A Scalable, High-Throughput, and Fine-Pitch Flexible Fan-Out Package for the Advanced Packaging Era.

다국어 초록 (Multilingual Abstract)

Packaging has been a driver for performance scaling in CMOS. Dieletization has been a driver for package scaling with several technology offerings provided at different cost and performance levels: organic packages, silicon interposers, fan-out wafer level packaging (FOWLP) to name just a few. Amongst these fan-out wafer level packaging and fan-out panel level packaging are attractive, cost-effective solutions to heterogeneous integration as compared to monolithic fabrication. The current state-of-the-art for FOWLP as deployed in the semiconductor industry utilizes die-to-die I/O (pad) pitch of 36 µm. The pad pitches that is achievable in fan-out is limited by two factors: die shift and warpage. In this work, we have developed TrueAdapt™, a methodology to fabricate 10 µm (pad) pitch wiring in FOWLP which is scalable (to large area format) and is high-throughput (for high-volume manufacturing). It consists of a suite of techniques: computer vision is used to identify and measure die shift, which is utilized to dynamically adjust the layout. Then, a direct-write laser lithography system is used to adjust the patterning of the wiring layer in real-time. In addition, a novel technique in direct-write laser lithography called focal extension is utilized, which increases the depth of focus (DOF) of laser direct-write. To fully demonstrate the reliability and repeatability of our method, we demonstrate a 25-die daisy-chain assembly using TrueAdapt™ in which all 25 dies are connected at a minimum of 10 µm pad pitch. Furthermore, this demonstration uses the FlexTrate™ platform, which is a flexible FOWLP process utilizing polydimethylsiloxane (PDMS) as the molding compound. We demonstrate, with high yield (100%), the electrical and flexibility results of the daisy chain assembly. We further demonstrate a real-world application in applying TrueAdapt™ to address die-shift in flexible display technology (FlexPlay). We fabricate a 635 pixel per inch (ppi) flexible GaN micro-LED display in the FlexTrate™ with a LED pitch of 40 µm and with two level metallization. A driver die is integrated to complete the flexible display with high yield (>90%) for the approximately 100,000 LEDs.