Nanoscale flow deformation of silicate glass ultrathin films for development of nano-patterned glass surfaces
- PDF / 465,578 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 32 Downloads / 200 Views
The nanoscale behavior of high-temperature flow deformation for silicate-based oxide glass ultrathin films was characterized with focus on forming a nano-patterned glass surface. The oxide glass thin films were deposited at room temperature by pulsed laser deposition onto the ultrasmooth sapphire substrates with 0.2-nm-high atomic steps. It was found from atomic force microscopy (AFM) measurements that the silicate ultrathin films (about 3 nm thick) started to deform at a temperature 50 °C lower than the glass transition point of the bulk glass. The glass thin films annealed at high temperatures exhibited the nano-stepped surface structure reflecting the sapphire substrate surface. By scanning the AFM tip on the as-deposited glass film in a contact mode and then thermal annealing the film, we could pattern the nano-stepped glass surface at a nanoscale.
I. INTRODUCTION
Nanoscale fabrication technologies are of great importance for developing nanoelectronics, nanomachines, and nano-optics. Electron-beam lithography and dry etching are generally used to fabricate nanostructured devices. Recently, nanoimprint lithography, which often uses the thermal deformation of polymer resists above their glass transition temperatures around 200 °C, has been attracting much attention as one of the high throughput and low-cost nanopatterning processes.1–3 On the other hand, silicate glasses are typical inorganic amorphous materials and have large glass-forming region and high vitreousstate stability. They have practical applications for microscale optical components.4 As oxide glasses have higher thermal stability and mechanical strength than polymer materials, the nano-patterned oxide glass films are expected to be used as nano-imprint stamps even at high temperatures. For fabrication of nano-patterned surfaces for oxide glasses, it is significant to examine the thermal behavior of glass ultrathin film surfaces at a nanoscale. The physical and chemical properties of ultrathin films having the large surface-to-volume ratio might deviate from those of the bulk materials due to the dominant free-surface and confinement effects.5 Glass transition behavior and viscous flow resulting from the supercooled a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2004.0344 J. Mater. Res., Vol. 19, No. 9, Sep 2004
http://journals.cambridge.org
Downloaded: 13 Mar 2015
state below the melting point are characteristic of glassy materials. For glassy polymer thin films, there have been many reports on the change of the glass transition temperature as a function of nanoscale film thickness.6–9 Oxide glass ultrathin films are also thought to have different thermal behaviors such as glass transition or crystallization from the bulk glass.10 However, few works have reported the nanoscale thermal deformation of oxide glass films. The pulsed laser deposition (PLD) method has been recognized as a promising technique for fabricating highquality multicomponent oxide thin films such as cuprate superconducto
Data Loading...
