One of the core challenges that Rapidus will face when it kicks off volume production of chips on its 2nm-class process technology in 2027 is lining up customers. With Intel, Samsung, and TSMC all slated to offer their own 2nm-class nodes by that time, Rapidus will need some kind of advantage to attract customers away from its more established rivals. To that end, the company thinks they've found their edge: fully automated packaging that will allow for shorter chip lead times than manned packaging operations.
In an interview with Nikkei, Rapidus' president, Atsuyoshi Koike, outlined the company's vision to use advanced packaging as a competitive edge for the new fab. The Hokkaido facility, which is currently under construction and is expecting to begin equipment installation this December, is already slated to both produce chips and offer advanced packaging services within the same facility, an industry first. But ultimately, Rapidus biggest plan to differentiate itself is by automating the back-end fab processes (chip packaging) to provide significantly faster turnaround times.
Rapidus is targetting back-end production in particular as, compared to front-end (lithography) production, back-end production still heavily relies on human labor. No other advanced packaging fab has fully automated the process thus far, which provides for a degree of flexibility, but slows throughput. But with automation in place to handle this aspect of chip production, Rapidus would be able to increase chip packaging efficiency and speed, which is crucial as chip assembly tasks become more complex. Rapidus is also collaborating with multiple Japanese suppliers to source materials for back-end production.
"In the past, Japanese chipmakers tried to keep their technology development exclusively in-house, which pushed up development costs and made them less competitive," Koike told Nikkei. "[Rapidus plans to] open up technology that should be standardized, bringing down costs, while handling important technology in-house."
Financially, Rapidus faces a significant challenge, needing a total of ¥5 trillion ($35 billion) by the time mass production starts in 2027. The company estimates that ¥2 trillion will be required by 2025 for prototype production. While the Japanese government has provided ¥920 billion in aid, Rapidus still needs to secure substantial funding from private investors.
Due to its lack of track record and experience of chip production as. well as limited visibility for success, Rapidus is finding it difficult to attract private financing. The company is in discussions with the government to make it easier to raise capital, including potential loan guarantees, and is hopeful that new legislation will assist in this effort.
SemiconductorsKioxia's booth at FMS 2024 was a busy one with multiple technology demonstrations keeping visitors occupied. A walk-through of the BiCS 8 manufacturing process was the first to grab my attention. Kioxia and Western Digital announced the sampling of BiCS 8 in March 2023. We had touched briefly upon its CMOS Bonded Array (CBA) scheme in our coverage of Kioxial's 2Tb QLC NAND device and coverage of Western Digital's 128 TB QLC enterprise SSD proof-of-concept demonstration. At Kioxia's booth, we got more insights.
Traditionally, fabrication of flash chips involved placement of the associate logic circuitry (CMOS process) around the periphery of the flash array. The process then moved on to putting the CMOS under the cell array, but the wafer development process was serialized with the CMOS logic getting fabricated first followed by the cell array on top. However, this has some challenges because the cell array requires a high-temperature processing step to ensure higher reliability that can be detrimental to the health of the CMOS logic. Thanks to recent advancements in wafer bonding techniques, the new CBA process allows the CMOS wafer and cell array wafer to be processed independently in parallel and then pieced together, as shown in the models above.
The BiCS 8 3D NAND incorporates 218 layers, compared to 112 layers in BiCS 5 and 162 layers in BiCS 6. The company decided to skip over BiCS 7 (or, rather, it was probably a short-lived generation meant as an internal test vehicle). The generation retains the four-plane charge trap structure of BiCS 6. In its TLC avatar, it is available as a 1 Tbit device. The QLC version is available in two capacities - 1 Tbit and 2 Tbit.
Kioxia also noted that while the number of layers (218) doesn't compare favorably with the latest layer counts from the competition, its lateral scaling / cell shrinkage has enabled it to be competitive in terms of bit density as well as operating speeds (3200 MT/s). For reference, the latest shipping NAND from Micron - the G9 - has 276 layers with a bit density in TLC mode of 21 Gbit/mm2, and operates at up to 3600 MT/s. However, its 232L NAND operates only up to 2400 MT/s and has a bit density of 14.6 Gbit/mm2.
It must be noted that the CBA hybrid bonding process has advantages over the current processes used by other vendors - including Micron's CMOS under array (CuA) and SK hynix's 4D PUC (periphery-under-chip) developed in the late 2010s. It is expected that other NAND vendors will also move eventually to some variant of the hybrid bonding scheme used by Kioxia.
StorageKioxia's booth at FMS 2024 was a busy one with multiple technology demonstrations keeping visitors occupied. A walk-through of the BiCS 8 manufacturing process was the first to grab my attention. Kioxia and Western Digital announced the sampling of BiCS 8 in March 2023. We had touched briefly upon its CMOS Bonded Array (CBA) scheme in our coverage of Kioxial's 2Tb QLC NAND device and coverage of Western Digital's 128 TB QLC enterprise SSD proof-of-concept demonstration. At Kioxia's booth, we got more insights.
Traditionally, fabrication of flash chips involved placement of the associate logic circuitry (CMOS process) around the periphery of the flash array. The process then moved on to putting the CMOS under the cell array, but the wafer development process was serialized with the CMOS logic getting fabricated first followed by the cell array on top. However, this has some challenges because the cell array requires a high-temperature processing step to ensure higher reliability that can be detrimental to the health of the CMOS logic. Thanks to recent advancements in wafer bonding techniques, the new CBA process allows the CMOS wafer and cell array wafer to be processed independently in parallel and then pieced together, as shown in the models above.
The BiCS 8 3D NAND incorporates 218 layers, compared to 112 layers in BiCS 5 and 162 layers in BiCS 6. The company decided to skip over BiCS 7 (or, rather, it was probably a short-lived generation meant as an internal test vehicle). The generation retains the four-plane charge trap structure of BiCS 6. In its TLC avatar, it is available as a 1 Tbit device. The QLC version is available in two capacities - 1 Tbit and 2 Tbit.
Kioxia also noted that while the number of layers (218) doesn't compare favorably with the latest layer counts from the competition, its lateral scaling / cell shrinkage has enabled it to be competitive in terms of bit density as well as operating speeds (3200 MT/s). For reference, the latest shipping NAND from Micron - the G9 - has 276 layers with a bit density in TLC mode of 21 Gbit/mm2, and operates at up to 3600 MT/s. However, its 232L NAND operates only up to 2400 MT/s and has a bit density of 14.6 Gbit/mm2.
It must be noted that the CBA hybrid bonding process has advantages over the current processes used by other vendors - including Micron's CMOS under array (CuA) and SK hynix's 4D PUC (periphery-under-chip) developed in the late 2010s. It is expected that other NAND vendors will also move eventually to some variant of the hybrid bonding scheme used by Kioxia.
Storage
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