Improvement Of The Uniformity And Consistency Of The Resistivity And Thickness Of The Silicon Epitaxay Layers

Silicon epitaxy material is an important information functional material. It has so many advantages that the silicon monocrystal wafers haven't, such as integrity of epitaxy layers crystal, high GOI, perfect surface quality, less soft errors and latching effects. Nowadays, the silicon epitaxy material is getting more and more regards and widely used along with the rapid progress of the Microelectronic Industry. Thickness and resistivity are two parameters of silicon epitaxy wafers which are very important.It is known that the resistivity of silicon epitaxy layers is a very important parameter in the silicon epitaxy production. The stability of the parameter will influence the performances and yields of the final electronic devices. The resistivity of silicon epitaxy wafers with Sb-doping substrate is easy to control, well, the resistivity of silicon epitaxy wafers with As and B substrates are hard to control. It is because that, it is hard to remove the impurity in the stagnant layer during growth, which will result in serious auto-doping. Some manufacturers in our country and abroad find some ways to solve this problem, such as back-seal, substrate silicon etch coating, temperature increasing in pre-bake, increasing of the rate of flow of carrier gas, add HC1, etc. but these will increase the complexity of processes. Further more ,Few producers in our country use back-seal technology because of some technical problems.This paper studied the mechanism of auto-doping theoretically and analyzed the factors influencing the auto-doping of p-type epitaxy, such as substrate, temperature, growth rate, gas flow, purity of silicon source, etc. Based on the idea, i put forward a new process . The boron auto-doping are restrained sufficiently and good uniformity and consistency (within 4%) of the resistivity of the p-type silicon epitaxial wafers are obtained, at the same time, the cost is reduced and the quality and yields are increased. I also study the N/P+ type Silicon epitaxy growth and findout the relation between Auto-doping and the thickness Consistency, thus the theory of Silicon epitaxy growth technics is consummated.