Radio frequency monitor for semiconductor process control
First Claim
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1. A radio frequency (RF) sensor, coupled to a transmission line disposed between a plasma reactor and an electrical source providing RF voltage and current to said plasma reactor, for monitoring said RE voltage and current on said transmission line comprising:
- a first capacitance coupled between a first node and said transmission line;
a second capacitance coupled between said first node and a second node;
said first and second capacitances providing a capacitive voltage divider network wherein a first voltage output at said first node is a proportional representation of said RF voltage on said transmission line;
a wire loop disposed next to said transmission line at a point on said transmission line where said first capacitance is coupled but having an air gap between said loop and said transmission line, such that electromagnetic field lines generated by current flow in said transmission line is inductively coupled to said loop, wherein voltage induced in said loop by said current flow provides a second voltage output which is a proportional representation of said RF current on said transmission line;
an electromagnetic shielding, disposed around said first and second capacitances, inhibits electromagnetic interference from interacting with said first and second capacitances which interference can cause erroneous first voltage output at said first node;
said first and second voltage outputs providing for accurate measurement of said RF voltage and current and said measurement is also used to accurately determine a phase relationship between said RF voltage and current.
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Abstract
A RF sensor for monitoring voltage, current and phase angle of a RF signal being coupled to a plasma reactor. Outputs from the sensor are used to calculate various properties of the plasma. These values are then utilized to characterize the process and/or used to provide feedback for in-situ control of an ongoing plasma process.
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Citations
10 Claims
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1. A radio frequency (RF) sensor, coupled to a transmission line disposed between a plasma reactor and an electrical source providing RF voltage and current to said plasma reactor, for monitoring said RE voltage and current on said transmission line comprising:
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a first capacitance coupled between a first node and said transmission line; a second capacitance coupled between said first node and a second node; said first and second capacitances providing a capacitive voltage divider network wherein a first voltage output at said first node is a proportional representation of said RF voltage on said transmission line; a wire loop disposed next to said transmission line at a point on said transmission line where said first capacitance is coupled but having an air gap between said loop and said transmission line, such that electromagnetic field lines generated by current flow in said transmission line is inductively coupled to said loop, wherein voltage induced in said loop by said current flow provides a second voltage output which is a proportional representation of said RF current on said transmission line; an electromagnetic shielding, disposed around said first and second capacitances, inhibits electromagnetic interference from interacting with said first and second capacitances which interference can cause erroneous first voltage output at said first node; said first and second voltage outputs providing for accurate measurement of said RF voltage and current and said measurement is also used to accurately determine a phase relationship between said RF voltage and current. - View Dependent Claims (2, 3, 4)
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5. A radio frequency (RF) sensor;
- coupled to a transmission line disposed between a plasma reactor and an electrical source providing RF voltage and current to said plasma reactor, for monitoring said RF voltage and current on said transmission line in order to control operating parameters of said plasma reactor comprising;
a first capacitor coupled between a first node and said transmission line; a second capacitor coupled between said first node and a common return; said first and second capacitors providing a capacitive voltage divider network wherein a first voltage output at said first node is a proportional representation of said RF voltage on said transmission line; a wire loop disposed next to said transmission line at a point on said transmission line where said first capacitor is coupled but having an air gap between said loop and said transmission line, such that electromagnetic field lines generated by current flow in said transmission line is inductively coupled to said loop, wherein voltage induced in said loop by said current flow provides a second voltage output which is a proportional representation of said RF current on said transmission line; an electromagnetic shielding, disposed around said first and second capacitors, inhibits electromagnetic interference from interacting with said first and second capacitors which interference can cause erroneous first voltage output at said first node; said first and second voltage outputs providing for accurate measurement of said RF voltage and current and said measurement is also used to accurately determine a phase difference between said RF voltage and RF current. - View Dependent Claims (6, 7, 8, 9, 10)
- coupled to a transmission line disposed between a plasma reactor and an electrical source providing RF voltage and current to said plasma reactor, for monitoring said RF voltage and current on said transmission line in order to control operating parameters of said plasma reactor comprising;
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