Etching Rate and Mechanism of Doped Oxide in Buffered Hydrogen Fluoride Solution

Etching rates of borosilicate, borophosphosilicate, phosphosilicate, and arsenosilicate glass films in various buffered hydrogen fluoride solution (BHF) have been studied. Etching rates were found to depend on the glass composition and dopant concentration as well as the concentration of ammonium fluoride in the BHF. This phenomenon is clearly different from the etching rate of thermal SiO 2 oxide which is hardly affected by the concentration of ammonium fluoride in excess of equimolar to the HF concentration