Bonding of silicon wafers (e.g. silicon wafer having high resistivity and low resistivity) together makes it possible to produce a wafer substitute for epitaxial wafer. The characteristic thereof is that autodoping of the wafers on the bonding interface hardly occurs due to direct bonding of wafers.
Depending on thickness, it can also lead to cost reduction compared with thick epi layer.

Production method is as follows: two silicon wafers are bonded and device layer to be polished to target thickness. Si-Si bonding wafer (Si-Si bonded wafer) is regarded as an useful substitute with lower cost compared with thick epitaxial layer which has been used conventionally for applications such as power device and pin-diode.