Benefit Several Back-end Equipment Players
The author is an analyst of NH Investment & Securities. He can be reached at hwdoh@nhqv.com. -- Ed.
TSMC is building exclusive fabs for SoIC back-end processing in Chunan and Southern Taiwan Science Park which are scheduled to open in 2021 and 2022, respectively. We expect the rise of SoIC to drive up demand for AFM, laser dicing, and flip chip bonders going forward.
TSMC opening dedicated fab for high-performance packages in 2021
TSMC is building two fabs dedicated to next-gen 3D back-end processing. Of these, its Chunan fab is on track to start mass production in 2H21, with operations at the other (located in the Southern Taiwan Science Park) slated to kick off in 2022. We expect a range of high-performance packaging (eg, 3D system on integrated chip (SoIC), integrated fan-out (InFO), and chip-on-wafer-on-substrate (CoWoS)) to be carried out at these fabs.
Using hybrid bonding, SoIC stands as the most notable technology among the next-gen back-end processes in our view. SoIC enables a 10μm bonding pitch and is said to have 0.25x the bump-pad pitch versus existing schemes. Thanks to such technological advancement, energy efficiency and chip-to-chip communication can be enhanced by 20x and 10x, respectively. SoIC is scheduled for mass production in 2021.
Related plays: Park Systems, EO Technics, Hanmi Semiconductor
The hybrid bonding used in SoIC entails the following process. First, tiny vias are patterned and etched on wafers for electrical connection. The vias are then filled with copper using a CVD process to form a copper pad on the surface of the wafer. The wafer surface is then polished using a CMP process. During the CMP process, the copper pads are slightly recessed on the surface of the wafer, creating roughly 10µm bump pitches for the vertical electrical connections. After cleaning and annealing processes, the finished die is cut and pasted together with other dies to form a 3D package.
The introduction of hybrid bonding is to benefit several back-end equipment players. We note that atomic force microscopy (AFM) is used to check whether grooves (made by cutting out the copper pad) are suitably formed. Due to the small pad size of the finished die, laser dicing equipment becomes all but essential. For die-to-die attachment, flip chip bonding equipment is employed. Related companies include Park Systems (AFM), EO Technics (laser dicing), and Hanmi Semiconductor (flip chip bonders). Of note, Samsung Electronics (SEC) is developing its X-Cube technology to compete with TSMC’s SoIC. And, ASE is planning to mass-produce fan-out chip on substrate (FOCoS) technology in 2021 to compete with TSMC’s CoWoS.