What is Silicon?
Silicon (Si) is one of the most common elements on this planet.
Many research and production facilities increasingly seek successful methods of thinning down the top wafer of a two Silicon wafer fusion bonded assembly to achieve a final thickness as low as 2 μm. A typical application for such a process would be the use of ultra-thin wafers as “flexing” mirrors to redirect laser light for HD screens.
Two Silicon wafers bonded together with a fused silicon oxide coating between the wafers, has a typical thickness of several μm. This is done in order to thin the upper wafer to within the sub 5 μm level. Bonding can be easily achieved using the Logitech range of Wafer Substrate Bonding Units (WSBUs).
As these thicknesses tend to be at the limit of flatness of commercially available silicon, it is important to characterise the wafer flatness and thickness uniformity of individual wafers prior to bonding. It may also be necessary to lap or polish the wafers to improve upon the initial specification.