# Patent

## Title
Photometrically modulated delivery of reagents

## Abstract

A process system adapted for processing of or with a material therein. The process system includes: a sampling region for the material; an infrared photometric monitor constructed and arranged to transmit infrared radiation through the sampling region and to responsively generate an output signal correlative of the material in the sampling region, based on its interaction with the infrared radiation; and process control means arranged to receive the output of the infrared photometric monitor and to responsively control one or more process conditions in and/or affecting the process system.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation of U.S. patent application Ser. No. 10/641,576 filed Aug. 14, 2003 in the name of Jose I. Arno, et al. for “In-Situ Gas Blending and Dilution System for Delivery of Dilute Gas at a Predetermined Concentration,” issued Jun. 21, 2005 as U.S. Pat. No. 6,909,973, which in turn is a continuation-in-part of U.S. patent application Ser. No. 10/402,759 filed Mar. 28, 2003 in the names of Jose I. Arno, et al. for “In-Situ Gas Blending and Dilution System for Delivery of Dilute Gas at a Predetermined Concentration.” The disclosures of these prior applications are hereby incorporated herein by reference, in their respective entireties.


FIELD OF THE INVENTION
The present invention relates to apparatus and method for photometrically modulating the delivery of reagent, e.g., in a semiconductor manufacturing operation including processing of or with such reagent. In a specific aspect, the invention relates to supply of reagent gas deriving from solid and/or liquid sources.
DESCRIPTION OF THE RELATED ART
The semiconductor industry uses a wide variety of reagent gases in applications where the source materials for such reagent gases are solid and/or liquid in character. Such source materials may be highly toxic or hazardous and the dosage of active gas species may in some instances be very small.
When solid and/or liquid source materials are employed, metering the delivery of such non-gaseous materials to a semiconductor processing tool is difficult. Typically, the non-gaseous material is bubbled or swept from a vessel containing the material, by means of a carrier gas that is flowed through the vessel to entrain the vapor of the source material. The resulting carrier gas/active material vapor is then transported as a feed gas stream to the semiconductor tool.
The feed gas stream is flowed to the tool through flow circuitry including lines that typically are heated to prevent condensation and/or freezing of the reagent in the piping, valving, etc. of such flow circuitry.
In design and construction of the semiconductor process system including such tool and the delivery system for the solid and/or liquid source material, it is often necessary to rely on published vapor pressure values for the source material in order to estimate the delivery rate of the source material. Vapor pressure curves in the literature, however, relate to steady state conditions involving vapor-saturated streams. They do not take into account time-varying fluctuations in source material delivery rate, such as may be attributable to (i) changes in liquid levels in the system that may result in non-saturated vapor streams, (ii) concentration spikes that can occur during initial opening of carrier gas valves, (iii) changes in the rate of vaporized material deriving from changes in available surface area of solid source materials, (iv) losses of transported source material due to condensation of the material from the feed stream on cold spots in the flow circuitry, (v) thermal degradation of source material in regions of the flow circuitry or in other process system components that are heated to temperatures above the decomposition temperature of the source material, and (vii) fluctuations in carrier gas flow rates that result in corresponding changes of concentration and delivered amount of the source material.
The foregoing problems involving use of solid and/or liquid source materials has resisted solution, and pose continuing obstacles to the successful utilization of solid and/or liquid source materials for industrial process use, such as in semiconductor manufacturing processes, in which metalorganic compounds and a wide variety of other reagent materials are of non-gaseous form, and require volatilization, vaporization, sublimation or similar operations to provide gaseous or vapor forms of the material to the process for use therein.
SUMMARY OF THE INVENTION
The present invention relates to apparatus and method for photometrically modulating the delivery of reagent, such as may derive from solid and/or liquid sources.
In one aspect, the invention relates to a process system adapted for processing of or with a material therein, said process system comprising:

    
    
        a sampling region for the material;
        an infrared photometric monitor constructed and arranged to transmit infrared radiation through the sampling region and to responsively generate an output signal correlative of the material in the sampling region, based on its interaction with the infrared radiation; and
        process control means arranged to receive the output of the infrared photometric monitor and to responsively control one or more process conditions in and/or affecting the process system.
    
