Glass wafer mechanical properties: A comparison to silicon

Glass wafers derived from extensions of Coming's fusion process have many attributes that make them attractive for use as carrier wafers in semiconductor manufacturing processes. Fusion is a mature manufacturing process that produces extremely high quality glass wafers with very low TTV and low warp. The wafers are cut from sheets, which makes it straightforward to scale up to 450 mm diameter wafers. Coming's glass wafers have a CTE that closely matches that of silicon wafers, which is advantageous in avoiding deformation as the wafer stacks are heated and cooled. The optical properties of the material allow for easy inspection techniques to evaluate the quality of the bonds as well as other light/laser based processing. Since glass is a brittle material like silicon, it is important to carefully manage finishing processes. The glass is formed in thin sheets to a target thickness in the fusion process. Therefore it is not necessary to grind and polish the surface, thus avoiding strength limiting micro-flaws that can remain on the surface. Finally, it was shown that glass edges can be extremely strong when processed correctly. We have shown properties of Coming glass wafers to similar properties of silicon wafers.