Patent ID: 8574821
Filing Date: 2013-11-05
Classification: G03F

Abstract:
1. A process for fabricating features into a wafer using a combination of negative and positive photoresists for use with positive photomasks, resulting in masking layers suitable for bulk micromachining in the fabrication of microelectromechanical systems (MEMS); comprising the steps of: (a) spinning a negative photoresist onto the wafer; (b) spinning a positive photoresist buffer layer onto the negative photoresist; (c) depositing a barrier layer onto the positive photoresist buffer layer; (d) spinning on an image reversal photoresist layer onto the barrier layer; (e) exposing the image reversal photoresist layer with a positive mask; (f) performing a post exposure bake; (g) flood exposing the image reversal photoresist layer; (h) developing away unexposed areas of the image reversal photoresist, creating windows in the image reversal photoresist to the barrier layer; (i) etching away the barrier layer through the windows; (j) flood exposing the positive photoresist buffer layer and the negative photoresist; (k) post exposure baking the negative photoresist; (l) removing remaining image reversal photoresist, barrier layer, and positive photoresist; (m) developing away unexposed areas of the negative photoresist to form features in the negative photoresist; and, (n) etching the features into the substrate.