WO2005072161A2 - Appareil et procede pour detecter des especes gazeuses cibles dans des systemes de traitement de semi-conducteur - Google Patents

Appareil et procede pour detecter des especes gazeuses cibles dans des systemes de traitement de semi-conducteur Download PDF

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Publication number
WO2005072161A2
WO2005072161A2 PCT/US2005/001409 US2005001409W WO2005072161A2 WO 2005072161 A2 WO2005072161 A2 WO 2005072161A2 US 2005001409 W US2005001409 W US 2005001409W WO 2005072161 A2 WO2005072161 A2 WO 2005072161A2
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WIPO (PCT)
Prior art keywords
gas
gas sensor
sensing
nickel
sensor element
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PCT/US2005/001409
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English (en)
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WO2005072161A3 (fr
Inventor
Philip S. H. Chen
Ing-Shin Chen
Frank Dimeo, Jr.
Jeffrey W. Neuner
James Welch
Jeffrey F. Roeder
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Advanced Technology Materials, Inc.
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Priority claimed from US10/758,825 external-priority patent/US7228724B2/en
Priority claimed from US10/784,750 external-priority patent/US20040163445A1/en
Application filed by Advanced Technology Materials, Inc. filed Critical Advanced Technology Materials, Inc.
Priority to EP05711523A priority Critical patent/EP1714135A2/fr
Priority to JP2006549662A priority patent/JP2007519905A/ja
Publication of WO2005072161A2 publication Critical patent/WO2005072161A2/fr
Publication of WO2005072161A3 publication Critical patent/WO2005072161A3/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/14—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature
    • G01N27/16—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of an electrically-heated body in dependence upon change of temperature caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
    • H01L21/3065—Plasma etching; Reactive-ion etching

Definitions

  • the present invention relates generally to a device and a method for sensing a target gas species, which have utility for monitoring of gaseous compounds and ionic species in semiconductor process operations.
  • etch endpoints are reached when a prescribed amount of time has elapsed.
  • Over etch in which the process gas continues to flow into the reactor chamber after the cleaning etch is finished, is common and leads to longer process cycles, reduced tool lifetimes, and unnecessary global-warming-gas losses to the atmosphere (Anderson, B.; Behnke, J.; Berman, M.; Kobeissi, H.; Huling, B.; Langan, J.; Lynn, S-Y., Semiconductor International, October (1993)).
  • U.S. Patent Application No. 10/273,036 filed October 17, 2002 for "APPARATUS AND PROCESS FOR SENSING FLUORO SPECIES IN SEMICONDUCTOR PROCESSING SYSTEMS” discloses an apparatus and method for sensing solid-state fluoro species, using a fluoro-reactive metal filament weaved around metal packaging posts or Vespel® polyimide blocks on a KF flange. Detection of the fluoro species using such metal filament-based sensors relies on monitoring the resistance changes in the metal filaments caused by their reactions with the fluorine-containing compounds.
  • the dimensions and the positions of the metal filaments are controlled and optimized via uses of the metal packaging posts or the Vespel® polyimide blocks, to provide an absolute resistance that is adequate for endpoint detection.
  • the present invention relates generally to apparatus and method for sensing a target gas species, especially a fluoro gas species, in an environment susceptible to the presence of such gas species, such as an ambient environment, a gaseous effluent stream from a semiconductor manufacturing process, etc.
  • the invention relates to a gas sensor assembly comprising a gas-sensing filament comprising nickel or nickel alloy.
  • Another aspect of the invention relates to a gas sensor assembly comprising a gas- sensing filament comprising a coating structure encapsulating a core structure, wherein such coating structure comprises nickel or nickel alloy, wherein such core structure is characterized by an electrical resistivity that is higher than that of the coating structure and a heat capacity that is lower than that of the coating structure.
  • such core structure is characterized by an electrical resistivity that is at least fifty (50) times larger than that of the coating structure, and a heat capacity that is less than three fourth (3/4) of that of the coating structure. More preferably, such core structure is characterized by an electrical resistivity that is at least one thousand (1000) times larger than that of the coating structure, and a heat capacity that is less than one half (1/2) of that of the coating structure. Most preferably, such core structure is characterized by an electrical resistivity that is at least 10 m ⁇ -cm and a heat capacity that is less than 2.5 J/K-cm 3 .
  • the core structure comprises silicon carbide.
  • the core structure further comprises a composite structure formed by coating a carbon core fiber with silicon carbide.
  • Yet another aspect of the invention relates to a gas sensor assembly comprising a gas- sensing filament comprising nickel or nickel alloy, wherein such gas-sensing filament is fabricated by electrochemical thinning techniques and is therefore characterized by an average diameter of not more than 50 microns, preferably not more than 25 microns, more preferably not more than 10 ⁇ m, and most preferably within a range of from about 0.1 ⁇ m to about 5 ⁇ m.
