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AssigneeLam Research Corporation
InventorsArthur M. Howald, John P. Holland
Estimating the term…
A glass workpiece processed in a vacuum plasma processing chamber is dechucked from a monopolar electrostatic chuck by gradually reducing the chucking voltage during processing while maintaining the voltage high enough to clamp the workpiece. The chucking voltage during processing is controlled in response to flow rate of a heat transfer fluid flowing to the chuck to maintain the chucking force and the flow rate approximately constant. A reverse polarity voltage applied to the chuck at the end of processing assists in dechucking. The workpiece temperature is maintained at a high value at the end of processing to assisting in dechucking. Peak current flowing through the chuck during workpiece lifting from the chuck controls the amplitude and/or duration of the reverse polarity voltage during the next dechucking operation. An inert plasma in the chamber removes residual charge from the workpiece after workpiece lifting from the chuck.
A method of processing a dielectric workpiece in a vacuum plasma processor chamber having a metal wall at a reference potential and an electrostatic chuck with an electrode comprising applying the workpiece to the chuck, applying a DC chucking voltage to the electrode while the workpiece is on the chuck, processing the workpiece with a plasma in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, controlling the workpiece temperature while the workpiece is being processed by the plasma by supplying a heat transfer fluid to a back face of the workpiece unexposed to the plasma, the fluid having a tendency to move the workpiece relative to the chuck, the chucking voltage producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and insulator having determined passive electrical properties, including resistivity, the passive electrical properties being such that chucking charge derived by the chucking voltage is conducted through the dielectric workpiece from its exposed to its unexposed surface during processing of the workpiece so that application of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece, selecting at least one of plural dechucking processing steps dependent on the determined passive electrical properties, the selected at least one dechucking processing step being known to facilitate removal of the workpiece from the chuck despite the tendency to produce increasing chucking forces on the workpiece, and executing the at least one selected dechucking process step to facilitate removal of the workpiece from the chuck when workpiece processing is completed.
A method of processing a dielectric workpiece in a vacuum plasma processor chamber having a metal wall at a reference potential and an electrostatic chuck with an electrode comprising applying the dielectric workpiece to the chuck, applying a DC chucking voltage to the electrode, the chucking voltage being applied to the electrode while the workpiece is on the chuck, processing the workpiece with a plasma in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, cooling the workpiece while the workpiece is being processed with the plasma by supplying a cooling fluid to a back face of the workpiece unexposed to the plasma, the fluid having a tendency to move the workpiece relative to the chuck, the chucking voltage producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and an insulator between the electrode and a back face of the workpiece unexposed to the plasma having capacitances and resistances such that chucking charge derived by the chucking voltage is conducted through the dielectric workpiece from its exposed to its unexposed surface during processing of the workpiece so that application of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece, and substantially overcoming the tendency to produce increasing chucking forces on the workpiece by reducing the voltage applied to the chuck during workpiece processing while maintaining the electrostatic chucking force applied by the electrode to the workpiece via the insulator sufficiently high to overcome the tendency of the fluid to move the workpiece relative to the chuck.
A method of processing a glass workpiece having a resistivity of up to about 10.sup.14 .OMEGA..multidot.m in a vacuum plasma processor chamber having a metal wall at a reference potential and an electrostatic chuck with an electrode comprising applying the workpiece to the chuck, applying a DC chucking voltage to the electrode while the workpiece is on the chuck, processing the workpiece with a plasma in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, controlling the workpiece temperature while the workpiece is being processed with the plasma by supplying a heat transfer fluid to a back face of the workpiece unexposed to the plasma, the fluid having a tendency to move the workpiece relative to the chuck, the chucking voltage producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and an insulator between the electrode and the workpiece back face having capacitances and resistances such that chucking charge derived by the chucking voltage is conducted through the dielectric workpiece from its exposed to its unexposed surface during processing of the workpiece so that application of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece, and reversing the polarity of the DC voltage applied to the electrode upon completion of the workpiece processing to then reduce the chucking force to a low enough value to enable the workpiece to be removed from the chuck without damage, and then removing the workpiece from the chuck.
A method of processing a dielectric workpiece in a vacuum plasma processor chamber having a metal wall at a reference potential and an electrostatic chuck with an electrode comprising applying the workpiece to the chuck, applying a DC chucking voltage to the electrode, the chucking voltage being applied to the electrode while the workpiece is on the chuck, processing the workpiece with a plasma in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, and facilitating removal of the workpiece from the chuck by preventing a substantial decrease in workpiece resistivity after the plasma has been extinguished.
