摘要:
A plasma reactor for processing a workpiece includes a reactor chamber, an electrostatic chuck within the chamber having a top surface for supporting a workpiece and having indentations in the top surface that form enclosed gas flow channels whenever covered by a workpiece resting on the top surface. The reactor further includes thermal control apparatus thermally coupled to the electrostatic chuck, an RF plasma bias power generator coupled to apply RF power to the electrostatic chuck, a pressurized gas supply of a thermally conductive gas, a controllable gas valve coupling the pressurized gas supply to the indentations to facilitate filling the channels with the thermally conductive gas for heat transfer between a backside of a workpiece and the electrostatic chuck at a heat transfer rate that is a function of the pressure against the backside of the workpiece of the thermally conductive gas. The reactor further includes an agile workpiece temperature control loop including (a) a temperature probe in the electrostatic chuck, and (b) a backside gas pressure controller coupled to an output of the temperature probe and responsive to a specified desired temperature, the controller governing the gas valve in response to a difference between the output of the temperature probe and the desired temperature.
摘要:
A method of controlling the temperature of a workpiece on a workpiece support in a plasma reactor includes placing coolant in a flow channel thermally coupled to the workpiece support, supporting a thermally conductive gas between the workpiece and the workpiece support to establish a backside gas pressure, providing sensors to measure the temperature of the workpiece support and the workpiece, and determining whether the rate of change in workpiece temperature is less or more than a rate limited by a thermal mass of the workpiece support. If the rate is less or equal, the thermal conditions of the coolant in the flow channel are changed to reduce a difference between the measured workpiece support temperature and a target workpiece support temperature. If the rate is more, the pressure of the thermally conductive gas is changed to reduce a difference between the measured workpiece temperature and a target workpiece temperature.
摘要:
A method of processing a workpiece in a plasma reactor having an electrostatic chuck for supporting the workpiece within a reactor chamber, the method including circulating a coolant through a refrigeration loop that includes an evaporator inside the electrostatic chuck, while pressurizing a workpiece-to-chuck interface with a thermally conductive gas, sensing conditions in the chamber including temperature near the workpiece and simulating heat flow through the electrostatic chuck in a thermal model of the chuck based upon the conditions. The method further includes obtaining the next scheduled change in RE heat load on the workpiece and using the model to estimate a change in thermal conditions of the coolant in the evaporator that would hold the temperature nearly constant by compensating for the next scheduled change in RF heat load, and making the change in thermal conditions of the coolant in the evaporator prior to the time of the next scheduled change by a head start related to the thermal propagation delay through the electrostatic chuck.
摘要:
A plasma reactor for processing a workpiece includes a reactor chamber, an electrostatic chuck within the chamber for supporting a workpiece, an RF plasma bias power generator coupled to apply RF power to the electrostatic chuck and a refrigeration loop having an evaporator inside the electrostatic chuck with a refrigerant inlet and a refrigerant outlet. Preferably, the evaporator includes a meandering passageway distributed in a plane beneath a top surface of the electrostatic chuck. Preferably, refrigerant within the evaporator is apportioned between a vapor phase and a liquid phase. As a result, heat transfer between the electrostatic chuck and the refrigerant within the evaporator is a constant-temperature process. This feature improves uniformity of temperature distribution across a diameter of the electrostatic chuck.
摘要:
A plasma reactor for processing a workpiece includes a reactor chamber, an electrostatic chuck within the chamber having a top surface for supporting a workpiece and having indentations in the top surface that form enclosed gas flow channels whenever covered by a workpiece resting on the top surface. The reactor further includes thermal control apparatus thermally coupled to the electrostatic chuck, an RF plasma bias power generator coupled to apply RF power to the electrostatic chuck, a pressurized gas supply of a thermally conductive gas, a controllable gas valve coupling the pressurized gas supply to the indentations to facilitate filling the channels with the thermally conductive gas for heat transfer between a backside of a workpiece and the electrostatic chuck at a heat transfer rate that is a function of the pressure against the backside of the workpiece of the thermally conductive gas. The reactor further includes an agile workpiece temperature control loop including (a) a temperature probe in the electrostatic chuck, and (b) a backside gas pressure controller coupled to an output of the temperature probe and responsive to a specified desired temperature, the controller governing the gas valve in response to a difference between the output of the temperature probe and the desired temperature.
摘要:
A method of processing a workpiece in a plasma reactor having an electrostatic chuck for supporting the workpiece within a reactor chamber, the method including circulating a coolant through a refrigeration loop that includes an evaporator inside the electrostatic chuck, while pressurizing a workpiece-to-chuck interface with a thermally conductive gas, sensing conditions in the chamber including temperature near the workpiece and simulating heat flow through the electrostatic chuck in a thermal model of the chuck based upon the conditions. The method further includes obtaining the next scheduled change in RF heat load on the workpiece and using the model to estimate a change in thermal conditions of the coolant in the evaporator that would hold the temperature nearly constant by compensating for the next scheduled change in RF heat load, and making the change in thermal conditions of the coolant in the evaporator prior to the time of the next scheduled change by a head start related to the thermal propagation delay through the electrostatic chuck.
摘要:
A plasma reactor having a reactor chamber and an electrostatic chuck with a surface for holding a workpiece inside the chamber includes a backside gas pressure source coupled to the electrostatic chuck for applying a thermally conductive gas under a selected pressure into a workpiece-surface interface formed whenever a workpiece is held on the surface and an evaporator inside the electrostatic chuck and a refrigeration loop having an expansion valve for controlling flow of coolant through the evaporator. The reactor further includes a temperature sensor in the electrostatic chuck and a memory storing a schedule of changes in RF power or wafer temperature. The reactor further includes a thermal model capable of simulating heat transfer between the evaporator and the surface based upon measurements from the temperature sensor, and a control processor coupled to the thermal model and to the memory and governing the backside gas pressure source in response to a prediction from the model of a change in the selected pressure that would compensate for the next scheduled change in RF power or implement the next scheduled change in wafer temperature.
摘要:
In a plasma reactor having an electrostatic chuck with an electrostatic chuck top surface for supporting a workpiece, thermal transfer medium flow channels in the interior of the electrostatic chuck, a method for controlling temperature of the workpiece during plasma processing includes circulating thermal transfer medium through the thermal transfer medium flow passages and supplying a thermally conductive gas between the workpiece and the electrostatic chuck top surface, and changing thermal transfer medium thermal conditions of thermal transfer medium flowing in the thermal transfer medium flow channels so as to change the temperature of the electrostatic chuck at a first rate limited by the thermal mass of the electrostatic chuck. The method further includes changing the backside gas pressure of the thermally conductive gas so as to change the temperature of the workpiece at a second rate faster than the first rate.