The TFT—circuit for addressing the picture elements of a flat liquid crystal(LC) display and the staggered structure of thin film transistors (TFT’s) will be explained. The main focus is on the vacuum processes
required for the preparation of the TFT’s together with storage capacitors and the matrix of interconnections. The gates are dc-sputtered Ta doped with 02 and N2, whereas the gate-dielectric is a double layer of anodized Ta2O5 and CVD-processed SiO2. One type of TFT’s uses evaporated CdSe, the second type works with chemical vapor deposited (CVD) a-Si:H as a semiconductor. The interconnections consist of evaporated Al, whereas the transparent electrode is sputtered ITO. A description of some types of flat LC—displays concludes the presentation.
