Under-Layer Effects For Block Levels: Are They Under Control?

Challenges in block levels due to the dilemma of cost control and under-layer effects have been addressed in several papers already, and different approaches to solve the issue have been addressed. Among the known approaches, developable BARC and under-layer aware modeling are the most promising. However, in this paper we will discuss and explain the limitation and inefficiency of both methods. In addition, as more block levels are employing etching step, the under-layer dependent etch behavior that we see in some of the block levels is also discussed. All these place great challenges for block level process development. We discuss here possible solutions/improvements including: developable BARC (dBARC) thickness optimization for specific under layers; Simplified model based corrections for litho and etch. This work was performed at the IBM Microelectronics Div, Semiconductor Research & Development Center, Hopewell Junction, NY 12533