  • the invention in a corresponding aspect relates to a method for fabricating a gas sensor assembly comprising a nickel-containing gas-sensing filament that is characterized by an average diameter of not more than 50 microns, comprising the step of: (1) providing a gas sensor assembly comprising a nickel-containing gas-sensing filament having an average diameter that is more than 50 microns; and (2) electrically thinning such nickel-containing gas- sensing filament for a sufficient period of time so as to reduce the average diameter of such nickel-containing gas-sensing filament to 50 microns or less.
  • a further aspect of the present invention relates to a gas sensor assembly comprising a gas-sensing filament comprising nickel-copper alloy.
  • nickel-copper alloy contains from about 10% to 90% nickel by weight, and from about 10%) to about 90%> copper by weight. More preferably, such nickel-copper alloy further comprises aluminum in the amount of from about 10% to about 90% by weight.
  • nickel-copper alloy may also comprise other fluoro-resistant metal components, including but not limited to Ti, V, Cr, Mn, Nb, Mo, Ru, Pd, Ag, Ir, and Pt.
  • a still further aspect of the present invention relates to a gas sensor assembly comprising a nickel-containing gas-sensing filament having a porous surface having about 20% to about 80% total porosity, and more preferably 60%> total porosity.
  • a porous surface of such gas-sensing filament is characterized by open pore structures.
  • Another aspect of the invention relates to a gas sensor assembly as described hereinabove, which further comprises means coupled with the gas-sensing filament for detecting a change in at least one property of such gas-sensing filament upon contact with a target gas species and responsively generating an output signal indicative of the presence of such target species.
  • Another aspect of the invention relates to a gas sensor assembly comprising an above- described gas-sensing filament and a support structure, wherein the gas-sensing filament is mounted on such support structure in a free-standing manner.
  • Yet another aspect of the present invention relates to a gas sensor assembly as described hereinabove, arranged in sensing relationship to a process chamber that is susceptible to presence of one or more target fluoro species, wherein the gas-sensing filament is mounted on a fluoro-resistant support structure and coupled to means for detecting a change in at least one property of such gas-sensing filament upon contact with the target fluoro species and responsively generating an output signal indicative of the presence of said target fluoro species.
  • the invention in a further aspect relates to a gas sensor assembly as described hereinabove, which is constructed and arranged to monitor an effluent from a semiconductor manufacturing plant or a fluid derived from the effluent, wherein the effluent or fluid derived therefrom is susceptible of comprising a fluoro species, and wherein such gas sensor assembly further comprises means for detecting a change in at least one property of the gas-sensing filament upon contact with the fluoro species and responsively generating an output signal indicative of the presence of such fluoro species.
  • a still further aspect of the invention relates to a method of monitoring a fluid locus for the presence of a target gas species therein, said method comprising: exposing fluid at said fluid locus to a gas-sensing assembly as described hereinabove; monitoring at least one property of the gas-sensing filament of such gas-sensing assembly; and responsively generating an output signal when the gas-sensing filament exhibits a change in the at least one property thereof, indicating the presence of the target gas species in the fluid locus, or a change in concentration of the target gas species in the fluid locus.
  • Yet another aspect of the present invention relates to an elongated gas sensor element formed by one or more gas-sensing filaments, such elongated gas sensor element comprising two electrical connection terminals and a longitudinal axis, wherein the longitudinal axis of the sensor element is substantially perpendicular to a line defined by the two electrical connection terminals thereof.
  • Such elongated gas sensor element may comprise any number of gas-sensing filaments and has any suitable shape or conformation, as long as its longitudinal axis is substantially pe ⁇ endicular to the line defined by its two electrical connection terminals.
  • the elongated gas sensor element is formed of two gas- sensing filament attached together at first ends thereof and has a wishbone shape.
  • Such elongated gas sensor element preferably, but not necessarily, comprises a gas- sensitive coating that encapsulates a core structure, wherein the core structure has an electrical resistivity that is higher than that of the gas-sensitive coating and a heat capacity that is lower than that of the gas-sensitive coating.
  • Nickel-containing coating is particularly sensitive to fluoro gas species, and therefore in a particularly preferred embodiment of the present invention, the elongated gas sensor element comprises a nickel-containing coating encapsulating a core structure, such core structure being characterized by a higher electrical resistivity and a lower heat capacity than those of such nickel-containing coating.
  • the invention in a further aspect relates to a method for monitoring a fluid locus for the presence of a target gas species therein, said method comprising the steps of: exposing fluid at said fluid locus to a gas-sensing assembly as described hereinabove; monitoring at least one property of the elongated gas sensor element of such gas-sensing assembly; and responsively generating an output signal when the elongated gas sensor element exhibits a change in the at least one property thereof, indicating the presence of the target gas species in the fluid locus, or a change in concentration of the target gas species in the fluid locus.
