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WO2003038421A1 - Systeme et procede de detection de gaz hybrides a de faibles concentrations et en presence de taux d'humidite varies - Google Patents

Systeme et procede de detection de gaz hybrides a de faibles concentrations et en presence de taux d'humidite varies Download PDF

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Publication number
WO2003038421A1
WO2003038421A1 PCT/US2002/035048 US0235048W WO03038421A1 WO 2003038421 A1 WO2003038421 A1 WO 2003038421A1 US 0235048 W US0235048 W US 0235048W WO 03038421 A1 WO03038421 A1 WO 03038421A1
Authority
WO
WIPO (PCT)
Prior art keywords
hydride
sensor system
moisture
moisture filter
holes
Prior art date
Application number
PCT/US2002/035048
Other languages
English (en)
Inventor
Elena Nikolskaya
Original Assignee
Advanced Technology Materials, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Advanced Technology Materials, Inc. filed Critical Advanced Technology Materials, Inc.
Publication of WO2003038421A1 publication Critical patent/WO2003038421A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0011—Sample conditioning
    • G01N33/0014—Sample conditioning by eliminating a gas
    • 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
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
    • G01N27/4045—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors for gases other than oxygen

Definitions

  • the present invention relates to hydride gas sensors, which have high sensitivity to hydrides but low sensitivity to varying humidity levels in air. This property is critical for providing sufficiently high signal to noise ratio (S/N). If a hydride sensor responds strongly to both, a false positive signal can arise due to the humidity change. More specifically, the present invention provides a system and method for detecting low levels of arsine (ArH 3 ) in the presence of varying humidity levels.
  • Electrochemical sensors have been used for many years to detect arsine. Current sensors have insignificant change in their zero current i o at constant humidity. However, under the conditions of changing water concentration, there is a change in the i 0 of the sensor. This change in i o can be interpreted as a hydride challenge.
  • TLV Threshold Limit Value
  • the zero current io is not strongly dependent on the humidity.
  • changes in the humidity level result in reorganization of the double layers of the sensor electrode, which subsequently causes changes in the current flow.
  • the current cannot be unambiguously assigned to humidity changes, and a possible false positive will result.
  • the present invention therefore provides a hydride sensor that substantially eliminates or reduces the above limitations of the conventional electrochemical hydride sensors.
  • the present invention provides a method and system for detecting a target hydride gas at low concentration levels and in the presence of varying humidity levels, by incorporating a moisture filter onto a hydride detector for absorbing and desorbing moisture as humidity level changes.
  • One aspect of the present invention relates to a hydride sensor system comprising: a housing; a hydride sensing element disposed in such housing for detecting presence of a target hydride gas; and an output element communicatively connected to the hydride sensing element for providing an output signal when the hydride sensing element detects the presence of the target hydride gas, wherein the housing comprises a moisture filter.
  • Such moisture filter preferably comprises a solid material that is hydrophilic, porous, and/or having a sorption affinity for moisture that is higher than that for the target hydride gas. More preferably, such solid material has a sorption affinity for moisture at least twice higher, or ten times higher, or a hundred times higher, than that for the target hydride gas. In such manner, the moisture filter effectively removes moisture without significantly affecting the sensitivity of such hydride sensor system with respect to the target hydride gas.
  • Such moisture filter may be formed of drying gels having a globular structure, such as silica gel, alumina gel, aerogel, metal oxide, or any like materials suitable for absorbing moisture without significantly reducing sensitivity to the target hydride gas.
  • Such moisture filter may take any suitable conformation, such as tablets, plates, disks, nets, domes, spheres, semi-spheres, ellipsoids, polyhedrons, etc.
  • such moisture filter takes the form of a tablet having one or more small holes therein, while such tablet comprises a solid hydrophilic material having a higher sorption affinity for moisture than that for a specific hydride gas, such as arsine.
