Selective surface doping method of P atoms in lateral solid phase epitaxy and its applications to device fabrication

Growth characteristics and device application of the selective surface doping method in lateral solid phase epitaxy (L-SPE) are presented. In this method, P atoms are incorporated near the surface of amorphous Si (a-Si) films to enhance the L-SPE growth and the underlying undoped layers are used for device fabrication. First, the growth characteristics are investigated by changing thicknesses of the a-Si film and the P-doped layer, and a quantitative model to explain the experimental results is presented. Then, it is shown that redistribution of the P atoms during L-SPE annealing is negligibly small, and the P-doped layer is selectively etched by combination of a wet chemical etchant and subsequent reactive ion etching. Finally, metal-oxide-semiconductor field-effect transistors (MOSFETs) with upper and lower gate electrodes are fabricated in the undoped layer and the electrical properties of both the upper and lower channel FETs are investigated.