FTIR measurements in an ICP etching plasma using CF{sub 4}

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:163155

Abraham, I C; Jung, G; Breun, R A; Woods, R C ^[1]

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1. Univ. of Wisconsin, Madison, WI (United States). Engineering Research Center for Plasma-Aided Manufacturing

Spectroscopic measurements using Fourier Transform Infrared (FTIR) were made between 700 cm{sup {minus}1} and 4,000 cm{sup {minus}1} in a Magnetically Confined Inductively Coupled Plasma (MCICP) etching tool. The operating pressure range was 2--9 mTorr. The peak plasma density was of the order of 5 {times} 10{sup 11} cm{sup {minus}3} (at 750 W), and extended over the inner 30 cm diameter of the 40 cm diameter vacuum system. The axial length of the source is 50 cm. The electron temperature is 2--3 eV. Two fluorocarbon gases have been studied so far. The breakup of the tetrafluoromethane (CF{sub 4}) parent gas was measured vs. power and pressure. The vibrational temperature of the parent gas was measured vs. power between 500--1,000 W and ranged between 315--350 K. The temperatures were slightly lower than previous results in an Electron Cyclotron Resonance (ECR) etching tool. These results show that the rotational temperatures are close to the temperature of the vacuum walls. The MCICP has water cooled walls ({approximately} 25 C). The ECR source chamber typically operates at 50--70 C. Products of the CF{sub 4} plasma discharge identified were SiF{sub 4}, CO, CO{sub 2}, and a fluorocarbon film that deposited on the windows. No substantial signal in the CF{sub 3} absorption region was observed. The rotational temperature of CO was measured at 500 W and 1,000 W. The goal of this research is to correlate the FTIR spectra with etching parameters observed for these plasmas. In particular, the presence and growth rate of the different polymer films may correlate with the difference in selectivity of etching SiO{sub 2} over Si.

• OSTI ID: 163155
• Report Number(s): CONF-950612--; ISBN 0-7803-2669-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBON TETRAFLUORIDE
CHEMICAL REACTORS
ETCHING
INFRARED RADIATION
PLASMA DIAGNOSTICS
SEMICONDUCTOR MATERIALS
SILICON
SILICON OXIDES