Roll-to-Roll Fabrication Technology for Organic Semiconductors Jae Young Choi Nov. 13, 2007

Cost Saving, Simple Fabrication Process Produces Flexible Semiconductor Devices ! Roll-to-Roll Process Motivation - Low-temperature deposition - Mechanically Flexible - Light weight and shock proof - Chemical Sensitivity - Solution Processing Organic Semiconductors Non-Flexible Device Expensive Manufacturing Process Complex Fabrication Process Silicon Based Semiconductors Why?

Background OTFT (Organic TFT)

Overview Roll-to-Roll Processing Example: e-paper manufacturing

Technology I Substrate Materials GlassPlastic (PEN, PI)Stainless Steel Optical Properties (Transparency) Surface Smoothness Thermal Expansion (Maximum Process Temperature) Stiffness ( Durability, Flexibility, Young’s Modulus) Properties to be Considered

Technology II Novel Patterning Techniques (1) Soft Lithography - Mask and substrate contact may result in defects - Mask damage & stamping material life time Issues

Technology II Embosser Mold & Embossed Microcups Novel Patterning Techniques (2) E-paper by SiPix

Technology II Novel Patterning Techniques (3) Laser Ablation Recent Technology - Resolution: 120 pt/in - Droplet size: picoliters - Speed: 200 mm/sec Suffer form Drop Displacement Accuracy -Faster than RIE -Produces Cleaner lines than Thermal and Mechanical Drilling Inkjet Printing

Technology III Packaging: Barrier Layer Low work function metals oxide very easily  Moisture & Oxygen Free Environment Needed Requirement Water transmission rate = less than g m ‐ 2 /day Oxygen transmission rates = less than 10 ‐ 5 mL m ‐ 2 /day Barix Coating Technique Using continuous, roll-to-roll vacuum processing Directly Coating on the Top  Eliminating the glued-on metal ca n or the extra sheet of glass  Much thinner, lighter, more reliable display with low cost

Conclusion: Now & Future Organic LED (OLED) Organic Solar Cell Organic TFT Organic Sensors APPLICATIONS $5M $339M 83.5 % Per year Flexible Display Market Growth Cost Saving 2. Simple Fabrication Process 3. Flexible Semiconductor Devices Roll-to-Roll Process Not so much cost saving yet “Killer Application” is Needed

Reference 1.Evan Schwartz, “Roll to Roll Processing for Flexible Electronics,” 2.Jain, K. Klosner, M. Zemel, M. Raghunandan, S., “Flexible electronics and displays: high-resolution, roll-to-roll, projection lithography and photoablation processing technologies for high-throughput production,” 3.Chin, Spencer. “Report: Flex display market to grow 83.5% a year.” EETimes Online. March 23, Jain, K. “Flexible Electronics and Displays: High ‐ Resolution, Roll ‐ to ‐ Roll, Projectio n Lithography and Photoablation Processing Technologies for High ‐ Throughput Production.” Proc. IEEE, 93, 1500 ‐ 1510, (2005). 5.Tan et. al. “Roller Nanoimprint Lithography.” J. Vac. Sci. Technol. B 16, 3926 (1998 ). 6.Vitex Systems, Inc. “The Guardian Tool.” Available online: m/guardian.html. 7.SiPix Imaging, Inc. “roll-to-roll© Manufacturing Process. Flexible Displays & Electronics”, 2004.