  • the walls of the small holes in such tablet absorb and desorb moisture as the humidity level changes, while permitting hydride gas such as arsine to pass through unobstructed. Since the electrical current signal responds to changes in the humidity level, but the oxidation of arsine responds to changes in the arsine concentration, the signal to noise ratio is therefore improved by using such moisture filter. [0014] Accordingly, it is an object of the present invention to provide a sensor system that has a high hydride gas sensitivity (given the low concentration challenge) and a significantly reduced response to changes in the humidity level.
  • the sensor system of the present invention has a sufficiently high S/N ratio at the lower arsine concentrations, i.e., below 10 ppb by volume, more preferably below 5 ppb by volume, and most preferably below 2 ppb by volume.
  • such sensor system is equipped with additional electronic devices to accommedate any changes in the electronic algorithms.
  • the temperature changes likely result in changes in the zero current (io) of the hydride sensor system of the present invention
  • an independent temperature sensor e.g., thermistor, resistance temperature detector, etc.
  • Such correction can be conducted by any computational means, which include, but are not limited to, computers, central processing units (CPU), microprocessors, integrated circuitries, computational modules, or the like, which is constructed, operated and arranged to correct the output signals of the electrochemical sensors based on the temperature changes measured.
  • the computational means may be embodied in any suitable form, such as software operable in a general-purpose programmable digital computer, or available on-line as an operational applet at an Internet site.
  • the computational means may comprise electronic algorithms hard-wired in circuitry of a microelectronic computational module, embodied as firmware.
  • Figure 1 is a schematic view of a moisture filter in form of a tablet that is attachable to a housing of an arsine sensor, according to one embodiment of the present invention.
  • Figure 2 is a graph that plots the S/N ratio as a function of the number of holes in the moisture filter.
  • Figure 3 is a graph that plots system sensitivity to arsine as a function of the hole diameter in a moisture filter having 4 holes.
  • Figure 4 is a graph that plots the system response to moisture changes as a function of hole size in a moisture filter having 4 holes.
  • Figure 5 is a response curve of an arsine sensor in response to to a two ppb arsine challenge.
  • Figure 6 shows the response curves of two arsine sensors N2 and N3 in response to a
  • Figure 7 shows the response curve of an arsine sensor in room air, with and without a fan blowing on the sensor system (1.22 pa/bit on the vertical axis).
  • Figure 8 shows a graph plotting the output signal from an arsine sensor, as a function of the number of 0.9 mm holes in the moisture filter, while relative humidity changes from 10% to 50%.
  • Figure 9 shows the current output from two arsine sensors (N23.4 and N2) in response to temperature changes.
  • Figure 10 is a graph depicting the effect of temperature changes on the zero signal output of the N23.4 and N2 arsine sensors.
  • Figure 11 depicts the sensitivity of the arsine sensor to arsine gas, as a function of the number of 0.9mm holes provided in the moisture filter.
  • Figure 12 is a graph showing the concentration dependence of the sensitivity of three arsine sensors (N23.4, N2, and N6) with respect to arsine gas.
  • the present invention provides a hydride gas sensor with a high S/N ratio. This has been achieved by placing a moisture filter, which in one embodiment is a solid tablet made of hydrophilic material and having small holes drilled in the tablet, on the housing of such sensor. The function of such tablet with holes is to provide surface to absorb moisture and, thereby, buffer the rate of change of the moisture concentration in the electrochemical sensor.
  • the tablet of the moisture filter in one embodiment comprises one or more hydrophilic and porous materials, either artificial or natural.
  • Such materials preferably include, but are not limited to, drying gels having a globular structure, such as silica gel, alumina gel, aerogel, or metal oxides, or any like materials as known to those skilled in the art.
  • This moisture filter must have a sorption affinity for moisture that is much higher than that for the hydride of interest, i.e., twice higher, ten times higher, or a hundred times higher. Therefore, such filter will effectively remove moisture without reducing the sensitivity of the hydride sensor to the hydride of interest.
  • Use of damping resistors in the circuit may further reduce the high frequency noise of the hydride sensor.
  • the signal can be integrated over an interval time (usually > 2 minutes) that is longer than the conventional 30 seconds, to further smooth out the signal.
  • interval time usually > 2 minutes
  • Various electronic filtering methods can also be used.
