Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1999-07-08
2001-04-10
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C034S058000, C118S724000, C392S416000
Reexamination Certificate
active
06215106
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to systems and methods of thermally processing a substrate.
Substrate processing systems are used to fabricate semiconductor logic and memory devices, flat panel displays, CD ROMs, and other devices. During processing, such substrates may be subjected to chemical vapor deposition (CVD) and rapid thermal processes (TP). RTP processes include, for example, rapid thermal annealing (RTA), rapid thermal cleaning (RTC), rapid thermal CVD (RTCVD), rapid thermal oxidation (RTO), and rapid thermal nitridation (RTN). RTP systems usually include a heating element formed from one or more lamps which radiatively heat the substrate through a light-transmissive window; RTP systems may also include one or more other optical elements, such as an optically reflective surface facing the backside of the substrate and one or more optical detectors for measuring the temperature of the substrate during processing. Many rapid thermal processes require precise control of substrate temperature over time.
SUMMARY OF THE INVENTION
The invention features a thermal processing method in which a temperature response of a substrate may be controlled during a heat-up phase or a cool-down phase, or both. This reduces the thermal budget of the substrate and improves the quality and performance of devices formed on the substrate. In particular, the inventors have realized that by controlling the rate of heat transfer between the substrate and a thermal reservoir (e.g., a water-cooled reflector plate assembly) during the thermal process, the temperature response of the substrate may be controlled.
In one aspect of the invention, the substrate is heated in accordance with a heating schedule and, during the heating schedule, the rate of heat transfer between the substrate and a thermal reservoir inside the thermal processing system is changed.
The rate of heat transfer may changed by changing the thermal conductivity between the substrate and the thermal reservoir, by changing the emissivity of a surface of the thermal reservoir, or by changing the distance between the substrate and the thermal reservoir.
The thermal conductivity may be changed by changing the characteristics of a thermal transport medium (e.g., a purge gas) located between the substrate and the thermal reservoir. For example, the thermal conductivity may be changed by changing the composition of the purge gas or the pressure of the purge gas between the substrate and the thermal reservoir. The thermal reservoir may include a relatively cool surface inside the processing chamber. The thermal conductivity between the substrate and the relatively cool surface may be increased during a cool-down phase of the heating schedule. The thermal conductivity may be increased by supplying a gas with a relatively high thermal conductivity between the substrate and the relatively cool surface. A first purge gas (e.g., nitrogen, argon and xenon) may be supplied between the substrate and the relatively cool surface during a heat-up phase of the heating schedule, and a second purge gas (e.g., helium and hydrogen) may be supplied between the substrate and the relatively cool surface during the cool-down phase of the heating schedule, the second purge gas having a thermal conductivity that is greater than the thermal conductivity of the first purge gas.
In another aspect of the invention, a first purge gas is supplied into the thermal processing system, the substrate is heated in accordance with a heating schedule, and a second purge gas that is different from the first purge gas is supplied into the thermal processing system.
The second purge gas may be supplied into the thermal processing system during a cool-down phase of the heating schedule. In one embodiment, the second purge gas is supplied into the thermal processing system at or near the time the substrate temperature has been heated to a target peak temperature. The second purge gas may be supplied into the thermal processing system while the substrate temperature is decreasing. The first purge gas may be supplied into the thermal processing system during a heat-up phase of the heating schedule.
In one embodiment, the thermal conductivity of the second purge gas is greater than the thermal conductivity of the first purge gas. In this embodiment, the second purge gas includes helium or hydrogen or both, and the first purge gas includes nitrogen and the second purge gas includes helium. The second purge gas may be supplied into the thermal processing system between the substrate surface and a thermal reservoir inside the thermal processing system. During a heat-up phase of the heating schedule, the first purge gas may be supplied into the thermal processing system between the substrate surface and the thermal reservoir. During a cool-down phase of the heating schedule, the second purge gas may be supplied into the thermal processing system between the substrate surface and the thermal reservoir.
Among the advantages of the invention are the following. The results of certain thermal processing methods (e.g., methods of forming ultra shallow junctions) are improved if the rates at which substrates are heated or cooled inside the thermal processing system are high. By changing the rate at which heat is transferred between a substrate and a thermal reservoir inside the processing chamber during the thermal process, the heat-up phase or the cool-down phase, or both phases, may be optimized to improve the quality of the devices produced.
Other features and advantages will become apparent from the following description, including the drawings and the claims.
REFERENCES:
patent: 5238499 (1993-08-01), Van De Ven et al.
patent: 5281552 (1994-01-01), King et al.
patent: 5624499 (1997-04-01), Mizuno et al.
patent: 5711815 (1998-01-01), Lee et al.
patent: 5773337 (1998-06-01), Lee
patent: 5882991 (1999-03-01), Paranjpe
patent: 5884412 (1999-03-01), Tietz et al.
patent: 5960555 (1999-10-01), Deaton et al.
patent: 6035100 (2000-03-01), Bierman et al.
Aderhold Wolfgang R.
Balakrishna Ajit
Bierman Benjamin B.
Boas Ryan C.
Haas Brian L.
Applied Materials Inc.
Fish & Richardson
Fuqua Shawntina T.
Walberg Teresa
LandOfFree
Thermally processing a substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermally processing a substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermally processing a substrate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2436000