  • a still further aspect of the present invention relates to a method for fabricating an elongated gas sensor element having a wishbone shape, comprising the steps of: (a) aligning a pair of gas-sensing filaments side by side; and (b) connecting such pair of gas-sensing filaments at first ends thereof, while leaving the opposite, second ends of said pair of gas-sensing filaments separated from each other, wherein the separated opposite, second ends of such pair of gas-sensing filaments form the two electrical connection terminals of the wishbone-shaped gas sensor element.
  • such wishbone-shaped gas sensor element can be formed by a method comprising the steps of: (a) aligning a pair of filaments side by side; (b) connecting such pair of filaments at first ends thereof, while leaving the opposite, second end of such pair of filaments separated from each other, so as to form a wishbone-shaped precursor structure; and (c) forming a gas-sensitive coating over such wishbone-shaped precursor structure.
  • Yet another aspect of the present invention relates to a gas-sensing assembly arranged in sensing relationship to a process chamber that is susceptible to presence of one or more target fluoro gas species, wherein such gas-sensing assembly comprises a nickel-containing gas sensor element mounted on a surface of a support structure and coupled to means for detecting a change in at least one property of such gas sensor element upon contact with the target fluoro gas species and responsively generating an output signal indicative of the presence of the target fluoro gas species, wherein such nickel-containing gas sensor element has a longitudinal axis that is oriented pe ⁇ endicular to or substantially pe ⁇ endicular to the mounting surface of the support structure.
  • fluoro species is intended to be broadly construed to encompass all fluorine-containing materials, including without limitation, gaseous fluorine compounds, fluorine per se in atomic and diatomic (F 2 ) forms, fluorine ions, and fluorine- containing ionic species.
  • the fluoro species may for example include species such as NF 3 , SiF 4 , C 2 Fg, HF, F 2 , COF 2 , C1F 3 , IF 3 , etc., and activated fluorine-containing species (denoted collectively as F * ) thereof, including ionized fragments, plasma forms, etc.
  • FIG. 1 illustratively depicts the cross-sectional view of a gas-sensing filament comprising a Monel coating structure encapsulating a silicon carbide core structure, according to one embodiment of the present invention.
  • FIG. 2 shows a partial cross-section view of a composite core structure, according to one embodiment of the present invention.
  • FIG. 3 shows the output signals produced over time by a gas sensor assembly that employs a nickel-coated silicon carbide filament, in comparison with the output signals produced over time by a residual gas analyzer (RGA) unit.
  • RAA residual gas analyzer
  • FIG. 4 shows the output signals produced over time by a gas sensor assembly that employs a nickel filament, in comparison with the output signals produced over time by a residual gas analyzer (RGA) unit.
  • RAA residual gas analyzer
  • FIG. 5 shows a perspective view of a nickel filament comprising a neck portion that is electrochemically thinned, according to one embodiment of the present invention.
  • FIG. 6. illustratively depicts the cross-sectional view of a gas-sensing filament comprising a porous nickel coating, according to one embodiment of the present invention.
  • FIG. 7 is a SEM micrograph of a gas-sensing filament comprising a porous nickel coating formed on a dense substrate, according to one embodiment of the present invention.
  • FIG. 8. is a SEM micrograph of a gas-sensing filament comprising a porous nickel coating characterized by an open pore structure, according to one embodiment of the present invention.
  • FIGS. 9A and 9B show a gas-sensing assembly comprising two nickel-coated silicon carbide filament suspended by press fit electrical pins over a KF flange.
  • FIG. 10 shows a wishbone-shaped gas sensor element formed by two gas-sensing filaments, according to one embodiment of the present invention.
  • FIG. 11-13 show elongated gas sensor elements of various shapes and configurations.
  • FIG. 14 shows a wishbone-shaped gas sensor element that is vertically mounted on a support structure, according to one embodiment of the present invention.
  • FIG. 15 shows the signal responses produced over time by a vertically mounted wishbone-shaped gas-sensing element (WISHBONE), in comparison with the signal responses produced over time by a horizontally mounted straight nickel-coated SiC carbon fiber (XENA) under the same testing conditions.
  • WISHBONE vertically mounted wishbone-shaped gas-sensing element
  • XENA horizontally mounted straight nickel-coated SiC carbon fiber
  • fluoro species react with most metals to form compounds that have a high, and sometimes, mixed oxidation state (Inorganic Solid Fluorides, Chemistry and Physics. Academic Press, 1985, Ed P. HagenmuUer).
  • transition metals and noble metals including, for example, but not limited to Ni, Cu, Al, Ti, V, Cr, Mn, Nb, Mo, Ru, Pd, Ag, Ir, and Pt
  • noble metals including, for example, but not limited to Ni, Cu, Al, Ti, V, Cr, Mn, Nb, Mo, Ru, Pd, Ag, Ir, and Pt
  • the present invention therefore employs fluoro-reactive metal filaments.
  • fluoro-reactive metal filaments By monitoring changes in the properties of such metal filaments as caused by their reaction with fluoro species, one can determine the presence and/or concentration of one or more target fluoro species in a particular gaseous environment, such as a effluent gas stream discharged by a semiconductor chamber clean process.
