Combustion – Process of combustion or burner operation – Heating feed
Reexamination Certificate
1999-07-02
2001-01-30
Lazarus, Ira S. (Department: 3743)
Combustion
Process of combustion or burner operation
Heating feed
C431S208000, C431S160000, C431S259000, C431S181000, C431S012000, C431S347000, C060S039828
Reexamination Certificate
active
06179609
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to torches for use in semiconductor processing.
BACKGROUND OF THE INVENTION
A number of the processes in semiconductor production require introduction of particular chemical substances in an ultrapure state into the process chamber or furnace. For example, wet processes require steam and dry processes require hydrogen chloride (HCl). Both of these are typically produced by oxidation in a torch chamber which feeds the oxidation products into the processing chamber. Known torches are Pyrogenic External Torches (PET) which typically include an external ignition element, a quartz hydrogen/oxygen injector, a quartz torch chamber, a safety shield, and an electronic controller for safety interlocks and operation communications with a main computer controller. Heated streams of hydrogen and oxygen are injected via a nozzle into the torch chamber, in which they ignite, thereby producing steam. These torches may also be configured for HCl production, but they then require additional heaters to maintain HCI oxidation. Existing torches in both cases tend to produce more heat than is needed by the semiconductor processing and are subject to expensive downtime when changing the input gases or in cases of heater failure. A further disadvantage is that flow control of the oxidation products is achieved by mechanical valves, which may introduce contaminants into the gas flow being controlled, especially in the case of hot and/or chemically reactive flows as in semiconductor production.
An indication of the state of the art is the torch assembly disclosed in U.S. Pat. No. 5,257,926 issued to the same assignee as the present application, the contents of which are incorporated herein by reference.
SUMMARY OF THE INVENTION
The present invention seeks to provide a compact torch for use in semiconductor processing which may be used to produce both steam and wet or dry Hydrogen Chloride at varying concentrations with no reconfiguration of the torch, providing full temperature of control of the oxidation product gases, with redundancy to provide automatic backup of heating and ignition elements, and with non-mechanical flow control of the oxidation product gases.
There is thus provided, in accordance with a preferred embodiment of the present invention, for use with a reactor chamber for semiconductor processing, a torch assembly for both combustion and flameless oxidation processes including:
a quartz chamber for sustaining therein combustion and flameless oxidation processes with a longitudinal axis and an open end to allow exit of gaseous oxidation products;
a gas injection subassembly mounted either integrally or removably with sealing apparatus at the other end of the quartz chamber with nozzles and supply conduits for first and second gases;
a starter unit which includes a radiant energy emitter and at least one radiant energy absorber to provide at least one hot spot to initiate oxidation of the gases in a preselected zone of the quartz chamber;
at least one heater mounted within the chamber and generally parallel to the chamber axis for heating the gases to a temperature sufficient to sustain oxidation thereof in the preselected zone of the chamber;
a cooling arrangement in heat exchange association with a wall portion of the chamber; and
a controller associated with the torch assembly for controlling operation thereof.
Additionally in accordance with a preferred embodiment of the present invention, the chamber wall portion is a double wall portion with inner and outer leaves defining an interspace and the cooling arrangement includes apparatus for directing a flowable cooling medium via the interspace to be in heat exchange contact with the inner leaf of the wall portion of the chamber, the interspace further having ridges for defining a generally helical flow path for the flowable cooling medium.
Further in accordance with a preferred embodiment of the present invention, the radiant energy emitter includes at least one lamp, which may be a quartz-halogen lamp with a tungsten filament, and the at least one radiant energy absorber includes at least one blackbody member, which may be made of silicon carbide which may be quartz-encapsulated and evacuated, positioned at a predetermined distance from the lamp.
Still further in accordance with a preferred embodiment of the present invention, the at least one heater is at least two heaters each of which is operable alone to heat the gases to a temperature sufficient to sustain oxidation thereof in the preselected zone of the chamber, and wherein the controller is operative, in the case of a failure of at least one of the heaters, to cause a non-failing heater to operate alone so as to heat the gases to a temperature sufficient to sustain oxidation thereof in the preselected zone of the chamber.
Additionally in accordance with a preferred embodiment of the present invention, the gas injection nozzles provide streams of the gases with at least minimum predetermined exit velocities and at predetermined angles each in the range of 5°-90° with respect to the chamber axis, thereby to mix the gases and produce a mixed stream generally parallel to the chamber axis. The nozzles each further have one or more orifices which may be of different diameters; and the supply conduits selectably supply the respective gases to their respective orifices so that the gas outflows will have the minimum predetermined exit velocities. The gas injection subassembly may further have a single emitting surface with all the orifices thereon, wherein the gas streams are emitted at predetermined angles each in the range of 5°-90° with respect to the emitting surface, or two emitting surfaces, one for each gas and its respective orifices, wherein the gas streams are generally perpendicular to the respective emitting surfaces. The gas conduits further include branching and mixing conduits to supply mixtures at preselected concentrations of the gases, where the first gas may be oxygen or a mixture at a preselected concentration of oxygen and dichlorethylene (DCE) vapor suspended at predetermined concentrations in nitrogen and the second gas is hydrogen, which is supplied when steam production is required. The torch assembly may also include a flame detector and a number of temperature sensors associated with the controller.
In accordance with an additional preferred embodiment of the present invention, the torch assembly further includes a flow divertor situated between the open end of the quartz chamber and a reactor chamber for semiconductor production for controlling the flow of the gaseous oxidation products. The flow divertor has:
a primary conduit for conducting gaseous oxidation products from the quartz chamber to the reaction chamber, which may include an auxiliary input conduit for adding preselected auxiliary chemical substances to the gaseous oxidation products flowing in the primary conduit;
a secondary conduit intersecting with and communicating with the primary conduit via an outlet formed in a side wall thereof at a location upstream of the reactor chamber; and
apparatus for selectably applying a pressure drop across the primary conduit and the secondary conduit, employing a flow of a carrier fluid or gas, which may be controlled by valves, to produce a Venturi effect in the secondary conduit, thereby causing the gaseous oxidation products in the primary conduit to flow into the secondary conduit, thus to prevent the gaseous oxidation products from reaching the reactor chamber.
REFERENCES:
patent: 3964943 (1976-06-01), Anderson
patent: 4342551 (1982-08-01), Browning
patent: 4825658 (1989-05-01), Beebe
patent: 4916904 (1990-04-01), Ramsaier et al.
patent: 5149261 (1992-09-01), Suwa et al.
patent: 5257926 (1993-11-01), Drimer et al.
patent: 5314008 (1994-05-01), Garcia-Mallol
patent: 2501894A1 (1975-07-01), None
Borivker Nachum
Drimer Gideon
Mendelovici Leo
Cocks Josiah C.
Lazarus Ira S.
Nixon & Vanderhye P.C.
Persys Technology Ltd.
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