US4888988A
Expired / Lapsed
US
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Silicon based mass airflow sensor and its fabrication method
Assignee: Siemens Automotive LP
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Filing: 1987-12-23
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Granted: 1989-12-26
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Expires: 2007-12-23
Abstract
Abstract A mass airflow sensor is fabricated on a semiconductor substrate and which includes (1) a dielectric diaphragm, (2) p-etch-stopped silicon rim, (3) thin-film heating and temperature sensing elements, and (4) tapered chip edges. The dielectric diaphragm is formed with thin silicon oxide and silicon nitride in a sandwich structure and provides excellent thermal insulation for the sensing and heating elements of the sensor. The diaphragm dimensions, including thickness, are accurately controlled through the use of the heavily-p-doped silicon rim to help ensure uniform and reproducible sensor performance.
Inventors
- 👤 Ki W. Lee
- 👤 Il-Hyun Choi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:43
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01L; G01L9/00; G01L9/0041; G01L9/0042; G01L9/0048; G01F1/684; G01F1/6845
Claims Analysis
Total Claims: 47
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.
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USPTO Annuity & Maintenance Windows
| 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 |