Anhydrous HF processing as an alternative to HF/water processes

The HF/water treatment of silicon surfaces is among the most frequently applied steps in surface cleaning processes. It is utilized for clearing oxides from the silicon surface. Large amounts of ultrapure water are necessary to carry out this operation, both in the HF/water solution itself and the thorough rinse which must follow HF/water processes. Therefore, a gas-phase alternative to this process would significantly reduce deionized (DI) water consumption. The focus of this paper is the anhydrous hydrofluoric acid (AHF)/alcoholic solvent process which has shown promise as an alternative to the aqueous HF process. In particular, the AHF/methanol process has been studied extensively. This paper presents a comparison between properties of silicon surfaces prepared through the dilute HF/water (dHF) process and those of surfaces prepared through AHF/alcoholic solvent processes.