Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1998-04-27
2001-02-13
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C118S050100, C392S416000, C362S290000
Reexamination Certificate
active
06188044
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and system for device fabrication on a substrate and, more particularly, to a method and system for transferring energy from a radiative energy source to a substrate for rapid thermal processing applications in support of microelectronic and semiconductor device fabrication.
BACKGROUND OF THE INVENTION
Semiconductor devices can be formed on silicon wafer substrates by the use of certain fabrication processes some of which involve the application of heat (e.g., in the range of 200° C. to 1100° C.) to the substrate in a controlled environment. Several processing methods for fabricating a device onto a substrate have evolved which include the application of thermal energy to the substrate to drive thermally activated fabrication processes. For instance, chemical-vapor deposition (CVD) processes can deposit various materials on a substrate, including metallic, semiconductor and insulating material layers. Thermal deposition processes and thermal anneal processes can support silicide formation. These chemical and thermal processes can form a microelectronic device such as an insulated gate field-effect transistor (IGFET) on a substrate by manipulating, forming or modifying materials such as silicon dioxide, silicon nitride, tungsten, polysilicon and other known materials. Well-known single-wafer rapid thermal processing (RTP) applications include rapid thermal annealing (RTA), rapid thermal oxidation (RTO), rapid thermal chemical-vapor deposition (RTCVD) processes, and rapid thermal nitridation (RTN).
During the formation of a device such as an IGFET on a substrate by thermal processing techniques such as RTP methods, consistent production of a high-quality semiconductor integrated circuit (IC) with high production yield is enabled when the thermal energy is applied in a uniform and repeatable manner. CVC, Inc. (“CVC”) has introduced several significant improvements over conventional thermal processing systems and methods for semiconductor IC fabrication. For instance, CVC has developed a multi-zone radiant-energy illuminator for producing heat in silicon substrates during device fabrication as is disclosed in U.S. patent application Ser. No. 08/678,321 filed on Jul. 11, 1996, and entitled “Multi-Zone Illuminator for Rapid Thermal Processing,” which is incorporated herein by reference as if fully set forth. This multi-zone illuminator provides improved wafer-to-wafer process and temperature repeatability as well as within-wafer temperature uniformity by monitoring and controlling optical energy produced by plural lamps arranged in multiple heating zones. The multi-zone illuminator also includes a multi-zone temperature measurement system having plural pyrometry sensors for real-time wafer temperature measurement.
Although the multi-zone illuminator provides improved device fabrication uniformity and repeatability, a number of process control difficulties remain with respect to fabrication by rapid thermal processing (RTP). For instance, in one implementation of rapid thermal processing (“RTP”) or rapid thermal chemical-vapor deposition (“RTCVD”), a substrate is generally supported by a susceptor during the application of heat. The susceptor can absorb the radiant optical energy and redistribute thermal energy across the substrate thus nullifying or minimizing effectiveness of the control inputs to a multi-zone illuminator. Another limitation relates to the varying emissivity of the substrate during processing due to the dependence of substrate emissivity on temperature and thin films. Although CVC's multi-zone temperature sensing and control technology in conjunction with multi-zone illuminators can compensate for variations in wafer emissivity (due to any source such as temperature and/or material layers), this compensation can introduce some errors and requires complicated control algorithms which can depend upon extensive testing and calibration runs for each type of substrate being processed. Another difficulty relates to the size and makeup of the susceptor used to support a substrate. The heating susceptor can introduce residue contaminants (e.g., metallic contaminants) to the substrate when the susceptor is in physical contact with the substrate. Also, to provide adequate mechanical support of the substrate, the susceptor can be made of a relatively large mass of thermally conductive material. The larger the mass of a conventional heating susceptor, the more difficult it is to estimate and control the heat energy absorbed and emitted by the susceptor. Moreover, high-thermal-mass susceptors significantly slow down the wafer heating and cooling times, resulting in reduced wafer processing throughout.
SUMMARY OF THE INVENTION
Therefore a need has arisen for a method and apparatus that provides improved temperature control and uniformity during thermal processing of a substrate during fabrication of semiconductor devices on the substrate in a thermal processing equipment.
A further need exists for a method and apparatus that provides improved accuracy and repeatability in measuring the temperature distribution of a substrate during thermal processing applications.
A further need exists for a method and apparatus that provides enhanced spatial control of incident optical radiation to improve the accuracy, uniformity, and repeatability with which a multi-zone illuminator heats a substrate in rapid thermal processing (RTP) including rapid thermal chemical-vapor deposition (RTCVD) applications.
In accordance with the present invention, a high-performance radiant energy transfer system and method is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed methods and apparatus for providing energy to a substrate during thermal processing (e.g., in RTP and RTCVD) for the fabrication of a device such as semiconductor chips. A housing forming a reactor process chamber can be used to isolate a substrate for thermal processing (such as RTA, RTO, RTN, or RTCVD). A radiative heat source such as a multi-zone illuminator can direct radiative energy flux at the substrate to provide thermal energy in support of the thermal fabrication process. An energy transfer device can be disposed between the substrate and the heat source to efficiently and accurately and repeatably transfer energy originated from the radiative energy source to the substrate. The energy transfer device can also substantially decouple the substrate heating as well as temperature measurement and control tasks from the substrate emissivity effects. The energy transfer device can comprise first and second regions, the first regions having a first emissivity and thermal conductivity, and the second regions having a second emissivity and thermal conductivity wherein the first regions can provide a higher degree of energy transfer and the second regions can provide a lower degree of energy transfer. The low energy transfer characteristics of the second regions allow the second regions to act as spacers or energy zone buffers that separate the first regions from each other. In one embodiment, the second regions can be empty spaces formed between adjacent first regions. This arrangement enables excellent multi-zone substrate heating and temperature control via improved controllability of the spatial profile of the incident radiant power on the substrate.
More specifically, the reactor chamber can support any conventional thermal processing system or method for device fabrication onto a substrate, including single-wafer RTP and RTCVD. The radiative energy source can include any known equipment for thermal processing, including the multi-zone illuminator available through CVC, Inc. The radiative energy source can provide thermal energy with conventional tungsten halogen lamps arranged in plural spatially resolved heating zones, such as the concentric or spiral lamp distribution arrangements developed by CVC. The radiant energy provided by the multi-zone illuminator, can be controlled by a multi-zone
Belikov Sergey
Kamali Jalil
Lee Yong Jin
Moslehi Mehrdad M.
Baker & Botts L.L.P.
CVC Products Inc.
Fuqua Shawntina T.
Walberg Teresa
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