Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-10-06
2001-11-13
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S405000, C219S411000, C118S724000, C118S050100, C392S416000
Reexamination Certificate
active
06316747
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for the thermal treatment of substrates, and includes a reaction chamber, at least one elongated heat source, and at least one reflection wall having at least one rib for reflecting at least a portion of the radiation given off by the heat source.
An apparatus of this type is known, for example, from JP 5-190558 A. The reflection walls have grooves that extend parallel to the heating lamps and in which the heating lamps are at least partially disposed and which form the at least one rib. With this type of reflection wall, a reflected radiation results that is parallel to the lamps. Such devices with contours in a reflection wall that extend parallel to the heating lamps are furthermore known from JP 61-125021 A, as well as JP 60-193343 A.
An apparatus for the thermal treatment of substrates is disclosed in the not prepublished DE 197 37 802 that belongs to the applicant of the present application. With this apparatus, a reaction chamber of quartz glass is disposed within a second, larger chamber having reflection walls. Disposed above and below the reaction chamber are heating sources in the form of rod lamps in order to heat up a substrate, especially a semiconductor wafer, that is disposed in the reaction chamber. The reflection walls of the apparatus are flat, so that again a reflected radiation parallel to the lamps results. Due to this parallel reflection at the reflection wall there results within the reaction chamber a certain, periodic intensity distribution of the incident light for heating the substrate. In so doing, parts of the substrate can be heated more than other parts, which, however, is a drawback since the substrate must be heated as uniformly as possible.
It is therefore an object of the invention to provide an apparatus for the thermal treatment of substrates of the aforementioned general type, according to which a uniform heating of the substrates is possible.
SUMMARY OF THE INVENTION
This objective of the invention is realized in that the heating source or sources are disposed at an angle to the longitudinal direction of the at least one rib. As a result of this arrangement, the reflective image of the heating sources is rotated by an amount that depends upon the angle between the tubes and the ribs, so that a more uniformly directed distribution of the radiation intensity in the reaction chamber results.
Pursuant to one preferred specific embodiment of the invention, the reflection wall has a plurality of ribs that are disposed parallel to one another. Due to this plurality of ribs, there results a simple possibility of distributing the radiation intensity more uniformly within the entire reaction chamber. In this connection, the ribs are preferably formed by grooves.
Pursuant to a particularly preferred specific embodiment of the invention, the heating sources are rod lamps that provide a simple heating source that is simple to control.
The angle between the ribs and the heating sources is preferably 45° so that the reflected image of the heating sources is rotated in an angle of 90°. There thus results a reflection radiation that extends perpendicular to the direct radiation of the lamp tubes, as a result of which a particularly uniform radiation intensity is produced within the reaction chamber.
Pursuant to one specific embodiment, the ribs extend uniformly over the entire reflection wall in order to produce the aforementioned effect over the entire reflection wall.
Pursuant to a further specific embodiment, the ribs extend at least over portions of the reflection wall, especially in the outer regions of the reflection wall, in order to enable a reflection of the thermal radiation in the direction of the substrate that is to be heated.
Pursuant to a particularly advantageous specific embodiment of the invention, at least one turning mechanism is furthermore provided for rotating the reflection wall that has at least one rib. Due to the rotation, it is possible to adapt the intensity distribution of the radiation field in a treatment chamber to the respective process conditions. In particular, due to the rotation of the reflection wall the intensity distribution can be homogenized over time, thereby enabling a more uniform heating of the substrate. Furthermore, due to the rotation of the reflection wall the intensity distribution of the radiation is modulated with the rotational frequency of the reflection wall. A modulation can, for example, also be advantageously utilized for measuring the temperature via pyrometry.
A control unit is advantageously provided for controlling the turning mechanism in order to adapt the rotation, and hence the intensity distribution of the radiation within a treatment chamber, to the respective process conditions and process steps.
The term substrate in the present context includes semiconductor wafers, masks, plates, and all objects which, or the surface of which, is to be subjected to a thermal treatment.
REFERENCES:
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patent: 4550245 (1985-10-01), Arai et al.
patent: 5154512 (1992-10-01), Schietinger et al.
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patent: 5861609 (1999-01-01), Kaltenbrunner et al.
patent: 5863843 (1999-01-01), Green et al.
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patent: 5906533 (1999-05-01), Harris et al.
patent: 6200634 (2001-03-01), Johnsgard et al.
Blersch Werner
Walk Heinrich
Becker Robert W.
Fuqua Shawntina T.
Robert W. Becker & Associates
Steag RTP Systems GmbH
Walberg Teresa
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