Combination of thick resist and electroforming technologies for monolithic inkjet application

Abstract

This paper reports a novel method for fabricating a monolithic inkjet chip by combination of thick resist photolithography and electroforming technologies. It integrates two-step photolithography process by two kinds of thick photoresists, SU-8 and JSR, and one-step nickel electroplating process to form the channels, chambers and nozzles of monolithic inkjet chip. The nickel nozzle plate can be replaced by SU8 material as second thick SU8 resist is used. The first thick resist of SU8 for both kinds of nozzle plates, nickel and SU8, is used for the structure formation of ink channel and chamber. Followed the nickel or SU8 nozzle plates are fabricated on SU8 chambers. The nickel nozzle plate is performed by second thick resist JSR and electroforming process while the SU8 nozzle plate is only by second thick SU8 resist process. A light-absorbing polymer layer is coated between two thick resist layers for protecting the first SU8 layer from overheating during the metal seed layer deposition or over-exposure during the second thick resist lithography process. A prototype of monolithic inkjet chip with a 300 dpi resolution has been successfully demonstrated.