This Small Business Innovation Research (SBIR) Phase II project focuses on fabrication of flexible display backplanes using transfer printed electronics. The display industry has been successful at fabricating amorphous silicon (a-Si) thin film transistor (TFT) backplanes on rigid glass. However, a-Si TFT manufacturing does not easily translate to flexible substrates due to handling issues and the high temperature process of a-Si deposition. In transfer printing, a novel elastomeric stamp is used to pick-up specially designed circuits from the parent wafer and transfers the circuits to the desired target substrate. The parent wafer is fabricated using a standard silicon IC foundry and the single crystal silicon transistors have much better performance than the a-Si counterparts. The SBIR Phase I project demonstrated chip transfer printing process yields of 99.9% and chip placement accuracies better than +/- 5 ìm. Phase II objectives include design, fabrication and characterization of flexible backplane prototypes and further optimization of transfer printing by increasing throughput and demonstrating rework methods. The anticipated result is a manufacturing approach to flexible electronics that is cost competitive, low temperature and well suited to handle flexible substrates.
The competitive advantage of the proposed approach is the fact that all the demanding fabrication process steps necessary to fabricate high performance electronic systems are performed on the ?mother? substrate and not on the final plastic substrate. If successful the inherent mechanical or chemical instabilities of the receiving plastic substrate do not limit the choice of semiconductor manufacturing processes for fabricating devices. The ability to manufacture flexible display backplanes to the demanding standards of the display industry will open up a broad market of opportunity in flexible electronics far beyond displays, including configurable X-ray sensors, RFID tags, and wearable electronics and biosensors. In displays, backplanes using the proposed technology will be utilized by all major display manufacturers and many specialty manufacturers.
