Fabrication of three-dimensional microstructures by one-step lithography with Multi-Film Thickness mask

This paper presents a 3-D microstructures forming technique by inventing a new photomask making technique called multi-film thickness mask (MFT mask). The paper also includes experiments using two 3-D microstructure forming techniques: (i) gray scale lithography mask (GSL mask) and (ii) multi-film thickness mask (MFT mask). The MFT mask is economical for the lithography process of 3-D microstructure forming, which is typically applicable to the making of micro electro mechanical systems (MEMS). A limitation of the MFT mask is that only 3-D microstructures with vertical sidewall profiles can be made.