Leading-Edge Wafer Technology Elements Strained Silicon SOI-based Technology
Smaller, faster, and more power-efficient transistors are the building blocks for improving future microprocessor performance and power consumption. As transistors become smaller, they usually run faster. But they also risk requiring too much power or generating excess heat due to electrical leakage and inefficient switching.
Strained silicon helps address this problem by enhancing the transport properties of the electrical charge carriers in the channel region of the transistor. Electrons (or holes) can transport more quickly through the transistor. The result: better chip performance and lower energy consumption without increased leakage. Working with IBM, GLOBALFOUNDRIES' parent company developed numerous improvements to its SOI-based technologies. These have culminated in the latest implementation featuring "Stress Memorization Technique (SMT)," which GLOBALFOUNDRIES introduced at the 45nm node.
High-K Dieletrectrics & Metal Gate
As miniaturization continues, many of the traditional materials used in semiconductor manufacturing are "hitting the wall." One critical materials system that is being introduced is high-k dielectrics (HK) and metal gates (MG), which make up the fundamental switching element of a transistor and allow continued improvement in circuit performance and power-efficient scaling of microelectronic components. HKMG technology allows the size of transistors to shrink while significantly minimizing leakage current, a key factor to reducing power consumption. The addition of metal gates along with high-k electrodes gives GLOBALFOUNDRIES one more tool to further enhance performance and power efficiency at the 32nm node and beyond, as we continue to tailor our solutions for evolving customer requirements.
HKMG is a critical component of the GLOBALFOUNDRIES technology roadmap, especially for applications in the fast-growing market for ultra-portable notebooks and smartphones with extended battery life. In the past few years, with our development partners, we have made breakthroughs in HKMG that enable our "Gate First" approach. GLOBALFOUNDRIES is taking a leadership position in the foundry industry with our introduction of HKMG at the 32nm node. We are seeing performance improvements of up to 50 percent in the 32nm generation at the same leakage levels of the 45nm generation. The "Gate Last" approach to HKMG is costly and requires a number of additional processing steps. GLOBALFOUNDRIES has chosen to implement a "Gate First" approach because it is simpler and more scalable to future generations. The process flow is very similar to what was used for previous technology generations. The "Gate First" maximizes power efficiency and transistor scaling while minimizing die size and design complexity when compared to the alternative "Gate Last" approach.
Immersion Lithography for Enhanced Microprocessor Design
Immersion lithography is a leading-edge process technology that allows GLOBALFOUNDRIES to deliver enhanced microprocessor design definition and manufacturing consistency, further increasing our ability to deliver industry-leading, highly sophisticated products. By placing a liquid, instead of air, between the final element of the lens of a lithographic exposure tool and the wafer, it is possible to increase lithographic capability, thereby providing customers with greater functional density on the wafers. For features of moderate size, desired density levels can be achieved with reduced optical proximity corrections and design rule restrictions, relative to exposures in air, which eliminates issues for GLOBALFOUNDRIES' customers. Because the part of the wafer being exposed is "œimmersed" in a fluid, this approach to lithography is referred to as "immersion lithography."
Currently, purified water is used for the fluid. Water evaporation will cool silicon wafers, causing them to contract locally, thereby increasing overlay errors. Particle defects are more difficult to control in liquids than in air, so extensive research and development has been required to bring defect levels with immersion lithography to the same levels achieved using "dry" lithography. GLOBALFOUNDRIES lithographers have worked to solve these problems, and today GLOBALFOUNDRIES is considered to have one of the world's leading immersion lithography capabilities. Click here for a more detailed look at immersion lithography.