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4. Filing Rapid Thermal Chemical Vapor (RTCVD)

RTCVD (Rapid Thermal Chemical Vapor Deposition) is the atmospheric pressure CVD (APCVD) has, based on induction heating, optical or radio frequency heating of the substrate and material support substrate so that the temperature the plant quickly reach the reaction temperature. Laboratories RTCVD graphite boat by radio frequency (RF) heating. Aspire 3000 battery LCBTP03003 RTCVD inner wall of the reaction temperature is lower, it does not react to the energy deposition occurs, so RTCVD are cold reactor wall. With the high deposition temperature polysilicon thin film of other commonly used methods: such as low pressure CVD (LPCVD) and liquid phase epitaxy (LPE) over, TRCVD The main advantage is the relatively simple devices, the deposition rate of high-speed heating and cooling (and hence less energy consumption) Simple answer, there are a variety of combinations to choose gas source. Some method of deposition on the growth rate anisotropy is strong (as EPA), this effect is much lower in the CVD process, which is heterogeneous in the polycrystalline and epitaxial thin film on a substrate is very important.

 

CVD deposition of a thin film of crystalline silicon crystal growth from the vapor phase of the complex physicochemical processes. Growth process can be divided into the following steps:

 

1) The transport of reaction gases in the drop zone and spreads to the substrate surface; PB991A PB992A PB994A

 

2) The reaction of molecules adsorbed on the surface of the substrate;

 

3) The reactive chemical reactions between molecules. Generated silicon atoms on the surface migration, aggregation, deposition;

 

4) The adsorption reaction by-products and left the drop zone.

 

The above steps took place one after another, the total deposition rate is determined by the slowest step in the decision, then the rate of deposition of layers mainly by the decision, the above measures 1 3. Overall, the temperature is low, the reaction of the chemical reaction between molecules determine the rate of growth of thin films (a situation that control the reaction rate), the temperature is high, the deposit rate will be more subject to control chemical reaction rate. At that time, to reach the reaction surface of the substrate will determine the number of molecules the size of the deposition rate (a situation that the transfer of control of mass). PP2182D PP2182L HSTNN-LB31

 

Secondly, the solid phase crystallization of amorphous silicon thin film method (SPC)

 

Solid-phase crystallization technique (CPS) is to the solid state in the thin amorphous silicon atoms in silicon layers are activated, restructuring, so that thin layers of amorphous silicon thin polysilicon crystallization technology Film. It is characterized by the occurrence of crystallisation of amorphous solids below their melting temperature after the temperature of crystallization. Low-cost poly-silicon thin-film solar cell, tends to be used as a substrate of glass cheap, silane gas as raw materials, the growth method of PECVD a-Si: H film, then heat-treated in a polycrystalline silicon thin film method. This technique has the advantage of large area thin films can be prepared, may be far from in-situ doped, low cost, a simple, easy to form a production line. Conventional furnace annealing at high temperature, rapid thermal annealing, the metal-induced crystallization, the crystallization induced by microwave part of the scope of the solid phase crystallization. Inspiron 1300 battery Inspiron 1318 battery

 

1. Conventional high-temperature furnace annealing

 

The method is of high purity nitrogen in a vacuum, or under the protection of the thin layer of amorphous silicon in the annealing furnace into the amorphous polysilicon. It is the use of the recrystallization of thin amorphous silicon to polycrystalline silicon thin films prepared by one of the most direct and simplest method, but also the first country people to adopt a crystallization technology.

 

In addition to the grain size of a thin film of polycrystalline silicon by effects of temperature, the condition of the initial structure of amorphous silicon film is also closely linked. Preparation of thin films of amorphous silicon in many ways, such as magnetron sputtering, the CVD method. Under normal circumstances, the use of the CVD method and prepared a-Si: H thin films after solid-phase crystallization, the grain can be better quality and larger size of polycrystalline silicon thin film. Because the method of depositing thin films of amorphous silicon, which contains large quantities of hydrogen. In fact, the deposition conditions on the preparation of a-Si: H films in the H content and its relationship with the combination of Si means the monitoring of solid phase crystallization process of thin layers of polysilicon and nature material plays a crucial impact. Sony VGP-BPS8 Sony VGP-BPS8A  a-Si: H films deposited at low temperature, solid phase materials in thin layers of polycrystalline silicon crystals obtained after the grain will be. Because the low temperature deposition of amorphous silicon materials has led to a higher state of disorder, making the nucleation method of solid phase crystallization (SPC) of thin films of polysilicon prepared by low density and therefore greater grain size.

 

For the CVD method is used, compared to direct deposit obtained materials in thin layers of polysilicon columns, using solid phase crystallized thin film polycrystalline silicon material obtained has a size larger grains, leading to its high carrier mobility rate. At the same time, it also found that the deposition of a-Si: H thin films after crystallization in solid phase, its increases in grain size with film thickness. Typically, for about the temperature to 400 ℃ under the conditions of depositing a-Si: H thin-film solid-phase crystallization process is the a-Si: H thin-film at about 600 ℃ under the conditions of heat treatment of approximately 15 hours. Through such a process may be CVD a-Si: H thin-film phase completely transformed into polycrystalline silicon. In addition, the study found that the use of PECVD deposition of thin films of amorphous silicon, low substrate temperature, deposition rate of the highest degree of disorder in the films of amorphous silicon will be higher using the crystallization polycrystalline silicon thin film amorphous silicon obtained grain size of the film will be larger; PA-10 PA-12 PA-16 a-Si film thicker polysilicon films crystallized after the grain size while the largest, but the time required for complete crystallization more long. In addition, other measures to facilitate access to large grain polysilicon thin-film quality, such as VCD thin film polysilicon increased processing ion implantation, using the method of strain polycrystalline silicon thin film was produced in the formation of some structural disorder of amorphous regions, reducing the nucleation center of origin, after annealing for more polysilicon thin photographic materials, and also can then take called “part of the doping method” to achieve the increase in grain size, two layers of film deposited on the substrate and the lower doped with phosphorus, as a nucleation layer, the upper part is Doping not, as a layer of crystal growth, after annealing can also obtain a larger grain, and found that the higher the degree of disorder of the undoped layer, the grain will be larger.

