Grown-in oxide precipitate nuclei in Czochralski silicon substrates and their role in device processing

Using a method to study the grown-in defect density spectra in Czochralski silicon wafers we elucidate the changes in the size distribution of grown-in oxide precipitate nuclei caused by thermal processing in a common CMOS device process. The first thermal step determines which parts of the grown-in defects grow to large stable defect formations and how many harmful defects appear in the defect denuded zone. The cooling rate of the crystal considerably influences the defect evolution during CMOS processing. The choice of the appropriate silicon material for a device process or adjusting processing conditions to suit the material are important for the defect generation during processing and consequently also for the device yield.