Study of the Sol-gel thin-film ammonia curing process

Study of the Sol-gel thin-film ammonia curing process

Christophe Boscher  Jérémy Avice  Philippe Belleville  Herve Piombini  Karine Vallé 

CEA, DAM Le Ripault, 37260 Monts, France

Corresponding Author Email: 
christophe.boscher@cea.fr
Page: 
165-174
|
DOI: 
https://doi.org/10.3166/i2m.16.1-4.165-174
Received: 
|
Accepted: 
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Published: 
31 December 2017
| Citation

ACCESS

Abstract: 

The adhesion of sol-gel antireflective coatings on optical components is improved by an exposition into ammonia vapors. Coatings of 70 or 210 nm thickness are deposited by dip-coating and consisted in a collection of nanoparticles having an average diameter of 10 nm. The micro- porosity is about 55% and by the way the refractive index can be as low as 1.22. The synthesis results of the hydrolyze-condensation in a basic environment of tetraethyl orthosilicate in an alcoholic  solution. Like coatings  have  a   low  adhesion,  they’re consequently easily damaged mechanically. To increase the cohesion of these colloidal thin films, a chemical modification of the nanoparticles is achieved thanks to a post-processing using  ammonia   vapors,   called  ”ammonia   curing   process”.  This  process  induces a modification of the noncontact chemical bonds from Van der Walls to Hydrogen & Covalent bonds. The increase in strength of the films is accompanied by 20% shrinkage in thickness but without changing the antireflective properties. This change in thickness is also accompanied by a modification of the chemistry of the nanoparticles. The purpose of this study is to follow these two main coating changes resulting from the post treatment in order to optimize it for an industrial process

Keywords: 

sol-gel, antireflective, silica, ammonia, curing

1. Introduction
2. Revêtement antireflet à base de silice colloïdale
3. Évolution de l’épaisseur en fonction de la durée du durcissement
4. Évolution de la chimie de surface en fonction de la durée du durcissement
5. Conclusion
  References

André M. L. (1999). The French MegaJoule Project (LMJ). Fusion Eng. and Des. 44:43-49.

Avice J., Vaudel G., Boscher C., Belleville P., Gusev V., Brotons G., Piombini H., P. Ruello (2017). Sonder  les  propriétés  élastiques  de  matériaux  nanostructurés  par  acoustique ultrarapide, Actes du colloque CMOI’17, Le Mans.

Ayouch A., Dieudonné X., Vaudel G., Piombini H., Vallé K., Gusev V., Belleville P. and, Ruello P. (2012). Elasticity of an Assembly of Disordered Nanoparticles Interacting via Either  van  der  Waals-Bonded  or  Covalent-Bonded  Coating  Layers.  ACS  NANO 6, p. 10614-10621.

Belleville P., Floch H. (1994).Ammonia hardening of porous silica antireflective coatings Proc. SPIE 2288, p. 25-32.

Cant N.W. et Little L.H. (1964). An infrared study of the adsorption of ammonia on porous vigor glass, Canadian Journal of Chemistry, vol. 42.

Dieudonné X. (2011). Etude d’empilements multicouches colloïdaux préparés par voie sol- gel : Propriétés optiques et mécaniques, Thèse de l’université François Rabelais (Tours).

Ferguson J. D., Smith E. R., Weimer A. W., George S.M. (2004). ALD of SiO2 at Room Temperature Using TEOS and H2O with NH3 as the catalyst, Journal of The Electrochemical Society, vol. 151, n° 8, p. 528-535.

French Patent. Procédé de fabrication de couches minces présentant des propriétés optiques et de résistance à l’abrasion, n° 93 03987, assigned to CEA.

Guo Y. J., Zu X. T., Jiang X. D., Yuan X. D., Xu S. Z., Lv H. B., Wang B. Y. (2009). Effect of ammonia  treatment  on  laser-induced  damage  of  nano-porous  silica  film,  Optik  120, p. 437-441.

Li X., Gross M., Oreb B., Shen J. (2012). Increased Laser-Damage Resistance of Sol-Gel Silica Coating by Structure Modification. Journal of Chemical C 2012, vol. 116, p.18367-18371.

Mouchart J.J., Lagier G., Pointu B. (1985). Détermination des constantes optiques n et k de matériaux faiblement absorbants. Applied Optics, vol. 24, n° 12.

Piombini H., Boscher C., Barre A. L., Avice. J. (2017). Indentification de faïençage de couche mince sol-gel, Actes du colloque CMOI 2017, Le Mans.

Stöber W., Fink A., Bohn E. (1968). Controlled growth of monodisperse silica spheres in the micron size range. Journal of colloid and interface science, vol. 26, n° 1, p. 62-69