Thesis
High yield and accuracy transfer printing of micron-scale opto-electronic devices for volume manufacturing
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17087
- Person Identifier (Local)
- 201974546
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Increasing demands on the performance and scale of opto-electronic systems for displays and on-chip photonics require the integration of a diverse range of photonic materials at micron scales. The primary goal of this thesis is to develop and test a novel transfer printing technique for the large-scale micro-assembly of integrated optoelectronic devices, with a particular focus on microLED displays. Initial work involved designing and fabricating large arrays of membrane devices in a cleanroom laboratory, emphasizing the necessity for these devices to be suspended to facilitate the transfer printing process. The fabrication steps for both miniLED (100×100 μm2) and microLED (30×30 μm2) arrays are detailed, followed by the introduction of a new automated transfer method based on continuous roll transfer printing. The experimental setup, along with critical process parameters, is analysed comprehensively, showing how this continuous process enables the parallel transfer of thousands of devices in less than 30 seconds. A new membrane device design compatible with the roller process is introduced. In order to test this new method, as well as to inspect the individual position of thousands of devices, an automated assessment method is developed. High accuracy and throughput in the automated spatial registration of micron-scale devices on planar chips are demonstrated, utilizing simple optical microscopy tools to assess yield, spatial pitch, and rotation. By using this method, an entire chip of 1 cm size consisting of 4,000 devices in total, was imaged with 94 nm pixel resolution and mean value of 0.06 ± 0.26 μm. Following this, the continuous, single-shot roller transfer printing process was used for the large-scale hybrid integration of over 75,000 microLED devices with sub-micron relative position accuracy, maintaining array geometry with less than 1 μm deviation. This work shows the potential for hybrid materials device integration at scale, compatible with the well-established infrastructure and semiconductor processes developed in industrial foundry manufacturing. Additionally, a novel method for inducing and maintaining strain in silicon through physical bending is proposed. Controlled bending generates strain levels up to 0.4% that persist after removing external stress. This phenomenon is explored through a finite element mechanical model, analytical analysis and experimentally verified using electron backscatter diffraction measurements. The fabrication of the thin film silicon membranes, as well as the results of each method are presented and explained. The findings suggest significant potential for strain engineering in high-performance silicon-based technologies without the need for complex fabrication techniques.
- Advisor / supervisor
- McKnight, Loyd
- Dawson, Martin R.
- Strain, Michael
- Resource Type
- Note
- Previously held under moratorium from 17 September 2024 until 19 October 2026.
- DOI
Relations
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PDF of thesis T17087 | 2024-11-28 | Public | Download |
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