Semiconductor device manufacturing: process – Including control responsive to sensed condition – Electrical characteristic sensed
Reexamination Certificate
2001-10-16
2002-12-24
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Including control responsive to sensed condition
Electrical characteristic sensed
Reexamination Certificate
active
06498046
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed towards a method of screening semiconductor materials for use as chemical sensors, and a method to determine the conductivity type of semiconductors.
BACKGROUND OF THE INVENTION
The need for chemical sensors capable of detecting gases such as nitrogen oxides, hydrocarbons, carbon monoxide and oxygen at the ppm to the percent level is longstanding. These sensors can be used in many applications, such as automotive exhaust sensing, or detection of toxic atmospheres. Taguchi, or semiconducting resistance-type, sensors are seen as the most likely candidates for these types of applications. Of particular value are semiconducting metal oxides whose electrical resistance varies with the composition of the surrounding gaseous atmosphere. To date only a very limited number of semiconducting compositions have been examined. Thus there is a further need to develop a rapid parallel screening technique for candidate materials.
In semiconducting materials, conduction of electricity is explained in terms of majority and minority carriers of electric charge. In n-type semiconductors, electrons are the majority carriers and holes, i.e. the spaces left by electrons, are the minority carriers. In p-type semiconductors the opposite is true; the holes are the majority carriers and the electrons are the minority carriers.
Previously researchers have used the “hot probe” technique to measure p- or n-type. Another test for p- or n-type involves forming a contact diode with a wafer by means of a probe. The direction of current flow, either d.c. or a.c., through the diode indicates conduction type. Both of these methods are slow and use expensive, bulky equipment. They are also not suitable for rapid, parallel methods of screening for large numbers of materials.
SUMMARY OF THE INVENTION
Disclosed is a method for determining the change in resistance of a semiconducting material in response to exposure to a sample gas by: a) applying a voltage bias across the semiconducting material; b) measuring the difference between the temperature of the material as exposed to said sample gas and the temperature of the material as exposed to a reference gas; and c) relating the measured difference in temperature to a change in resistance. The voltage bias is preferably about 0.5 V to about 200 V, and the difference in the temperature is preferably measured with an infrared thermographic measuring system. The semiconducting material is preferably a metal oxide deposited on a solid substrate.
Also disclosed is a method for parallel screening of semiconducting materials for suitability as chemical sensing materials by determining the resistance change in a plurality of semiconducting materials in response to a sample gas by: a) applying a voltage bias across each semiconducting material; b) simultaneously measuring the difference between the temperature of each material as exposed to said the sample gas and the temperature of each material as exposed to a reference gas; and c) relating the measured difference in temperature for each material to a change in resistance of that material.
Also disclosed is a method for the parallel screening of a plurality of semiconducting materials for suitability as chemical sensing materials by:
a) applying a voltage bias across each semiconducting material;
b) simultaneously measuring the difference between the temperature of each material as exposed to a sample gas and the temperature of each material as exposed to a reference gas; and
c) comparing the measured difference in temperature exhibited by a first material to the measured difference in temperature exhibited by a second material.
Also disclosed is a method for determining the conductivity-type of a semiconducting material by: a) applying a voltage bias across the semiconducting material; b) measuring the difference between the temperature of the material as exposed to a sample gas and the temperature of the material as exposed to a reference gas; and c) relating the measured difference in temperature to a conductivity type.
REFERENCES:
patent: 4007435 (1977-02-01), Tien
patent: 4151503 (1979-04-01), Cermak et al.
patent: 4225842 (1980-09-01), Schleselman et al.
patent: 4234542 (1980-11-01), Romine
patent: 4387359 (1983-06-01), Tien et al.
patent: 4535316 (1985-08-01), Wertheimer et al.
patent: 4542640 (1985-09-01), Clifford
patent: 4646009 (1987-02-01), Mallory
patent: 4770760 (1988-09-01), Noda et al.
patent: 5239483 (1993-08-01), Weir
patent: 5554273 (1996-09-01), Demmin et al.
patent: 5630920 (1997-05-01), Friese et al.
patent: 5683569 (1997-11-01), Chung et al.
patent: 5731510 (1998-03-01), Jones et al.
patent: 5736028 (1998-04-01), Hjortsberg et al.
patent: 5776601 (1998-07-01), Fournier et al.
patent: 5879526 (1999-03-01), Dietz et al.
patent: 6012282 (2000-01-01), Kato et al.
patent: 6082176 (2000-07-01), Kondo et al.
patent: 6084418 (2000-07-01), Takami et al.
patent: 6085576 (2000-07-01), Sunshine et al.
patent: 6235243 (2001-05-01), Fleischer et al.
patent: 6315574 (2001-11-01), Kamieniecki et al.
patent: 4408361 (1995-09-01), None
patent: 4408504 (1995-09-01), None
patent: WO0000808 (2000-01-01), None
S.W. Moore, et al., A modified multilayer perceptron model for gas mixture analysis, Sensors and Actuators B, 15-16 (1993) pp. 344-348, Elsevier Sequoia.
H. Meixner, et al., Metal oxide sensors, Sensors and Actuators B 33 (1996) pp. 198-202, Elsevier Science.
J. Getino, et al., Integrated sensor array for gas analysis in combustion atmospheres, Sensors and Actuators B 33 (1996) pp. 128-133, Elsevier Science.
Corrado Di Natale, et al., Study of the effect of the sensor operating temperature on SnO2-based sensor-array performance, Sensors and Actuators B 23 (1995) pp. 187-191, Elsevier Science.
Brent T. Marquis, et al., A semiconducting metal oxide sensor array for the detection of NOxand NH3,Sensors and Actuators B 77 (2001) pp. 100-110, Elsevier Science.
G. Huyberechts, et al., Simultaneous quantification of carbon monoxide and methane in humid air using a sensor array and an artificial neural network, Sensors and Actuators B 45 (1997) pp. 123-130, Elsevier Science.
Kazimierz Brudzewski, et al., Gas analysis system composed of a solid-state sensor array and hybrid neural network structure, Sensors and Actuators B 55 (1999) pp. 38-46, Elsevier Science.
P.C. Jurs, et al., Computational methods for the analysis of chemical sensor array data from volatile analytes, Chem Rev. 2000, 100, pp. 2649-2678, American Chemical Society.
Keith J. Albert, et al., Cross-reactive chemical sensor arrays, Chem. Rev. 2000, 100, pp. 2595-2626, American Chemical Society.
P. Vincenzini, et al., Solid state chemical and biochemical sensors, Advances in Science and Technology, 26, pp. 335-345, National Research Center, Italy.
Antonio Parado, et al., Nonlinear inverse dynamic models of gas sensing systems based on chemical sensor arrays for quantitative measurements, IEEE Transactions on Instrumentation and Measurement, vol. 47, No. 3, Jun. 1998, pp. 644-651.
BS Hoffheins, et al., Performance of simplified chemical sensor arrays in a neural network-based analytical instrument, Analysis (1992) 20, pages 201-207, Elsevier, Paris.
Corrado Di Natale, et al., Performance evaluation of an SnO2-based sensor array for the quantitative measurement of mixtures of H2S and NO2,Sensors and Actuators B, 20 (1994) pp. 217-224.
H. Meixner, et al., Chemosensors for motor management systems of the future, Fresenius J. Anal Chem. (1994) 348, pp. 536-541.
McCarron Eugene Michael
Morris Patricia A.
E. I. du Pont de Nemours and Company
Hoang Quoc
Nelms David
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