Influence of Thermal Spray Parameters on Two-Wire Arc Aluminum Semiconductor Equipment Coatings

摘要

Thermal spray metallic coatings are used for a range of applications in the semiconductor equipment industry including applications from particle reduction to precious metal reclaim in chamber operations during thin film deposition. Thermal spray coatings assist in reducing part costs, increasing product performance and lifetimes, and reducing chamber maintenance. The processing parameters in two-wire arc spraying of aluminum are traditionally used to provide a range of coating properties in industry from dense coatings for corrosion control applications-to rough texture coatings for anti-slip applications. Thus, the two-wire arc processing parameters selected for use for semiconductor applications are critical for surviving the semiconductor processing environment and increasing product performance. Important two wire processing parameters include current, voltage, atomizing air pressure, and stand-off distance between the gun and target (sprayed part). Secondary processing parameters including robotic traverse rate, air cooling, part manipulation (turntable speed, etc.) and others. Further, the specifics of the two-wire arc gun design (make/model), nozzle diameter, air caps, and wire diameter are also important variables. Current and voltage are important parameters for generating the electric arc for melting the aluminum wire. An optimum processing window exists for the range of current and voltage used for producing the aluminum coatings. The atomizing air pressure also has an optimum range for atomizing the molten aluminum produced from the electric arc. A range of atomizing air pressures are used to produce a range of coatings from dense to rougher textured coatings. Higher operating current increases the quantity of molten producing the coatings, and the lower operating current reduces the spray rates of the aluminum to be atomized. This paper examines the two-wire arc parameters producing aluminum coatings. Two-wire arc parameters to be examined include current, voltage, atomizing air pressure and stand-off distance varied to produce coatings. The coating produced from these parameter changes will be investigated in terms of microstructure and mechanical properties. The microstructural investigation will involve porosity analysis. Mechanical property testing will include tensile-adhesion bond strength. The surface roughness will also be investigated.