Heating – Accessory means for holding – shielding or supporting work... – Support structure for heat treating ceramics
Reexamination Certificate
1998-04-01
2001-08-28
Lu, Jiping (Department: 3749)
Heating
Accessory means for holding, shielding or supporting work...
Support structure for heat treating ceramics
C432S253000, C432S259000
Reexamination Certificate
active
06280183
ABSTRACT:
BACKGROUND
This invention relates to a substrate support for a thermal processing chamber.
In many semiconductor device manufacturing processes, the required high levels of device performance, yield, and process repeatability can only be achieved if the temperature of the substrate (e.g., a semiconductor wafer) is tightly monitored and controlled during processing of the substrate.
Rapid thermal processing (RTP), for example, is used for several different fabrication processes, including rapid thermal annealing (RTA), rapid thermal cleaning (RTC), rapid thermal chemical vapor deposition (RTCVD), rapid thermal oxidation (RTO), rapid thermal nitridation (RTN), and rapid thermal silicidation (RTS). The temperature in an RTP chamber may exceed 1100° C. and is subject to rapid change, thereby making precise control of the substrate temperature more complicated and more difficult.
Additionally, although it is desirable to provide a substantially uniform temperature throughout the substrate during many manufacturing processes, the support on which the substrate rests can affect the manufacturing system's ability to achieve such uniformity. In susceptorless systems, for example, the substrate is usually only supported around its perimeter with an edge ring. In some situations, however, the edge ring acts as a thermal load which removes heat from the edge of the substrate, thereby making it difficult to provide a uniform temperature across the substrate and interfering with the temperature measurements.
SUMMARY
In general, in one aspect, a substrate support includes an inner portion, and an outer portion contiguous with the inner portion and extending radially outward therefrom. The inner portion includes a raised annular extension for supporting a substrate. In one implementation, the substrate support is an edge ring.
In another aspect, a method of processing a substrate in a thermal process chamber includes supporting the substrate on an edge ring within the chamber. The edge ring includes an inner portion and an outer portion contiguous with the inner portion and extending radially outward therefrom. The inner portion includes an annular ridge for supporting the substrate.
Various implementations include one or more of the following features. The inner portion can include a substantially flat surface formed in a first plane and the outer portion can include a substantially flat surface formed in a second plane. The annuler extension can extend from the first plane toward the second plane.
The inner portion can be annular-shaped with an inner radius and an outer radius larger than the inner radius. The raised extension can form a ridge along the inner radius.
An upstanding structure can connect the inner and outer portions to retain the substrate on the ridge. The ridge can have a height less than the height of the upstanding structure, and the height of the upstanding structure can be at least as great as the combined height of the ridge and a nominal thickness of the substrate.
The ridge can be substantially parallel to the upstanding structure and can be located at an inner diameter less than the diameter of the substrate. In some implementations, the ridge has a radial width equal to or less than approximately 0.015 inches and a height of at least approximately 0.020 inches above an upper surface of the inner portion. The foregoing dimensions are suitable for use with 8-inch (200 mm) substrates in certain processing chambers, such as the RTP Centura™ or the RTP Centura XE™, manufactured by Applied Materials, Inc. Other dimensions may be suitable for wafers of different sizes, for example, a 6-inch (150 mm) or a 12-inch (300 mm) semiconductor wafer, or for different wafer processing systems.
The substrate support can include silicon or silicon carbide and can be disposed in a thermal processing chamber. A process gas can be provided in the chamber. Additionally, the chamber can be heated, and the substrate support and the substrate can be spun about a central axis during heating.
Various implementations include one or more of the following advantages. A substrate support with the raised extension or ridge provides a substantially uniform contact area with the semiconductor substrate regardless of the precise position of the substrate on the support. Moreover, since a constant contact area can be formed near substantially the entire perimeter of the substrate, the difference in temperature from one radial slice of the substrate to another is reduced. Thus, a more uniform temperature can be obtained across the substrate surface. As a result, better control over thermal processing of substrates can be provided and the likelihood of substrate breakage due to thermal gradients across the substrate can be reduced.
The substrate support also can provide the capability of transferring heat to and from the entire substrate in a repeatable fashion, thereby resulting in less variation in the processing of one substrate to the next. The configuration of the substrate support still allows the substrate to remain within the inner portion of the substrate support when the support is rotated during substrate processing.
The distance between the substrate and a reflector beneath the substrate can be kept constant with respect to edge rings in existing systems by providing the new edge ring with a relatively deep pocket for retaining the substrate. In this manner, the edge ring can be used in existing systems without requiring significant adjustment of other system components to compensate for the presence of the new raised edge.
Additional features and advantages will be readily apparent from the following detailed description, drawings and claims.
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Mayur Abhilash
Stern Lewis A.
White Anthony
Applied Materials Inc.
Lu Jiping
Pennie & Edmonds LLP
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