A method is disclosed to form a large-grain, lightly p-doped polysilicon
film suitable for use as a channel region in thin film transistors. The
film is preferably deposited lightly in situ doped with boron atoms by an
LPCVD method at temperatures sufficiently low that the film is amorphous
as deposited. After deposition, such a film contains an advantageous
balance of boron, which promotes crystallization, and hydrogen, which
retards crystallization. The film is then preferably crystallized by a
low-temperature anneal at, for example, about 560 degrees for about
twelve hours. Alternatively, crystallization may occur during an
oxidation step performed, for example at about 825 degrees for about
sixty seconds. The oxidation step forms a gate oxide for a thin film
transistor device, for example a tunneling oxide for a SONOS memory thin
film transistor device.