Gallium Arsenide Semiconductor Manufacturer – Closed Loop Water Reuse System Optimization
Bill Potochniak, PE
A gallium arsenide (GaAs) semiconductor manufacturer in the northeast began experiencing water quality issues with its closed loop water reuse system which consisted of a series of step-down bag and cartridge filters. Due to increased production, and process water needs, the system was requiring daily filter changeouts where in the past filter change outs were weekly. The increased filter change outs were causing the water reuse system to be more labor intensive, expensive to maintain, and increased the level of worker exposure to arsenic during change outs. In addition, with the increased use, the system required monthly shutdowns to conduct a complete cleaning and refill of the system with fresh deionized water. These shutdowns, along with the other challenges outlined above, led directly to several environmental, safety, and economic impacts. Even more critical, the deteriorating process water quality was determined to be having a direct impact on product quality and loss of product.
This presentation will discuss methods for evaluating water quality produced by gallium arsenide re-use systems and for assessing the efficiency of filtration systems to determine if modifications, retrofits, or a system redesign can reduce maintenance costs while increasing process capacity. Tighe & Bond began by collecting numerous process water and wastewater samples for laboratory analysis and field settleability testing. We also interviewed process engineers to determine water quality needs in the wafer processing area. We will review some of this data and highlight the initial conclusions and next steps that were developed from it. We also evaluated the existing re-use system to identify potential areas for improvement or upgrade. We will present the original system layout and design and identify challenges with