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1、无 锡 职 业 技 术 学 院毕业设计说明书(英文翻译)- 7 -Preparation of polysilicon thin film Abstract: The low pressure chemical vapor deposition, solid-phase crystallization, excimer laser crystallization, rapid thermal annealing, metal-induced crystallization, and plasma enhanced chemical vapor deposition reaction is us
2、ed for the preparation polysilicon thin film of several major ways. They have their different preparation principle, the crystallization mechanism, and their advantages and disadvantages.Key words: hydrogenated amorphous silicon and polysilicon grain The preparation methods of polycrystallinesilicon
3、 film 1 Introduction At the same time polysilicon thin film materials with silicon materials and the high mobility of amorphous silicon materials can be large, the advantages of low-cost preparation. Therefore, the polysilicon thin film materials of growing concern, the preparation of polycrystallin
4、e silicon thin films can be divided into two categories: one category is high-temperature process, the preparation of the temperature is higher than 600 , and the use of expensive substrate quartz, but the preparation of relatively simple. The other is low-temperature process, the processing tempera
5、ture is below 600 , can be used for low-cost glass substrate, thus producing large area, but the preparation of more complex. Currently polysilicon thin film preparation methods have the following main categories: 2 low pressure chemical vapor deposition (LPCVD) This is a direct polysilicon producti
6、on methods. LPCVD IC is used in the preparation of polysilicon thin film commonly used by the standard method, a fast-growing, film-forming dense, uniform and equipment, such as large-capacity features. Silane gas polysilicon thin film can be directly deposited by LPCVD method in the substrate, the
7、typical deposition parameters are: silane pressure of 13.3 to 26.6 Pa, deposition temperature Td = 580 630 , the growth rate of 5 to 10 nm / min . The deposition temperature higher, such as ordinary glass softening temperature at 500 to 600 , it can not use cheap glass and must be used for expensive
8、 quartz substrate. LPCVD of polysilicon thin film growth, grain is preferred orientation, morphology in a V shape, containing high-density micro-twin crystal defects, and small grain size, carrier mobility rate is not big enough and to the device application subject to certain restrictions. Despite
9、the reduction silane pressure to increase the grain size, but often accompanied by the increase of surface roughness of the carrier mobility of the devices electrical stability and have a negative impact. Solid-phase crystallization 3 (SPC) The so-called solid-phase crystallization of amorphous soli
10、ds refers to the temperature of crystallization occurred below its melting after crystallization temperature. This is a kind of indirect way polysilicon production, the first to use silane gas as raw materials, with LPCVD method in about 550 of a-Si: H film, then films at 600 to a high temperature a
11、bove the melting, then a lower temperature when the nucleus, with lower melting temperature of the silicon crystal in the nuclei of to continue to increase grain into polysilicon films. Use this method, the polysilicon thin film grain size depends on the thickness of thin films and crystallization t
12、emperature. Crystal annealing temperature is an important factor in the effect of the 700 following annealing temperature range, the lower the temperature, the lower the rate of nucleation, annealing at the same time the grain size can be greater, and in more than 700 , at the grain boundary movemen
13、t has caused the mutual annexation of the grain, makes this temperature range, grain size increased with temperature increase. After a 无 锡 职 业 技 术 学 院毕业设计说明书(英文翻译)- 8 -considerable amount of research shows that the method used in the system of grain size polysilicon thin film samples with the initia
14、l degree of the disorder closely related to T. Aoyama, and others on the initial conditions for the deposition of solid-phase crystallization of the impact of the study found that the initial material disorder, solid-phase crystallization process of nucleation rate and the lower, larger grain size.
15、As the crystallization process of the formation of nuclei is spontaneous, therefore, SPC polysilicon thin film grain crystal orientation is random. Grain adjacent crystal orientation will be different from a high barrier, and the need for hydrogenation processing to improve the performance of SPC po
16、lysilicon. The advantages of this technology can be of large areas of films, the grain size larger than the direct deposition of polysilicon. Doping can be carried out in-situ, low cost, simple process, easy to form lines. SPC is due to the melting temperature of crystallization of amorphous silicon, high temperature of the crystallization process, the temperature is higher than 600 , usually require about 1100 , annealing time for more than 10 hours, doe