Towards Active Monitoring of The Micro Transfer Printing Process
Current microelectronics and micro-electromechanical systems (MEMS) fabrication techniques are optimized for the production of very large volume of parts on a limited range of substrates. These processes have been designed to produce excellent results but still consume large amounts of time and resources and require expensive machinery and facilities. Over the past few years many low cost, fast printing processes have begun to emerge capable of economically producing electronics and MEMS on a variety of substrates. Examples of printed electronic devices include sensors, organic photovoltaic, intelligent packaging, radio frequency identification devices and flexible displays. One such process currently under development at the University of Illinois is micro transfer printing. Micro transfer printing is a process by which micro devices and circuit elements fabricated using standard micro fabrication techniques are picked up and printed onto a destination substrate using a patterned flexible elastomeric stamp. The advantages of the process are low cost, high flexible, high through put, novel target substrates and the devices maintain performance of the host semiconductor. Commercialization of this process depends on the development of innovative technologies for the application of the process to fast and flexible process paradigms realizing innovative products and the ability to integrate the process into existing fabrication processes. This thesis describes the theoretical and practical design of a suite of technologies designed to increase the ease of usage, flexibility, robustness and printing capabilities of the transfer printing tool. We present the design and construction of an instrumented stamp for contact sensing at the device level to close the loop around the pickup and printing process and iv provide a means of feedback. This method has provided an alternative to detect process events and has also been shown to provide means of diagnosing the process as it is running. Along with the instrumented stamps a remote center of compliance tip tilt stage used to perform alignment with minimal loss of registration was also designed and developed for the transfer printer.
Micro Transfer Printing, Heterogeneous Integration
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign