Reclamation of wafers results in significant cost savings for integrated circuit manufacturers. To successfully reclaim wafers, particle, metallic, and organic contamination must be removed from the wafer surface after etch-back, grinding, lapping, and polishing. The cleaning and surface conditioning processes used during the reclaim process will be presented in this chapter. Specification for reclaiming wafers, especially removal of copper and other metal contamination and methods to obtain a pristine, particle-free surface are discussed. Comparison of different processes, including standard RCA cleaning compared to simplified cleaning, will be shown and their advantages and disadvantages discussed, and evidence will be provided for how the chemistry and process affects the yield and defect levels of the reclaimed wafers.
Keywords: wafer reclaim, wafer recycle, photoresist stripping, silicon life-cycle, metal induced pitting, contamination specifications
13.1 Introduction to Wafer Reclaim
Semiconductor manufacturing uses test wafers for particle, film thickness, etching rate, and tool marathon testing monitors, as well as for characterizing new and existing equipment and processes. Depending on the capacity of a fab, test wafer usage can be as high as tens of thousands of wafers per month. As a result of the ever-increasing demand for silicon and the high cost of wafers, integrated ...