The Study on mechanism of contact etching stop with C_4F_8/CF4 chemistry in Lam Exelan tool

摘要

In Contact etch process, owing to contact profile and bottom ECD control, when used C_4F_8/ CF_4 gas mixture reaction in RIE tool, It was easy to etch stop when etched to HDP oxide film due to HDP oxide interface formed a organic by-product layer during stack film deposition, it will caused polymer formation too rich. There were easy to suffered contract resistance fail in 0.18um flash device.