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A Study on Si$_3$N$_4$ Thin Film Etching Using H$_3$PO$_4$ by Using Wafer Direct Heating
New Physics: Sae Mulli 2017; 67: 936~939
Published online August 31, 2017;
© 2017 New Physics: Sae Mulli.

Seunghoon LEE*, Sungwon MO, Yangho LEE

ZEUS, Osan 18148, Korea
Correspondence to:
Received April 21, 2017; Revised June 13, 2017; Accepted July 11, 2017.
cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The high-temperature phosphoric acid process is a typical method of nitride etching. This process is characterized by a high selectivity ratio that does not cause much oxide film etching as compared with nitride film etching. There is also a need for higher selection ratios. However, when phosphoric acid is used at high temperatures, nitride etching increases exponentially with the temperature of the phosphoric acid solution, but the etching rate is physically limited by the boiling point. In order to overcome this limitation on the etching rate, most have tried to obtain a better etch rate by adding a small amount of an additive to phosphoric acid. In this study, instead of using a special phosphoric acid solution, we achieved a high nitrate etching rate when the wafer was heated above the boiling point by directly heating the wafer and applying phosphoric acid on the wafer.
PACS numbers: 82.33.Pt
Keywords: H$_3$PO$_4$, Etch, Temperature, Boiling point

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