Post Blast Component Cleaning Techniques to Reduce Particle Generation in Etch and Deposition Chambers
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Post Blast Component Cleaning Techniques to Reduce Particle Generation in Etch and Deposition Chambers
Ronald Burgess, BOC Edwards-Kachina, Phoenix, Arizona Dave Laube, BOC Edwards-Kachina, Phoenix, Arizona Ardy Sidhwa, ST Microelectronics, Phoenix, Arizona Chuck Spinner, ST Microelectronics, Phoenix, Arizona Sanyi Zheng, ST Microelectronics, Phoenix, Arizona Tin Bun Chew, ST Microelectronics, Phoenix, Arizona Todd Gandy, ST Microelectronics, Phoenix, Arizona Steve Melosky, ST Microelectronics, Phoenix, Arizona Jerome Vetier, ST Microelectronics, Phoenix, Arizona
INTRODUCTION Particles emanating from the walls, shields, and other components of the chambers in which integrated circuit wafers are processed, are among the factors which have been shown to contribute to the formation of defect sites on the completed wafers. Typically, the generation rate of these particles is influenced by the final treatment that the surfaces of these components receive prior to installation in the chamber, whether or not the components are new or recycled. Parameters affecting one such source of particulate contamination have been examined in the present studies. Initially, quartz coupons, prepared from material characteristic of contemporary bell jar manufactures, were subjected to typical post cleaning steps. These were surface texturing, post blast etching, pressure washing, and ultrasonic rinsing. To assess the effectiveness of each step in reducing particle generation, they were combined in a conventional experimental matrix. The coupons comprising this matrix were evaluated for potential particle generation by two methods: First, a carbon lift-off technique was used to evaluate relative numbers of weakly attached particles on coupon surfaces; second, cross sections were taken to examine the depth and type of subsurface damage capable of contributing to particle generation. Current methods to promote adhesion of deposits to PVD shielding require increasing surface roughness using aluminum oxide abrasive blasting. This technique is known to embed fractured aluminum oxide particles into the metal substrate. The level of embedded grit is a function of grit size, blasting pressure, nozzle departure from the substrate, operator technique, contact angle, and the surface roughness. Cleaning processes intended to remove micro-particles subsequent to grit blast are marginally successful at lowering embedded grit levels; therefore, this experiment was designed to optimize post grit blast processing for embedded grit removal. Stainless steel samples, prepared from used shield components, were utilized in a matrix to evaluate the effectiveness of ultrasonic agitation, chemical etching, and CO2 pellet blasting at removing embedded grit. These samples were analyzed using beta backscattered electron imaging. Subsequently, samples were subjected to thermal cycling representative of that experienced in chamber operation, to determine whether or not any remaining grit would be released as a result of these temperature excursions.
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