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Abstract Two-photon lithography (TPL) is a photopolymerization-based additive manufacturing technique capable of fabricating complex 3D structures with submicron features. Projection TPL (P-TPL) is a specific implementation that leverages projection-based parallelization to increase the rate of printing by three orders of magnitude. However, a practical limitation of P-TPL is the high shrinkage of the printed microstructures that is caused by the relatively low degree of polymerization in the as-printed parts. Unlike traditional stereolithography (SLA) methods and conventional TPL, most of the polymerization in P-TPL occurs through dark reactions while the light source is off, thereby resulting in a lower degree of polymerization. In this study, we empirically investigated the parameters of the P-TPL process that affect shrinkage. We observed that the shrinkage reduces with an increase in the duration of laser exposure and with a reduction of layer spacing. To broaden the design space, we explored a photochemical post-processing technique that involves further curing the printed structures using UV light while submerging them in a solution of a photoinitiator. With this post-processing, we were able to reduce the areal shrinkage from more than 45% to 1% without limiting the geometric design space. This shows that P-TPL can achieve high dimensional accuracy while taking advantage of the high throughput when compared to conventional serial TPL. Furthermore, P-TPL has a higher resolution when compared to the conventional SLA prints at a similar shrinkage rate.
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This content will become publicly available on December 15, 2026
Fabrication of robust suspended structures using tilted e-beam lithography
We report a technique for fabricating suspended structures using tilted electron beam lithography. This technique enables the formation of beveled anchor profiles, which significantly increase structural integrity compared to previous techniques. We demonstrate the technique by fabricating a suspended top gate over a graphene device, achieving a breakdown electric field of up to 1.5 V/nm, and induced carrier densities of ∼ 7 × 1012 cm−2, both representing more than 10-fold increase from previous methods. This technique provides a pathway to robust suspended electronic structures capable of withstanding large electrostatic forces common in two-dimensional material systems and nanoelectromechanical devices.
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- Award ID(s):
- 2011876
- PAR ID:
- 10682982
- Publisher / Repository:
- AIP
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 127
- Issue:
- 24
- ISSN:
- 0003-6951
- Page Range / eLocation ID:
- 243102
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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