    


Another aspect of the invention relates to a method of operating a process including processing of or with a material, such method comprising exposing the material to infrared radiation and responsively generating with an infrared photometric monitor an output correlative of the material, based on its interaction with the infrared radiation; and controlling one or more conditions in and/or affecting the process, in response to the output.
Other aspects, features and embodiments will be more fully apparent from the ensuing disclosure and appended claims.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a semiconductor manufacturing process system including photometrically modulated delivery of reagent from a non-gaseous source material, according to one embodiment of the present invention.



DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF
The disclosures of copending U.S. patent application Ser. No. 10/402,759 filed Mar. 28, 2003 and U.S. patent application Ser. No. 10/140,848 filed May 8, 2002 are hereby incorporated herein by reference in their respective entireties.
The present invention relates to utilization of an infrared photometer in a metering arrangement for delivery of reagent, which is useful for delivery of reagent to a process from a non-gaseous source material. The infrared photometer in such arrangement operates as a mass flow meter permitting an output from the infrared photometer to be employed for responsively controlling one or more process conditions in and/or affecting the process system.
More specifically, an infrared photometric monitor is constructed and arranged to transmit infrared radiation through a sampling region, such as a gas cell, and to responsively generate an output correlative of the material in the sampling region, based on its interaction with the infrared radiation.
The process system in addition to a gas-utilizing facility, such as a semiconductor manufacturing facility, e.g., a semiconductor manufacturing tool, or other process unit adapted for processing of or with the monitored material therein, advantageously includes a source for such material providing same in gaseous form for monitoring and subsequent utilization.
The source means may comprise a storage and dispensing vessel for the material, or a synthesis or generating unit for such material, or other suitable supply containers, bulk storage facilities, or the like. The material itself may be in an initially gaseous form, but in a preferred aspect, described more fully hereinafter, the invention is advantageously employed with materials that are in an initially non-gaseous form, e.g., in a liquid state and/or a solid state. The invention thus is amenable to implementation for metered delivery of reagents deriving from source materials that are vaporizable, sublimable, volatilizable, atomizable or otherwise able to be delivered in a gaseous form. The term “gaseous” in such context includes gases as well as vapors.
Infrared photometers usefully employed in the practice of the invention can be of any suitable type including an infrared radiation source and detector elements and associated componentry, e.g., infrared radiation modulation components. Illustrative IR photometers include the CLEANSENS® NDIR photometer commercially available from CS Clean Systems Inc. (Fremont, Calif., USA), the MCS 100E IR photometer commercially available from SICK AG (Waldkirch, Germany) and the PIR3502 Multiwave Process Photometer commercially available from ABB USA (Norwalk, Conn., USA).
The IR photometric monitor can be installed in-line between the material source and the process facility utilizing the gaseous reagent being monitored. In application to a semiconductor manufacturing facility, the IR photometric monitor can be situated in-line in the flow circuitry between a chemical vapor deposition reactor and a liquid material vaporizer or bubbler. Where the flow circuitry coupled with the IR photometric monitor is heated to prevent condensation or freezing of the gaseous reagent being monitored, the IR photometric monitor can be heated to a temperature in the same temperature regime as the flow circuitry.
By such arrangement, the IR photometric monitor provides a time-dependent concentration profile of the material delivered to the gas-utilizing facility. The IR photometric monitor enables concentration of the material of interest to be tracked in real time in a qualitative and quantitative mode. The IR photometric monitor can be arranged to monitor the reagent species of interest, as well as one or more decomposition by-products of such reagent species, thereby providing the capability of detecting unwanted degradation of the reagent, so that process conditions and operation can be responsively altered to suppress any significant decomposition from occurring, when changes in process variables or settings would otherwise cause such degradation to occur.
