AVS 45th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Invited Paper MS-MoA1
Green House Effect and LSI Process Technology

Monday, November 2, 1998, 2:00 pm, Room 317

Session: Contamination Free Manufacturing
Presenter: K. Okumura, Toshiba Corporation, Japan
Authors: K. Okumura, Toshiba Corporation, Japan
T. Ohiwa, Toshiba Corporation, Japan
Correspondent: Click to Email
While LSI devices contribute to saving energy, their fabrication consumes large amounts of electric power and PFC gases. This paper will discuss the new LSI process technology to alleviate such negative aspects. Among the process tools, especially the furnaces and dry pumps consume a large quantity of electric power. The fast temperature processor (FTP), which realizes ramp temperature up and down at high speed, succeeds in maintaining temperature at 300 - 400 °C and ramping up to 800 - 900 °C only when processing. This leads to a 30 - 50 % power reduction compared to the conventional furnace which constantly maintains its temperature at 800 - 900 °C. Dry pumps with an inverter controlled DC motor drive consume half as much power as conventional induction motor drive systems. Furthermore, quick response of the DC motor without over-current makes it possible to turn it on only when necessary and off during machine idling, which leads to 15 - 80 % less power. In RIE and CVD machines, as much as 10 - 15 SLM of purge N@sub 2@ gas is used in order to prevent clogging of dry pumps by by-products. Pure N@sub 2@ gas generation also requires a vast amount of electric power. Therefore, reduction of N@sub 2@ gas is another effective approach. A dual in-line cold trap was newly developed for this. It consists of two traps. One traps by-products before the dry pump, and the other can be flashed meanwhile. Improving the efficiency of gas usage leads to reduction of PFC consumption. A new gas circulation system was developed, which pumps the exhausted gas still containing usable process gas into the RIE reaction chamber to be reused. Because many kinds of PFC gases after plasma processing eventually change to the most stable CF@sub 4@ gas, recycling of CF@sub 4@ gas is a key point. We have developed a dual trap system which operates at liquid N@sub 2@ temperature. It is capable of trapping CF@sub 4@ gas exhausted from an RIE reaction chamber. This system has the possibility of distillation of PFC gas by the appropriate control of regeneration temperature.