Structure Analysis Of Polycrystalline Silicon Films Prepared By ECR-PECVD At Low Temperature

By its outstanding photoelectricity performance and the low cost of manufacture, the polycrystalline silicon(poly-Si) thin film becomes one kind of extremely important electronic material in. the energy and information industries, and applied widely in the large scale integrated circuit and the semiconductor separation component. Recently, in order to reduce the manufacturing cost of the poly-Si thin film, many kinds of low temperature deposition technology have been developed. The electron cyclotron resonance (ECR) microwave plasma enhanced chemical vapour deposition (ECR-PECVD) is a particularly good means of depositing thin films at low temperatures because the ion energy in the plasma is very low and electron energy is high, and it has the advantage of high plasma density and activity.The polycrystalline silicon thin films were prepared on glass by ECR-PECVD technique using SiH4 and H2 as source gases. The microstructure and the effects of the deposition parameters, which include the substrate temperature, the flow ratio of H2, the microwave power and the seed layers were investigated by RHEED, TEM,XRD and Raman spectrum.The results showed that most of the poly-Si films have a (220) preferential orientation. The interface states of the poly-Si films were observed by TEM. It consists of two layers, which are amorphous incubation and polycrystalline silicon columnar texture layer. The films without the seed layers with the optimum crystal state can be deposited at a substrate temperature of 300℃, a hydrogen flow ratio of 25sccm, and a microwave power of 600W. The films with the seed layers have a higher crystalline fraction, and grow with a strong texture.