Hydrofluoric (HF) Acid Corrosion study of corrosion resistant alloys used in semi-conductor etching process equipment

Corrosion studies require the use of complementary analytical techniques, as each method provides results based on the interaction of the investigated material with a probing medium [1]. Obtaining elemental, molecular, and crystal/grain structure information at diferent spot sizes and probing depths is crucial, particularly for elements that are challenging to observe simultaneously, such as hydrogen and fluorine.

In this study, the dissolution of gaseous phase anhydrous hydrogen fluoride and difusion of fluorine into various metal superalloys were monitored by analyzing changes in concentration, depth, and difusion rate using Glow Discharge Optical Emission Spectroscopy (GD-OES). A representative area of ultra-high purity (UHP) 316L (composition compliant with SEMI standard F20) and Inconel® 600 alloys were rapidly sputtered to obtain fast elemental depth profiles with nanometer resolution [2].Atomic Force Microscopy (AFM) provides complementary data with relevance to corrosion studies, ranging from the subtle efects of surface passivation uniformity on the measured surface potential and conductivity of the material to the simple evolution of the surface topography with progression of corrosion (even in the earliest stages) [3].

The corrosion test samples are representative of alloys used in semiconductor manufacturing equipment, where improved alloy durability and the prevention of leaching of corrosion byproducts is critical. The goal is to understand the prevalent corrosion mechanisms in these common semiconductor alloys in order to find ways to increase equipment longevity and minimize contamination to the semiconductor manufacturing processes.