12/10/2003 - Texas Instruments Incorporated (TI) (NYSE: TXN) will present results demonstrating the viability of a new high-k dielectric material at the prestigious International Electron Devices Meeting (IEDM). TI´s process to integrate Hafnium Silicon Oxynitride (HfSiON) high-k dielectric material in its transistor is a critical development in continuing to deliver the promised improvements of Moore´s Law. As transistor dimensions get ever smaller, using a higher-k material can prevent the dielectric in the transistor from becoming so thin that leakage current reaches unacceptable levels. TI´s work addresses concerns about HfSiON regarding thermal and electrical compatibility with standard CMOS processes, carrier mobility and threshold voltage stability.
"TI believes it has found an effective way of balancing the right material combinations to begin replacing the present silicon oxynitride layer with a Hf-based high-k dielectric in the next few technology generations," commented Hans Stork, senior vice president and director of silicon technology development. "We are seeing mobility that is 90% of the silicon dioxide universal mobility curve with dramatically lower leakage current without sacrificing reliability or adding significant cost to the CMOS process."
The potential of Hafnium-based dielectrics has been known in the industry for years, but issues of how much Hafnium to use in combination with other materials, as well as how to successfully apply it, were not well understood. Integration of high-k gate dielectrics into future CMOS devices will be possible only if the dielectric is thermally stable during CMOS processing and electrically stable during normal operating conditions. TI began a focused effort in 1998 to tackle the obstacles, resulting in the paper presented this week.
"The industry has been exploring a variety of different materials to address transistor leakage, but Texas Instruments is the first to highlight a material with results that have the right combination of electrical and thermal compatibility," said Dan Hutcheson of VLSI Research. "By sharing such positive results with the rest of the industry, TI has put HfSiON firmly on the roadmap to be the high-k dielectric of choice."
TI´s paper at IEDM will explore the comparison of the threshold stability of HfSiON to that of HfO2. The stability of HfSiON is found to be far superior to that of HfO2. This is a critical result at this stage of the technology development since the industry would benefit from focusing on one gate dielectric material to iron out any potential issues with introducing the new material.
Dielectric Development Leadership
In addition to high-k development, TI was one of the first companies to offer a lower, 2.9 k (OSG) dielectric material at each interconnect level from the 3.6 k (FSG) used in the previous generation. Low-k materials reduce capacitance and propagation delays within the interconnect layers of a device more effectively, boosting the overall chip performance. Lower-k dielectrics also allow metal lines to be packed closer together on a chip with less risk of electrical signal leakage.
TI closely links its chip design with advanced process technology development to manufacture products competitive with any company in the world. By offering a variety of optimized process flows for each step on its technology roadmap, TI provides the best performance for different end equipment requirements. Adjustments to the transistors' gate length, threshold voltage, gate oxide thickness or bias conditions all change the performance specification of the millions of transistors on the final integrated circuit. The different flows are carefully targeted to achieve a specific application balance between transistor performance and power consumption, providing customers a range of product options.
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