Crystallization of a-Si by doubled frequency YAG laser using a self-heating layer technology was proposed in this paper. The grain size and the hall mobility of the resulted poly-Si thin film were enhanced up to almost two times by using the self-heating layer technology. This technology has a dual heating effect:heat-retaining and self-heating with an easier process and wider process window, compared to the conventional capping-layer technology.

The hydrogen passivation is adopted to enhance the performance of poly-Si crystallized by YAG laser annealing (LA polySi). The effects of passivation time, passivation power and passivation temperature on the hall mobility of the LA poly-Si are investigated and the mechanism of the hydrogen passivation is preliminarily analyzed. It is found that the effect of the hydrogen passivation on the qulity of YAG laser annealed poly-Si is also correlated with the deposition method and the defect type in it.The low-temperature polycrystalline Si (LTPS) has attracted dramatic interest because of its possible applications in flat panel displays [1,2] , solar cells [3,4] , sensors [5] , etc. Laser annealing (LA) is commonly used to crystallize the amorphous Si (a-Si) in LTPS thin film transistor (TFT) fabrication process due to its good performance. However, there are still many defects in the poly-Si materials after the crystallization by laser annealing, which restrict the further improvement of its electrical performance and stability, as well as the quality of its TFTs. In this paper, the hydrogen passivation treatment is adopted to enhance the performance of poly-Si crystallized by laser annealing. This method has been used in solar cell to improve its open voltage [1] , but the application in microelectrical field has seldom concerned yet. Additionally, the double-frequency YAG (2 YAG) laser is used in this paper. The YAG laser does not require daily maintenance or highcost working materials, so its cost is lower than that of the widely used excimer laser annealing (ELA) laser. The effects of passivation time, passivation power and passivation temperature on the hall mobility of poly-Si crystallized by 2 YAG and TFTs are investigated and the mechanism is also preliminarily analyzed.Firstly, the a-Si thin films are deposited by plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LPCVD), respectively, and then annealed by 2 YAG laser with the wavelength of 543 nm. The laser annealing condition is fixed as follows: the pulse frequency is 10 Hz, the pulse width is 2-3 ns, the spot diameter is 5 mm, the scanning speed is 0.5 mm/s and the pulse energy is 380 mJ/cm 2 . Next, the resulted poly-Si is treated by H plasma with varying conditions. The H plasma emission spectra are measured by PR650 spectrascan colorimeter.During the H plasma passivation process, the hydrogen can be excited into several kinds of H plasma in the chamber and each kind of H plasma will emit light at its unique wavelength. Consequently, the passivation process can be investigated by means of optical emission spectra (OES) *

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