Image Number 5 for United States Patent #7374978.
A mask is formed selectively on a crystalline silicon film containing a catalyst element, and an amorphous silicon film is formed so as to cover the mask. Phosphorus is implanted into the amorphous silicon film and the portion of the crystalline silicon film which is not covered with the mask. The silicon films are then heated by rapid thermal annealing (RTA). By virtue of the existence of the amorphous silicon film, the temperature of the crystalline silicon film is increased uniformly, whereby the portion of the crystalline silicon film covered with the mask is also heated sufficiently and the catalyst element existing in this region moves to the phosphorus-implanted, amorphous portion having high gettering ability. As a result, the concentration of the catalyst element is reduced in the portion of the silicon film covered with the mask. A semiconductor device is manufactured by using this portion.