Study On The Kinetic Mechanism And Thermodynamic Mechanism Of Aluminum - Induced Amorphous Silicon Crystallization

To alleviate the amorphous silicon thin film’s optical-induced degradation and broaden the scope of spectral absorption, people widely used annealing crystallization of amorphous silicon film currently to preparation polysilicon, microcrystalline silicon and nanometer silicon thin film materials which are superior performance and widely use. Direct annealing often requires high annealing temperature and its preparation takes a long time. Using metal induced crystallization, can effectively reduce the crystallization temperature, and improve crystallization efficiency. Al is a kind of low cost and simple preparation metal materials.Not only well induce crystallization,but also can be a p-type doped of silicon thin film materials.It is the ideal induced crystallization metal. Using cheap substrate prepare amorphous silicon thin film by aluminum induced, can achieve the goal of low temperature, fast and low doping.In this paper, based on the film’s thermodynamics mechanism and kinetics mechanism, put forward the theoretical hypothesis of the aluminum induced amorphous silicon crystallization process. Using the magnetron sputtering coating system preparation of amorphous silicon thin film and aluminum thin film. Using rapid optical thermal annealing to annealing. Combining theory assumes discuss the dynamics process of low temperature rapid growth and growth mechanism. According to the growth of nucleation theory, to study the function of surface energy, interface energy and activation energy. To clarify the amorphous silicon thermodynamic driving force and kinetics mechanism. Emphasis was study the low temperature and rapid growth of the high quality silicon thin film. At the same time explore method to reduce using metal aluminium and elimination of excess aluminum.This paper mainly completed the following several aspects of the research work:1. Sort out literature, preparing the early stage experiment. In this magnetron sputtering system, preparing amorphous silicon thin film and aluminum thin film. Measure the film thickness and uniformity, and calculate the deposition rate. Summarizes the system within the best annealing time by rapid thermal annealing. The results show that: The radio frequency(rf) magnetron sputtering system power 100 w can prepare amorphous silicon thin film well. Double pulse power 70 w can prepare Al thin film well.2. According to the theory of the thin film growth dynamics, proposing aluminium film heat treatment to improve the annealing effect. By using substrate heating or room temperature and aluminium film heat treatment to prepare Si(400)/Al/a-Si thin film. Results show that aluminum induced amorphous silicon have four dynamic process. Confirmed the aluminum film play a key role in the crystallization process. It can effectively enhance the induced crystallization effect.3. According to the thermodynamic theory of thin film growth, research from two of the amorphous silicon crystallization process: The diffusion of the Si, nucleation and grew up. Through natural oxidation of Al film preparation of the middle oxide layer. Explore the diffusion rule of Si. Try to annealing crystallization by the low temperature. The results show that: the middle oxide layer made crystallization well and can get larger grain and uniform structure film. Under low temperature, temperature decide the diffusion of Si. Too thick oxide layer can block the diffusion of the Si. Big Al grain and "wetting" of Al to Si grain can induce nucleation at low temperatures4. According to the laws of Al diffusion process, using standard aluminum corrosion liquid corrosion and double Al thin film structure, explore the technology of excess eliminate and reduce aluminum dosage. The results showed that: Al layer thinner, annealing crystallization effect is poorer. Increase the thickness of Al layer, can effectively improve the effect of crystallization. Using standard Al corrosion liquidcan effectively remove excess Al. Using double Al films structure annealing well in a short period of time. Double Al film structure use less Al.