Porous SiOCH Thin Films Obtained by Foaming

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• 作者：Julien El Sabahy ; Gaël Castellan ; Florence Ricoul ; Vincent Jousseaume
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：120
• 期：17
• 页码：9184-9191
• 全文大小：420K
• 年卷期：0
• ISSN：1932-7455

文摘

Porous organosilicate thin films (SiOCH) deposited by plasma-enhanced chemical vapor deposition (PECVD) are used as dielectric layers in advanced microelectronic interconnections and as chemical layers in chemical sensors and biosensors. One challenge is to increase the porosity in these films, the classical method being limited to porosity rate close to 50%. In this paper, we report an innovative and simple strategy to perform highly nanoporous SiOCH thin films without the use of any templates or external blowing agents. This approach uses a SiOCH deposited by PECVD (without any porogens) intentionally covered by a dense crust. The porosity generation is obtained through an ultraviolet (UV)-assisted thermal annealing of the stack. The highest porosities ever demonstrated for SiOCH PECVD thin films are obtained (porosity close to 65%). The impact of different process parameters (choice of precursor, deposition, and annealing conditions) on the creation of porosity is studied. The porosity introduction with this original method can be related to a foaming mechanism: a gas is produced inside the film during the UV-assisted curing which causes a film expansion and allow the creation of porosity.