ETCHING OF INFRARED SENSOR MEMBRANE
First Claim
1. An infrared thermal sensor comprising:
- a semiconductor substrate having a cavity defined therein, wherein a bottom wall of said cavity is formed by a continuous surface of the semiconductor substrate,a membrane disposed in or over said cavity, the membrane being adapted for receiving heat transferred by infrared radiation incident on said membrane, said membrane comprising a plurality of openings extending through the membrane,at least one beam for suspending the membrane over the semiconductor substrate, andat least one thermocouple disposed in or on said at least one beam,wherein said plurality of openings are adapted for facilitating the passage of an anisotropic etchant for etching the cavity during manufacture of the infrared thermal sensor,wherein at the top surface of the membrane, each opening of the plurality of openings has a cross-section with a length to width ratio of at least four,wherein the width direction of a first set comprising at least two openings of said plurality of openings is substantially oriented according to a first crystallographic orientation of the semiconductor substrate, said first crystallographic orientation corresponding to a direction lying in a loosely packed crystal lattice face of the semiconductor substrate, andwherein the width direction of a second set of said plurality of openings is substantially oriented along a second crystallographic orientation of the semiconductor substrate, said first crystallographic orientation and said second crystallographic orientation corresponding to different directions lying in loosely packed crystal lattice faces of the semiconductor substrate.
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Accused Products
Abstract
The invention relates to an infrared thermal sensor comprising a substrate having a cavity, a cavity bottom wall formed by a continuous substrate surface. The sensor comprises a membrane adapted for receiving heat from incident infrared radiation, a beam suspending the membrane, and a thermocouple. This membrane comprises openings extending through the membrane for facilitating the passage of an anisotropic etchant for etching the cavity during manufacture. Each opening has a cross-section with a length to width ratio of at least 4. The width direction of respectively a first and a second set of openings is oriented according to respectively a first crystallographic orientation and a second crystallographic orientation, these orientations corresponding to different directions lying in loosely packed crystal lattice faces of the semiconductor substrate.
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Citations
15 Claims
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1. An infrared thermal sensor comprising:
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a semiconductor substrate having a cavity defined therein, wherein a bottom wall of said cavity is formed by a continuous surface of the semiconductor substrate, a membrane disposed in or over said cavity, the membrane being adapted for receiving heat transferred by infrared radiation incident on said membrane, said membrane comprising a plurality of openings extending through the membrane, at least one beam for suspending the membrane over the semiconductor substrate, and at least one thermocouple disposed in or on said at least one beam, wherein said plurality of openings are adapted for facilitating the passage of an anisotropic etchant for etching the cavity during manufacture of the infrared thermal sensor, wherein at the top surface of the membrane, each opening of the plurality of openings has a cross-section with a length to width ratio of at least four, wherein the width direction of a first set comprising at least two openings of said plurality of openings is substantially oriented according to a first crystallographic orientation of the semiconductor substrate, said first crystallographic orientation corresponding to a direction lying in a loosely packed crystal lattice face of the semiconductor substrate, and wherein the width direction of a second set of said plurality of openings is substantially oriented along a second crystallographic orientation of the semiconductor substrate, said first crystallographic orientation and said second crystallographic orientation corresponding to different directions lying in loosely packed crystal lattice faces of the semiconductor substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for manufacturing an infrared thermal sensor, the method comprising:
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providing a membrane stack on a semiconductor substrate, said membrane stack comprising an etch stop layer, patterning the membrane stack such as to define a membrane and at least one beam for suspending the membrane over the semiconductor substrate, forming a plurality of openings in said membrane stack extending through the etch stop layer such that at the top surface of the membrane, each opening of the plurality of openings has a cross-section with a length to width ratio of at least four, etching a cavity underneath the membrane and the at least one beam using an anisotropic etchant, and providing at least one thermocouple in or on said at least one beam, wherein etching the cavity underneath the membrane comprises forming a bottom wall of said cavity defined by a continuous surface of the semiconductor substrate, herein forming the plurality of openings comprises providing a first set comprising at least two openings of said plurality of openings, the width direction of said first set being substantially oriented according to a first crystallographic orientation of the semiconductor substrate, said first crystallographic orientation corresponding to a direction lying in a loosely packed crystal lattice face of the semiconductor substrate, and wherein forming the plurality of openings comprises providing a second set of said plurality of openings, the width direction of the second set being substantially oriented along a second crystallographic orientation of the semiconductor substrate, said first crystallographic orientation and said second crystallographic orientation corresponding to different directions lying in loosely packed crystal lattice faces of the semiconductor substrate. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification