Method of fabrication of AI/GE bonding in a wafer packaging environment and a product produced therefrom
First Claim
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1. A method for providing a wafer, the method comprising:
- providing a first substrate including a microelectromechanical systems (MEMS) feature and a patterned, germanium layer, the patterned, germanium layer being an exposed layer on the first substrate;
providing a second substrate including a patterned, aluminum layer and an electrical contact, the patterned, aluminum layer being an exposed layer on the second substrate;
bonding the patterned, germanium layer of the first substrate to the patterned, aluminum layer of the second substrate to create an electrical and mechanical bond between the first substrate and the second substrate; and
using a forming gas to deoxidize a bonding surface of the patterned, aluminum layer of the first substrate and a bonding surface of the patterned, germanium layer of the second substrate.
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Abstract
A method of bonding of germanium to aluminum between two substrates to create a robust electrical and mechanical contact is disclosed. An aluminum-germanium bond has the following unique combination of attributes: (1) it can form a hermetic seal; (2) it can be used to create an electrically conductive path between two substrates; (3) it can be patterned so that this conduction path is localized; (4) the bond can be made with the aluminum that is available as standard foundry CMOS process. This has the significant advantage of allowing for wafer-level bonding or packaging without the addition of any additional process layers to the CMOS wafer.
79 Citations
28 Claims
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1. A method for providing a wafer, the method comprising:
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providing a first substrate including a microelectromechanical systems (MEMS) feature and a patterned, germanium layer, the patterned, germanium layer being an exposed layer on the first substrate; providing a second substrate including a patterned, aluminum layer and an electrical contact, the patterned, aluminum layer being an exposed layer on the second substrate; bonding the patterned, germanium layer of the first substrate to the patterned, aluminum layer of the second substrate to create an electrical and mechanical bond between the first substrate and the second substrate; and using a forming gas to deoxidize a bonding surface of the patterned, aluminum layer of the first substrate and a bonding surface of the patterned, germanium layer of the second substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for providing a wafer, the method comprising:
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providing a first substrate including a microelectromechanical systems (MEMS) feature and a patterned, germanium layer, the patterned, germanium layer being an exposed layer on the first substrate; providing a second substrate including a patterned, aluminum layer and an electrical contact, the patterned, aluminum layer being an exposed layer on the second substrate; bonding the patterned, germanium layer of the first substrate to the patterned, aluminum layer of the second substrate to create an electrical and mechanical bond between the first substrate and the second substrate;
wherein bonding the patterned, germanium layer of the first substrate to the patterned, aluminum layer of the second substrate includes using a controlled ambient including forming gas.
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13. A method for providing a wafer, the method comprising:
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providing a first substrate including a microelectromechanical systems (MEMS) feature and a patterned, germanium layer, the patterned, germanium layer being an exposed layer on the first substrate; providing a second substrate including a patterned, aluminum layer and an electrical contact, the patterned, aluminum layer being an exposed layer on the second substrate; and cleaning a bonding surface of the patterned, germanium layer of the first substrate and a bonding surface of the patterned, aluminum layer of the second substrate by sputter etching.
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14. A method for bonding a CMOS wafer and a MEMS wafer, the CMOS wafer including an integrated circuit, the MEMS wafer including a MEMS device, the method comprising:
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depositing a germanium bonding layer on the MEMS wafer; forming a aluminum bonding layer on the CMOS wafer; cleaning the CMOS wafer and the MEMS wafer, including deoxidizing contact surfaces of the CMOS wafer and the MEMS wafer; after cleaning, aligning CMOS wafer and the MEMS wafer; and forming a eutectic bond between the germanium bonding layer on the MEMS wafer and the aluminum bonding layer on the CMOS wafer using a bonding recipe, wherein a temperature of the CMOS wafer and a temperature of the MEMS wafer does not exceed 450°
C. during the bonding recipe, wherein the aluminum bonding layer on the CMOS wafer is a ratio mix of 97.5;
2;
.5 Al;
Si;
Cu (Aluminum;
Silicon;
Copper). - View Dependent Claims (15, 16, 17, 18)
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19. A method for bonding a CMOS wafer and a MEMS wafer, the CMOS wafer including an integrated circuit, the MEMS wafer including a MEMS device, the method comprising:
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depositing a germanium bonding layer on one of the wafers; forming a substantially aluminum bonding layer on one of the wafers, wherein the CMOS wafer is placed in a first chuck and the MEMs wafer is placed in a second chuck; aligning CMOS wafer and the MEMS wafer; and forming a eutectic bond between the germanium bonding layer and the aluminum bonding layer, wherein the eutectic bond is formed by applying a force across the first chuck and the second chuck, and ramping the temperature over the eutectic point of the aluminum/germanium bond to a second predetermined temperature that is less than 500°
C., andinducing a forming gas at atmospheric pressure prior to bonding and providing a vacuum to remove the forming gas. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification