Varian Semiconductor Equipment Associates, Inc.

Chris Leavitt

Bon-Woong Koo

Timothy J Miller

Costel Biloiu

Steven Raymond Walther

Jay Thomas Scheuer

Rajesh Dorai

Harold M Persing

Bjorn O Pedersen

Alexander Soskov

A hardware interlock system for monitoring operation of RF plasma sources. The hardware interlock system includes an RF generator operative to transmit a forward RF power used to generate plasma in a plasma chamber. A derivative based hardware interlock circuit is coupled in series with the RF generator. The derivative based hardware interlock circuit determines a reflected RF power derivative value indicative of the speed of change in reflected RF power values in the RF plasma ion source. An analog/digital (A/D) logic circuit is coupled with the derivative based hardware interlock circuit. The A/D logic circuit can shut down the RF generator output when the reflected RF power derivative value exceeds a threshold.

Hardware plasma interlock system

A Faraday dose and uniformity monitor can include a magnetically suppressed annular Faraday cup surrounding a target wafer. A narrow aperture can reduce discharges within Faraday cup opening. The annular Faraday cup can have a continuous cross section to eliminate discharges due to breaks. A plurality of annular Faraday cups at different radii can independently measure current density to monitor changes in plasma uniformity. The magnetic suppression field can be configured to have a very rapid decrease in field strength with distance to minimize plasma and implant perturbations and can include both radial and azimuthal components, or primarily azimuthal components. The azimuthal field component can be generated by multiple vertically oriented magnets of alternating polarity, or by the use of a magnetic field coil. In addition, dose electronics can provide integration of pulsed current at high voltage, and can convert the integrated charge to a series of light pulses coupled optically to a dose controller.

Faraday dose and uniformity monitor for plasma based ion implantation

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Gloucester, MA, United States of America

Chris Leavitt