  • the electrical resistance increase observed for a fluoro-reactive metal filament when placed in a gaseous environment susceptible to contamination by a fluoro species, has been found to be a good indicator of the presence and concentration of such fluoro species in the environment. Because the metal filament possesses higher thermal conductivity than the gaseous environment, a significant portion of the heat generated by the exothermic reactions between the metal filament and the fluoro species is channeled to the metal filament, causing temperature increase in such metal filament, which in turn raises the electrical resistance of such metal filament.
  • the present invention relates to the uses of nickel-containing filaments, which contains either pure nickel or nickel alloys, in gas-sensing assembly for detection of target fluoro species.
  • One preferred embodiment of the invention employs a gas-sensing filament comprising a fluoro-reactive coating structure that contains nickel or nickel alloy, while such coating structure encapsulates a high resistivity, low thermal mass core structure, which is characterized by an electrical resistivity that is higher than that of the coating structure and a heat capacity (i.e., the product of specific heat C p and density D) that is lower than that of the coating structure.
  • such core structure is characterized by an electrical resistivity that is at least fifty (50) times larger than that of the coating structure, and a heat capacity that is less than three fourth (3/4) of that of the coating structure. More preferably, such core structure is characterized by an electrical resistivity that is at least one thousand (1000) times larger than that of the coating structure, and a heat capacity that is less than one half (1/2) of that of the coating structure. Most preferably, such core structure is characterized by an electrical resistivity that is at least 10 mO -cm and a heat capacity that is less than 2.5 J/K-cm 3 .
  • coating and core structures Many combinations of materials are available for forming such coating and core structures. Without limiting the broad scope of the present invention, examples of materials suitable for forming the coating and core structures are herein provided, which include: (1) pure nickel for the coating and a nickel alloy (such as Monel, a nickel-copper alloy) for the core; (2) pure nickel or nickel alloy for the coating and silicon carbide for the core; (3) pure nickel or nickel alloy for the coating and carbon for the core, etc.
  • a nickel alloy such as Monel, a nickel-copper alloy
  • Silicon carbide is particularly preferred for forming the core structure in the present invention, because the high electrical resistivity (usually greater than 10 m ⁇ -cm) and low heat capacity (usually less than 2.5 J/K-cm 3 ) of silicon carbide further enhances the signal strength and responsiveness of the nickel-containing filament sensor, without inducing significant heat loss. Moreover, silicon carbide is resistant to attack by the corrosive fluorine plasma, which, although is not a necessary feature of the encapsulated core structure, advantageously improves the mechanical robustness and reliability of the filament sensor when used in corrosive gaseous environment for detecting fluoro species.
  • Figure 1 illustratively shows the cross-sectional view of a gas-sensing filament 1 according to one embodiment of the invention, which comprises a core structure 6 made of ⁇ - silicon carbide encapsulated by a coating 2 fabricated by using the nickel-copper alloy, Monel.
  • Composite structures comprising multiple layers of high resistivity, low thermal mass materials can also be used to form the core structure for the filament sensors of the present invention.
  • Various combinations and configurations of suitable core materials can be employed to further improve the performance of the filament sensors.
  • silicon carbide fibers can be used, upon which a thin layer of nickel is formed as the gas-sensing layer.
  • Figure 2 shows a partial cross-sectional view of a silicon carbide fiber 10.
  • Such silicon carbide has an overall diameter of from about 78 microns to about 140 microns, which includes a carbon core 12 enclosed in a 0-SiC sheath 16 with a carbon rich surface 18.
  • the SCS silicon carbide fibers have a heat capacity (C p times D) that is about one half of that of nickel, and are resistant to fluoro species.
  • effluent gas containing fluoro species from a semiconductor cleaning chamber is first contacted with such gas-sensing assemblies that contain nickel-containing filaments, to generate a set of sensor signal outputs.
  • effluent gas is then passed through a residual gas analyzer (RGA) unit, to generate a set of control outputs.
  • RGA residual gas analyzer
  • the graphical outputs produced by the gas-sensing assemblies of the invention and the control outputs produced by the RGA unit can be supe ⁇ osed as a function of time, to visualize the relative signal strength and responsiveness of such gas-sensing assemblies of the invention.
  • Figure 3 shows in the upper portion thereof, the signal outputs generated over time by a gas-sensing assembly comprising a nickel-coated SiC fluoro-sensitive filament, and the control outputs produced over time by a RGA unit are shown in the lower portion of Figure 3.
  • Figure 4 shows the signal outputs over time from a gas-sensing assembly that employs a nickel filament, in comparison with the control outputs produced over time by a RGA unit. Both gas-sensing assemblies demonstrate high sensitivity and high responsiveness, although the gas-sensing assembly containing the nickel-coated SiC filament shows better sensitivity and shorter response time than the one employing nickel filament.
