Coating processes – Measuring – testing – or indicating
Reexamination Certificate
1997-06-30
2001-08-28
Bueker, Richard (Department: 1763)
Coating processes
Measuring, testing, or indicating
C427S248100, C118S712000, C118S715000, C156S345420
Reexamination Certificate
active
06280790
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a system and a method for reducing the deposition rate of volatile contaminants onto an optical element of a substrate processing system.
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 (RTP). RTP processes include, for example, such 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.
Layers of doped glass, such as borophosphosilicate glass (BPSG) or phosphosilicate glass (PSG), are used extensively in pre-metal dielectric (PMD) layers in logic and memory devices. Doped glass layers are typically deposited onto a substrate in a CVD system and are subsequently heated to a high temperature in an RTP chamber or a furnace. In one heating process, doped glass is densified by heating the doped glass to a temperature of 700-800° C. in an RTP chamber. Heating the doped glass in this way reduces the porosity of the layer, relieves stress in the film, drives off residual impurities left from CVD deposition, stabilizes the dopants against atmospheric instability, and activates the gettering capability of the phosphorous oxides (PO
x
) in the film for trapping alkali ions. BPSG can be heated to higher temperatures, such as 850-950° C., to decrease the viscosity of the BPSG and cause macroscopically visible flow (reflow) that planarizes the BPSG surface and enables the BPSG to fill surface features of underlying layers.
Various volatile contaminants are produced during an RTP process as a result of heating a substrate to a high temperatures. These volatile contaminants can condense onto the walls and other surfaces inside the processing chamber and, over time, the build-up of such deposits may detrimentally impact the operation of the processing system. For example, boron oxides (BO
x
) and PO
x
have high vapor pressures and are produced at a rapid rate when BPSG and PSG layers are heated to high temperatures. To reduce the detrimental impact of these volatile contaminants upon the fabrication process, such RTP systems must be periodically shutdown and cleaned. Replaceable liners (and the like) have been developed for reducing the time needed to clean the processing chamber.
SUMMARY OF THE INVENTION
In one aspect, the invention features a scheme for reducing the rate at which volatile contaminants are deposited onto one or more optical components of a substrate processing system. According to the invention, a purge fluid is introduced into the processing system at an interior surface of the processing system, a flow of purge fluid is produced across the interior surface to form a contaminant-entraining barrier between a source of the volatile contaminants and the one or more optical components and thereby reduce the rate at which volatile contaminants are deposited onto the optical components of the system. The purge fluid is substantially removed from the processing system.
The purge fluid may flow across the interior surface of the processing system as a substantially laminar flow. The purge fluid may be introduced into the processing system from a peripheral region of the interior surface and directed toward a central region of the interior surface. The purge fluid may be introduced from a peripheral region of the interior surface and removed from a peripheral region at an opposite side of the interior surface. If the interior surface is substantially circular, the purge fluid may be introduced from different locations around the periphery of the interior surface. The purge fluid may removed from the processing system through an exhaust port in the interior surface. In one embodiment, the flow of purge fluid is produced by directing a flow of a purge fluid against a deflector spaced a distance from the interior surface of the processing system where the purge fluid is introduced. The one or more optical components may comprise an optical detector that receives radiation from inside the processing system that passes through an optical port, and the flow of purge fluid is directed toward the optical port. In one embodiment, the flow of purge fluid is produced by directing a flow of purge fluid against a slot-shaped deflector constructed to deflect the flow of purge fluid as a rectangular curtain of fluid across the optical port. The rectangular curtain of fluid may be removed from the processing chamber through a slot-shaped opening in the interior surface of the processing system. In another embodiment, the purge fluid is introduced from a circumferential region surrounding the optical port. The one or more optical components may comprise an optically reflective surface, and the flow of purge fluid is produced across this surface. The flow rate at which the purge fluid is introduced into the processing system is preferably substantially the same as the flow rate at which the purge fluid is removed from the processing system.
In another aspect, the invention features a scheme for processing a layer (such as doped glass) supported on a substrate. According to the invention, the substrate is heated inside a processing system having one or more optical components, a purge fluid is introduced into the processing system at an interior surface of the processing system, a substantially laminar flow of the purge fluid is produced across the interior surface to form a contaminant-entraining barrier between a source of the volatile contaminants and the one or more optical components, thereby reducing the rate at which volatile contaminants are deposited onto the optical components of the system, and purge fluid is removed from the processing system.
The contaminant-entraining barrier produced by the flow of purge fluid across the interior surface of the substrate processing system prevents volatile contaminants from contacting one or more optical components of the system. The invention thereby reduces the rate at which volatile contaminants condense onto the optical components and increases the number of substrates that can be processed before the processing system must be cleaned; in contrast, the use of a replaceable liner (and the like) to shield the optical components of the system does not extend the period between cleanings.
Other features and advantages will become apparent from the following.
REFERENCES:
patent: 4976996 (1990-12-01), Monkowski et al.
patent: 5062386 (1991-11-01), Christensen
patent: 5574247 (1996-11-01), Eisuke et al.
patent: 5653808 (1997-08-01), MacLeish et al.
patent: 5755886 (1998-05-01), Wang et al.
patent: 5755888 (1998-05-01), Torii et al.
patent: 5884412 (1999-03-01), Teitz et al.
patent: 6103014 (2000-08-01), Lei et al.
patent: EP 0825 279 A1 (1998-02-01), None
patent: FR 1553985 (1969-01-01), None
patent: JP 59058326 (1984-04-01), None
patent: JP 01312078 (1989-12-01), None
patent: WO 9637763 A (1996-11-01), None
Haas Brian L.
Kuppurao Satheesh
White Anthony F.
Applied Materials Inc.
Bueker Richard
Pennie & Edmonds LLP
LandOfFree
Reducing the deposition rate of volatile contaminants onto... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reducing the deposition rate of volatile contaminants onto..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reducing the deposition rate of volatile contaminants onto... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503274