Study of high efficient Plasma Immersion Ion Implantation hydrogenation for CMOS poly-Si TFTs using an ICP plasma source

Summary form only given. A low energy (1-2 keV), high dose rate (/spl sim/10/sup 16//cm/sup 2/ sec) plasma immersion ion implantation (PIII) hydrogenation process has been performed for defect passivation in polycrystalline silicon (poly-Si) thin film transistors (TFTs). An ICP source and a 16.7 kHz pulse generator were used. The device parameter improvements are saturated in 5 minutes, which is much shorter than other hydrogenation methods. These results have been achieved in one sixth the implant time of our previous PIII hydrogenation experiment. A combination of implantation and diffusion of hydrogen species during PIII has been found to be a major mechanism of PII hydrogenation. Compared to our previous PIII hydrogenation experiment, the low energy, high dose-rate PII hydrogenation experiment has a higher hydrogenation efficiency. The ICP system allows higher dose rate due to its higher hydrogen ion density (6/spl times/10/sup 10//cm/sup 3/ in contrast to 2.5/spl times/10/sup 10//cm/sup 3/) from our microwave plasma source and lower working pressure (0.6 mTorr in contrast to 50 mTorr needed for our microwave plasma source). Ion implantation in the lower pressure plasma can obtain higher dose than the higher pressure plasma under the same process conditions because there are less collisions. In addition, low energy ion implantation can reduce etching rates of Si and SiO/sub 2/ materials and charging effects. Low energy ion implantation can also decrease the secondary electron emission. All of these effects increase the dose rate.