  • High A s /A c ratio can be effectively achieved by configuring the nickel-containing filaments at average outer diameters of less than 500 microns, more preferably less than 150 microns or less than 50 microns, and most preferably in a range of from about 0.1 micron to about 30 microns, and average lengths of more than 1 cm, more preferably more than 5 cm, and most preferably more than 10 cm, as a balance between performance and ease of fabrication.
  • filaments having a diameter of about or less than 50 microns are extremely fragile and difficult to handle, rendering the fabrication of a gas-sensing assembly with such small filaments nearly impossible.
  • the present invention provides a solution to such problem, by first fabricating a gas- sensing assembly using a nickel-containing gas-sensing filament that has an average diameter larger than 50 microns, and then electrochemically thinning such gas-sensing filament to reduce its average diameter to increase the A A C ratio.
  • the thinning process is carried out on a gas-sensing filament that has already been inco ⁇ orated into the gas-sensing assembly, and no further handling of the gas-sensing filament is necessary after thinning, therefore significantly reducing the risk of damaging the ultra-thin filament.
  • Figure 5 shows a partially thinned nickel filament 22, which has an original average diameter of about 100-110 microns. After electrochemical thinning at a portion of such filament 22, the average diameter is effectively reduced to about 35-45 microns.
  • High A s /A 0 ratio can also be achieved by forming a nickel-containing filament having a porous surface, which functions to increase the surface area A s of the filament sensor without comprising the cross-sectional area A c thereof.
  • FIG. 6 illustratively shows a nickel-containing filament 25 that comprises a relatively dense core 26 and a porous surface 28.
  • the porous surface of the nickel-containing filament may be provided by a two-stage plating process, wherein at an initial seeding stage, the plating of nickel or nickel alloy on a substrate (such as a core structure) is carried out at a relatively low speed, so as to allow improved bonding between the layer of nickel or nickel alloy plated and the underlying substrate, and wherein at the subsequent growth stage, the plating is conducted at a significantly faster rate, so as to form rough plating surface with microporosity or nanoporosity.
  • FIG 7 shows a SEM micrograph of a nickel coating 34 of nanoporosity formed on a non-porous, dense substrate 32.
  • porous nickel coating can be formed by using liquid crystal templates from proper surfactants. This technique is particularly suitable for forming open pore structures, which maximizes the fluoro-accessible surface area of the porous nickel coating and therefore further improves the sensitivity of the filament sensor.
  • Figure 8 shows a SEM micrograph of a porous nickel coating 44 characterized by open pore structures and having a thickness of about 4.93 microns, formed on a dense silicon carbide substrate 42.
  • the porous nickel coating may be characterized by, for example, a total porosity of 60%, as determined by X-ray fluorescence analysis.
  • the performance of the nickel-containing gas-sensing filaments of the present invention can be further enhanced, by using various nickel-copper alloys, such as Monel, which are characterized by electrical resistance that are even higher than the pure nickel.
  • such nickel-copper alloy contains from about 10% to 90% nickel from about 10% to about 90% copper by weight.
  • Such nickel-copper alloy may further comprise other fluorine-resistant metals such as Al, Ti, V, Cr, Mn, Nb, Mo, Ru, Pd, Ag, Ir, and Pt.
  • the gas-sensing filaments of the invention can be readily mounted in any manner to form a gas-sensing assembly, which may also comprise means for detecting changes in such gas-sensing filament upon contact thereof with a target gas species, and means for responsively generating an output signal indicative of such changes.
  • a gas-sensing filament may be mounted in various free-standing manners to a fluoro-resistant support structure, as disclosed by U.S. Patent Application No. 10/273,036 filed October 17, 2002 for "APPARATUS AND PROCESS FOR SENSING FLUORO SPECIES IN SEMICONDUCTOR PROCESSING SYSTEMS," the contents of which are inco ⁇ orated herein by reference in their entirety.
  • the free-standing gas-sensing filaments can be integrated as part of a device package in any suitable manner, and additional protection or insulation layers may be applied to such device package, for enhancing the resistance of the overall device package to corrosions by the fluorine-containing target compounds.
  • the ability to integrate the free-standing gas-sensing filaments into a standard microelectronic device package such as a chip carrier package enables the gas sensor apparatus of the invention to be variously configured as a single-element device structure, or alternatively as a multi-element array, e.g., using varied metal structures, different geometries, or redundant structures operating at different temperatures, to enhance the gas detection capability of the overall sensing device.
  • the gas-sensing filament of the present invention is supported on a fluoro-resistant flange material, e.g., a KF flange formed of Vespel® polyimide, aluminum, or nickel.
  • a fluoro-resistant flange material e.g., a KF flange formed of Vespel® polyimide, aluminum, or nickel.
  • Vespel® polyimide is a preferred polyimide material of construction in various embodiments of the invention, but it will be recognized that other polyimide or polymeric (e.g., polysulfone) materials of construction may alternatively be used.
