TSMC has announced plans to build its first test chips for data center applications using its 7 nm fabrication technology. The chip will use compute cores from ARM, a Cache Coherent Interconnect for Accelerators (CCIX), and IP from Cadence (a DDR4 memory controller, PCIe 3.0/4.0 links). Given the presence of the CCIX bus and PCIe 4.0 interconnects, the chip will be used to show the benefits of TSMC’s 7 nm process primarily for high-performance compute (HPC) applications. The IC will be taped out in early Q1 2018.
The 7 nm test chips from TSMC will be built mainly to demonstrate capabilities of the semiconductor manufacturing technology for performance-demanding applications and find out more about peculiarities of the process in general. The chip will be based on ARMv8.2 compute cores featuring DynamIQ, as well as a CMN-600 interconnect bus for heterogeneous multi-core CPUs. ARM and TSMC do not disclose which cores they are going to use for the device – the Cortex A55 and A75 are natural suspects, but that’s a speculation at this point. The new chip will also have a DDR4 memory controller as well as PCI Express 3.0/4.0 links, CCIX bus and peripheral IP buses developed by Cadence. The CCIX bus will be used to connect the chip to Xilinx’s Virtex UltraScale+ FPGAs (made using a 16 nm manufacturing technology), so in addition to implementation of its cores using TSMC’s 7 nm fabrication process, ARM will also be able to test Cadence’s physical implementation of the CCIX bus for accelerators, which is important for future data center products.
|TSMC’s 7 nm Test Chip at Glance|
|Compute Cores||ARM v8.2 with DynamIQ|
|Internal Interconnect Bus||ARM CMN-600|
|DDR4 DRAM Controller||?||Cadence|
|PCI Express 3.0/4.0||Cadence|
|Peripheral Buses||I2C, SPI and QSPI by Cadence|
|Verification and Implementation Tools||Cadence|
As reported multiple times, TSMC’s 7 nm manufacturing process will be a “long” node and the foundry expects the majority of its large customers to use it. By contrast, the current 10 nm technology is aimed primarily at developers of smartphone SoCs. TSMC projects that its first-generation CLN 7FF fabrication technology, compared to its CLN16FF+, will enable its customers to reduce power consumption of their chip by 60% (at the same frequency and complexity), increase their clock rate by 30% (at the same power and transistor count) and shrink their die sizes by 70% at the same complexity. Sometime in 2019, TSMC plans to start making chips using its CLN7FF+ process technology with EUV for critical layers. TSMC claims that the CLN7FF+ will enable the company’s customers to further increase transistor density while improving other areas, such as yields and power consumption.
TSMC does not disclose which of its 7 nm process technologies announced so far it is going to use for the test chip, but the use of EUV for test chips is something that cannot be excluded. For example, GlobalFoundries claims that they use EUV to accelerate production of test chips. On the other hand, since design rules for CLN7FF and CLN7FF+ are different, it is highly likely that TSMC conservatively uses the former for the test chip.
TSMC’s CLN7FF process tech passed qualification in April and was expected to enter risk production in Q2 2017, according to TSMC’s management. The foundry expected 13 CLN7FF tape outs this year and it is projected that the fabrication technology would be used commercially starting from Q2 2018. Therefore, taping out the test vehicle using the first-gen DUV-only 7 nm process in Q1 2018 seems a bit late for early adopters who intend to ship their 7 nm SoCs in the second half of next year. Meanwhile, early adopters (read: Apple, Qualcomm, and some others) get access to new process technologies long before their development is completed and final PDKs (process development kits) are ready. Keeping in mind that the test chips feature a CCIX and PCIe 4.0 buses, it is clearly designed to show advantages of TSMC’s 7 nm process technologies for HPC applications. In fact, this is what TSMC says itself:
“Artificial intelligence and deep learning will significantly impact industries including media, consumer electronics and healthcare,” said Dr. Cliff Hou, TSMC vice president, Research & Development/Design and Technology Platform. “TSMC’s most advanced 7nm FinFET process technology provides high performance and low power benefits that satisfy distinct product requirements for High-Performance Computing (HPC) applications targeting these markets.”