Sacrifice-layer-free transfer of wafer-scale atomic-layer-deposited dielectrics and full-device stacks for two-dimensional electronics

Introduction

Transfer printing is a widely used assembly technique for device fabrication and heterostructure construction in soft electronics^{1, 2, 3, 4–5} and low-dimensional physics^{6, 7, 8, 9, 10, 11–12}. Comparatively, transfer printing technique can loosen the constraints of processing compatibility in terms of thermal stability, chemical tolerance, and deposition damage, thus allowing the fabrication of devices on flexible or delicate substrates that are incompatible with conventional manufacturing processes^{13, 14–15}. Typically, the transfer printing process includes three steps: (1) pre-pattern the device constituents on a rigid substrate; (2) pick up the pre-patterned objects from the mother substrate; (3) release these objects to a receiver substrate. Generally, the pick-up process is the key step determining the fabrication yields of transfer printing^{16, 17–18}. However, owing to strong interfacial adhesion, it usually requires an additional sacrificial layer on top of the mother substrate to make all the device constituents transferrable^19,20. Besides, the sacrificial layer is typically removed by another destructive step, such as O₂ plasma and chemical etching, which will inevitably increase the processing complexity and cause damage to the quality of device interfaces. Therefore, it is highly appealing to develop a sacrifice-layer-free approach for damage-free transfer printing of electronic materials, especially for those with strong adhesions with rigid substrates.

As we know, the metal electrode and atomic-layer-deposited (ALD) dielectric are two of the most important device constituents to fabricate top-gated transistors^{21, 22–23}. Thus, the prerequisite for successful transfer printing is to simultaneously transfer and delaminate the metal electrodes and ALD dielectrics from the mother substrate. With great efforts by scientists, sacrifice-layer-free transfer printing of metal contacts can be achieved by surface engineering such as hexamethyldisilazane treatments^24,25, graphene passivation^26,27, precise stress control^1,28, and using specific substrates^29,30. On the other hand, ALD dielectrics, such as Al₂O₃ and HfO₂, play an indispensably important role in modern electronic industry, for their conformal growth characteristic, precise film thickness control, and remarkable deposition reproducibility³¹. In general, the ALD process involves a long-time H₂O and heat treatment, thus making the ALD process incompatible with fragile two-dimensional (2D) materials. Besides, the as-deposited Al₂O₃...