  • FIGS. 9A and 9B depict a gas sensor array 70 including a Vespel® polyimide flange 74 supporting a Vespel® polyimide block 76, and two sets of nickel-coated press-fit electrical pins 78 thereon, for suspending two nickel-coated SiC gas-sensing filaments 72, which may or may not be the same in structure.
  • the free-standing architecture of the nickel-coated SiC filaments allow them to be used both as the fluoro-sensing elements and the heat sources (e.g., susceptible to electrical resistance heating or other mode of heating), as well as maximizing the sensing area, as a result of the high surface-to-volume character of such filaments.
  • the integrated design of the gas- sensing filaments and associated packaging obviates the problem of chemical attack by aggressive fluorinated gas species in the sensing environment, thereby achieving a fundamental advance in the art over standard silicon MEMS structures.
  • the present invention thus in one aspect provides a group of novel solid-state filament gas sensors that can be coupled in sensing relationship to a process chamber, e.g., a semiconductor process chamber, and can achieve various degrees of sensitivity and responsiveness, by appropriate selection of materials and structures for such filament sensors.
  • a process chamber e.g., a semiconductor process chamber
  • the present invention in another aspect provides a new filament-based gas sensor element, which is elongated in shape and has two electrical connection terminals and a longitudinal axis.
  • the two electrical connection terminals of such gas sensor element define a line, to which the longitudinal axis of the gas sensor element is substantially pe ⁇ endicular.
  • the aspect ratio between its longitudinal dimension (L) and its lateral dimension (D) has significant influences on its signal strength and response time.
  • L longitudinal dimension
  • D lateral dimension
  • the longitudinal axis of the new gas sensor element of the present invention is substantially pe ⁇ endicular to the lateral line defined by the two electrical connection terminals
  • the longitudinal dimension of such gas sensor element i.e., the dimension along its longitudinal axis
  • the longitudinal dimension of such gas sensor element is not limited by the lateral distance between its electrical connection terminals, and it therefore can be increased to maximize the L/D ratio, which in turn improves signal strength and reduces response time.
  • Figure 10 shows an elongated gas sensor element 110, according to a preferred embodiment of the present invention.
  • the elongated gas sensor element 110 has a wishbone-shape and is formed by attaching two gas-sensing filaments 111 and 112 together at their upper ends, while leaving the lower ends of such filaments separated from each other.
  • the separated lower ends of the filaments 111 and 112 therefore form two electrical connection terminals 110A and HOB, by which an electrical current can be passed through the elongated gas sensor element 110 for gas-sensing at elevated temperatures.
  • the longitudinal axis HOC of the gas sensor element 110 (as shown by the vertical dotted line) is oriented pe ⁇ endicular to the line (as shown by the horizontal dotted line) defined by the two electrical connection terminals 110A and HOB.
  • the elongated gas sensor element 110 has a longitudinal dimension that is not limited by the distance between the two electrical connection terminals.
  • the longitudinal dimension of such elongated gas sensor element 110 can be increased significantly for improving signal strength and reducing response time required for gas-sensing, without having to increase the lateral dimension thereof (i.e., either the dimension along the line defined by the two electrical connection terminals or the distance between the two electrical connection terminals).
  • FIG 11 shows another elongated gas sensor element 120, according to an alternative embodiment of the present invention.
  • the elongated gas sensor element 120 has a keyhole- shape and is formed by bending and shaping a single gas-sensing filament.
  • the two ends of such bent/shaped gas-sensing filament form the two electrical connection terminals 120 and 120B of the gas sensor element 120, and an electrical current therefore can be passed through the elongated gas sensor element 120 via such electrical connection terminals 120A and 120B for gas-sensing at elevated temperatures.
  • the longitudinal axis 120C of the gas sensor element 120 (as shown by the vertical dotted line) is oriented pe ⁇ endicular to the line (as shown by the horizontal dotted line) defined by the two electrical connection terminals 120A and 120B.
  • Figure 12 shows another elongated gas sensor element 130, which has an open hai ⁇ in- shape and is formed by bending a single gas-sensing filament.
  • the two ends of the bent gas- sensing filament form the two electrical connection terminals 130 A and 130B of the gas sensor element 130, and an electrical current therefore can be passed through the elongated gas sensor element 130 via such electrical connection terminals 130A and 130B for gas-sensing at elevated temperatures.
  • the longitudinal axis 130C of the gas sensor element 130 (as shown by the vertical dotted line) is oriented pe ⁇ endicular to the line (as shown by the horizontal dotted line) defined by the two electrical connection terminals 130A and 130B.
  • Figure 13 shows another elongated gas sensor element 140, which has an M-shape and is formed by attaching four gas-sensing filaments 141, 142, 143, and 144 in a zigzagged manner at respective ends.
  • One end of filament 141 and one end of filament 144 form the two electrical connection terminals 140A and 140B for the gas sensor element 140, and an electrical current therefore can be passed through the elongated gas sensor element 140 via such electrical connection terminals 140A and 140B for gas-sensing at elevated temperatures.