The output of the IR photometric monitor can be used to control delivery parameters such as carrier gas flow rates, vaporizer temperatures, pressures, etc., so that a desired delivery rate of the reagent of interest can be achieved and maintained even under fluctuations in process conditions and operating modes.
Referring now to the drawing of FIG. 1, there is illustrated a schematic representation of a semiconductor manufacturing process system 10 including photometrically modulated delivery of reagent from a non-gaseous source material, according to one embodiment of the present invention.
The semiconductor manufacturing process system 10 as illustrated includes an infrared photometric monitor 12 and a semiconductor manufacturing facility 114. The semiconductor manufacturing facility 114 may comprise a semiconductor manufacturing tool such as a chemical vapor deposition (CVD) reactor, an ion implantation chamber, a lithotracks unit, or other processing unit in which a reagent in gaseous form is used.
The gaseous form reagent is supplied to the semiconductor manufacturing facility 114 from a reagent material source 40.
Reagent material source 40 includes a bubbler vessel 42 containing a source material 62 in liquid form. The bubbler vessel 42 is disposed in a heating jacket 44 that is coupled by electrical line 50 to the heating jacket controller 46 that in turn is connected by power line 48 to a suitable power source. The heating jacket controller thus is arranged to vary the extent of resistive heating of the vessel 42 by the heating jacket, by correspondingly varying the current flowed in line 50 to the heating jacket 44.
The liquid 62 in vessel 42 is contacted with a gas in the form of bubbles 64 by flow of carrier gas, e.g., helium, argon, nitrogen, hydrogen, or other suitable single component or multi-component carrier medium, from carrier gas supply 52 (e.g., a compressed gas cylinder, bulk gas storage tank, or the like) in carrier gas feed line 54 containing flow control valve 56 therein to the diptube 60. The diptube 60 is open-ended at its lower extremity, thereby permitting the carrier gas to bubble through the non-gaseous source material 62 so as to entrain the source material in the carrier gas.
The carrier gas entraining the source material therein disengages from the liquid 62 in the headspace 66 of the vessel 42, and is discharged from the vessel in line 68 as a feed stream containing the source material and the carrier gas. The feed stream flows in line 68, containing flow control valve 70 therein, and traced with a heat tracing element 92, to the gas sampling chamber 29 of the IR photometric monitor 12. The gas sampling chamber 29 is arranged to be heated by heater 96, to provide an input heat flux denoted schematically by arrow Q.
From the gas sampling chamber 29, the feed stream flows in delivery line 73, traced with heat tracing element 94, to the semiconductor manufacturing facility 114.
By this arrangement, involving heat tracing of the flow circuitry lines 68 and 73, and heating of the gas sampling chamber 29 by the heater 96, the temperature of the feed stream is maintained at a temperature level that ensures that no condensation of the source material takes place in the flow circuitry or the gas sampling chamber.
In the semiconductor manufacturing facility 114, the reagent material is utilized, e.g., as a precursor from which a layer of metal, dielectric, insulator, is deposited under appropriate deposition conditions therefor, or in other manner as a process gas, cleaning fluid, etc. Effluent gas from the semiconductor manufacturing facility 114, which may derive at least in part from the reagent material, is discharged from the semiconductor manufacturing facility 114 in line 73 and flowed to effluent pump 74.
From pump 74, the effluent flows in line 75 to effluent treatment unit 76 for abatement of hazardous species therein, e.g., by scrubbing (wet and/or dry scrubbing), catalytic oxidation, incineration, chemical treatment, or the like. From the effluent treatment unit 76, the final treated effluent is discharged from the process system in vent line 78.
The IR photometric monitor 12 comprises a source of infrared radiation 14 whose output radiation 24 is directed along a path illustratively shown in dashed line representation. The output radiation 24 is modulated by diaphragm wheel 16 having openings 18 and 20 therein. The rotation of the wheel 16 thereby permits the radiation to pass through opening 18 or 20, or alternatively be blocked by the opaque portions of the wheel intermediate the openings 18 and 20. The wheel is rotatable by means of axle 22, which may be operatively coupled with suitable drive means, e.g., an electric motor, generator, gearing assembly, power take-off assembly, flywheel, etc., to effect rotation of the wheel 16 in the direction indicated by arrow A in FIG. 1.
