Method of heating a substrate in a variable temperature process using a fixed temperature chuck
View Patent ↗A method is provided for heating a substrate in a process chamber using a heated chuck. In accordance with the method, the substrate is lowered onto the chuck and heated to a first temperature less than a temperature of the chuck. The substrate is then raised away from the chuck, and a process is carried out on the substrate while the substrate is supported above the chuck. The substrate is then lowered back to the chuck and heated to a second temperature greater than the first temperature for further processing of the substrate.
1. A method of heating a substrate in a process chamber using a heated chuck, comprising:
lowering the substrate onto the chuck;
heating the substrate to a first temperature less than a temperature of the chuck;
raising the substrate away from the chuck while the substrate is at the first temperature;
processing the substrate while the substrate is at the first temperature and raised away from the chuck;
lowering the substrate back onto the chuck;
heating the substrate to a second temperature greater than the first temperature; and
further processing the substrate after heating the substrate to the second temperature.
2. The method of claim 1 , wherein the processing comprises photoresist ashing.
3. The method of claim 1 , wherein the temperature of the chuck is maintained constant throughout all of the method steps.
4. A method of controlling a temperature of a substrate during a substrate processing sequence, the method comprising:
providing a thermal chuck at a first temperature that is at least a maximum desired substrate temperature and maintaining the chuck at said first temperature;
supporting a wafer above the chuck;
lowering the wafer into a heating position until the wafer reaches a low processing temperature, then raising the wafer to an upper position above the chuck;
conducting processing of the wafer at the upper position while the wafer is at the low processing temperature;
lowering the wafer into the heating position until the wafer reaches a high processing temperature, then raising the wafer to the upper position above the chuck; and
conducting processing of the wafer at the upper position while the wafer is at the high processing temperature;
wherein each of the above steps is performed while maintaining the chuck at the first temperature.
5. The method of claim 4 , further comprising maintaining the substrate in proximity to the chuck for a pre-determined length of time in order to increase the temperature of the substrate to a desired temperature.
6. The method of claim 4 , further comprising varying a chamber pressure during a heating or cooling step to facilitate increased heat transfer between the chuck and the substrate.