A joint research team headed by Professor Keon-jae Lee from the Department of Materials Science and Engineering at KAIST and by Dr. Jae- hyun Kim from the Korea Institute of Machinery and Materials has recently developed a continuous roll-processing technology. This innovation delivers flexible large-scale integrated circuits, a crucial component in the construction of CPUs in computers. It then packages them with plastic material, rendering flexible electronics possible.
Applications of flexible electronics such as wearable computers depend on the underlying technology of productive roll-processing. With flexible large-scale integrated circuits, commercialization of these technologies could be realized much faster. However, there are many barriers yet to be overcome. Roll-based packaging poses challenges not only in the perspective of manufacturing but also in its interaction with other flexible devices, such as batteries and displays.
Previously in 2013, Professor Lee had used the 0.18 CMOS (Complementary Metal-Oxide Semiconductor) process to achieve flexible large-scale integrated circuits on a silicon base. This time, the research team tackled existing challenges by fabricating NAND flash memories on a silicon wafer through semiconductor processes. A sacrificial wafer was then removed, leaving a thick layer of circuit. They used an anisotropic conductive film to transfer and connect the device onto a flexible material through continuous roll-packaging technology. The resulting NAND memory was proven to operate successfully, even when severe bending was applied. This technology could potentially be used in processors, memories, and communication devices.
Professor Lee stated, “highly productive roll-processing was successfully applied to flexible LSIs to continuously transfer and interconnect them onto plastics. For example, we have confirmed the reliable operation of our flexible NAND memory at the circuit level by programming and reading letters in ASCII codes. Our results may open up new opportunities to integrate silicon-based flexible LSIs on plastics with the ACF packing for roll- based manufacturing.”
Dr. Kim added, “we employed the roll-to-plate ACF packaging, which showed outstanding bonding capability for continuous roll-based transfer and excellent flexibility of interconnecting core and peripheral devices. This can be a key process to the new era of flexible computers combining the already developed flexible displays and batteries.”
Professor Lee and Dr. Kim’s research results were published in the August issue of Advanced Materials under “Simultaneous Roll Transfer and Interconnection of Silicon NAND Flash Memory.”