The modulated radiation passes through an interference filter 26 that is transmissive of radiation of a specific frequency range. The resulting infrared radiation enters the sampling chamber 29 through inlet window 30 and interacts with the feed stream introduced into the chamber in line 68, thereby altering the radiation so that the radiation passing out of the sampling chamber 29 through exit window 32 to detector 34 differs from the radiation passing into the chamber through inlet window 30, in a manner that is characteristic of the presence of the reagent species in the feed stream at that point in time. The inlet and exit windows 30 and 32 are formed of IR-transmissive material, such as for example zinc selenide or other suitable material.
The detector 34 of the IR photometric monitor is coupled by terminals 36 to the central processor unit (CPU) 38, to transmit to the CPU a signal that is correlative of the reagent species of interest and its concentration in the feed stream.
The CPU thus is inputted a signal from the IR photometric monitor that is indicative of the presence and amount of the reagent species of interest. The CPU may comprise any suitable means such as a programmable general purpose digital computer, microprocessor, logic unit, integrated circuitry, etc. that is effective for signal processing of the IR photometric monitor signal to produce an output for controlling one or more process conditions in and/or affecting the process system.
In the FIG. 1 system, the CPU is shown as being illustratively operatively linked for control purposes to valve actuator 58 of flow control valve 56, by signal transmission line 82; to valve actuator 72 of flow control valve 70, by signal transmission line 84; to the heating jacket controller 46 by signal transmission line 86; to the semiconductor manufacturing facility 114 by signal transmission line 88; and to the pump 74 by the signal transmission line 90.
By these respective control linkages, which may be used singly, alternatively, or in various combinations, the photometric monitor and associated control assembly can be operated to photometrically sense the concentration of the reagent species of interest in the feed stream and to responsively adjust (i) the flow rate of carrier gas flowed to the bubbler, (ii) the flow rate of the feed stream comprising the carrier gas and the reagent species that is flowed to the sampling chamber and the downstream gas-utilizing process, (iii) the heating of the liquid source material in the bubbler, (iv) any of the tool settings, process conditions, etc. in the semiconductor manufacturing facility, and/or (v) the pumping rate of the pump used to flow the effluent from the semiconductor manufacturing facility to the effluent treatment unit. Additionally, or alternatively, the CPU may be arranged to control the heating of material in gaseous or non-gaseous form in the process system, e.g., by controlling rate of heat input to the heat tracing elements and the sampling chamber.
It will be appreciated that the specific control linkages shown in FIG. 1 are of illustrative character only, and that the monitoring and control system and methodology of the invention can be widely varied to control any specific devices, elements, process units, process conditions, set points, alarm settings, operational modes, cycle times, emergency procedures, etc. based on the photometrically determined presence of the reagent species of interest.
Thus, the system is arranged so that the gas-utilizing process is controlled in response to the photometric sensing of the reagent species of interest, thereby permitting optimal process operation to be achieved and maintained throughout the temporal duration of the gas-utilizing process.
It will be further recognized that although the illustrative embodiment of FIG. 1 has been shown as comprising a single IR photometer detection arrangement, the invention is not thus limited, and that the invention contemplates the provision of IR photometric capability for real-time contemporaneous sensing of multiple specific components of a gaseous feed stream, and that the CPU may be programmatically arranged to accommodate such multi-species monitoring by suitable control algorithms and protocols, so as to provide a highly integrated monitoring and control functionality sensitive to very small variations of any of a number of components in the source material.
As will be apparent from the foregoing, the present invention provides the capability for monitoring and control of a gas-utilizing process system that permits the efficient use of non-gaseous source materials for generating gaseous reagent species, thereby obviating the numerous deficiencies of prior art approaches for using non-gaseous source materials, as discussed in the Background of the Invention section hereof.
While the invention has been described herein with reference to specific aspects, features and embodiments, it will be recognized that the invention is not thus limited, but is susceptible to implementation in numerous other variations, modifications, and alternative embodiments. Accordingly, the invention is intended to be broadly construed as encompassing such variations, modifications and alternative embodiments, within the spirit and scope of the invention as hereinafter claimed.

