Ultra-dilute silicon wafer clean chemistry for fabrication of RF microwave devices

Abstract

An ultra-dilute clean chemistry was successfully employed for effective removal of both surface haze and submicron particulate contamination from silicon wafer substrates. The cleaning chemistry was ultra-dilute RCA-SC1 followed by RCA-SC2 solutions. All chemical cleaning and deionized water (DI) rinsing steps were performed in the same processing vessel. The drying vessel was a "motionless" system. The chemical cleaning, DI water rinsing and drying processes were carried out at an ambient temperature. A laser beam scanning system was employed to directly measure surface haze concentration and light point defects (LPD's) density at or above 0.5-/spl mu/m particle size. Ultra-dilute clean chemistry has been in active use for various manufacturing processes including prebonding, pre-diffusion/oxidation, preepitaxial deposition, post-lasermark, post-chemical mechanical polishing (CMP) cleaning operations. The manufacturing data in terms of particle removal efficiency are discussed The electrical data for total oxide surface charge, density of interface traps, as well as regeneration lifetime are also presented in this paper. A key advantage of this ultra-dilute cleaning system over a conventional wet bench is an approximate 3-fold reduction in the volume of chemical usage. The net cost saving for chemicals including DI water is estimated at $2.32 for each 25-wafers product lot. In addition, an approximate 8-fold reduction could be realized in the wastewater loading. Therefore, this ultra-dilute cleaning operation is both environmental friendly and cost effective.