Photoresist planarized trench isolation for monolithic GaN µLED displays

Bryan Melanson; Matthew Seitz; Jing Zhang

doi:10.1117/12.2649346

15 March 2023 Photoresist planarized trench isolation for monolithic GaN μLED displays

Bryan Melanson, Matthew Seitz, Jing Zhang

Proceedings Volume 12421, Gallium Nitride Materials and Devices XVIII; 124210L (2023) https://doi.org/10.1117/12.2649346
Event: SPIE OPTO, 2023, San Francisco, California, United States

Abstract

Micro-Light-Emitting Diode (μLED) displays have seen increasing interest over the past decade due to their promising advantages over other display technologies, especially in applications requiring extremely high resolutions such as virtual and alternate reality headsets. Most modern full-color μLED displays rely on red, green, and blue (RGB) pixels based on different material systems combined together on a thin-film transistor back panel, which is often costly and has poor yield. An alternative approach is to create a monolithic display in the GaN/InGaN material system, capable of covering the entire visible spectrum through tuning of quantum well (QW) Indium content or phosphor down conversion. However, monolithic GaN displays present the issue of pixel isolation, as the lack of truly insulating undoped GaN (u-GaN) makes it difficult to electrically isolate rows or columns of μLEDs from one another. In this work, we demonstrate a novel solution to this issue which utilizes photoresist to fill deep trench isolation features, enabling interconnection of μLED p-contacts in a single-color passive matrix display. A photoresist layer is used to fill deep trenches isolating columns of μLEDs from one another. This photoresist layer is patterned and baked at 250 °C for 30 minutes, crosslinking it and making it extremely durable. This process allows for formation of p-interconnects using liftoff, and avoids the issues involved in bridging high aspect ratio trenches. This photoresist planarized trench isolation process could contribute to creation of improved monolithic full color μLED displays which require multiple deep isolation features to be bridged by conductive interconnects.

Conference Presentation

Citation Download Citation

Bryan Melanson, Matthew Seitz, and Jing Zhang "Photoresist planarized trench isolation for monolithic GaN μLED displays", Proc. SPIE 12421, Gallium Nitride Materials and Devices XVIII, 124210L (15 March 2023); https://doi.org/10.1117/12.2649346

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