Resonant Soft X-ray Scattering for the Stochastic Origin Analysis in EUV Resist

Abstract

The resist development is a critical issue in EUV lithography for high volume manufacturing of semiconductor devices. Especially, the resist should have low line-width roughness (LWR) performance in fine patterning. To reduce the LWR, it is significant to control and reduce the stochastic behavior in the resist material. We employed the resonant soft X-ray scattering (RSoXS) method to evaluate the non-uniformity of the resist material components such as base polymer, functional group, and photo-acid generator and so on. In RSoXS method, the soft X-ray scattering intensity from the resist is recorded by a CCD camera, which the incident photon energy irradiated to the resist sample was varied around the carbon absorption K-edge of 284 eV. Around the carbon absorption edge, the absorption spectrum had resonant absorption peaks that depended on the chemical bonding structure of carbon. The scattering signal profile of a commercial chemical-amplified resist was different at each absorption peaks, which indicated non-uniformity of resist material. Thus, the non-uniformity of the resist material was measured by RSoXS method, which was important for development of low LWR resist.