Liquid phase silylation for the DESIRE process

摘要

Abstract: Liquid phase silylation is presented in this paper as a technique with improved silylation and dry development selectivity and hence improved process windows. Using this technique, the requirements imposed on silylation and dry development equipment are relaxed. The diffusion enhanced silylated resist process (DESIRE) has been presented as an attractive solution to overcome the inherent limitations of conventional wet develop lithography, such as the control of critical dimensions over highly reflective topography. Traditionally, the silylation process has been carried out using hexamethyl disilazane (HMDS), although lately, alternative gaseous agents such as tetramethyl disilazane (TMDS) have begun to exhibit certain advantages. The liquid phase silylation process simplifies the process and equipment requirements, and results in improved silylation selectivity. Liquid silylation has been found to be useful both for i-line and DUV exposures. The influences of resist and silylation solution composition have been investigated. Characterization of the silylation reaction and mechanism have been performed using thickness measurements, Fourier transform infrared spectrometry (FTIR), and Rutherford backscattering spectroscopy (RBS). Surface imaging based on liquid phase silylation has also been evaluated using phase shifting masks. The influence of partial coherence on the resolution and process latitudes using both conventional transmission masks and phase shifting masks have additionally been studied. !18