Micro-light-emitting diodes (μLEDs) can be used in mobile and virtual reality display applications where high efficiency, resolution, service life and image quality are necessary. However, μLED displays require the alignment of millions of devices, and mass production methods are currently at an early stage of development. Here we report a method to rapidly align μLED chips at the wafer scale by controlling the van der Waals force between the chips and interposer. We engineer the upper and lower surfaces of the μLED chips to have different van der Waals forces, thus enabling their selective bonding to substrates in fluidic and drying processing conditions. The process allows single-faced and irreversible alignment of 259,200 μLED chips with an accuracy of 100% and a transfer yield of 99.992% over 40 trials. To illustrate the capabilities of the approach, we create μLED-based passive- and active-matrix displays by bonding the μLED-loaded interposer to backplanes based on low-temperature polysilicon thin-film transistor.
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This work was supported by the Samsung Advanced Institute of Technology (SAIT), Samsung Electronics.
The authors declare no competing interests.
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Nature Electronics thanks Shin-Tson Wu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Supplementary Figs. 1–9.
Supplementary Video 1
Source Data Fig. 2
AFM topo-/lateral force data and F–D data.
Source Data Fig. 3
Yield data of the FAST method.
Source Data Fig. 4
The μLED performance data.
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Hwang, J., Kim-Lee, HJ., Hong, S.W. et al. Wafer-scale alignment and integration of micro-light-emitting diodes using engineered van der Waals forces. Nat Electron (2023). https://doi.org/10.1038/s41928-022-00912-w
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