  • the longitudinal axis 140C of the gas sensor element 140 (as shown by the vertical dotted line) is oriented pe ⁇ endicular to the line (as shown by the horizontal dotted line) defined by the two electrical connection terminals 140A and 140B.
  • the L/D ratio of the elongated gas sensor element of the present invention is preferably larger than 3, and more preferably larger than 10, and most preferably larger than 50.
  • the elongated gas sensor element as described hereinabove can be mounted on a support structure, to form a gas-sensing assembly that can be placed at a fluid locus for detecting the presence of a target gas species.
  • gas-sensing assembly may also comprise means for detecting changes in such gas sensor element upon contact thereof with the target gas species, and means for responsively generating an output signal indicative of such changes.
  • the support structure comprises a fluoro-resistant flange material, e.g., a KF flange formed of Vespel® polyimide or aluminum.
  • Vespel® polyimide is a preferred polyimide material of construction in various embodiments of the invention, but it will be recognized that other polyimide or polymeric (e.g., polysulfone) materials of construction may alternatively be used.
  • Such support structure provides physical support as well as electrical connection to the gas sensor element via the two electrical connection terminals, and the supporting or mounting surface of the support structure therefore must be able to accommodate at least the two electrical connection terminals of the gas sensor element.
  • the gas sensor element of the present invention is arranged and configured so that its longitudinal axis is substantially pe ⁇ endicular to the supporting or mounting surface of the support structure. In such manner, the footprint of the support structure is reduced without affecting or comprising the L D ratio of the gas sensor element.
  • Figure 14 shows a gas-sensing assembly 150 comprising a support structure 152 with a planar supporting or mounting surface 154.
  • the mounting surface 154 comprises two press-fit pints 153 for mounting the two electrical connection terminals 151A and 151B of the wishbone-shaped gas sensor element 151.
  • the gas sensor element 151 is mounted to the support structure 152 in a "vertical" manner, i.e., having its longitudinal axis 151C oriented pe ⁇ endicular to or substantially pe ⁇ endicular to the mounting surface 154 of the support structure 152.
  • the longitudinal axis of the gas sensor element is substantially pe ⁇ endicular to the mounting surface of the support structure, the longitudinal dimension of the gas sensor element can be increased significantly for improving signal strength and reducing response time, but without having to increase the area of the mounting surface. Therefore, the gas- sensing assembly of the present invention advantageously provides enhanced gas-sensing capacity with reduced footprint.
  • vertical mounting of the gas sensor element provides flexibility to accommodate thermal expansion and contraction of such gas sensor element along its longitudinal axis.
  • the present invention achieves significant advancement in the gas-sensing field, by providing an elongated gas sensor element as described hereinabove, which can be vertically mounted on a support structure.
  • the present invention preferably employs fluoro- reactive metal filaments, such as the nickel-containing filaments as described hereinabove, to form such elongated gas sensor element.
  • fluoro- reactive metal filaments such as the nickel-containing filaments as described hereinabove.
  • a pair of nickel-coated SiC carbon fibers can be aligned side by side and then attached at one ends thereof, while leaving the opposite ends of such nickel-coated SiC carbon fibers unattached and separated from each other, to form a wishbone-shaped gas sensor element as described hereinabove with two electrical connection terminals.
  • such wishbone-shaped gas sensor element may be formed by aligning a pair of uncoated SiC carbon fibers and attaching them at one ends thereof, so as to form a wishbone-shaped precursor structure, which can be subsequently coated with a layer of gas- sensitive material, such as nickel or nickel alloy.
  • effluent gas containing fluoro species from a semiconductor cleaning chamber was concurrently contact with a first gas-sensing assembly comprising a vertically mounted wishbone-shaped gas sensor element (WISHBONE) and a second gas- sensing assembly comprising a horizontally mounted straight nickel-coated SiC carbon fiber, both of which generated a set of sensor signal outputs.
  • the signal outputs produced by the vertically mounted wishbone-shaped gas sensor element of the invention and by the horizontally mounted straight nickel-coated SiC carbon fiber were then supe ⁇ osed as a function of time, to visualize the relative signal strength and responsiveness thereof.
  • Figure 15 shows in the solid line the signal outputs generated over time by the gas- sensing assembly comprising the vertically mounted wishbone-shaped gas sensor element, which was formed by two nickel-coated SiC carbon fibers.
  • the signal outputs generated over time by the gas-sensing assembly comprising the horizontally mounted straight nickel-coated SiC carbon fiber is shown thereby in dotted lines. It is clear that the wishbone-shaped gas sensor element provides faster responses and stronger signals in comparison with those provided by the straight nickel-coated SiC carbon fiber sensor.
