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前言在N沟MS4096单管单元随机存储器的研制中,设计要求在电阻率为9～10Ω—cm的P型衬底上,作出增强型器件(V_T=0.2～0.5V),这就意味着硅中的表面态要在10~(11)/cm~2数量级以下。但在通常的氧化条件下,获得的样品表面态往往是10~(11)～10~(12)数量级。据国内外一些文献报导,在氧化气氛中,加入一定比例的HCl,则可大大降低表面态密度。针对这个问题,我们借助C—V测试技术,作了大量的实验工作,结果表明,掺HCl氧化所得到的样品表面态密度可以减少到10~(10)/cm~2数量级。用体积比为6—7％的HCl氧化气氛加上适当的退火条件,现已做出了合格的模拟4096位的4×4单管单元随机存储器。掺HCl氧化确实是降低表面态的一种行之有效的工艺措施。
Preface In the development of N-channel MS4096 single-pipe unit RAM, the design requires an enhancement device (V_T = 0.2 ~ 0.5V) on a P-type substrate with a resistivity of 9 ~ 10Ω-cm. This means that the silicon In the surface state to 10 ~ (11) / cm ~ 2 orders of magnitude below. However, under normal oxidation conditions, the surface state of the sample obtained is often on the order of 10-11 (10-12). According to some domestic and foreign reports, in the oxidizing atmosphere, adding a certain proportion of HCl, can greatly reduce the surface state density. In response to this problem, we have done a lot of experiments with the C-V test technique. The results show that the surface state density of the sample obtained by HCl oxidation can be reduced to the order of 10 ~ 10 / cm ~ 2. With a 6-7% by volume HCl oxidation atmosphere with appropriate annealing conditions, a qualified 4096-bit 4x4 single-cell random access memory has been made. HCl-doped oxidation is indeed an effective way to reduce the surface state of the measures.