A semiconductor process and apparatus provide a planarized hybrid substrate (18) by exposing a buried oxide layer (80) in a first area (99), selectively etching the buried oxide layer (80) to expose a first semiconductor layer (70) in a second smaller seed area (98), and then epitaxially growing a first epitaxial semiconductor material from the seed area (98) of the first semiconductor layer (70) that fills the second trench opening (100) and grows laterally over the exposed insulator layer (80) to fill at least part of the first trench opening (99), thereby forming a first epitaxial semiconductor layer (101) that is electrically isolated from the second semiconductor layer (90). By forming a first SOI transistor device (160) over a first SOI layer (90) using deposited (100) silicon and forming first SOI transistor (161) over an epitaxially grown (110) silicon layer (101), a high performance CMOS device is obtained.