Feedback control of chlorine inductively coupled plasma etch processing

Journal Article · Tue Mar 01 04:00:00 EST 2005 · Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films

DOI:https://doi.org/10.1116/1.1861055· OSTI ID:20637025

Chaung, Lin; Leou, K -C; Shiao, K -M ^[1]

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1. Department of Engineering and System Science, National Tsing Hua University, 100, section 2, Kuang Fu Road, Hsinchu, Taiwan 30043 (China)

Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2{sup 2} factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained.

• OSTI ID: 20637025
• Journal Information: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films Journal Issue: 2 Vol. 23; ISSN 0734-2101; ISSN JVTAD6
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTUATORS
CATIONS
CHLORINE
CLOSED-LOOP CONTROL
ETCHING
FEEDBACK
ICP MASS SPECTROSCOPY
ION DENSITY
MHZ RANGE 01-100
PLASMA
PROCESS CONTROL
SILICON
VARIATIONS