A three-dimensional CMOS circuit having at least a first N-conductivity field-effect transistor and a second P-conductivity field-effect transistor respectively formed on first and second crystalline substrates. The first field-effect transistor is oriented, in the first substrate, with a first secondary crystallographic orientation. The second field-effect transistor is oriented, in the second substrate, with a second secondary crystallographic orientation. The orientations of the first and second transistors form a different angle from the angle formed, in one of the substrates, by the first and second secondary crystallographic directions. The first and second substrates are assembled vertically.