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1 March 1991 Reactive ion etching of deep isolation trenches using sulfur hexafluoride, chlorine, helium, and oxygen
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Proceedings Volume 1392, Advanced Techniques for Integrated Circuit Processing; (1991)
Event: Processing Integration, 1990, Santa Clara, CA, United States
Four micron deep trenches are etched in a non-loadlock diode reactor using a gas mixture of 5F6/C12/He. It is an I. B. M. designed batch system. The tool is a typical planar design reactor with an aluminum upper anode and a copper lower cathode. The cathode is covered by a quartz pallet upon which the wafers are placed. It was advantageous to use a copper electrode because it was water cooled adsorbed moisture necessary in the passivation of the trench wall and minimized the deposition of residuals on the upper electrode. The use of copper as the cathode material however proved to have many disadvantages when coupled with the corrosive Cl2 gas chemistry. The corrosive nature of the Cl2 chemistry caused rapid degradation (corrosion) of the copper cathode resulting in frequent cathode changes. This corrosion was also responsible for a narrow and consistently changing process window. As the corrosion increased the ability to retain more moisture increased. The change in the amount of moisture retained would result in a shifting process window and a degradation in process control over time. This in turn made the process sensitive to the amount of silicon in the plasma that was available to recombine and form the SiOx necessary for passivation. The result would inevitably be " black silicon" (silicon spikes formed by micromasking). 2 . EXPERIMENTAL Alternatives to the copper electrode were investigated. A
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Theresa M. Krawiec and Nicholas J. Giammarco "Reactive ion etching of deep isolation trenches using sulfur hexafluoride, chlorine, helium, and oxygen", Proc. SPIE 1392, Advanced Techniques for Integrated Circuit Processing, (1 March 1991);

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