  • the fluoro sensor assembly of the invention may include a single gas-sensing filament or a single elongated gas-sensing element in any of the numerous suitable forms described hereinabove, or a plurality of such gas-sensing filaments and/or gas-sensing elements, wherein the multiple filaments and/or sensor elements provide redundancy or back-up sensing capability, or in which different ones of the multiple filaments and/or sensor elements are arranged for sensing of different target gas species in the stream or gas volume being monitored.
  • the filaments and/or sensor elements in the array can be operated in different modes or in interrelated modes, which include, but are not limited to, constant current (CC) modes and constant resistance (CR) modes, for production of respective signals that are algorithmically manipulated, e.g., subtractively, to generate a net indicating signal, or alternatively, additively to produce a composite indicating signal, or in any other suitable manner in which the multiplicity of filaments and/or sensor elements is efficaciously employed to monitor the flow of target gas species in the stream or fluid volume of interest, for generation of correlative signal(s) for monitoring or control pu ⁇ oses.
  • CC constant current
  • CR constant resistance
  • different ones of the multiple gas-sensing filaments and/or sensor elements may be constructed and arranged for sensing of different gas species in the fluid environment being monitored, and/or same gas species at different temperatures, and different geometries and configurations of the filaments and/or sensor elements may be employed for redundancy and/or ensuring accuracy, etc.
  • advanced data processing techniques can be used to enhance the output of the sensor system.
  • examples of such techniques include, but are not limited to, the use of compensating signals, the use of time-varying signals, heater currents, lock-in amplifying techniques, signal averaging, signal time derivatives, and impedance spectroscopy techniques.
  • advanced techniques that fall into the category of chemometrics may also be applied. These techniques include least squares fitting, inverse least squares, principal component regression, and partial least square data analysis methods.
  • gas-sensing filament(s) and or gas-sensing element(s) of the invention may therefore be coupled in a suitable manner, within the skill of the art, to transducers, computational modules, or other signal processing units, to provide an output indicative of the present or change in amount of one or more target gas species in the fluid environment being monitored.
  • micro-hotplate structures of a type adaptable to the practice of the present invention may be employed in the gas sensor assemblies of the present invention, as more fully described in U.S. Patent No. 6,265,222 issued July 24, 2001 in the names of Frank DiMeo, Jr. and Gautam Bahndari, the disclosure of which hereby is inco ⁇ orated herein by reference in its entirety.

Abstract

La présente invention concerne un détecteur de gaz et un procédé pour détecter une espèce gazeuse cible, telle qu'une espèce contenant du fluor, dans un gaz contenant celle-ci, par exemple dans un effluent d'un outil de traitement de semi-conducteur soumis à un nettoyage de gravure avec HF, NF3, etc. Selon un aspect, le détecteur de gaz utilise un filament contenant du nickel, qui est sensible à l'espèce contenant du fluor et qui peut fonctionner à la fois comme composant de détection et comme source de chaleur lorsqu'une température de détection élevée est nécessaire. Selon un aspect, le détecteur de gaz utilise un élément capteur de gaz allongé qui peut être monté verticalement sur une structure de support. Le montage vertical d'un tel élément capteur de gaz allongé sur la structure de support améliore la puissance du signal, réduit le temps de réponse, minimise l'encombrement du détecteur de gaz et offre une souplesse structurelle pour permettre une dilatation/contraction thermique d'un tel élément capteur de gaz.
PCT/US2005/001409 2004-01-16 2005-01-14 Appareil et procede pour detecter des especes gazeuses cibles dans des systemes de traitement de semi-conducteur WO2005072161A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP05711523A EP1714135A2 (fr) 2004-01-16 2005-01-14 Appareil et procede pour detecter des especes gazeuses cibles dans des systemes de traitement de semi-conducteur
JP2006549662A JP2007519905A (ja) 2004-01-16 2005-01-14 半導体処理システム内の対象ガス種を検知するための装置及び方法

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US10/758,825 2004-01-16
US10/758,825 US7228724B2 (en) 2002-10-17 2004-01-16 Apparatus and process for sensing target gas species in semiconductor processing systems
US10/784,750 2004-02-23
US10/784,750 US20040163445A1 (en) 2002-10-17 2004-02-23 Apparatus and process for sensing fluoro species in semiconductor processing systems

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WO2005072161A2 true WO2005072161A2 (fr) 2005-08-11
WO2005072161A3 WO2005072161A3 (fr) 2005-12-29

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EP1861868A2 (fr) * 2005-03-16 2007-12-05 Advanced Technology Materials, Inc. Procede et dispositif de surveillance des conditions plasmatiques dans une installation de traitement pour gravure au plasma

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US5841017A (en) * 1996-03-25 1998-11-24 Cerberus Ag Photo-acoustic gas sensor
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Publication number Priority date Publication date Assignee Title
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TWI360152B (en) 2012-03-11
WO2005072161A3 (fr) 2005-12-29
JP2007519905A (ja) 2007-07-19
EP1714135A2 (fr) 2006-10-25
KR20060127091A (ko) 2006-12-11
TW200529289A (en) 2005-09-01

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