Low cost micro-led tft technology using ltps and oxide semiconductors

We developed bulk-accumulation (BA) mode oxide TFTs by electrical connection between bottom and top gates to keep high electron density inside of TFT channel [1-4]. The drain currents of BA TFTs are 3 to 5 times higher than those of single gate, conventional oxide TFT. These are confirmed from ES/BCE inverted staggered and coplanar TFTs. Therefore, The oscillation frequency of ring oscillator and rising/fall times of shift register could be greatly improved by adopting BA mode concept. The uniformity of TFT performance and stability of TFTs are all greatly improved. We had developed blue laser annealing (BLA) of a-Si to replace the current ELA technique [5-6]. The drawbacks of ELA are high manufacturing cost, very weak under mechanical strain such as rolling and folding. This comes from the small grain size and the protrusions at the grain boundaries which could be easily broken during the folding of the substrate. On the other hand, there is no protrusion in BLA TFT channel so that very stable under mechanical strain [5-6].