Effects of wet chemistry pre-gate clean strategies on the organic contamination of gate oxides for metal-oxide-semiconductor field effect transistor

II is known that organic contamination can seriously degrade the electrical performance of gate oxides for metal-oxide-semiconductor field effect tran sistor (MOSFET) applications. In this paper, organic contamination of wafer surfaces cleaned by different pre-gate clean conditions and subsequently e xposed to cleanroom ambience was investigated using time-of-flight secondar y ion mass spectroscopy (TOF-SIMS), and the carbon level from thermally dec omposed organic species directly trapped in the gate oxides after thermal o xidation and polysilicon deposition was probed using secondary ion mass spe ctroscopy (SIMS) depth profiling. The C concentration in the oxide-polysili con gate stack obtained from SIMS depth profiling closely correlates with t he total TOF-SIMS peak intensity of organic contaminants detected on post c lean wafer surfaces. A quantified carbon concentration on the order of 10(1 2) atoms/cm(2) was obtained at the interfaces using SIMS depth profiling ca librated with an implanted C standard. It was found that the susceptibility of wafer surfaces to organic contamination that eventually affects the lev el of oxide-polysilicon interfacial carbon appears to be highly dependent o n the surface termination.