Drying and gas or vapor contact with solids – Material treated by electromagnetic energy – Radio or high-frequency energy
Reexamination Certificate
1998-05-28
2001-02-13
Gravini, Stephen (Department: 3749)
Drying and gas or vapor contact with solids
Material treated by electromagnetic energy
Radio or high-frequency energy
C034S060000, C034S210000
Reexamination Certificate
active
06185839
ABSTRACT:
BACKGROUND
This invention relates to a process chamber for processing semiconductor substrates, and in particular to a gas distributor for distributing process gas into the process chamber.
A process gas distributor that provides a non-uniform distribution of process gas in a process chamber can cause large variations in processing rates and uniformity across a surface of a substrate processed in the chamber. In semiconductor fabrication, process gas is introduced into the chamber and a plasma is formed from the process gas to etch or deposit material on the substrate. However, current semiconductor substrates have increased in diameter from 100 mm (4 inches) to 300 mm (12 inches). The proportionate increase in the volume of the chamber has made it more difficult to provide a uniform distribution of process gas or plasma species across the entire processing surface of the substrate. As a result, there is often considerable variation in processing rates and processing uniformity from the center to the periphery of the substrate.
Achieving a uniform process gas distribution is a particular problem in process chambers having ceramic walls or ceilings because it is difficult to fabricate the ceramic components with feed-throughs that allow gas nozzles to extend therethrough to uniformly distribute process gas into the process chamber. The ceramic walls are composed of polycrystalline ceramic material, such as aluminum oxide or silicon, which are brittle materials and difficult to machine holes for holding a gas feedthrough without breaking or otherwise damaging the ceramic component. Also, other components, such as RF induction coils, adjacent to the ceramic walls further reduce the space available for locating a gas nozzle through the wall. Thus there is a need for a gas distributor that provides a uniform distribution of process gas in a process chamber having ceramic walls or ceilings without requiring a hole or other feed-through to be drilled through the ceramic component.
Yet another problem with current process chambers is that a relatively large amount of process gas is required to provide uniform processing rates across the substrate as compared to the amount of process gas actually consumed during processing of the substrate. Conventional process chambers require an abundance of process gas to assure complete processing of the semiconductor substrates. For example, typical CVD processes are 30 to 68% efficient, which leaves 70 to 32% of the unconsumed process gas exhausted in the effluent gas. Typical etch processes are even less efficient and often use as little as 10% of the total volume of process gas. These inefficiencies in process gas utilization increase the processing cost per substrate, particularly when the process gas is expensive. Also, excessive emissions of unconsumed process gases necessitate some form of effluent abatement apparatus to reduce the toxic or environmentally hazardous compounds in the effluent process gas, which is also expensive.
Thus there is a need for a process chamber having a gas distributor that provides a uniform distribution of process gas in the chamber, particularly for large diameter substrates. There is a further need for a gas distributor that increases the efficiency of utilization of process gas in the chamber, and thereby reduces environmentally hazardous emissions. There is also a need for a gas distributor that does not require holes or feed-throughs in ceramic walls in order to provide a uniform distribution of gas in the chamber.
SUMMARY
A process chamber according to the present invention for processing a semiconductor substrate comprises a support, a gas distributor adapted to inject process gas at an inclined angle relative to a plane of the substrate into the process chamber, a gas energizer, and an exhaust. A substrate held on the support is processed by process gas distributed by the gas distributor, energized by the gas energizer, exhausted by the exhaust. More preferably, the gas distributor comprises a plurality of gas nozzles that inject process gas at an inclined angle that is sufficiently large to cause two or more streams of process gas to impinge against one another to form a circulating gas stream in the process chamber.
In another embodiment, the gas distributor comprises a plurality of gas nozzles to provide process gas into the process chamber, and a gas flow controller that alternates the flow of process gas between the gas nozzles. Preferably, the gas distributor comprises first and second gas nozzles adapted to inject process gas into the process chamber, and a gas flow controller comprising a computer controller system and computer-usable medium comprising computer program code that operates the gas distributor to (1) flow process gas through the first gas nozzle for a time period, and thereafter, stop the flow of process gas through the first gas nozzle, and (2) flow process gas through the second gas nozzle for another time period, and thereafter, stop the flow of process gas through the second gas nozzle.
In another embodiment, the process chamber comprises a dome ceiling above the support, and an inductor antenna adjacent to the dome ceiling to couple RF energy to process gas in the process chamber. A gas distributor comprises gas nozzles facing one another for injecting process gas at an inclined angle relative to a plane of the substrate, into the process chamber, and an exhaust exhausts the process gas from the process chamber. Preferably, the dome ceiling comprises a semiconductor material having an electrical susceptibility that is sufficiently low to allow RF energy from the inductor coil to permeate therethrough.
In another aspect, the present invention is to a method of processing a semiconductor substrate in which a substrate is placed on a support in a process chamber, and a process gas stream is injected into the process chamber at an inclined angle relative to a plane of the substrate. The process gas can be energized to process the substrate either before or after introduction of the process gas into the process chamber. Preferably, the method further comprises maintaining a curved surface opposite the substrate, the curved surface having a radius of curvature sufficiently large to direct the process gas stream downward and along a periphery of the substrate.
In yet another aspect, the present invention is to a method of processing, in which a substrate is supported in the process chamber. A first burst of process gas is injected into the process chamber through a first gas nozzle and the process gas is energized. Thereafter, a second burst of process gas is injected into the process chamber through a second gas nozzle while continuing to energize the process gas. Preferably, these steps are repeated at least once.
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PCT Search Report dated Oct. 20, 1999.
Kholodenko Arnold
Loewenhardt Peter K.
Lubomirsky Dmitry
Shamouilian Shamouil
Shiau Guang-Jye
Applied Materials Inc.
Gravini Stephen
Janah and Associates
Mattera Michelle A
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