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High Acid Amplification EUV Photo Resists

IP.com Disclosure Number: IPCOM000124187D
Publication Date: 2005-Apr-11
Document File: 3 page(s) / 45K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a series of EUV photo resists with side chains of secondary alcohols to increase acid efficiency. Benefits include increasing the sensitivity of the resist, without increasing out gassing.

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High Acid Amplification EUV Photo Resists

Disclosed is a method for a series of EUV photo resists with side chains of secondary alcohols to increase acid efficiency. Benefits include increasing the sensitivity of the resist, without increasing out gassing.

Background

Currently, there is no clear roadmap for meeting EUV resist sensitivity requirements. Some resist suppliers have tried reducing base loading to increase sensitivity of EUV resists, but this has a negative impact on LWR. In addition, the use of photodegradable bases is being investigated, but this will likely increase the out gassing levels for EUV resists.

General Description

In ionizing radiation (EUV, e-beam, x-ray), the resists (primarily polymer resins) are ionized to generate electrons that are scavenged by PAGs. Acid from the PAG is believed to be from a series of reactions between the PAG, electrons, and other free radical molecules. The efficiency of acid generation from the PAG can be increased by generating stable free radical molecules that react with the PAG. Furthermore, secondary alcohol free radicals are regenerated after decomposition of the PAG, resulting in an acid amplification effect.

The increase in acid quantum efficiency in the presence of secondary alcohols is believed to be due to the fact that secondary alcohols create stable radicals that react with the PAG. It has been shown that incorporating secondary alcohols into acrylate resins (193nm resists) increase the quantum efficiency. However in polyhydroxystyrene (PHS) resins (248nm resists), there is no improvement in the quantum efficiency of the acid when secondary alcohols are blended into the PHS resist polymers. 

The difference between PHS and acrylate systems is that the PHS groups form very stable radicals. Therefore in PHS systems, the most favorable reaction pathway is for the electrons to react with the PHS to form phenoxy (see Figure 1). Since the phenoxy radical is so stable, the transfer of the radical from the phenoxy to the PAG becomes unfavorable. Therefore onc...