Optimization of pre-metal Dielectric (PMD) materials

It is very important to select superior interlayer pre-metal dielectric (PM D) materials that can act as a penetration barrier to various impurities cr eated by the chemical mechanical polishing (CMP) process. In this paper, ho t carrier degradation and device characteristics were studied on various ma terials of PMD-1 layers, which included low-pressure tetra-ethyl-ortho-sili cate glass (LP-TEOS), Si-rich (SR)-oxide, plasma-enhanced (PE)-oxynitride, PE-nitride and PE-TEOS films. Pressure cooker test (PCT) analysis was used to obtain the electrical characteristics of devices, such as the shifts in threshold voltage and transconductance as a function of stress time, juncti on leakage current and breakdown voltage of field transistors with variatio n of these PMD-1 materials. Also, the most effective PMD-1 materials which can prevent degradation effects due to hot carrier stress were investigated . From experimental results, it is clearly shown that silicon oxide turned out to be a better PMD-1 material than both PE-oxynitride and PE-nitride. F rom the results, it is suggested that LP-TEOS film is the best PMD-1 materi al among the silicon oxide samples. (C) 2001 Kluwer Academic Publishers.