High Rate Deep Si Etching using Capacitively Coupled Plasma

Abstract

High rate deep Si etching using SF6/O2 gas chemistry by Magnetically-Enhanced Reactive Ion Etch (MERIE) system using a Dipole-Ring Magnet (DRM) is studied. It is capable of etching holes 40 μm in diameter in a Si substrate at etch rates as high as 50 μm/min. It was found that the Si etch reaction is dominated by the density of fluorine radicals, which is realized at high frequency and pressure. In holes with higher aspect ratios, it was found that the Si etch rate at the bottom of holes is determined not only by the supply of fluorine radicals, but is also influenced by an etch-inhibiting effect related to the sidewall of the hole. Using an 8 μm square mask, holes with straight sidewalls were etched to a depth of 60 μm at an etch rate of 24 μm/min.