Nucleation and growth of hemispherical-grained Si by rapid thermal CVD

Hemispherical-grained Si (HSG) coating was deposited on an amorphous Si layer by using a rapid thermal chemical vapor deposition (RTCVD) process. The formation of the HSG coating consists of “seeding” and subsequent isothermal annealing stages. The microstructure and surface morphology of the HSG coating was studied after various stages of its formation by TEM and HRSEM techniques. The “seeding” process results in formation of nanometer size Si crystals on the substrate. Each Si crystal is covered with a thin amorphous Si film which forms a hemisphere shape. The annealing process results in growth and crystallization of polycrystaline Si hemispheres. The RTCVD process enables high control of the size and crystallinity of the Si hemispheres. The mechanism of formation and growth of the HSG coating is discussed and compared with other fabrication methods.