CMOS integrated method for the release of thermopile pixel on a substrate by using anisotropic and isotropic etching
First Claim
1. A method for manufacturing an imaging device, comprising the steps of:
- providing a wafer comprising a first layer, a second layer, and a third layer, the second layer having a front surface adjacent to the first layer and a back surface adjacent to the third layer, the first layer having a pair of inner openings therethrough;
anisotropic etching of a portion of the second layer back surface beneath a central part of the first layer to form a cavity between the pair of inner openings, the pair of inner openings not extending into the cavity; and
performing a first isotropic etching of a first portion of the second layer front surface through the pair of inner openings to form cavity extensions such that the pair of inner openings provide a channel from a top side of the wafer through the first layer into the cavity.
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Accused Products
Abstract
A method for manufacturing an imaging device is presented. The method starts with providing a wafer having a membrane with an opening bonded to a substrate. A photoresist layer is deposited over the membrane and wafer surface. A portion of the substrate back surface under a central part of the membrane is etched anisotropicly. A first region of the photoresist layer is removed, exposing an opening in the membrane, so that a first isotropic etching of the substrate is performed through the membrane opening. A second region of the photoresist layer is stripped, exposing a second membrane opening, providing access for a second isotropic etching of the substrate through the first and/or second membrane opening.
27 Citations
25 Claims
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1. A method for manufacturing an imaging device, comprising the steps of:
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providing a wafer comprising a first layer, a second layer, and a third layer, the second layer having a front surface adjacent to the first layer and a back surface adjacent to the third layer, the first layer having a pair of inner openings therethrough; anisotropic etching of a portion of the second layer back surface beneath a central part of the first layer to form a cavity between the pair of inner openings, the pair of inner openings not extending into the cavity; and performing a first isotropic etching of a first portion of the second layer front surface through the pair of inner openings to form cavity extensions such that the pair of inner openings provide a channel from a top side of the wafer through the first layer into the cavity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for manufacturing an imaging device, comprising the steps of:
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first providing a wafer comprising a substrate having a first surface and a second surface opposite the first surface, and a membrane attached to the first surface, wherein the membrane includes an opening exposing the first surface; subsequently, depositing a photoresist layer over the membrane and wafer first surface; after depositing the photoresist layer, masking a portion of the photoresist layer to form a first region and a second region; subsequently, anisotropic etching a portion of the substrate second surface under a central part of the membrane; after the anisotropic etching, removing the first region of the photoresist layer; subsequently, performing a first isotropic etching of the substrate through the membrane opening; after the first isotropic etching, stripping the second region of the photoresist layer; and subsequently, performing a second isotropic etching of the substrate through the membrane opening. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method for manufacturing an imaging device, comprising the steps of:
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providing a wafer comprising a first layer, a second layer, and a third layer, the second layer having a front surface adjacent to the first layer and a back surface adjacent to the third layer, the first layer having a pair of inner openings therethrough; anisotropic etching of a portion of the second layer back surface beneath a central part of the first layer to form a cavity between the pair of inner openings, the pair of inner openings not extending into the cavity, the first layer acting as an etch stop to the anisotropic etching such that the anisotropic etching only etches the entire thickness of the second layer up to the first layer; and performing a first isotropic etching of a first portion of the second layer front surface through the pair of inner openings to form cavity extensions such that the pair of inner openings provide a channel from a top side of the wager through the first layer into the cavity.
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21. A method for manufacturing an imaging device, comprising the steps of:
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providing a wafer comprising a first layer, a second layer, a third layer, a CMOS structure, and a photoresist layer, the second layer having a front surface adjacent to the first layer and a back surface adjacent to the third layer, the first layer having a pair of inner openings therethrough and a pair of outer openings therethrough, the at least one CMOS structure disposed on an outer portion of the wafer relative to the pair of outer openings, the photoresist layer disposed on a front surface of the first layer so as to cover at least the pair of outer openings and the CMOS structure; anisotropic etching of a portion of the second layer back surface beneath a central part of the first layer between the pair of inner openings, the first layer acting as an etch stop layer, to form a cavity in the second layer between the pair of inner openings; and performing a first isotropic etching of a first portion of the second layer front surface through the pair of inner openings to form first cavity extensions primarily undercutting inwards away from the pair of outer openings and the CMOS structure. - View Dependent Claims (22, 23, 24, 25)
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Specification