Cap Wafer for Wafer Bonded Packaging and Method for Manufacturing the Same
First Claim
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1. A method for preparing a cap wafer for wafer bonded packaging comprising the steps of:
- i) forming an etch mask layer on Stop and back sides of a silicon wafer;
ii) selectively removing said etch mask layer to form a cavity etch window on the back side of said silicon wafer, and then forming a via etch window on the top side of said silicon wafer to overlap with said cavity etch window;
iii) forming a cavity and a via by wet etching of said silicon wafer that has been exposed by said cavity etch window and said via etch window, provided that a silicon diaphragm with a certain thickness is temporarily maintained between said cavity and said via;
iv) forming a cavity interconnection and a wafer bonding pad on the back side of said silicon wafer to which said cavity has been formed;
v) forming a through silicon via by removing the temporary silicon diaphragm under the bottom of said via so that the bottom of said via is in contact with the cavity interconnection;
vi) forming a via interconnection which contacts said cavity interconnection on the top side of said silicon wafer with said through silicon via formed thereon; and
vii) with a metallic bonding material, forming a device contact pad and a hermetic seal ring, respectively, on said cavity interconnection which is present on periphery of said cavity and on top of said wafer bonding pad.
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Abstract
The present invention relates to semiconductor device manufacturing techniques, and specifically to a field of device packaging techniques at wafer level. More specifically, it relates to a cap wafer for wafer bonding application that is bonded to top part of a device wafer. The method of the present invention excludes the use of deep reactive ion etching of silicon to form a through silicon via. The present invention provides a method for the preparation of cap wafer for wafer bonding application with a simple process of through silicon via interconnection and a wafer level packaging method using the same.
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Citations
21 Claims
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1. A method for preparing a cap wafer for wafer bonded packaging comprising the steps of:
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i) forming an etch mask layer on Stop and back sides of a silicon wafer;
ii) selectively removing said etch mask layer to form a cavity etch window on the back side of said silicon wafer, and then forming a via etch window on the top side of said silicon wafer to overlap with said cavity etch window;
iii) forming a cavity and a via by wet etching of said silicon wafer that has been exposed by said cavity etch window and said via etch window, provided that a silicon diaphragm with a certain thickness is temporarily maintained between said cavity and said via;
iv) forming a cavity interconnection and a wafer bonding pad on the back side of said silicon wafer to which said cavity has been formed;
v) forming a through silicon via by removing the temporary silicon diaphragm under the bottom of said via so that the bottom of said via is in contact with the cavity interconnection;
vi) forming a via interconnection which contacts said cavity interconnection on the top side of said silicon wafer with said through silicon via formed thereon; and
vii) with a metallic bonding material, forming a device contact pad and a hermetic seal ring, respectively, on said cavity interconnection which is present on periphery of said cavity and on top of said wafer bonding pad. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Wafer bonded packaging method comprising the steps of:
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i) forming an etch mask layer on top and back sides of a silicon wafer;
ii) patterning said etch mask layer to form a cavity etch window on the back side of silicon wafer, and then forming a via etch window on the top side of said silicon wafer to overlap with said cavity etch window;
iii) forming a cavity and a via by wet etching of said silicon wafer that has been exposed by said cavity etch window and said via etch window, provided that a silicon diaphragm with certain thickness is temporarily maintained between said cavity and said via;
iv) forming a cavity interconnection and a wafer bonding pad on the back side of said silicon wafer to which said cavity has been formed;
v) forming a through silicon via by removing the temporary silicon diaphragm under the bottom of said via in contact with the cavity interconnection;
vi) forming a via interconnection which contacts said cavity interconnection on the top side of said silicon wafer with said through silicon via formed thereon;
vii) with a metallic bonding material, forming a device contact pad and a hermetic seal ring, respectively on said cavity interconnection which is present on the periphery of said cavity and on top of said wafer bonding pad; and
viii) bonding the silicon cap wafer wherein said device contact pad and said hermetic seal ring have been formed to the device wafer wherein the device has been formed. - View Dependent Claims (16, 17, 18)
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15. A water bonded packaging method comprising the steps of:
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i) forming an etch mask layer on top and back sides of a silicon wafer;
ii) selectively removing the said etch mask layer to form a cavity etch window on the back side of said silicon wafer, and then forming a via etch window on the top side of said silicon wafer to overlap with said cavity etch window;
iii) forming a cavity and a via by wet etching of said silicon wafer that has been exposed by said cavity etch window and said via etch window, provided that a silicon diaphragm with certain thickness is maintained between said cavity and said via;
iv) forming a cavity interconnection and a wafer bonding pad on the back side of said silicon wafer to which said cavity has been formed;
v) with a metallic bonding material, forming a device contact pad and a hermetic seal ring, respectively on said cavity interconnection which is present on the periphery of said cavity and on top of said wafer bonding pad;
vi) bonding the silicon cap wafer wherein said device contact pad and said hermetic seal ring have been formed to the device wafer wherein the device has been formed;
vii) forming a through silicon via by removing the temporary silicon diaphragm under the bottom of said via that the bottom of said via is in contact with the cavity interconnection; and
viii) forming a via interconnection which contacts said cavity interconnection on the top side of said silicon wafer with said through silicon via formed thereon. - View Dependent Claims (19, 20, 21)
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Specification