Progress of hard mask material for multi-layer stack application

Abstract

Multi-layer stack application will be established at manufacturing process beyond 65nm node. Multi-layer stack application means laminated layer like a Photoresist, Si contained hard mask, and Carbon hard mask on substrate. Multilayer stack application can be solved anti-reflection at hyper NA (that means more than 1 numerical aperture) and less etching resistance in thinner film resist, so Multi-layer stack application is required for 193nm immersion lithography process. And criteria of our material in Multi-stack application are spin-on and drain compatible type. In this report, we will discuss about Spin-on Si-contained hard mask and spin-on carbon hard mask criteria, our experiment and results to solve issue. Spin-on Si-contained hard mask is required 3-factors that is unti-reflection from substrate at hyper NA conditions, resist matching, and higher etching resistance. It is general that higher Si-content ratio in based polymer can't be matched with current 193nm photoresist. But Lower Si-contained Hard Mask can't be resisted by dry etching. In this report, we will discuss about our material approach for good resist matching (no footing issue) without reduction of Si-content ratio, pattern transfer ability by dry etching, and reflectivity simulation results at Hyper-NA condition. LWR issue after dry etching is key factor of Multi-layer stack application. We estimate that composition of based polymer in carbon hard mask material and film density in carbon Hard Mask is relative to LWR issue after dry etching. In this report, we will discus about our material approach for less LWR issue after dry etching.