A method of processing a dielectric workpiece in a vacuum plasma processor chamber having a metal wall at a reference potential and an electrostatic chuck with an electrode comprising applying the workpiece to the chuck, applying a DC chucking voltage to the electrode, the chucking voltage being applied to the electrode while the workpiece is on the chuck, processing the workpiece with a plasma in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential and extinguishing the plasma to complete processing of the workpiece, then removing the workpiece from the chuck, charge developed across the workpiece during workpiece processing having a tendency to remain on the workpiece after removal of the workpiece from the chuck, and removing the charge remaining on the workpiece by applying an inert plasma to the chamber while the workpiece is in the chamber and removed from the chuck.
Apparatus for processing a dielectric workpiece comprising a vacuum plasma processor chamber having a metal wall at a reference potential, an electrostatic chuck in the chamber, the chuck including an electrode, a DC chucking voltage source connected to the electrode, a plasma source for processing the workpiece in the chamber, the plasma of the source having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, a heat transfer fluid source for a back face of the workpiece unexposed to the plasma, the fluid when applied to the workpiece back face having a tendency to move the workpiece relative to the chuck, the chucking voltage having a value for producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and an insulator between the electrode and workpiece back face having capacitances and resistances such that chucking charge derived by the chucking voltage is conducted through the dielectric workpiece from its exposed to its unexposed surface during processing of the workpiece so that application by the chucking voltage source of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece as a result of increasing charge trapped in the workpiece, the chucking voltage having a time rate of amplitude change for approximately overcoming the tendency to produce increasing chucking forces on the workpiece during workpiece processing while maintaining the charge applied by the electrode to the workpiece via the insulator sufficiently high to overcome the tendency of the fluid to move the workpiece relative to the chuck during workpiece processing.
Apparatus for processing a dielectric workpiece comprising a vacuum plasma processor chamber having a metal wall at a reference potential, an electrostatic chuck in the chamber, the chuck including an electrode, a DC chucking voltage source connected to the electrode, a plasma source for processing the workpiece in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, a heat transfer fluid source for a back face of the workpiece unexposed to the plasma, the fluid when applied to the workpiece back face having a tendency to move the workpiece relative to the chuck, the chucking voltage having a value for producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and an insulator between the electrode and workpiece back face having capacitances and resistances such that chucking charge derived by the chucking voltage is conducted through the dielectric workpiece from its exposed to its unexposed surface during processing of the workpiece so that application by the chucking voltage source of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece as a result of increasing charge trapped in the workpiece, a controller for overcoming the tendency to produce increasing chucking forces on the workpiece during workpiece processing while maintaining the force applied by the electrode to the workpiece via the insulator sufficiently high to overcome the tendency of the fluid to move the workpiece relative to the chuck during workpiece processing.
Apparatus for processing a dielectric workpiece comprising a vacuum plasma processor chamber having a metal wall at a reference potential, an electrostatic chuck in the chamber, the chuck including an electrode, a DC chucking voltage source connected to the electrode, a plasma source for processing the workpiece in the chamber, the plasma having sufficiently low electric impedance to cause a front face of the workpiece exposed to the plasma to be at substantially the same potential as the reference potential, a heat transfer fluid source for a back face of the workpiece unexposed to the plasma, the fluid when applied to the workpiece back face having a tendency to move the workpiece relative to the chuck, the chucking voltage having a value for producing a chucking force on the workpiece to overcome the tendency of the fluid to move the workpiece relative to the chuck, the workpiece and an insulator between the electrode and workpiece back face having capacitances and resistances such that chucking charge derived by the chucking voltage source migrates between the electrode and the unexposed face across the insulator and through the workpiece during processing of the workpiece so that application by the chucking voltage source of a constant DC chucking voltage to the electrode during processing of the workpiece tends to produce increasing chucking forces on the workpiece as a result of charge trapped in the workpiece, a monitor for effectively detecting the chucking force applied to the workpiece during workpiece processing, and a controller responsive to the chucking force detected by the monitor during workpiece processing for reducing the voltage of the source as a function of time during workpiece processing so the chucking force applied to the workpiece during workpiece processing remains sufficiently high to overcome the tendency of the fluid to move the workpiece relative to the chuck during workpiece processing.
Dependencies are inferred from the claim text.