GlobalFoundries Enters 2.5D/3D Chip Foundry Market
By Mark LaPedus
Setting the stage for intense competition in an emerging market, GlobalFoundries Inc. on Thursday (April 26) officially entered the 2.5D/3D chip-stacking foundry arena. The company’s 2.5D/3D foundry strategy is far different than that of rival Taiwan Semiconductor Manufacturing Co. Ltd. (TSMC).
At its new Fab 8 campus in Saratoga County, N.Y., GlobalFoundries said that it has begun installation of a special set of production tools to create 3D-based TSV devices processed on its 20nm technology platform. The first full-flow silicon with TSVs is expected to start running at Fab 8 in Q3 2012, said David McCann, senior director of technical business operations for packaging and central engineering at GlobalFoundries.
Mass production is not expected until the 2014 time frame. The silicon foundry vendor is also devising a 2.5D line based on interposers in Singapore. The company said that it is developing 2.5D and 3D parts for unidentified customers.
The move follows TSMC’s bold efforts in the 2.5D/3D foundry arena. Two other leading-edge foundries — Samsung Electronics Co. Ltd. and United Microelectronics Corp. (UMC) — are also expected to enter this fray.
GlobalFoundries’ foundry strategy in the 2.5D/3D stacking arena is markedly different than rival TSMC, which has recently moved into production with a turnkey line that includes both the front- and back-end steps. In contrast, GlobalFoundries is developing a via-middle through-silicon via (TSV) flow, but the company does not plan to implement a full turnkey line.
Instead, GlobalFoundries is installing tools that will handle the “via creation” and traditional front-end steps. Then, the foundry vendor will hand off the traditional backend steps — such as temporary bonding/debonding, grinding, assembly and test — to the third-party packaging houses. Amkor Technology Inc. is one of GlobalFoundries’ assembly partners on a non-exclusive basis. Other subcontractors will also be named at a later date.
GlobalFoundries’ strategy, according to McCann, is more flexible and has more advantages over the turnkey effort implemented by TSMC. “Our customers want flexibility,” he said in an interview at its U.S. office in Milpitas, Calif. “We think it’s a better solution to engage with the OSATs. We think that it’s better to leverage the assembly expertise at the OSATs and not the foundries.”
GlobalFoundries belongs to IBM Corp.’s Common Platform alliance. IBM and Samsung Electronics Co. Ltd. are also members. Unlike process development – where the members work in unison – the Common Platform group is not coordinating their efforts in 2.5D/3D. GlobalFoundries may obtain IP from IBM. But the three entities do not have a “copy exact” strategy. IBM has been working on this technology for years. Samsung has its own efforts in the arena.
Turnkey or not?
It’s unclear which foundry strategy will prevail as the market is in its infancy. Clearly, though, it’s taking longer than expected for 2.5D/3D chips based on TSVs to enter mass production. Supply chain and technology issues are among the challenges. The temporary bonding/debonding steps and test are among the stumbling blocks on the manufacturing front.
Still, leading-edge integrated device manufacturers (IDMs) – such as IBM, Intel, Micron, Samsung and others – are working on 2.5D/3D chips. Many IDMs may do some or all of the 2.5D/3D TSV process steps in-house.
The fabless companies also want to jump into the market and are looking for help from the foundries. As reported, TSMC recently rolled out its strategy in the area, dubbed Chip-on-Wafer-on-Substrate (CoWoS). Among the first customers for CoWoS are FPGA houses Altera Corp. and Xilinx Inc.
What is surprising to some observers is that TSMC is providing an end-to-end solution in 2.5D and 3D, including all of the traditional assembly and test steps handled by the IC packaging houses. Some packaging houses believe TSMC is stepping on their toes, but clearly, the lines are blurring between traditional front-end production and backend assembly.
TSMC decided to go the turnkey route in order to control the yields and the reliability of the parts, said Shang-yi Chiang, TSMC’s executive vice president and co-chief operating officer, during the company’s recent technology symposium.
In contrast, GlobalFoundries does not plan to go the turnkey route. “There are some advantages” in the turnkey flow such as time-to-market, McCann said, “but we don’t think that’s a better solution.”
He said customers want a more flexible solution, in which chip makers can have some visibility and best-of-breed tools in the flow. Regarding the yields, GlobalFoundries has defined a PDK with its partners, which will ensure the quality of the flow and products, he said.
The silicon foundry vendor is pursuing both the 2.5D and 3D TSV foundry markets. In 3D, the company is installing the tools in Fab 8, a new 300mm fab in Malta, N.Y. The tools will enable 3D designs at the 20nm node, with vias at 6nm in diameter and 40-to-50u pitches.
In GlobalFoundries’ 3D flow, it will have the tools for the “via creation” process, bumping, probing and metrology. In the via creation process, the steps include etch, chemical-vapor deposition, physical-vapor deposition, electroplating, and chemical mechanical polishing. Once it completes the so-called via-middle flow, GlobalFoundries will hand off the wafer to the OSATs, which will handle the backend steps.
The tools within GlobalFoundries 3D line will be qualified in the Malta fab by the end of July. The first full-flow silicon with TSVs is expected to start running at Fab 8 in October. The initial products – such as graphics chips – may start production in 2013. “2014 will be the year of production,” he said.
The company also is devising a 2.5D line within its Fab 7 facility in Singapore. Initial products will be based on 28nm or 20nm processes with a similar time schedule as the 3D line in the United States.
Tags: GlobalFoundries, Samsung, TSMC, UMC