US4888988A — Silicon based mass airflow sensor and its fabrica…

Claim 1

Independent Claim 120 words

A mass airflow sensor having a longitudinal axis comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim comprising a heavily doped etch stopped region encompassing at least a major portion of said dielectric diaphragm; and at least one thin-film sensing element disposed on said diaphragm, said at least one sensing element being disposed at least in part over said semiconductor rim, whereby the temperature gradient between the heating element and said at least one sensing element may be monitored to determine the airflow rate, said heating element being centrally disposed substantially along the longitudinal axis of the sensor and a plurality of sensing elements disposed on both sides of said heating element.

Claim 2

Dependent Claim 120 words

A mass airflow sensor having a longitudinal axis comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim comprising a heavily doped etch stopped region encompassing at least a major portion of said dielectric diaphragm; and at least one thin-film sensing element disposed on said diaphragm, said at least one sensing element being disposed at least in part over said semiconductor rim, whereby the temperature gradient between the heating element and said at least one sensing element may be monitored to determine the airflow rate, said heating element being centrally disposed substantially along the longitudinal axis of the sensor and a plurality of sensing elements disposed on both sides of said heating element.

Claim 3

Dependent Claim 24 words

A sensor according to claim 1, wherein said dielectric diaphragm comprises a sandwich structure of dielectric materials having substantially different coefficients of thermal expansion.

Claim 4

Dependent Claim 28 words

A sensor according to claim 1, wherein the mass airflow sensor is fabricated from a semiconductor substrate and wherein the semiconductor substrate below the dielectric diaphragm is removed.

Claim 5

Dependent Claim 17 words

A sensor according to claim 3, wherein a semiconductor substrate region is disposed below the semiconductor rim.

Claim 6

Dependent Claim 23 words

A sensor according to claim 1, further including at least one thin-film sensing element disposed between said heating element and said semiconductor rim.

Claim 7

Dependent Claim 24 words

A sensor according to claim 1, wherein each of said heating element and said sensing element are substantially parallel with respect to each other.

Claim 8

Dependent Claim 16 words

A sensor according to claim 1, wherein the diaphragm dimensions are determined by the semiconductor rim.

Claim 9

Dependent Claim 42 words

A sensor according to claim 1, wherein said sensor is fabricated on a semiconductor substrate and further includes: read-out and control means fabricated on said semiconductor substrate for energizing said heating element and receiving signals from said at least one sensing element.

Claim 10

Dependent Claim 39 words

A sensor according to claim 1, wherein said sensor is fabricated on a semiconductor substrate and said heating element is disposed on a front surface of said substrate and wherein at least one side of the substrate is tapered.

Claim 11

Dependent Claim 17 words

A sensor according to claim 9, wherein said at least one side includes a double-side tapered edge.

Claim 12

Dependent Claim 55 words

A sensor according to claim 8, wherein said read-out and control means has a plurality of output lines emanating therefrom, and further including a support substrate having a like plurality of electrical lines for respectively contacting each of said plurality of output lines, to thereby provide electrical connection to external control and power supply circuitry.

Claim 13

Dependent Claim 56 words

A mass airflow sensor comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim encompassing at least a major portion of said dielectric diaphragm and comprised of p-etch-stopped silicon; and at least one thin-film sensing element disposed on said diaphragm, the diaphragm dimensions being determined by the semiconductor rim.

Claim 14

Dependent Claim 56 words

A mass airflow sensor comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim encompassing at least a major portion of said dielectric diaphragm and comprised of p-etch-stopped silicon; and at least one thin-film sensing element disposed on said diaphragm, the diaphragm dimensions being determined by the semiconductor rim.

Claim 15

Dependent Claim 24 words

A sensor according to claim 12, wherein said dielectric diaphragm comprises a sandwich structure of dielectric materials having substantially different coefficients of thermal expansion.

Claim 16

Dependent Claim 16 words

A sensor according to claim 13, wherein said sandwich structure comprises silicon dioxide and silicon nitride.

