Toshiba Corporation
Sony Corporation

Tokyo--Toshiba Corporation and Sony Corporation today announced the development of essential technologies for system LSI based on next-generation 45-nanometer (nm) process technology. The advances cover the development of carrier mobility enhancement technologies and wiring process technology for boosting LSI performance.

Toshiba and Sony have raised current drive performance in transistors by developing strained silicon technologies that enhance carrier mobility. They have also developed a performance-enhancing low dielectric constant (low-k) film technology for implementation between layers in multi-layer wiring.

Two advances in strained silicon technologies improve individual transistor performance and overall device performance. The first optimizes the thickness of a stress liner covering the transistor and improves current drive performance by approximately 40%. The second brings global stress into the device substrate in a low cost process that realizes an approximately 20% improvement of current drive performance.

In seeking improved low-k film technology, Toshiba and Sony enhanced the quality of the low-k film by appropriately allocating dummy wiring to improve removal of moisture from the film. In doing so, they overcame the problem of poor drain characteristics in low-k film.

In 45nm generation system LSI, miniaturization of circuitry is no guarantee of performance improvement. Miniaturization must be accompanied by performance enhancement technologies, including utilization of new materials and structures. In following this approach, Toshiba and Sony have clarified conditions for applying innovative support technologies to actual products. The breakthroughs announced today offer elemental technologies that will support continued efforts to optimize other technologies.

Toshiba and Sony announced details of the technologies at the International Electron Devices Meeting (IEDM), which runs in Washington D.C. from December 5 to December 7.

More details of the new technologies

1. Strained silicon technologies
1) Local strained silicon
Strained silicon technologies fall into two categories: local strained methods and global strained methods. Local strain enhances the mobility of carriers by forming a stress liner on top of transistors. While a thicker stress liner was recognized as bringing better transistor performance, Toshiba and Sony confirmed that, in a circuit layout of many transistors, exceeding a certain thickness prevents the stress enhancement from being transmitted to each transistor. This results from stress diffusion by unification of the stress liner of proximate transistors. Studies confirmed that the optimum stress liner thickness in 45nm circuits is 30nm. At that thickness, current drive performance was found to be improved by 15% at nMOSFET and by 60% at pMOSFET, in combination with eSiGe technology.

2) Global strained silicon
Global strained silicon technology makes use of a special silicon substrate embedded with stressed SiGe film throughout the substrate. Toshiba and Sony had already developed a strained silicon technology that horizontally rotates the silicon substrate by 45 degrees to enhance total transistor performance. Drawing on this, the two companies improved nMOS performance by producing a device on strained silicon substrate and embedding silicon in recessed Source/Drain of SiGe layer with epitaxial growth, causing tensile stress. This improved current drive performance by approximately 20% on average.

2. Low-k film technology
In 45nm generation, technology introducing porous low dielectric constant materials is regarded as a promising route to performance enhancement. The initial concern about introducing porous materials is potential deterioration in device solidity. An efficient solution was found in a hybrid structure that use of layers of organic and inorganic materials, which was introduced from the 65nm generation. Another bigger concern was increased resistance and performance deterioration from a build up of moisture in the porous materials. This was solved by adoption of an original layout that allocates dummy wiring around the via. This helps to release moisture from the porous materials, preventing oxidization of metal at the via.

About Sony Corporation
Sony Corporation is a leading manufacturer of audio, video, communications and information technology products for the consumer and professional markets. Its music, pictures and computer entertainment operations make Sony one of the most comprehensive entertainment companies in the world. Sony recorded consolidated annual sales of over $62 billion for the fiscal year ended March 31, 2003. Sony's Home Page URL: http://www.sony.net/