Thermal measuring and testing – Determination of inherent thermal property – Thermal conductivity
Reexamination Certificate
1999-03-05
2001-09-18
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Determination of inherent thermal property
Thermal conductivity
C374S001000, C374S164000, C374S165000, C374S178000, C257S467000, C257S470000, C073S025030, C073S204260
Reexamination Certificate
active
06290388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to environment temperature sensing devices and more particularly to a micro-fabricated sensor with improved temperature sensitivity.
2. Description of the Prior Art
Micro-fabricated structures are finding a wider range of scientific and technological uses. One advantage of micro-fabricated devices is that many properties do not scale adversely with decreasing size. For example, as a structure decreases in size, the amount of energy required to raise the temperature scales linearly with volume. Thermal losses due to conduction, radiation, and convection vary with appropriate areas. Consequently, for fixed energy input, a larger temperature arises in a smaller structure. This property has a number of advantages for sensor applications. If temperature is the primary intensive thermodynamic variable used in the sensing process, the amount of energy required to modulate the temperature decreases with size.
Existing integrated temperature sensor devices for measuring changes in environment temperature typically employ resistors as temperature sensing elements. Several limitations have been noted, however, in resistor-based temperature sensing devices. For example, resistor-based integrated temperature sensing devices lack consistency in the temperature coefficient of resistance between batches of resistors. Furthermore, platinum and similar materials which are typically employed as the resistive element of such devices are expensive. Additionally, in resistor based integrated temperature devices, since the resistor is used both as a heater and as a thermometer, there is a direct change in the device's response when the applied power is modified.
Accordingly, there is a need in the art for an improved environment temperature sensing device. Specifically, there is a need for an integrated sensing device which overcomes the above listed limitations associated with resistor-based integrated sensing devices and which also provides improved temperature sensitivity.
SUMMARY OF THE INVENTION
Briefly, the present invention is directed toward remedying these shortcomings in an integrated device having a diode sensor for sensing temperature changes in the environment instead of a resistor-based sensor. A device in accordance with the present invention comprises a heater element for creating a fixed quantity of heat energy. The inventive device further comprises an integrated circuit diode which receives the fixed quantity of heat energy from the heater element and which receives a constant forward bias current applied thereto. A change in environment temperature is reflected in a voltage change across the circuit diode. The inventive device also comprises an electrically insulating layer positioned substantially between the heater element and the circuit diode to electrically insulate them from each other.
According to another aspect of the invention, there is provided a method of manufacturing the integrated sensor device of the invention. The method comprises the following steps: masking and doping a wafer to form an integrated diode with a first and a second polarities; applying an insulating layer over the diode; applying a heating element to the insulating layer opposite the diode; etching contact holes in the insulating layer corresponding to the first and second polarities; and applying contact pads to the contact holes.
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Saul Cyro K.
Zemel Jay N.
Gutierrez Diego
Pruchnic Jr. Stanley J.
The Trustees of the University of Pennsylvania
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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