P‐7.7: Study on Improvement of Aberrant TFT Pattern by Mask Design

Abnormal TFT pattern were found after half‐tone exposure, development and etching process during the common "U" pattern type TFT process. The causes of abnormal TFT pattern were analyzed, and 9 kinds of TFTs with increased exposure dose in channel were designed in this paper. The experimental results showed that the 9 different designs of TFTs could solve the abnormal TFT pattern completely or partly. When the channel length at the position with the lowest exposure dose was designed to 5μm, the highest process tolerance was presented. Finally, a 32‐inch panel was produced by using TFT channel length with 4.7μm at the position of minimum exposure dose, and high yield & reliability results were obtained. Other types also provide improvement new idea for subsequent optimization.