Heat treatment method for growing silicide
View Patent ↗Ions of silicon are implanted into source/drain regions in a semiconductor wafer to amorphize an ion implantation region in the semiconductor wafer. A nickel film is deposited on the amorphized ion implantation region. First irradiation from a flash lamp is performed on the semiconductor wafer with the nickel film deposited thereon to increase the temperature of a front surface of the semiconductor wafer from a preheating temperature to a target temperature for a time period in the range of 1 to 20 milliseconds. Subsequently, second irradiation from the flash lamp is performed to maintain the temperature of the front surface of the semiconductor wafer within a ±25° C. range around the target temperature for a time period in the range of 1 to 100 milliseconds. This causes nickel silicide to grow preferentially in a direction perpendicular to the semiconductor wafer.
1. A method of heating a substrate of silicon to grow a silicide, said method comprising the steps of:
(a) implanting ions into said substrate to amorphize an ion implantation region in said substrate;
(b) depositing a metal film on the amorphized ion implantation region;
(c) heating said substrate with said metal film formed thereon at a predetermined preheating temperature;
(d) irradiating said substrate with light to increase the temperature of a front surface of said substrate from said preheating temperature to a target temperature for a time period in the range of 1 to 20 milliseconds; and
(e) irradiating said substrate with light to maintain the temperature of the front surface of said substrate within a ±25° C. range around said target temperature for a time period in the range of 1 to 100 milliseconds, said step (e) being performed after said step (d).
2. The method according to claim 1 , wherein:
a film of nickel is deposited in said step (b);
said preheating temperature is not greater than 300° C.; and
said target temperature is in the range of 600° C. to 1100° C.
3. The method according to claim 1 , wherein:
a film of titanium is deposited in said step (b);
said preheating temperature is not greater than 500° C.; and
said target temperature is in the range of 600° C. to 1100° C.
4. The method according to claim 1 , wherein:
a film of cobalt is deposited in said step (b);
said preheating temperature is not greater than 500° C.; and
said target temperature is in the range of 600° C. to 1100° C.
5. The method according to claim 1 , wherein:
a film of tungsten is deposited in said step (b);
said preheating temperature is not greater than 700° C.; and
said target temperature is in the range of 900° C. to 1100° C.
6. The method according to claim 1 , wherein
said substrate is irradiated with a flash of light from a flash lamp in said step (d) and in said step (e).
7. The method according to claim 1 , wherein
ions of one element selected from the group consisting of nitrogen, argon, silicon and germanium are implanted in said step (a).
8. The method according to claim 6 , wherein
a switching element intermittently supplies electrical charges from a capacitor to said flash lamp to control an emission output from said flash lamp in said step (d) and in said step (e).