Roll-process technology for transferring and packaging flexible LSI

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Research teams from the Korea Advanced Institute of Science and Technology (KAIST) and the Korea Institute of Machinery and Materials (KIMM) have developed a continuous roll-processing technology that transfers and packages flexible large-scale integrated (LSI) circuits on plastics for flexible computers, wearable electronics, application processors, and other high-density memory and high-speed communication devices.

Roll-processing is considered a core technology for accelerating the commercialisation of wearable electronics using flexible LSI. However, its execution has been a challenge from both the roll-based manufacturing perspective and for creating roll-based packaging for the interconnection of flexible LSI with flexible displays, batteries, and other peripheral devices.

To overcome these challenges, the research team created NAND flash memories on a silicon wafer using conventional semiconductor processes, and then removed the wafer, leaving a top circuit layer. Next, they simultaneously transferred and interconnected the thin device on a flexible substrate through the continuous roll-packaging technology using anisotropic conductive film (ACF). The final silicon-based flexible NAND memory is claimed to demonstrate stable memory operations and interconnections even under extreme bending conditions.

Professor Keon Jae Lee said: "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."