In-house Test Wafer Reclaim for Fab Cost and Wastage Reduction: MS: Manufacturing for Sustainability

In semiconductor fabrication facilities, non-production test wafers constitute a substantial amount of the non-equipment-related consumable expense. With the escalating demand and increased costs associated with bare silicon test wafers, as well as the limited viability of external reclamation, the imperative to extend the lifecycle of recycled wafers and establish an in-house reclamation process has become pronounced for major chip manufacturers. External reclaim usually comes with a higher cost per wafer and a limited recycle lifespan. In contrast, in-house reclaim offers a cost that is significantly lower, at only a fraction of the external reclaim cost per wafer, and provides a much longer recycle lifespan, making it a more cost-effective solution. Historically, Semiconductor fabs lacked the capability to recondition test wafers that had reached the end of their usable lifespan. Those silicon test wafers failed to reclaim global specification will be downgraded and directly outsourced to external vendors for reclaim once they are not able to meet the usable specifications. This paper's primary objective is to present an innovative approach that leverages existing in-house resources to develop a practical methodology for extending the lifespan of test wafers and providing a comprehensive reclamation solution. The recently developed in-house wafer reclamation process at Micron has significant yield improvements, met with the global reclaim specifications. Furthermore, a novel combination of new CMP (Chemical Mechanical Polishing) slurries and process optimization in both CMP and Wet processes has been devised and effectively applied to the reclamation process, achieving an impressive reclaim yield for high-volume operations. These advances have instilled confidence in in-house recycling and reclamation processes within semiconductor fabrication. While specific figures remain confidential, the results of this paper underscore the viability of in-house silicon wafer reclamation and elucidate a cost-effective, high-yield methodology. These insights are intended for dissemination as an innovative method to achieve hundreds of millions of dollars annualized network savings and significant wastage reduction.