Fundamental Decomposition Analysis of Chemically Amplified Molecular Resist for below 22 nm Resolution

Molecular resists of Prot-2 and Prot-1 were synthesized for decomposition analysis and lithographic evaluation. After checking their structure, purity and thermal property, decomposition behavior was analyzed by high performance liquid chromatography (HPLC). From the analysis, it was found that the main reaction in an exposed area was the deprotection reaction of the protecting group in electron beam (EB) and extreme ultraviolet (EUV) lithography. The exposure dose at which the conspicuous deprotection reaction occurs coincides with the exposure dose at which the resist film thickness reduces. Furthermore, the resists which include completely deprotected group, partially deprotected group and completely protected group, which dissolution rates were different coexist at the boundary between an exposed and an unexposed region. The fundamental decomposition-analysis results indicate that the line edge roughness (LER) is caused by the existence of the different dissolution rates of resist component materials at the boundary between an exposed and an unexposed region. After confirming the fundamental analysis, these molecular resists were evaluated on a lithographic performance by EB lithography. Resist-A consisting of Prot-1 showed 20 nm hp resolution at the exposure dose of 36 μC/cm2. In this paper, we will discuss about the resolution and the LER property of molecular resists at the point of their decomposition behavior.