MEMS | ARTICLE


Step 3: Bond Base Wafer to Top Wafer Once the Base wafer and Top wafer have completed the DRIE etch processes, the wafers are aligned and fusion bonded in a controlled environment. The accuracy of the wafer to wafer alignment after the completed fusion bond is ±10 μm.


Step 5:Deposit and Define Metal The Top device layer is blanket coated with a low stress TiW/Au metallisation. This is then patterned to form device elements such as electrodes, bond pads and highly reflective surfaces.


Step 4: Remove Top SOI Handle and Buried Oxide After fusion bond, the handle of the Top wafer is removed. The buried oxide of the Top wafer is also removed leaving a pristine optically flat silicon surface.


Step 6: Release Pattern and Etching The final DRIE process etches completely through the Top device layer and releases the MEMS structures.


Step 7: Singulation The dicing process is done with a laser, which enables singulation without damaging the released MEMS devices.


>> Continued on page 44


43 | commercial micro manufacturing international Vol 7 No.3


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