Formation of a Positive Photoresist Thin Film by Spin Coating: Influence of Atmospheric Temperature

Abstract

Experimental formation of a positive photoresist film by spin coating at various atmospheric temperatures was investigated. The weight of the photoresist solution on a wafer during spinning decreases sharply during the first stage of spinning and gradually during the later stages. At a high temperature, the rate of outflow increases and that of solvent evaporation decreases in the initial stage of spinning, but the former decreases and the latter increases in the intermediate stages. In the later stages, both of them decrease. The baked film spun at a high temperature is thin up to the intermediate stages of spinning due to the higher rates of outflow in the initial stage and evaporation in the intermediate stages more than that at a low one. However, it becomes thick in the later stages due to the lower rates of outflow and evaporation.