Characterization of Ion‐Implanted Photoresist Films by Fourier Transform Infrared Spectroscopy

Abstract

Positive photoresist was characterized by Fourier transform infrared (FTIR) spectroscopy after high dose, high power ion implantation. The concentration of individual components in the resist such as the photosensitizer and organic C‒H bonds were determined independently by examining the integrated absorbances at the corresponding infrared absorption peaks: 2040–2200 cm⁻¹ for the sensitizer, and 2820–2995 cm⁻¹ for the stretch of C‒H bonds. Degradation of the sensitizer was found to be largely due to the elevated wafer temperature which is dependent on the heat generated by the ion implant and the cooling mechanism of the implanter. The thickness of the carbonized layer can be estimated by the loss of C‒H bonds, which is in agreement with SEM results. A study of the implanted resist which was subjected to an oxygen plasma shows that the increased ashing resistance is due to the formation of the carbonized layer. The carbonized layer also reduces the degradation of the sensitizer in the implanted resist when exposed to an oxygen plasma.