Existing subtractive micro/nano-manufacturing techniques have limited geometric freedom (2/2.5D structures), slow fabrication speeds and poor multi-material capabilities. While additive manufacturing (AM) is potential alternative to these challenges, most of the AM processes are limited by feature size resolution (~50 microns), which renders them inefficient for micromanufacturing applications like fabrication of wafer-scale interconnect structures in an integrated chip. To fill these gaps, the researchers at Nanoscale Design and Manufacturing Lab at UT Austin have developed a novel 3D printing platform technology called Microscale Selective Laser Sintering (μ-SLS) which is capable of fabricating sub-5 micron 3D metallic features at high speeds. In this process, like most layer-by-layer AM approaches, a liquid nanoparticle bed is deposited on the substrate to form the first layer. A laser then scans across the material bed to fuse together the particles in the first layer. After the first layer is sintered, the next layer of material is deposited on top of it, followed by overlay alignment and sintering at specific locations by stepping a 2D nanopositioner. The process is repeated until all the sliced layers of the 3D geometry are deposited on top of each other to form the part. Excess material is then removed using an ultrasonication process to obtain the 3D part.
Design Embodiment of the μ-SLS research tool (Ref. Roy, N. K., Behera, D., Dibua, O. G., Foong, C. S., & Cullinan, M. A. (2019). A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts. Microsystems and Nanoengineering, 5(1). https://doi.org/10.1038/s41378-019-0116-8)
Exemplar features/geometries fabricated using the μ-SLS research tool. (a) Glass slide with sintered glass slide (50 mm x 7 mm rectangle) (b) 40 μm diameter circles with 80 μm pitch (c) Longhorn smallest feature – 10 μm (d) Full Areal Scale. 20 μm diameter circles with 40 μm pitch. (e) NDML logo before removing excess ink (f) NDML logo after removing excess ink. (Ref. Roy, N. K., Behera, D., Dibua, O. G., Foong, C. S., & Cullinan, M. A. (2019). A novel microscale selective laser sintering (μ-SLS) process for the fabrication of microelectronic parts. Microsystems and Nanoengineering, 5(1). https://doi.org/10.1038/s41378-019-0116-8)
- Michael Cullinan
Graduate Student Researchers
- Dipankar Behera
- Obehi Dibua
- Joshua Grose