An apparatus and method for a multilayer silicon over insulator (SOI)
device is provided. In the multilayer SOI device, the crystal orientation
of at least one active region of a device is different than the active
region of at least another device. Where the multilayer SOI device has a
first layer including a PMOS device with a silicon active region having a
crystal orientation of [100], the second layer may be an NMOS device with
a active region having a silicon layer having a crystal orientation of
[110]. The second layer is bonded to the first layer. The method and
apparatus can be extended to more than two layers thus forming a
multilayer SOI device having a different crystal orientation at each
layer. The multiple layer SOI device may form circuits of reduced surface
area.