Spray Coating Technology of Photoresist/Polymer for 3-D Patterning and Interconnect

A relatively little known form of photoresist coating or polymer application for special applications of 3-D structured wafer patterning and interconnection by spray technology has been studied. Specifically, the study was on the OmniSpray coating technology developed by Electronics Vision Group Austria [1,2]. Results of the present investigation confirm the superiority of the technique in comparison with the more conventional spin coating method in term of its ability to cover extreme 3-D structure conformally to enable 3-D patterning, and its significant reduction of expensive high-viscosity photoresist/polymer consumption for 3-D interconnect purposes. Special attention is paid to the improvement of photoresist coverage on the convex corners of the 3-D structure by rounding them off first in a TMAH solution, as well as the uniformity improvements in addition to the lower materials consumption for the application of intermediate layers for wafer interconnect purposes. The integrated method offers an enabling technology for patterning of extensive topography and wafer-level intermediate layer application typically required for a multitude of MEMS structures and designs, novel interconnect structures as well as advanced packaging applications. The method is simple, fast and low-cost in comparison with other photoresist coating techniques available and capable of 3-D structure patterning and interconnect.