construction of built-up structures on the surface of patterned masking used for polysilicon etch

Abstract

The present invention pertains to a method for depositing built-up structures on the surface of patterned masking material used for semiconductor device fabrication. Such built-up structures are useful in achieving critical dimensions in the fabricated device. The composition of the built-up structure to be fabricated is dependant upon the plasma etchants used during etching of underlying substrates and on the composition of the substrate material directly underlying the masking material. When the patterned mask is to be used to transfer a pattern to an underlying polysilicon layer, the polysilicon may be etched using a plasma source gas which is a combination of Cl2, HBr, and optionally O2. An alternative etchant plasma utilizes a plasma source gas which is a combination of SF6, Cl2 and N2. We have developed an alternative method for depositing built-up structures depending on whether the polysilicon plasma etchant includes an HBr component. One preferred method of the present invention for depositing built-up structures upon a patterned mask surface comprises the following steps: (a) providing a patterned mask surface, wherein said patterned mask rests on an underlying substrate; and (b) depositing a polymeric built-up structure over at least a portion of said patterned mask surface using a plasma formed from a source gas comprising Cl2, a compound which comprises fluorine, and an inert gas which provides physical bombardment of surfaces contacted by said plasma. This method may be used whether or not the polysilicon plasma etchant source gas includes HBr.

Dependencies are inferred from the claim text.