Claim 17

Dependent Claim 46 words

A sensor according to claim 12, wherein said at least one sensing element is disposed at least in part over said semiconductor rim, whereby the temperature gradient between the heating element and said at least one sensing element may be monitored to determine the airflow rate.

Claim 18

Dependent Claim 28 words

A sensor according to claim 12, wherein the mass airflow sensor is fabricated from a semiconductor substrate and wherein the semiconductor substrate below the dielectric diaphragm is removed.

Claim 19

Dependent Claim 17 words

A sensor according to claim 16, wherein a semiconductor substrate region is disposed below the semiconductor rim.

Claim 20

Dependent Claim 23 words

A sensor according to claim 12, further including at least one thin-film sensing element disposed between said heating element and said semiconductor rim.

Claim 21

Dependent Claim 41 words

A sensor according to claim 12 having a longitudinal axis, wherein said heating element is centrally disposed substantially along the longitudinal axis of the sensor and wherein a plurality of sensing elements are disposed on both sides of said heating element.

Claim 22

Dependent Claim 24 words

A sensor according to claim 19, wherein each of said heating element and said sensing element are substantially parallel with respect to each other.

Claim 23

Dependent Claim 42 words

A sensor according to claim 12, wherein said sensor is fabricated on a semiconductor substrate and further includes: read-out and control means fabricated on said semiconductor substrate for energizing said heating element and receiving signals from said at least one sensing element.

Claim 24

Dependent Claim 39 words

A sensor according to claim 12, wherein said sensor is fabricated on a semiconductor substrate and said heating element is disposed on a front surface of said substrate and wherein at least one side of the substrate is tapered.

Claim 25

Dependent Claim 17 words

A sensor according to claim 22, wherein said at least one side includes a double-side tapered edge.

Claim 26

Dependent Claim 55 words

A sensor according to claim 21, wherein said read-out and control means has a plurality of output lines emanating therefrom, and further including a support substrate having a like plurality of electrical lines for respectively contacting each of said plurality of output lines, to thereby provide electrical connection to external control and power supply circuitry.

Claim 27

Dependent Claim 89 words

A mass airflow sensor fabricated on a semiconductor substrate comprising: a dielectric diaphragm; a heating element and at least one temperature sensing element disposed on said diaphragm; a semiconductor region disposed adjacent said diaphragm; at least one temperature sensing element disposed over said semiconductor region, whereby an airflow therepast may be determined based on the temperature gradient between the heating element and said at least one temperature sensing element disposed over said semiconductor region, said semiconductor region comprising a heavily doped etch stopped region which surrounds said dielectric diaphragm.

Claim 28

Dependent Claim 89 words

A mass airflow sensor fabricated on a semiconductor substrate comprising: a dielectric diaphragm; a heating element and at least one temperature sensing element disposed on said diaphragm; a semiconductor region disposed adjacent said diaphragm; at least one temperature sensing element disposed over said semiconductor region, whereby an airflow therepast may be determined based on the temperature gradient between the heating element and said at least one temperature sensing element disposed over said semiconductor region, said semiconductor region comprising a heavily doped etch stopped region which surrounds said dielectric diaphragm.

Claim 29

Dependent Claim 20 words

A sensor according to claim 25, wherein said heating element and said at least one sensing elements are thin-film components.

Claim 30

Dependent Claim 24 words

A sensor according to claim 25, wherein said dielectric diaphragm comprises a sandwich structure of dielectric materials having substantially different coefficients of thermal expansion.

Claim 31

Dependent Claim 17 words

A sensor according to claim 25, wherein the semiconductor substrate below the dielectric diaphragm has been removed.

Claim 32

Dependent Claim 23 words

A sensor according to claim 25, further including at least one thin-film sensing element disposed between said heating element and said semiconductor region.

Claim 33

Dependent Claim 41 words

A sensor according to claim 25 having a longitudinal axis, wherein said heating element is centrally disposed substantially along the longitudinal axis of the sensor and wherein a plurality of sensing elements are disposed on both sides of said heating element.

Claim 34

Dependent Claim 33 words

A sensor according to claim 25, further including read-out and control means fabricated on said semiconductor substrate for energizing said heating element and receiving signals from said at least one temperature sensing element.

