Temperature control of chemical mechanical polishing
A chemical mechanical polishing system includes a support to hold a polishing pad, a carrier head to hold a substrate against the polishing pad during a polishing process, an in-situ monitoring system configured to generate a signal indicative of an amount of material on the substrate, a temperature control system to control a temperature of the polishing process, and a controller coupled to the in-situ monitoring system and the temperature control system. The controller is configured to cause the temperature control system to vary the temperature of the polishing process in response to the signal.
1. A chemical mechanical polishing system, comprising:
a support to hold a polishing pad;
a carrier head to hold a substrate against the polishing pad during a polishing process;
an in-situ monitoring system configured to generate a signal having a value representative of a thickness of a layer on the substrate during the polishing process;
a temperature control system to control a temperature of a component selected from a surface of the polishing pad, a polishing liquid on the polishing pad, the substrate, or a combination thereof; and
a controller coupled to the in-situ monitoring system and the temperature control system, the controller configured to
store, prior to polishing, a continuous function that receives only the value representative of the thickness of the layer from the signal and outputs a desired temperature of the component based on the value representative of the thickness, wherein the continuous function is continuous across changes in the thickness of the layer of the substrate, and
cause the temperature control system to drive the temperature of the component toward the desired temperature output by the continuous function in response to the signal such that the desired temperature and the temperature of the component vary according to the thickness of the layer.
2. The system of claim 1 , wherein the value of the signal is proportional to the thickness of the layer.
3. The system of claim 1 , wherein the controller is configured to cause the temperature control system to change the temperature of component in response to the value of the signal crossing a threshold.
4. The system of claim 3 , wherein the value of the signal crossing the threshold indicates that a remaining thickness of the layer has fallen below a threshold thickness.
5. The system of claim 4 , wherein the controller is configured to reduce the temperature in response to the remaining thickness of the layer falling below the threshold thickness.
6. The system of claim 5 , wherein the controller is configured to reduce the temperature by at least 10° C.
7. The system of claim 4 , wherein the controller is configured to increase the temperature in response to the remaining thickness of the layer falling below the threshold thickness.
8. The system of claim 4 , wherein the controller is configured to adjust the temperature of component by an amount sufficient to achieve a target polishing characteristic.
9. The system of claim 7 , further comprising a sensor to monitor the temperature of component, and wherein the controller receives a signal from the sensor, and wherein the controller comprises a closed-loop control of the temperature control system to drive a measured temperature from the sensor to the desired temperature.
10. The system of claim 1 , wherein the in-situ monitoring system comprises an optical monitoring system, eddy current monitoring system, a friction sensor, a motor current or motor torque monitoring system or a temperature sensor.
11. A method of chemical mechanical polishing, comprising:
holding a substrate against a polishing pad;
monitoring a thickness of a layer of material on the substrate with an in-situ monitoring system during a polishing process of the layer on substrate and generating a signal that depends on the thickness of the layer of material, wherein the in-situ monitoring system is configured to generate a value representative of the thickness of the layer being polished during the polishing process;
storing, prior to the polishing process, a continuous function that receives only the value representative of the thickness of the layer from the signal and outputs a desired temperature of the polishing process based on the value, wherein the continuous function is continuous across changes in the thickness of the layer of the substrate; and
causing a temperature control system to vary a temperature of a component selected from a surface of the polishing pad, a polishing liquid on the polishing pad, the substrate, or a combination thereof, such that a temperature of a surface of the component is adjusted according to the continuous function in response to the signal.