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Enhanced RF Plasma

IP.com Disclosure Number: IPCOM000062320D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+3]

Abstract

A device for producing an enhanced RF plasma is illustrated in Fig. 1. The electrodes 11 and 12 are electrically energized by RF power source 13. A plasma is thereby generated in volume 14 enclosed by end plates 15 and 16 and sidewall 17. A gas flow and pumping means (not shown) are provided to assure proper operating pressure within volume 14, usually in the 10-100 mTorr range. A plasma process is carried out on a workpiece 18. The baffles 19 and 20 serve to restrict the flow of RF current between electrodes 11 and 12, thereby causing an intense plasma to be formed in a portion of the discharge volume 21 near the workpiece. The configuration has several advantages. The intense discharge is more confined to a particular region, thereby reducing the incidental sputtering of surrounding hardware.

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Enhanced RF Plasma

A device for producing an enhanced RF plasma is illustrated in Fig. 1. The electrodes 11 and 12 are electrically energized by RF power source 13. A plasma is thereby generated in volume 14 enclosed by end plates 15 and 16 and sidewall 17. A gas flow and pumping means (not shown) are provided to assure proper operating pressure within volume 14, usually in the 10-100 mTorr range.

A plasma process is carried out on a workpiece 18. The baffles 19 and 20 serve to restrict the flow of RF current between electrodes 11 and 12, thereby causing an intense plasma to be formed in a portion of the discharge volume 21 near the workpiece. The configuration has several advantages. The intense discharge is more confined to a particular region, thereby reducing the incidental sputtering of surrounding hardware. Because of the arrangement of the baffles 19 and 20, energetic secondary electrons from electrodes 11 and 12, which tend to follow straight-line trajectories, cannot strike the workpiece. Finally, because the workpiece 18 is isolated from the electrodes 11 and 12, the presence of the workpiece will have less of an effect on the RF circuitry and the plasma production. Those skilled in the art will recognize that a variety of configurations and modifications are possible. For example, the presence of the baffles 19 and 20 will make it harder to initiate an RF discharge. For that reason, an auxiliary electrode 22 is provided, so that a discharge may first be started between electrode 11 and auxiliary electrode 22. For starting, then, electrode 11 is connected to one terminal of RF power supply 13, while both electrode 12 and auxiliary electrode 22 are connected to the other terminal of that supply. After starting, when a discharge plasma has been established, the discharge may be fully transferred to electrode 12 by disconnecting auxiliary electrode 22 from the RF power supply. An alternative embodiment may be understood with reference to the structural schematic diagram of Fig. 2. Primary electrodes 51 and 52 are energized by the primary RF power source 53. A plasma is thereby generated in the volumes 54 enclosed by the electrodes 51 and 52, as well as the connecting volume 55. Gas flows in through ports 56 and 57, together with pumping out through ports 58 and 59, serve to maintain operating pressure in volumes 54 through 55. Most of the voltage in an RF discharge...