Application of TMAH Reclamation in LSI/LCD Manufacturing

摘要

In the semiconductor industry, it is imperative to minimize environment loads and to reuse resources as much as possible. Authors have developed a new tetramethylammonium hydroxide (TMAH) reclamation system consisting of electrodialysis and ion exchange resin, which produces pure reclaimed TMAH from developer wastes. TMAH is a strong-alkali organic, and its high-concentration aqueous solution (2.38 wt% in general) is used as photoresist developer. Developer wastes containing TMAH in large amounts are difficult to be treated with the conventional methods. They are usually disposed off site as industrial waste after their volume is reduced by means of concentration. The cost of the development process remains high because expensive developer (TMAH) is used in large volume. It is urgently required, therefore, to develop an effective TMAH reclamation/reuse system. The newly-developed TMAH reclamation system consists of two steps: electrodialysis step and ion exchange step. In the first step, TMAH concentrate is selectively recovered from developer waste. Residual photoresist and other impurities are removed in the second step from the TMAH concentrate. TMAH reclaimed in the new system is found to feature the same purity as fresh TMAH.