提高E^2PROM中NMOS管源漏穿通电压的实验研究

An Experimental Study on the Improvement of the Source Drain Punch through Voltage of NMOS Transistor in E 2PROMs

为了提高Ｅ２ＰＲＯＭ中Ｎ管源漏穿通电压（ＶＰＴ），用实验的方法对制造工艺进行了研究。结果表明，高能量注入是提高ＶＰＴ的有效手段，但受到ｐｎ结击穿的限制，只适用于低压区短沟Ｎ管；ＤＤＤ工艺可大幅度提高ＶＰＴ，但ｐｎ结击穿电压低于２０Ｖ，不能应用于高压ＭＯＳ管；

To improve the S D punch through voltage ( V PT )of NMOS transistor in E 2PROMs,an experiment was conducted to demonstrate three different process schemes.It has been shown that 1)high energy implantation is an efficient means to improve V PT ,but it is only suitable for short channel transistor working at low voltage due to the limitation of the p n junction breakdown,2)the double diffusion drain(DDD) technique can greatly increase V PT ,but the low p n junction breakdown voltage (<20 V) prevents it from being used for high voltage MOS transistors,and 3) the most desirable method is a moderate anti punch through implantation plus properly increased channel length for MOS transistors operating at high voltage.