Polytypic heterojunctions for wide bandgap semiconductor materials

摘要

The bonding of crystallic semiconductor structures for getting polytypic heterojunctions on the basis of wide band gap semiconductor materials has considerably increased. The direct wafer bonding technology for the creation of polytypic heterojunctions (e.g. silicon carbide polytypes like 4H-SiC, 6H-SiC, 3C-SiC) gives an advantage in obtaining heterojunctions on the basis of different polytypes improves the electrical and physical properties of devices without lattice mismatch problems. The bonding of SiC wafers is an extremely challenging process even under ideal surface conditions. The hardness and inertness of SiC renders possesses a huge influence for surface preparation. Such parameters as roughness, flatness, waviness, and an extremely important aspect like cleanliness of surfaces have to be tightly controlled. This paper shows a state-of-the-art-today's situation: the physical background and surface preparation problems before the direct bonding; the technological possibilities and possible practical solutions.