ELECTRON DENSITY MEASUREMENT AND PLASMA PROCESS CONTROL SYSTEM USING CHANGES IN THE RESONANT FREQUENCY OF AN OPEN RESONATOR CONTAINING THE PLASMA

Title:

ELECTRON DENSITY MEASUREMENT AND PLASMA PROCESS CONTROL SYSTEM USING CHANGES IN THE RESONANT FREQUENCY OF AN OPEN RESONATOR CONTAINING THE PLASMA

Document Type and Number:

WIPO Patent Application WO2001006544

Kind Code:

A3

Abstract:

A system for measuring plasma electron densities (e.g., in the range of 1 010 to 1 01' cm-') and for controlling a plasma generator (320). Measurement of the plasma electron density is used as part of a feedback control in plasma-assisted processes, such as depositions or etches. Both the plasma measurement method and system generate a control voltage that in turn controls the plasma generator. A programmable frequency source (201) sequentially excites a number of the resonant modes of an open resonator placed within the plasma processing apparatus. The resonant frequencies of the resonant modes depend on the plasma electron density in the space between the reflectors of the open resonator. The apparatus automatically determines the increase in the resonant frequency of an arbitrarily chosen resonant mode of the open resonator due to the introduction of a plasma and compares that measured frequency to data previously entered. The comparison is by any one of (1) dedicated circuitry, (2) a digital signal processor, and (3) a specially programmed general purpose computer (100). The comparator calculates a control signal which is used to modify the power output of the plasma generator (320) as necessary to achieve the desired plasma electron density.

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Inventors:

VERDEYEN JOSEPH T (US)
JOHNSON WAYNE L (US)
SIRKIS MURRAY D (US)

Application Number:

PCT/US2000/019536

Publication Date:

July 05, 2001

Filing Date:

July 20, 2000

Export Citation:

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Assignee:

TOKYO ELECTRON LTD (JP)
VERDEYEN JOSEPH T (US)
JOHNSON WAYNE L (US)
SIRKIS MURRAY D (US)

International Classes:

H01J37/32; H05H1/00; H05H1/46; (IPC1-7): G01N27/62

Foreign References:

US5939886A	1999-08-17
US5936413A	1999-08-10

Other References: