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http://dx.doi.org/10.7464/ksct.2012.18.3.280

Effect of Alcohols on the Dry Etching of Sacrificial SiO2 in Supercritical CO2  

Kim, Do-Hoon (Department of Image Science & Engineering, Pukyong National University)
Jang, Myoung-Jae (Department of Image Science & Engineering, Pukyong National University)
Lim, Kwon-Taek (Department of Image Science & Engineering, Pukyong National University)
Publication Information
Clean Technology / v.18, no.3, 2012 , pp. 280-286 More about this Journal
Abstract
The dry etching of sacrificial $SiO_2$ was performed in supercritical carbon dioxide. The etching of boron phosphor silica glass (BPSG), tetraethyl orthosilicate (TEOS), thermal $SiO_2$, and Si-nitride (SiN) was investigated by using a two chamber system with HF/py etchant and alcohol additives. The etch rate of sacrificial $SiO_2$ increased upon the addition of methanol. The etch selectivity of BPSG with respect to SiN was highest with IPA although the highest etch rate was resulted from methanol except BPSG. The etch rate increased with the temperature in HF/py/MeOH system. Especially the increase of the etch rate was much higher for BPSG with an increase in the reaction temperature. The etch residue was not reduced apparently upon the addition of alcohol cosolvents to HF/py. While the etch rate in HF/$H_2O$ was higher than HF/py/alcohol system, the rate decreased with the addition of alcohols to HF/$H_2O$. The cantilever beam structure of high aspect ratios was released by the dry ething in supercritical carbon dioxide without damage.
Keywords
Supercritical carbon dioxide; Dry etching; Sacrificial oxide; Cantilever beam; Stiction;
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