## Claims

1. A system for delivery of a dilute semiconductor manufacturing material, comprising:
an active material source of semiconductor manufacturing material;
a diluent fluid source;
a fluid flow-metering device for dispensing of the semiconductor manufacturing material from the active material source thereof at a predetermined flow rate;
a mixing device arranged to mix active semiconductor manufacturing material from the active material source thereof that is dispensed at said predetermined flow rate by the fluid flow metering device, with diluent fluid to form a diluted active semiconductor manufacturing fluid mixture; and
a monitor arranged to measure concentration of active semiconductor manufacturing material in the diluted active semiconductor manufacturing fluid mixture, and responsively adjust the fluid flow-metering device, to control the dispensing rate of the active semiconductor manufacturing material, and maintain a predetermined concentration of active semiconductor manufacturing material in the diluted active semiconductor manufacturing fluid mixture.

2. The system of claim 1, further comprising a source for supplying the material in gaseous form.

3. The system of claim 2, wherein the material comprises a solid.

4. The system of claim 2, wherein the material comprises a liquid.

5. The system of claim 1, wherein the material is initially of a non-gaseous form.

6. The system of claim 5, wherein the initially non-gaseous form material comprises a liquid.

7. The system of claim 5, wherein the initially non-gaseous form material comprises a solid.

8. The system of claim 1, wherein the monitor comprises an infrared photometric monitor.

9. The system of claim 8, wherein the infrared photometric monitor comprises a sampling region for the material.

10. A system for delivery of a dilute material, comprising:
an active material source;
a diluent fluid source;
a fluid flow-metering device for dispensing of the material source at a predetermined flow rate;
a mixing device arranged to mix active material from the active material source that is dispensed at said predetermined flow rate by the fluid flow metering device, with diluent fluid to form a diluted active fluid mixture; and

a monitor comprising an infrared photometric monitor including a sampling region for the material and being arranged to measure concentration of active material in the diluted active fluid mixture, and responsively adjust the fluid flow-metering device, to control the dispensing rate of the active material, and maintain a predetermined concentration of active material in the diluted active fluid mixture, wherein the infrared photometric monitor is constructed and arranged to transmit infrared radiation through the sampling region and to responsively generate an output signal correlative of the material in the sampling region, based on its interaction with the infrared radiation; and a process controller arranged to receive the output of the infrared photometric monitor and to responsively control one or more process conditions in and/or affecting the process system.

11. A process for delivery of dilute semiconductor manufacturing material, comprising:
providing an active material source of semiconductor manufacturing material and a diluent fluid source;
controllably dispensing active material from the active semiconductor manufacturing material source at a predetermined flow rate;
mixing active semiconductor manufacturing material from the active material source that is dispensed at said predetermined flow rate, with diluent fluid from the diluent fluid source, to form a diluted active semiconductor manufacturing fluid mixture; and
monitoring concentration of active material in the diluted active semiconductor manufacturing fluid mixture, and responsively adjusting the dispensing rate of the active semiconductor manufacturing material, to maintain a predetermined concentration of active semiconductor manufacturing material in the diluted active gas mixture.

12. The process of claim 11, further comprising a source for supplying the material in gaseous form.

13. The process of claim 12, wherein the material comprises a solid.

14. The process of claim 12, wherein the material comprises a liquid.

15. The process of claim 11, wherein the material is initially of a non-gaseous form.

16. The process of claim 15, wherein the initially non-gaseous form material comprises a liquid.

17. The process of claim 15, wherein the initially non-gaseous form material comprises a solid.

18. The process of claim 11, wherein said monitoring comprises use of an infrared photometric monitor.

19. The process of claim 18, wherein the infrared photometric monitor comprises a sampling region for the material.

20. A process for delivery of dilute material, comprising:
providing an active material source and a diluent fluid source;
controllably dispensing active material from the active material source at a predetermined flow rate;
mixing active material from the active material source that is dispensed at said predetermined flow rate, with diluent fluid from the diluent fluid source, to form a diluted active fluid mixture; and

monitoring concentration of active material in the diluted active fluid mixture, and responsively adjusting the dispensing rate of the active material, to maintain a predetermined concentration of active material in the diluted active gas mixture wherein said monitoring comprises use of an infrared photometric monitor including a sampling region for the material, wherein the infrared photometric monitor is constructed and arranged to transmit infrared radiation through the sampling region and to responsively generate an output signal correlative of the material in the sampling region, based on its interaction with the infrared radiation; and wherein said adjusting comprises use of a process controller arranged to receive the output of the infrared photometric monitor and to responsively control one or more process conditions in and/or affecting the process.