| abstract |
A semiconductor device includes a first metal oxide semiconductor field effect transistor, a remaining gate stack, an insulating structure and a second metal oxide semiconductor field effect transistor. The first metal oxide semiconductor field effect transistor is over the substrate. The first metal oxide semiconductor field effect transistor includes a first gate stack, a first buffer layer and a first channel layer. The remaining gate stack is over the first channel layer. The remaining gate stack includes a first insulator, a first conductive material, and a plurality of first spacers. The insulating structure is on the first channel layer. The insulating structure includes a first dielectric material, a second dielectric material and a third dielectric material. The second MOS field effect transistor is located over the insulating structure and the remaining gate stack. The second metal oxide semiconductor field effect transistor includes a second channel layer and a second gate stack. The second gate stack is disposed over the second channel layer. |