Analysis of Chemical Contents Spatial Distribution in EUV Resist Using Resonant Soft X-ray Scattering Method

Abstract

EUV lithography is started to use in high volume manufacturing of 7-nm node semiconductor devices for smart phones. However, a resist development is still remained significant critical issue in EUV lithography. The EUV resist has to be achieved high resolution, high sensitivity, and low line-width roughness (LWR), simultaneously. Especially, the resist is required low LWR performance for a fine patterning. To reduce LWR, it is significant to control and reduce the stochastic behavior of the resist chemical contents such as the functional groups, photo reactive compound (photoacid generators：PAG), additives such as amines and so on. However, there is no method to measure the chemical contents spatial distribution. Therefore, the resonant soft X-ray scattering (RSoXS) method is applied to evaluate the chemical contents spatial distribution. Around the carbon absorption edge, the resonant absorption peaks are specific to the chemical contents of carbon. In RSoXS method, the soft X-ray scattering intensity from the resist is recorded by a CCD camera, which the incident photon energy irradiate to the resist sample is varied around the carbon absorption K-edge of 284 eV. If these chemical contents have large dispersion, the stochastic becomes worth. In this way, the chemical contents spatial distribution in photoresists is measured by RSoXS method, and this method is significant for development of low LWR resist.