  • An electrical hardware damper in the form of a series resistor may also be used to eliminate high frequency noises.
  • FIG. 1 shows an arsine sensor 10 with a cylindrical housing 12.
  • the upper side of such cylindrical housing 12 comprises an opening 14, to which a moisture filter 16 comprising silica gel can be fixed.
  • the moisture filter 16 is shaped like a tablet or a disk, having four holes 18 therein, each hole having a diameter of about 0.9mm.
  • the diameter of such moisture filter 16 is about 13 mm.
  • an arsine sensing element (not shown) that is capable of detecting presence of arsine gas at a sufficiently low concentration (i.e., below 50 ppb, or 10 ppb, or 5 ppb), and an output element (not shown) for providing an output signal when the presence of arsine gas is detected.
  • Figure 2 depicts the signal to noise ratio of the arsine signal and the moisture signal, as a function of holes within the moisture filter. As seen in Figure 2, a peak is observed with a 4-hole configuration. At this peak, the S/N ratio of arsine at 2 ppb is 11. For purpose of practicing the present invention, any number of holes ranging from about to about 10 is acceptable, although such number is preferably within a range of from about 2 to about 5.
  • Figure 3 shows the sensitivity of the arsine sensor of the present invention to arsine as a function of hole size, provided that the number of holes is 4. The sensitivity reaches a sufficiently high level when the hole diameter is above about 0.2 mm, and the sensitivity shows a plateau when the hole diameter is about 1 mm. Further increasing hole size must be balanced against sensitivity to humidity.
  • Figure 4 shows the moisture response of the arsine sensor as a function of hole size, provided that the number of holes is 4.
  • a 4-hole moisture filter can be designed to maximize the arsine sensitivity while minimizing the moisture interference, by optimizing the hole diameter.
  • the holes Preferably, the holes have an average diameter of from about 0.2 mm to about 1J mm, more preferably from about 0.45 mm to about 0.975 mm, and most preferably about 0.9 mm.
  • the diameter of the moisture filter used herein is about 13 mm, it is desirable to use a 4-hole moisture filter having holes of an average diameter that is about 1.5%-8.5% of the overall diameter of the moisture filter. More preferably, the holes have an average diameter that is about 3.5% to about 7.5% of the overall diameter of the moisture filter, and most preferably about 7% thereof.
  • Figure 5 is the response curve of an arsine sensor to a two ppb challenge, which shows the response time (t 9 o) of such arsine sensor, which is defined as the time taken by the output signal from the buffered sensor to change from 10% of the final value to 90% of the final value in response to a step change in the arsine concentration.
  • the response time (t 90 ) for the sensor is in the range of 2-3 minutes.
  • Figure 6 shows the response curves of two arsine sensors N2 and N3 to a 2 ppb arsine challenge, which evidence the stability and reproducibility of the measurement results as obtained by using the arsine sensors of the present invention.
  • Figure 7 shows the stability of an arsine sensor in room air with and without a fan blowing on the sensor system (1.22 pA/bit on the vertical axis).
  • Figure 8 shows a graph plotting the output signal from an arsine sensor, as a function of the. number of 0.9 mm holes in the moisture filter, while relative humidity changes from 10% to 50%). When the number of 0.9mm holes is above 10, the output signal is significantly influenced by the changes in humidity levels, giving rise to a false positive signal.
  • Figure 9 shows the current output from two arsine sensors (N23.4 and N2) in response to temperature changes.
  • Figure 10 is a graph depicting the effect of temperature changes on the zero signal output of the N23.4 andN2 arsine sensors.
  • Figure 11 depicts the sensitivity of an arsine sensor to arsine gas, as a function of the number of 0.9mm holes provided in the moisture filter.
  • Figure 12 is a graph showing the concentration dependence of the sensitivity of three arsine sensors (N23.4, N2, and N6) with respect to arsine gas.
  • the hydride sensor of the present invention has a large measuring range, i.e., from about 1 ppb to about 100 ppb, more preferably from 1 ppb to about 50 ppb, while the lower detection limit (LDL) of such hydride sensor is sufficiently low for detecting the target hydride gas at very low concentration.
  • LDL lower detection limit
  • such hydride sensor may have a LDL of less than 10 ppb, preferably less than 5 ppb, more preferably less than 3 ppb, and most preferably about 1 ppb.
  • Algorithms may also be used in the electronic software to provide high frequency damping of the signal noises from the signal.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Combustion & Propulsion (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

