Evolution, Challenges and Attributes of Near Micron Sized TaN Resistors for Mixed Signal IC Applications From a Lithography Perspective

In this paper, the evolution of various lithographic processes aimed at fabricating robust tantalum nitride (TaN) resistors in GaAs-based BiFET and BiHEMT technologies are discussed in detail. Such approaches include the common image reverse photograph process (via amine poisoning) using a positive tone resist, the use of a chemically amplified negative tone resist, and also straight patterning of a positive tone resist. The aforementioned approaches were found to have their own unique challenges as it applied to printing robust TaN-based resistors approaching nearly a micron in width which is needed for high density mixed signal designs. We will explore many of these challenges in detail for the various lithography schemes.