SIMOX wafers

SIMOX wafers are made by implanting oxygen at a certain depth into a conventional silicon wafer. 

Figure 4.23. Two methods used to fabricate silicon-on-insulator (SOI) wafers. Illustrated are the (a) Smartcut procedure where two oxidized wafers are bonded together and (b) SIMOX procedure where oxygen ions are implanted into a bulk Si wafer.

SIMOX and Unibond wafers require epitaxy to increase the thickness of the top layer. An epitaxial layer up to 60 pm thick can be grown on such wafers the resulting thickness tolerance depends on the epitaxy process tolerances and is typically in the range of 5% of the final thickness (4a value). 

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