Advances in production methods in VLSI and ULSI technology using isolated-chamber sputter deposition of Al 1% Si films

Sputtering process optimization is described as related to steady-state production of VLSI and ULSI devices using isolated deposition modules in a production environment. Improvements in step coverage for Al-1%-Si, obtained over VLSI and ULSI level topology typical of 1-Mb to 16-Mb semiconductor devices, are described, and data are presented. Techniques for improving the average step coverage and the worst-case step coverage over 1- mu m-thick BPSG contact openings are discussed. The process improvements require the use of isolated processing chambers for specific processing steps in the appropriate chambers. By taking advantage of the isolated processing chambers and fine tuning various process settings, the worst-case step coverage was improved from 25 to 40% for a typical VLSI topology. These techniques were also effective in reducing step coverage over opposing contact-opening sidewalls across the wafer. The factors and deposition conditions responsible for these improvements are presented. Corresponding data on grain size and silicon nodule size as a function of deposition conditions after contact alloy are presented.<
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