Dopant introduction method and heat treatment method
A thin film containing a dopant is deposited on a surface of a semiconductor wafer. The semiconductor wafer on which the thin film containing the dopant is deposited is rapidly heated to a first peak temperature by irradiation with light from halogen lamps, so that the dopant is diffused from the thin film into the surface of the semiconductor wafer. The thermal diffusion using the rapid heating achieves the introduction of the necessary and sufficient dopant into the semiconductor wafer without producing defects. The surface of the semiconductor wafer is heated to a second peak temperature by further irradiating the semiconductor wafer with flashes of light from flash lamps, so that the dopant is activated. The flash irradiation which is extremely short in irradiation time achieves a high activation rate without excessive diffusion of the dopant.
1. A method of introducing a dopant into a semiconductor substrate to activate the dopant, said method comprising the steps of:
(a) forming a thin film containing a dopant on a surface of said semiconductor substrate;
(b) irradiating said semiconductor substrate with light from a continuous lighting lamp to heat said semiconductor substrate to a first temperature, thereby diffusing said dopant from said thin film into the surface of said semiconductor substrate;
(c) turning off said continuous lighting lamp or decreasing an output from said continuous lighting lamp to decrease the temperature of said semiconductor substrate to a second temperature lower than said first temperature; and
(d) irradiating said semiconductor substrate with a flash of light from a flash lamp to heat the surface of said semiconductor substrate to a third temperature higher than said second temperature, thereby activating said dopant.
2. The method according to claim 1 , wherein
said third temperature is higher than said first temperature.
3. The method according to claim 1 , wherein
the pressure in a chamber for receiving said semiconductor substrate therein is decreased to not greater than 13330 Pa before said step (b).
4. The method according to claim 1 , wherein:
said thin film is a PSG film or a BSG film;
said step (b) is performed in a hydrogen-containing atmosphere; and
said step (d) is performed in a hydrogen-free atmosphere.
5. A method of heating a semiconductor substrate having a surface on which a thin film containing a dopant is formed to introduce the dopant into the semiconductor substrate and activate the dopant, said method comprising the steps of:
(a) irradiating said semiconductor substrate with light from a continuous lighting lamp to heat said semiconductor substrate to a first temperature, thereby diffusing said dopant from said thin film into the surface of said semiconductor substrate;
(b) turning off said continuous lighting lamp or decreasing an output from said continuous lighting lamp to decrease the temperature of said semiconductor substrate to a second temperature lower than said first temperature; and
(c) irradiating said semiconductor substrate with a flash of light from a flash lamp to heat the surface of said semiconductor substrate to a third temperature higher than said second temperature, thereby activating said dopant.