Demonstration of a Directly Photopatternable Spin-On-Glass Based on Hydrogen Silsesquioxane and Photobase Generators

Abstract

A commercially available spin-on-glass material, hydrogen silsesquioxane, has been rendered photopatternable to micrometer dimensions by the introduction of a photobase generator at concentrations of <5 wt %. The cure process proceeds via hydrolysis of the silyl hydride linkage by residual water in the film, as activated by a photogenerated base catalyst. Subsequent reaction of the generated silanol with neighboring silyl hydride groups yields a thermally stable siloxane cross-link. The photochemical cross-linking of hydrogen silsesquioxane shows high sensitivity (<40 mJ/cm2) and is not inhibited by molecular oxygen. The resultant oxide films can be further cured at elevated temperature either under an inert atmosphere to minimize the dielectric constant or heated in an air atmosphere to complete the conversion to silica glass. The oxidative nature of both the photo and thermal cure processes and the release of only traces of hydrogen as byproduct results in minimal weight loss in the film during processing.

Multiphoton Fabrication

“…Photocurable "spinon" glasses have been reported, [132] and it is possible to create 2D patterns of these materials by using MPA. Chalcogenide glass has also been patterned with MPA.…”

Mehrphotonen‐Mikrofabrikation

“…Mit Licht härtbare "Spin-on"-Gläser wurden beschrieben, [132] und man kann mit MPA zweidimensionale Strukturen aus diesen Materialien erzeugen. Über die Strukturierung eines Chalkogenidglases mit MPA wurde ebenfalls berichtet.…”

Photopatternable thin films from silyl hydride containing silicone resins and photobase generators

“…As might be expected, the sensitivity of the system is dependent on the amount of SiÐH functionality in the resin composition. A lower concentration of silyl hydride units should reduce the sensitivity of the composition by reducing the total number of crosslinks generated by the A spin-on-glass composition comprising a photobase generator and hydrogen silsesquioxane has recently been described in the literature, and provides a simple method for the generation of micrometer scale patterns in micrometer to submicrometer thick films [14]. Depending on the subsequent thermal cure process, the patterned film can be used as a low dielectric constant hydrogen silsesquioxane film or when heated in air at 400°C, converted to glass.…”

“…These two types of photobase generators are thermally stable to temperatures approaching 180°C, thus allowing for safe postexposure baking at temperatures up to 150°C. Major differences between the two catalysts are that N-methylnifedipine yields a stronger base and displays a strong absorption at longer wavelengths (between 300 and 400 nm), with a maximum at 332 nm (4 332 = 11,300) [14].…”

“…It has recently been demonstrated that simple photopatternable compositions can be prepared by mixing hydrogen silsesquioxane with photobase generators [14]. The mechanism for the photopatterning process is believed to involve the basecatalyzed hydrolysis of the silyl hydride bond by residual water trapped in the film (Scheme 3).…”