L'invention concerne un capteur hybride (10) comprenant un boîtier (12) doté d'une ouverture (14) dans laquelle est adapté un filtre d'humidité (16). Ce dernier (16) adsorbe l'humidité avant que les gaz traversent le boîtier (12) du capteur pour analyse, ce qui améliore le rapport signal-bruit par élimination des variations de courant produites par des changements au niveau de l'humidité.
PCT/US2002/035048 2001-11-01 2002-10-31 Systeme et procede de detection de gaz hybrides a de faibles concentrations et en presence de taux d'humidite varies WO2003038421A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US33987701P 2001-11-01 2001-11-01
US60/339,877 2001-11-01

Publications (1)

Publication Number Publication Date
WO2003038421A1 true WO2003038421A1 (fr) 2003-05-08

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2391622A (en) * 2002-07-31 2004-02-11 Amgas Ltd Protecting gas sensors from condensation
GB2400174B (en) * 2003-02-18 2006-08-23 Wagtech Internat Ltd Portable filtration apparatus
CN104330531A (zh) * 2014-10-29 2015-02-04 东南大学 一种测试气体传感器件快速响应特性的方法和装置
US9213016B1 (en) 2014-08-21 2015-12-15 Spec Sensors, Llc Automated self-compensation apparatus and methods for providing electrochemical sensors

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5827947A (en) * 1997-01-17 1998-10-27 Advanced Technology Materials, Inc. Piezoelectric sensor for hydride gases, and fluid monitoring apparatus comprising same
US5925232A (en) * 1995-12-06 1999-07-20 Electron Tranfer Technologies Method and apparatus for constant composition delivery of hydride gases for semiconductor processing

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5925232A (en) * 1995-12-06 1999-07-20 Electron Tranfer Technologies Method and apparatus for constant composition delivery of hydride gases for semiconductor processing
US5827947A (en) * 1997-01-17 1998-10-27 Advanced Technology Materials, Inc. Piezoelectric sensor for hydride gases, and fluid monitoring apparatus comprising same

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2391622A (en) * 2002-07-31 2004-02-11 Amgas Ltd Protecting gas sensors from condensation
GB2391622B (en) * 2002-07-31 2005-07-27 Amgas Ltd Condensation filter
GB2400174B (en) * 2003-02-18 2006-08-23 Wagtech Internat Ltd Portable filtration apparatus
GB2423582A (en) * 2003-02-18 2006-08-30 Wagtech Internat Ltd Arsenic detection method and apparatus
GB2423582B (en) * 2003-02-18 2006-10-25 Wagtech Internat Ltd Arsenic detection method and apparatus
US9213016B1 (en) 2014-08-21 2015-12-15 Spec Sensors, Llc Automated self-compensation apparatus and methods for providing electrochemical sensors
CN104330531A (zh) * 2014-10-29 2015-02-04 东南大学 一种测试气体传感器件快速响应特性的方法和装置
CN104330531B (zh) * 2014-10-29 2015-11-11 东南大学 一种测试气体传感器件快速响应特性的方法和装置

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