Pattern density and process related CD corrections at 32nm node

摘要

With mask critical dimension (CD) uniformity requirements becoming tighter with each new technology node, mask manufacturing must deploy a wide range of corrections to meet the CD specifications. These corrections compensate for e-beam proximity effects, fogging effects, etch loading effect, and other global process non-idealities. In this paper, we present data demonstrating that the current capability of universal e-beam dose corrections meets 32nm CD uniformity requirements in the presence of various systematic CD errors. Given that the resist process demonstrates enough latitude to accommodate the required dose variations, it is the stability and repeatability of the process itself that limits the ability to meet CD requirements. Substrates, resist coating, post-coat delay, develop variations, and etch stability all contribute to CD variations. Rather than simply focusing on reducing systematic errors, the process stability must be addressed.