Effect of Supercritical Drying on Sol-Gel Deposited Silica Aerogel Thin Films at Different Temperatures
Now a days silica aerogel thin films are attracted more attention as an interlayer dielectric (ILD) application in ULSI technology due to the lowest dielectric constant. In present work, we report the successful deposition of silica aerogel thin films on Si wafer by sol-gel technique. Further, in order to introduce porosity the deposited thin films were dried at supercritical condition with different temperatures. Elipsometric study shows that the refractive index (RI) of as deposited film is observed to 1.44 whereas RI of super critically dried thin films is observed to be decreased to 1.29 for the film dried at 40 °C. The film thickness observed to be decreased from 200 to 129 nm with increase in supercritical drying temperature. The dielectric constant of the films is observed to be lowered to 2.8 for the film dried at 40 °C temperature. The pore volume and porosity of the films increased up to 0.25 and 37 % respectively with increase in drying temperature while the density of the films is decreases with increasing temperature
KeywordsSilica aerogel thin film Super critical drying RI Elipsometry Sol-gel ULSI
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Authors are thankful to SERB, Department of Science and Technology, New Delhi for providing financial assistance for carrying out present work (Letter No. SR/S3/EECE/0131/2011 dated 29th August 2012).
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