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Resputtering Monitor and Controller for Driven Substrate RF Sputtering Systems

IP.com Disclosure Number: IPCOM000075369D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Burkhardt, PJ: AUTHOR [+2]

Abstract

This RF sputtering system monitor maintains a constant target-to-substrate voltage ratio for controlled resputtering to within 0.5% for long periods of time (hours). The target voltage is controlled independently in order to maintain a constant deposition rate. The monitor is particularly useful when high resputtering conditions are required such that deposition rates are low and long sputtering times are required.

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Resputtering Monitor and Controller for Driven Substrate RF Sputtering Systems

This RF sputtering system monitor maintains a constant target-to-substrate voltage ratio for controlled resputtering to within 0.5% for long periods of time (hours). The target voltage is controlled independently in order to maintain a constant deposition rate. The monitor is particularly useful when high resputtering conditions are required such that deposition rates are low and long sputtering times are required.

Substrate drive is obtained by tapping RF power from the target supply by means of variable inductor 8. High impedance RF attenuator probes 1 and 2 sense substrate and target DC voltages respectively through RF chokes 16 and
17. The signals are current amplified by operational amplifiers 3 and 4. The resultant DC signals are bucked against each other through variable potentiometer 5. Servo amplifier 6 operates motor 7 which adjusts the tap-off inductor 8 such that a voltage null appears at the preset wiper of potentiometer 5. This potentiometer is calibrated in terms of target-to-substrate DC voltage ratio.

Independent control of target voltage is accomplished by introducing the output of target probe 2 into servo amplifier 10 which in turn operates servo motor 11 to adjust potentiomenter 15. A portion of the DC voltage provided by supply 13 appears at the potentiometer wiper and is directed to the grid of the RF transmitters speech amplifier 14. When operated in the a.m. mo...