Motorola Corporation

Gary A DePinto

John G Franka

Michael R Cherniawski

Joe Steinberg

Ross A Fisher

Harry S Morgan

Steve Dunnigan

Brajendra Mishra

This application is dedicated to the public. A method and apparatus for reducing the emissions of a fluorinated gas from a wafer processing facility begins by providing a fluorinated exhaust gas from wafer processing tools (10) through (16) via an input line (17). The fluorinated exhaust gas is then optionally gettered via an gettering system (18) to remove oxygen from the exhaust gas. After gettering, the fluorinated exhaust gas is directed to a molten aluminum bath (44). The fluorine in the exhaust gas reacts with the aluminum to form AlF.sub.3. A measurement device (56) is used to monitor the amount of fluorine being exhausted from the molten aluminum bath (44). When the amount of fluorine in the exhaust is too high, the molten aluminum bath (44) is saturated with fluorine. The bath is then cooled to form an inert solid brick of AlF.sub.3. Therefore, fluorinated gases which are detrimental to the environment are cost-effectively removed from the output of a wafer fabrication facility.

Method and apparatus for using molten aluminum to abate PFC gases from a

A multi-directional flow of isopropyl alcohol vapor is used to uniformly dry a semiconductor substrate. In one embodiment of the invention, isopropyl alcohol vapor (19), which is generated by an external vapor source (30), is injected into the vapor drying system at a location near the top portion (28) of the semiconductor substrate (20), while internally generated isopropyl alcohol vapors (18) are directed toward the bottom portion (26) of the semiconductor substrate (20). Therefore, both the top (28) and the bottom (26) portions of the semiconductor substrate (20) are dried at approximately the same time.

Method for vapor drying

A polysilicon layer may need to have electrical characteristics which are relatively uniform from wafer to wafer. The use of polysilicon as a resistor is one such example. In order to obtain the requisite uniformity, the temperature of the wafers which are receiving the polysilicon must all be the same within a tight tolerance. The reaction takes place in a furnace which takes a long time to reach the requisite temperature tolerance. While the furnace is stabilizing the temperature, oxide, which is an insulator, is growing on the contact locations of the various substrates. To minimize the deleterious oxide formation, a thin layer of polysilicon is deposited at a time significantly prior to the time that the furnace stabilizes which ensures a good, low-resistance contact. The remainder of the polysilicon is then deposited on the thin layer of polysilicon after the temperature has stabilized to obtain the requisite wafer-to-wafer resistance uniformity. The result is consistently low-resistance contacts and wafer-to-wafer uniformity for the resistance of the resistors.

Deposition of a conductive layer for contacts

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Austin, TX, United States of America

Gary A DePinto