Taiwan Semiconductor Manufacturing Company (TSMC) is the world's largest semiconductor foundry, and as such is constantly under pressure from its customers and competitors. The company recently announced that its newest 28nm process has entered mass production. Smaller process geometries typically mean that a faster, smaller, and cheaper processor will be available.
Two of TSMC's biggest customers are AMD and NVIDIA. Both have taped out GPU designs using TSMC's 28nm High Performance (28HP) process. AMD's next-generation GPU series is codenamed Southern Islands. The Tahiti GPU is supposed to launch early in December, while NVIDIA's Kepler GPU will launch in February of 2012.
28HP is the first process from TSMC to use High-k Metal Gate (HKMG) technology, as opposed to the typical silicon oxynitride (SiON) found in 40nm GPUs. HKMG uses a material with a high dielectric constant instead of the traditional silicon dioxide gate dielectric. This allows for a substantial reduction in gate leakage, thus lowering overall power consumption and allowing for higher clock speeds.
According to sources within TSMC, the 28HP HKMG process is doing very well. So well, in fact, that it supports up to a 45 percent clock speed improvement over the firm's own 40G process used to make the last two generations of video cards. This speed improvement is based on the same leakage per gate, but the GPU firms may choose to favor lower power consumption over a pure speed boost.
Our AMD contacts declined to respond to these assertions and directed our attention to a presentation made in June at the AMD Fusion Developer Summit by Eric Demers, the Chief Technology Officer of AMD Graphics.
The flip side of the manufacturing process is the architecture and design, and AMD has already previewed the basis for its future graphics architectures, known as Graphics Core Next (GCN). The basic design of GCN will form the foundation for the next few generations of AMD graphics processors.
The fundamental unit of AMD’s previous designs has been the Streaming Processor, utilizing a Very Long Instruction Word (VLIW) architecture designed to take advantage of Instruction Level Parallelism (ILP). That will be supplanted by the Compute Unit, comprised of multiple 16-wide vector Single Instruction, Multiple Data (SIMD) units designed for Thread Level Parallelism (TLP).
L1 and L2 caches will support the CUs, while the GPU will have access to the main system memory. Support for C++ programming has been added, making it easier to program for the GPU and CPU within the same application.
While all of these changes will benefit compute applications, it is not yet clear what impact this will have on current games and those already in the pipeline. The architectural changes may end up helping or hindering performance. Nevertheless, the entire 28nm graphics lineup will support resolutions of up to 16000 x 16000 pixels.
Of course, yields have always been a big problem with introducing a new node. TSMC had significant challenges with its 40nm process, leading to shortages of the Radeon HD 5800 series. HKMG processes typically use atomic layer deposition for high-k materials, which has been a challenge even for Intel.
Ultimately, we know that the next-generation of GPUs will be "significantly" faster, but the effects of the new architecture are still unknown and could change things positively or negatively. The better the performance, the more likely it is to sell out. The final clock speeds are still being determined, so final performance numbers will have to wait until the first official launch. The latest word on the street is December 6.
