Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1998-11-18
2001-02-20
Walberg, Teresa (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S405000, C118S724000, C427S559000
Reexamination Certificate
active
06191388
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of the present invention is thermal processors for semiconductor articles.
Furnaces are used in the processing of semiconductor articles such as wafers. Chemical deposition, etching and the like are conducted in such furnaces through the injection of reactants into a process chamber within which the semiconductor articles are positioned.
Heating of reactants prior to introduction into the process chamber is frequently used to convert the reactant into a gaseous or vapor state, heat the reactant to near the interior temperature of the furnace, and/or chemically transform a precursor into an appropriate reactant for the process. The application of these reactants typically is advantaged by a continuous flow into the furnace during operation. Consequently, a steady state flow is advantageously achieved and one which provides sufficient residence time before entry into the process chamber for complete reactions, thermal equilibration with the interior of the furnace and the like.
Devices have been developed to increase residence time within an injector prior to introduction of the reactants into the furnace process chamber. Long and circuitous paths and paths of greater cross sectional area have been proposed for extended residence time. However, the presence of the cooler materials and the presence of the injectors themselves can have a deleterious effect on the uniformity of the thermal environment in the process chamber.
The reactants may be preconditioned outside of the process chamber. In such circumstances, column heaters may be employed to mix gas, reactant(s) and heat before introduction into the furnace itself. Such column heaters have been thought most efficient when flow is from top to bottom. However, thermal isolation from the furnace itself can create difficulties where an extended path is required from the bottom of the column heater to the heated environment of the process chamber.
SUMMARY OF THE INVENTION
The present invention is directed to the heating of reactants for employment in a vertical furnace for processing of semiconductor articles.
In a first, separate aspect of the present invention, an injector includes an elongate tube which has a discharge end above the semiconductor article support within the furnace. A circuitous section is arranged within the process chamber for increased residence time. This circuitous section is located below the semiconductor article support to avoid interference with the thermal environment surrounding the semiconductor articles. A substantially direct section may then extend adjacent to the support between the circuitous section and the discharge end.
In a second separate aspect of the present invention, a vertical column heater is arranged to flow in reverse order with the vapor outlet located at the top of the column adjacent to the bottom, entry point of the process chamber for the vertical furnace. Greater thermal efficiency has been experienced with less impact upon the reactant(s) in transitioning from the heater to the process chamber.
In a third separate aspect of the present invention, either of the foregoing aspects is contemplated to be employed with a double lift vertical furnace.
In a fourth separate aspect of the present invention, the combination of any of the foregoing separate aspects is contemplated.
Accordingly, it is an object of the present invention to provide an improved system for the introduction of reactant materials to a vertical furnace for the processing of semiconductor articles. Other and further objects and advantages will appear hereinafter.
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Cleaver Mark P.
Funk Larry J.
McHugh Paul R.
Wilson Gregory J.
Fuqua Showntina
Lyon & Lyon LLP
Semitool Inc.
Walberg Teresa
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