Interferometry for endpoint prediction in gate etching

We present results of an interferometric endpoint prediction technique for use in plasma etching of various gate structures in advanced CMOS device fabrication. Etch experiments were carried out in a production high-density plasma source (Decoupled Plasma Source). The prediction technique been successfully to many and types of structures commonly found in integrated circuit manufacturing. The ability to predict endpoint and avoid breakthrough of gate oxides as thin as 19 /spl Aring/ has been investigated. The flexibility of the endpoint algorithm together with the external trigger controller are demonstrated to be crucial for successful endpoint prediction.