Semiconductor device and method for fabricating semiconductor device

A method for fabricating a semiconductor device, comprising:

• providing a main substrate comprising a first substrate and a second substrate that are adjacent to each other, wherein the first substrate comprises a first surface and a second surface that are disposed opposite to each other, wherein the second substrate comprises a third surface and a fourth surface that are disposed opposite to each other, wherein the third surface is flush with the first surface, and wherein the fourth surface is flush with the second surface;
• forming a first electrical element on one side of the first substrate by forming a first shallow trench isolation region and a second shallow trench isolation region;
• and forming a first drain region and a second drain region, wherein the first drain region and the second drain region are opposite to each other and separated by a part of the first substrate, and wherein the first drain region and the second drain region are disposed between the first shallow trench isolation region and the second shallow trench isolation region;
• and
• forming a second electrical element on one side of the second substrate, wherein the second electrical element and the first electrical element are disposed on a same side of the main substrate, wherein the first substrate and the first electrical element constitute a tunnel field-effect transistor, wherein the second substrate and the second electrical element constitute a planar device, and wherein the planar device comprises at least one of a metal oxide semiconductor transistor, a capacitor, or a resistor.