TOKYO, JAPAN - Tokyo Electron Limited (TEL; Head Office: Minato-ku, Tokyo; C.E.O., President: Tetsuro Higashi) has released a 300mm version of their plasma nitridation system, the Trias^TM SPA. The new system can also be used for oxidation processes.

Recent years have seen active and concentrated efforts to reduce the thickness of gate-insulating films that will lead to faster semiconductor devices. Thinner films, however, increase gate leak currents, leading to increases in device power consumption. Processes of 100nm and below require new techniques for oxidation and nitridation of thin gate oxide films for both higher speeds and lower power consumption.

The Trias SPA uses unique Slot Plane Antenna (SPA) plasma, based on the Radial Line Slot Antenna (RLSA) microwave plasma developed by Professor Tadahiro Ohmi at Tohoku University. It produces high-density plasmas at low electron temperatures to enable damage-free processes at temperatures no higher than 400°C. By optimizing the slot configuration of the antenna, the plasma distribution can be adjusted to achieve excellent uniformity, which is comparable to those obtained with advanced furnace technology.

By combining TELFORMULA for oxide formation with SPA nitridation, it is possible to obtain a nitrided gate oxide with an electrically equivalent oxide thickness (EOT) of 1.1nm or lower, with leakage currents reduced by one order of magnitude compared to conventional oxide films. Also, the reduction of transconductance (Gm) can be minimized within 10%. As a significant competitive advantage, this system eliminates the need for post-annealing due to the damage free characteristics of the unique SPA plasma, resulting in an extremely low cost of ownership (COO).

In addition to the nitridation, SPA enables radical oxidation at temperatures no higher than 400°C to form high quality ultra thin oxide (UTO) with reliability equal or better than that of thermally grown oxide. Typical thickness non-uniformity is 0.7 to 1.0 % (1 for 0.8 to 1.5 nm UTO. Sequential SPA oxidation and nitridation yields reliable gate dielectrics without fluctuation of process queue time and with quick turn around time. All oxidation and nitridation processes during gate formation can be done at low temperatures, resulting in a steep nitrogen concentration profile, and increased transistor reliability for devices of 70nm generation.

Additional Trias SPA applications include tunnel oxide formation for next-generation flash memories, nitride barrier formation for high-k gate dielectrics, refinement of various high-k capacitor materials, oxidation for shallow trench isolation (STI), and post-gate etch recovery oxidation. These low temperature, damage-free radical processes by SPA plasma are expected to become key technologies for the manufacturing of future advanced devices.

The 300mm Trias SPA, can be converted from 200mm to 300mm wafers with minimal change in process performance. TEL released the 200mm Trias SPA nitridation system in December 2001 and is now ready to ship 200mm systems for oxidation applications.

* Trias is a trademark of Tokyo Electron Limited.