For a long time, ATI (a Canadia-based graphic card company) was the name of hope for PC gaming enthusiasts who wanted an alternative to Nvidia. ATI launched the Radeon product back in the year 2000 and, since then, Radeon has become ADI's flagship product and a direct competitor to Nvidia's GeForce.
The main, and most innovative, concept of the Radeon product line was the built-in 3-D-accelerator functions. In 2006, the company ATI was purchased by AMD for approximately $5 billion and, from that point onward, the Radeon family of graphics cards became a part of the AMD family. In retrospect, this expensive acquisition was probably not a bad decision for AMD as it was also not a bad move by ATI to become acquired. Post merger, ATI got the backing of a reputed processor manufacturer, which Nvidia did not have, and ATI was also able to continue with its main products. Similarly, AMD enjoyed the benefits of a larger portfolio and a bigger market share in consumer electronics. AMD even kept the ATI logo on their graphics card until 2010 and kept their business partnerships intact (including the partnership with foundry TSMC).
ATI relied on TSMC to manufacture key components for the Radeon line of products. For example, the ATI-GPU-Radeon HD 4670, codenamed RV730 and released in 2008, was fabricated using TSMC's 55-nm process. The die was done with oxide gate dielectric and poly-silicon gate. This device contained about 500 million transistors in a 146 mm2 die. Similarly, the ATI Radeon HD 4770 processor, codenamed RV740, was fabricated with TSMC's 40-nm process technology and was introduced to the market in late 2009. The HD 4770 contained 826 million transistors in 138 mm2 and employed embedded SiGe that boosted PMOS transistors' performance. The process also used, for the first time, an extreme low-k inter-metallic-dielectric (IMD), which had a dielectric constant lower than 2.5. With all this manufacturing history, a natural progression takes place with the new Radeon graphic card HD 7970. With more than a billion transistors in 360 mm2, the Radeon HD 7970 is manufactured with SiGe and high-k dielectric with metal gates (HKMG) technology.
There are two common methods for introducing HKMG into the standard CMOS process; it is either gate-first or gate-last. This terminology refers to the process steps to form the metal gates either prior to or after the source/drain implants. Depending on the method and the thermal budgets, the work-functions and the capping oxide are selected.
Radeon HD 7970's card's main processor is an AMD processor called Tahiti. Figure 1 shows a short summary of the teardown of the graphics card and the location of the Tahiti chip on the card. The card uses a fan-sink to cool the chamber. The card has twelve GDDR5 2GB DRAM components from Hynix, which are based on 45-nm node. The graphic processor is packaged in flip-chip grid array type package.
Figure 1: Teardown of the AMD-RADEON HD7970 graphics card (click on image to enlarge).
Figure 2: Determination of process node of the AMD-RADEON HD7970 graphics card processor (click on image to enlarge).
The structural analysis report based on the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed that the process node of the process is definitely sub-30 nm node. The metal 1 pitch and the area of the 6T-SRAM cell were taken to determine the process node and are plotted in Figure 2. The NMOS and PMOS have similar structures with the exception that the PMOS transistors use SiGe at source/drain level for mobility enhancement and have some additional metal layers in the gate stack to adjust the wok function. These details are discussed in the report.
It was expected that the third generation of Radeon graphics card would implement TSMC's latest process node. Nevertheless, having a HKMG product with embedded SiGe, along with ultra-low k IMDs makes the Radeon graphic card a member of an elite group of cutting edge processors and furthermore, becomes a showcase of long lasting partnership between a graphic card designer and a foundry. Hopefully the graphic card will unleash new creative gaming potential.Arabinda Das is a senior process analyst at UBM TechInsights, a sister company to EE Times.