In the last 2 decades, the thin film transistor (TFT) technology has advanced dramatically accompanied with extraordinary growth of market. In this paper, the author compared the history of TFTs and ULSIC as well as their markets. The unique material, process, and device properties of the a-Si:H TFT was responsible for its current success and established the foundation for developments beyond liquid crystal displays (LCDs). Due to different device characters and limits, TFTs and ULSIC have separate application areas. However, they can be properly integrated to create new functions and products. The knowledge obtained from the large- area TFT array studies can help ULSIC migration to 15-inch wafers.