Technique for manufacturing micro-electro mechanical structures
First Claim
1. A method for manufacturing micro-electro mechanical (MEM) structures, comprising the steps of:
- forming a cavity into a first side of a first wafer that functions as a handling wafer, wherein a sidewall of the cavity forms a first angle greater than 54.7 degrees with respect to a plane defined by the first side of the handling wafer, wherein the first angle extends from the plane into the cavity to the sidewall, and wherein the first angle subtends at least a portion of the cavity;
performing a bulk etch on the first side of the handling wafer to modify the sidewall of the cavity to a second angle greater than about 90 degrees with respect to a plane defined by the first side of the handling wafer, wherein the second angle extends from the plane into the cavity to the sidewall, and wherein the second angle subtends at least a portion of the cavity; and
bonding a second side of a second wafer to the first side of the handling wafer to cover the cavity such that the cavity is inaccessible, wherein the second side of the second wafer is opposite a first side of the second wafer, wherein the second wafer is an epitaxial wafer, and wherein the epitaxial wafer includes a buried etch stop layer positioned at a desired depth from the first side of the epitaxial wafer.
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Abstract
A technique for manufacturing a micro-electro mechanical structure includes a number of steps. Initially, a cavity is formed into a first side of a handling wafer, with a sidewall of the cavity forming a first angle greater than about 54.7 degrees with respect to a first side of the handling wafer at an opening of the cavity. Then, a bulk etch is performed on the first side of the handling wafer to modify the sidewall of the cavity to a second angle greater than about 90 degrees, with respect to the first side of the handling wafer at the opening of the cavity. Next, a second side of a second wafer is bonded to the first side of the handling wafer.
52 Citations
19 Claims
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1. A method for manufacturing micro-electro mechanical (MEM) structures, comprising the steps of:
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forming a cavity into a first side of a first wafer that functions as a handling wafer, wherein a sidewall of the cavity forms a first angle greater than 54.7 degrees with respect to a plane defined by the first side of the handling wafer, wherein the first angle extends from the plane into the cavity to the sidewall, and wherein the first angle subtends at least a portion of the cavity; performing a bulk etch on the first side of the handling wafer to modify the sidewall of the cavity to a second angle greater than about 90 degrees with respect to a plane defined by the first side of the handling wafer, wherein the second angle extends from the plane into the cavity to the sidewall, and wherein the second angle subtends at least a portion of the cavity; and bonding a second side of a second wafer to the first side of the handling wafer to cover the cavity such that the cavity is inaccessible, wherein the second side of the second wafer is opposite a first side of the second wafer, wherein the second wafer is an epitaxial wafer, and wherein the epitaxial wafer includes a buried etch stop layer positioned at a desired depth from the first side of the epitaxial wafer. - View Dependent Claims (2, 3, 4)
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5. A method for manufacturing micro-electro mechanical (MEM) structures, comprising the steps of:
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forming a cavity into a first side of a first wafer that functions as a handling wafer, wherein a sidewall of the cavity forms a first angle greater than about 54.7 degrees with respect to a plane defined by the first side of the handling wafer, wherein the first angle extends from the plane into the cavity to the sidewall, and wherein the first angle subtends at least a portion of the cavity; performing a bulk etch on the first side of the handling wafer to modify the sidewall of the cavity to a second angle greater than about 90 degrees with respect to a plane defined by the first side of the handling wafer, wherein the second angle extends from the plane into the cavity to the sidewall, and wherein the second angle subtends at least a portion of the cavity; bonding a second side of a second wafer to the first side of the handling wafer to cover the cavity such that the cavity is inaccessible, wherein the second side of the second wafer is opposite a first side of the second wafer; removing a portion of the second wafer from the first side of the second wafer to provide a membrane; and forming desired circuitry on the first side of the second wafer, wherein the first and second wafers are N-type silicon wafers. - View Dependent Claims (6, 7)
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8. A method for manufacturing micro-electro mechanical (MEM) structures, comprising the steps of:
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forming a cavity into a first side of a first wafer that functions as a handling wafer, wherein a sidewall of the cavity forms a first angle greater than 54.7 degrees with respect to a plane defined by the first side of the handling wafer, wherein the first angle extends from the plane into the cavity to the sidewall, and wherein the first angle subtends at least a portion of the cavity; performing a bulk etch on the first side of the handling wafer to modify the sidewall of the cavity to a second angle greater than about 90 degrees with respect to a plane defined by the first side of the handling wafer, wherein the second angle extends from the plane into the cavity to the sidewall, and wherein the second angle subtends at least a portion of the cavity; bonding a second side of a second wafer to the first side of the handling wafer to cover the cavity such that the cavity is inaccessible, wherein the second side of the second wafer is opposite a first side of the second wafer; and forming a hole through the handling wafer to the inaccessible cavity from a second side of the handling wafer that is opposite the first side of the handling wafer, rendering the cavity accessible. - View Dependent Claims (9, 10)
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11. A method for manufacturing micro-electro mechanical (MEM) structures, comprising the steps of:
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forming a cavity into a first side of a first wafer that functions as a handling wafer, wherein a sidewall of the cavity forms a first angle of about 90 degrees with respect to a plane defined by the first side of the handling wafer, wherein the first angle extends from the plane into the cavity to the sidewall, and wherein the first angle subtends at least a portion of the cavity; performing a bulk etch on the first side of the handling wafer to modify the sidewall of the cavity to a second angle of about 125.3 degrees with respect to a plane defined by the first side of the handling wafer, wherein the second angle extends from the plane into the cavity to the sidewall, and wherein the second angle subtends at least a portion of the cavity; bonding a second side of a second wafer to the first side of the handling wafer to cover the cavity such that the cavity is inaccessible, where in the second side of the second wafer is opposite a first side of the second wafer; removing a portion of the second wafer from the first side of the second wafer to provide a membrane, wherein a thickness of the membrane is between about 10 microns and 25 microns; and forming desired circuitry on the first side of the second wafer. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification