Classification of PECVD Technology
There are many ways to prepare SiNx films, including chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LPCVD). In the current industry, the PECVD method is commonly used.
The
PECVD method can be divided into two types according to the relationship between the plasma source and the sample in the deposition chamber.
Direct method: the sample is directly exposed to the plasma, and the support of the sample or sample is part of the electrode. The indirect method, or the method of delocalization. The samples to be deposited are not directly hit on the surface of the sample outside the plasma area, and the sample or its support is not a part of the electrode.
The direct method is further divided into two parts: (1) tube type PECVD system, that is, using quartz tube like diffusion furnace tube as the depositing chamber, and using resistance furnace as heating body, a graphite boat with multiple silicon wafers can be inserted into quartz tube to deposit. This is the main manufacturer of equipment manufacturers and Chinese Kejia crystal. (2):
PECVD system is multi chip type silicon wafer placed in a graphite or carbon fiber into the deposition chamber bracket, a metal electrode, a flat type chamber, forming a discharge circuit and a sample holder, the AC electric field process gas in the chamber between the two plate effect the formation of plasma in space, the Si decomposition of SiH4 and H, and NH3 for the formation of N SiNx deposited onto a silicon surface.
The indirect method is divided into two kinds: (1) microwave method: using microwave as the frequency band of the excited plasma. The microwave source is placed outside the sample area, and the ammonia gas is removed first, then the silane gas is bombarded, and the SiNx molecule is deposited on the surface of the sample. (2) direct current method: using the direct current source to stimulate the plasma, further ionization of ammonia and silane gas. The sample does not contact with the plasma. The equipment is produced by the OTB company in Holland.
At present, in the mainstream Chinese microwave
PECVD system to occupy the market, and the tube type PECVD system also occupy a lot of share in addition to the PECVD system of several models, the American Applied Material company has also developed a PECVD magnetron sputtering system, the system uses a magnetron sputtering source bombarding high purity silicon target reaction in ammonia atmosphere in sputtering. The formation of SiNx molecules deposited onto the sample surface. The advantage of this technique is that the explosive silane gas is not used, the safety is increased a lot, and the deposition rate is very high.
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