Batch-Fabricated PDMS Templates for the Robotic Transfer of 2D Materials

TL;DR

This paper introduces a scalable, controlled fabrication method for ultra-smooth PDMS templates used in robotic transfer of 2D materials, enhancing precision and uniformity for AI-driven assembly.

Contribution

A novel hot-casting PDMS template fabrication process with tunable curvature and ultra-smooth surfaces for improved 2D material transfer.

Findings

Reproducible control of PDMS dome curvature via curing temperature

Ultra-smooth PDMS templates with root-mean-square roughness of 0.3 nm

Potential for improved robotic assembly of 2D heterostructures

Abstract

Robotic stacking of van der Waals heterostructures has been at the verge thanks to the convergence between artificial intelligence (AI) and two-dimensional (2D) materials research. Key ingredients to fulfill this pursuit often include algorithms to identify layer compounds on chips, hard-wares to realize sophisticated operations of motion and/or rotation in a microscale, and, as importantly, highly-standardized and uniform transfer stamps that are often used in picking up layered materials under a microscope. Here, we report a hot-casted-droplet batch fabrication method for polydimethylsiloxane (PDMS) templates tailored for dry transfer of 2D materials. Controlled precursor formulation, degassing, and motorized-syringe dispensing produce dome-shaped PDMS templates with ultra-smooth surfaces (root-mean-square roughness about 0.3 nm at relatively low curing temperatures). By tuning the curing temperature, the reproducible and controllable apex curvature allows precisely defined contact area between the organic adhesive film and substrate, via thermal expansion. Our results further reveals thermalmechanical behaviors with different casting parameters of such PDMS domes. This scalable and parameterized fabrication protocol gives rise to uniform transfer-stamps with ultra-smooth surface, which may be beneficial for future AI-driven robotic assembly of 2D material heterostructures.