Study on the theorem of pits created in 12-inch raw wafering

The effect of crystal-originated particles (COPs) on ultra-thin gate oxide for recent ultra large-scale integration (ULSI) devices were studied. Various Czochralski (CZ) silicon wafers were prepared by controlling the pulling speed of silicon ingots to determine the relationships between COPs and the breakdown characteristics of the ultra thin-gate oxide. The distribution of COPs, measured by optical shallow defect analysis and the use of a particle counter, was compared with the results of time-independent dielectric breakdown (TZDB), time-dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) for gate oxides with thicknesses of 2.5 -5 nm. The results reveal no appreciable oxide degradation below an oxide thickness of approximately 3 nm; above this threshold value, the defect density depends strongly on the presence of crystal-originated particles. The COPs are a major factor in the degradation of ultra-thin gate oxide (less than 5 nm) in ULSI devices.