CHARACTERIZATION AND REMOVAL OF TRACE HEAVY-METAL CONTAMINATION ON SI-SURFACE RESULTED FROM CHF3 C2F6 REACTIVE ION ETCHING/

The characteristics of removal of trace heavy metal contamination on t he silicon surface resulted from CHF3/C2F6 reactive ion etching (RIE) was studied using total reflection X-ray fluorescence spectroscopy (TR XRF). In order to investigate the depth profile of metallic contaminan ts near the surface, TRXRF measurements containing glancing angle scan s were performed after slightly etching of silicon surface by repeatin g the cleaning procedures that diluted HF (DHF) removed the oxide grow n by the mixture of H2SO4 and H2O2 (SPM) or O-2 plasma ashing treatmen t. RIE and O-2 plasma ashing processes resulted in metal contamination such as Fe, Ni, Zn, etc. They were present as both of plate-type and bulk-type, and the large part of plate-type contamination was removed easily. Especially, Fe resulted from RIE was the most abundant contami nant and its concentration was similar to 10(11) atoms/cm(2). Fe was m ainly ditributed within similar to s nm from silicon surface and could be effectively reduced below similar to 2x10(10) atoms/cm(2) by etchi ng of similar to 2.5 mm depth of the silicon substrate.