 

People have always thought that this tradition of classic high-temperature furnace annealing is a problem that is limited only by the glass substrates at a lower temperature (600 ℃ or so) annealing, but at a lower annealing temperature, the annealing time up to 10 hours long. However, with the technology of preparation of glass is currently developing and improving a number of glass can withstand temperatures get higher and higher, such as Corning 1737, the softening point temperatures as high as 975 ℃. With the glass as9T215 P/N 310-4804 A1021

 

The method of crystallization of simple equipment, easy operation, process maturity, and easy to control the crystallization conditions, and may be a large area, processing large volumes, is used in the preparation of polycrystalline silicon thin polycrystalline silicon thin film solar cell materials, there is a good perspective of industrial applications.

 

2. Metal induced crystallization (MIC)

 

In the amorphous silicon thin film coating the top layer of metal film or metal film coated on the substrate plating layer of amorphous silicon film so that the amorphous silicon with metal contacts, which can significantly reduce temperature crystallization of amorphous silicon (300 ℃, the crystallization can take place), shorten the time crystallization, and so-called metal-induced crystallization in solid phase. Metal induced solid phase crystallized polysilicon films Prepared crystallization time, micro-structure and grain size with deposition PECVD a-Si: H thin film deposition temperature and substrate surface is completely foreign to the state. Therefore, the metal induced solid phase crystallization of amorphous silicon thin-film original condition asking a lot, you can significantly reduce the scope of conditions of thin film deposition process. However, they are heavily dependent on the choice of metal type and annealing temperature. Can be used to trigger a lot of metal, such as the A1, Au, Ni, Pt, Ni, Cr, Pd and so on, metals, induced effects are slightly different. Metal-induced crystallization phenomenon since the 20th century was discovered 70 years, there have been many theories to interpret, some are more successful, they can explain many phenomena observed experimentally. M7332 402018-001 371790-001 According to the theories related to the process of crystallization can be described as follows: when the temperature rises and supported, metal and silicon inter-diffusion and then react to form the metal-silicon, generating a mixture of a silicon. For silicide metal, this mixture is a silicide, for a total of dissolved metals, such a mixture is a total melt metal and silicon. Under certain temperature, the metal-Si bond formation and rupture processes, but because of the free energy of crystalline silicon in a low, metal-Si bond breakage following the liberation of atoms silicon tend to neighboring silicon atoms to form a stable crystalline keys If participation in this process of metal-sufficient if it would release a sufficient number of atoms of silicon to form silicon micro -grains. Silicon grains came after the formation of crystalline silicon / metal mixture of silicon / amorphous silicon structure system. Then the formation of silicon-metal bond and breaking the reaction process is still ongoing, but in the crystalline silicon / metal interface of a mixture of silicon bonds have dominated the process of fracture, while in the metal a mixture of silicon / amorphous silicon in the formation of the binding interface dominated. Producing this difference is due to the free energy remains with the amorphous silicon is higher than the crystalline silicon. The whole system (crystalline silicon or mixture of metal structure Si Si /) in the continuous process of thermal motion tends to the free energy is always decreasing. In addition to crystalline silicon interface generated by the excess metal atom must pass through the metal to achieve a mixture of side silicon amorphous silicon to make this response to be effective, a mixture of metal a silicon crystal thickness will be restricted when speed. PPP012L F1781A PA1650 In addition, if the metal mixture volume of silicon is too small, which is involved in metal-Si bond as reflected by the number is too small, then the interface per unit time per unit area to produce a quantity limited fracture effectively, thus limiting the rate of crystallization. This process makes the silicon grains grow older, while promoting the metal-silicon mixture of forward movement, the last metal layer and the layer switching layer of amorphous silicon occurs, the amorphous silicon polysilicon. Briefly, by co-melting metal or metal silicide metal-induced crystallization to participate, they are based on the same mechanism, namely, metal-Si bond breaking and reorganization of the audit process heat to promote a regional reorganization of the network, and because of its intrinsic crystalline silicon free energy lower than the amorphous.

 

In recent years, to prepare for the polycrystalline silicon thin-film solar cells, polycrystalline silicon thin film transistors of polycrystalline silicon materials, it is the crystallization technology, much research. As the aluminum content-rich, low price, so a number of aluminum-induced crystallization unit Beishou search of all ages. Many studies have shown that in aluminum-induced crystallization process that affect the quality of polycrystalline silicon thin film parameters are numerous, especially in annealing time, annealing temperature, aluminum, and the ratio thickness of amorphous silicon film, the grain size of aluminum, Al / a-Si interface conditions. The higher the annealing temperature, grain size, the largest, but the rate of crystallization is slower; thick amorphous silicon film is constant, with increases of films of aluminum thickness, the crystallinity of thin films polysilicon has increased the size of the largest grain. In addition, increasing the grain size of polycrystalline aluminum, or aluminum and A-Film increase if a thin layer between Al203, PCGA-AC16V6 PCGAAC19V3 VGP-AC16V7 also cause the increase of silicon grains with a reduced rate of crystallization.