Claim 35

Dependent Claim 30 words

A sensor according to claim 25, wherein said heating element is disposed on a front surface of said substrate and wherein at least one side of the substrate is tapered.

Claim 36

Dependent Claim 17 words

A sensor according to claim 32, wherein said at least one side includes a double-side tapered edge.

Claim 37

Dependent Claim 55 words

A sensor according to claim 31, wherein said read-out and control means has a plurality of output lines emanating therefrom and further including a support substrate having a like plurality of electrical lines for respectively contacting each of said plurality of output lines, to thereby provide electrical connection to external control and power supply circuitry.

Claim 38

Dependent Claim 141 words

A mass airflow sensor having a longitudinal axis comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim encompassing at least a major portion of said dielectric diaphragm; at least one thin-film sensing element disposed on said diaphragm, said at least one sensing element being disposed at least in part over said semiconductor rim, whereby the temperature gradient between the heating element and said at least one sensing element may be monitored to determine the airflow rate, said heating element being centrally disposed substantially along the longitudinal axis of the sensor and a plurality of sensing elements disposed on both sides of said heating element; and said dielectric diaphragm having a sandwich structure of dielectric materials having substantially different coefficients of thermal expansion, said sandwich structure being comprised of silicon dioxide and silicon nitride.

Claim 39

Dependent Claim 141 words

A mass airflow sensor having a longitudinal axis comprising: a dielectric diaphragm; a thin-film heating element disposed on said diaphragm; a thermally conductive semiconductor rim encompassing at least a major portion of said dielectric diaphragm; at least one thin-film sensing element disposed on said diaphragm, said at least one sensing element being disposed at least in part over said semiconductor rim, whereby the temperature gradient between the heating element and said at least one sensing element may be monitored to determine the airflow rate, said heating element being centrally disposed substantially along the longitudinal axis of the sensor and a plurality of sensing elements disposed on both sides of said heating element; and said dielectric diaphragm having a sandwich structure of dielectric materials having substantially different coefficients of thermal expansion, said sandwich structure being comprised of silicon dioxide and silicon nitride.

Claim 40

Dependent Claim 28 words

A sensor according to claim 35, wherein the mass airflow sensor is fabricated from a semiconductor substrate and wherein the semiconductor substrate below the dielectric diaphragm is removed.

Claim 41

Dependent Claim 17 words

A sensor according to claim 35, wherein a semiconductor substrate region is disposed below the semiconductor rim.

Claim 42

Dependent Claim 24 words

A sensor according to claim 35, wherein each of said heating element and said sensing elements are substantially parallel with respect to each other.

Claim 43

Dependent Claim 16 words

A sensor according to claim 35, wherein the diaphragm dimensions are determined by the semiconductor rim.

Claim 44

Dependent Claim 42 words

A sensor according to claim 35, wherein said sensor is fabricated on a semiconductor substrate and further includes: read-out and control means fabricated on said semiconductor substrate for energizing said heating element and receiving signals from said at least one sensing element.

Claim 45

Dependent Claim 39 words

A sensor according to claim 35, wherein said sensor is fabricated on a semiconductor substrate and said heating element is disposed on a front surface of said substrate and wherein at least one side of the substrate is tapered.

Claim 46

Dependent Claim 17 words

A sensor according to claim 41, wherein said at least one side includes a double-side tapered edge.

Claim 47

Dependent Claim 90 words

A sensor according to claim 35, wherein said sensor is fabricated on a semiconductor substrate and further includes: read-out and control means fabricated on said semiconductor substrate for energizing said heating element and receiving signals from said at least one sensing element, said read-out and control means having a plurality of output lines emanating therefrom, and further including a support substrate having a like plurality of electrical lines for respectively contacting each of said plurality of output lines, to thereby provide electrical connection to external control and power supply circuitry.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-12-25	1993-06-26	1993-12-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-12-25	1997-06-26	1997-12-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-12-25	2001-06-26	2001-12-26	$7700.00	Window Closed / Lapsed

Silicon based mass airflow sensor and its fabrication method

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