Paper TF-WeM12
Variable-Thickness Patterns using Full-Wafer Dynamic Stencil Lithography

Wednesday, November 11, 2009, 11:40 am, Room B4

Stencil lithography is a shadow mask technique allowing patterning at full-wafer scale from micro to nanostructures by material deposition, etching or ion implantation. It offers unique opportunities for processing where standard lithography cannot be applied, such as on top of 3-dimensional and flexible/functionalized substrates [1]. In the dynamic stencil mode, the stencil and substrate move in-situ relative to each other during or in between depositions. This mode can be used for multi-material, variable thickness patterning [2]. Here we present the in-situ fabrication of variable-thickness structures by using dynamic stencil lithography.

The dynamic stencil setup consists of an x-y moving stage with 20 nm encoding resolution each and three z-stages on which the stencil is attached, and a fixed part which holds the substrate, as described in [3]. The x-y stage is programmed to move along various trajectories. The movement parameters are the (x,y) coordinates of the start and end point (corners), the gap between stencil and substrate, and the stencil speed (0.04-5 µm/s).

By evaporating materials at a constant rate while changing the speed of the stencil, we obtained variable-height structures. We also varied substrate materials (SiO₂, SiN) and parameters such as the deposition rate and the stencil-substrate gap. These structures were characterized by scanning electron microscopy and atomic force microscopy. We also analyzed the pattern transfer integrity from the stencil to the substrate as a function of stencil-substrate gap and aperture size.

Dynamic stencils are used here for patterning two-dimensional variable-height structures by material deposition through a stencil at 4” wafer scale. The contamination-free, parallel-processing, and versatile nature of dynamic stencil lithography provides custom applications with a novel solution.

[1] K. Sidler, O. Vazquez-Mena, V. Savu, G. Villanueva, M. A. F. van den Boogaart, and J. Brugger, "Resistivity measurements of gold wires fabricated by stencil lithography on flexible polymer substrates," Microelectronic Engineering, vol. 85, pp. 1108-1111, May-Jun 2008.

[2] J. L. Wasserman, K. Lucas, S. H. Lee, A. Ashton, C. T. Crowl, and N. Markovic, "Fabrication of one-dimensional programmable-height nanostructures via dynamic stencil deposition," Review of Scientific Instruments, vol. 79, p. 4, Jul 2008.

[3] V. Savu, M. A. F. v. d. Boogaart, J. Brugger, J. Arcamone, M. Sansa, and F. Perez-Murano, "Dynamic stencil lithography on full wafer scale," Journal of Vacuum Science & Technology B, vol. 26, pp. 2054-2058, 2008.