掺磷（砷）多晶硅形成NPN晶体管发射结是提高fT及双极集成电路工作速度的最佳途径之一，目前被广泛应用。通过对LPCVD多晶硅生长、掺杂、退火及刻蚀工艺研究，确定制造高fT及β值的NPN晶体管最佳工艺条件及参数控制，研制出速度小于4ns高性能多元逻辑八位高速视频D／A转换器集成电路。该产品主要电参数性能已达到及部分超过了目前国际先进产品的水平。 Phosphorus (arsenic) polysilicon formation of NPN transistor emitter junction is to improve fT and bipolar integrated circuit speed is one of the best ways, is now widely used. Through the research on the growth, doping, annealing and etching of LPCVD polysilicon, the optimum process conditions and parameter control for NPN transistors with high fT and β values ​​are determined, and the high performance multi-element logic 8 bit high speed video D / A Converter IC. The main electrical parameters of the product performance has reached and partially exceeded the level of the current international advanced products.