Systems for buried electrical feedthroughs in a glass-silicon MEMS process

• US 6,888,233 B2
• Filed: 03/10/2003
• Issued: 05/03/2005
• Est. Priority Date: 03/10/2003
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Ridley, Jeffrey A., Horning, Robert D.
• Primary Examiner(s): TSAI, H JEY
• Application Number:
  US10/385,181
• Publication Number:
  US 20040180464A1
• Time in Patent Office: 785 Days
• Field of Search: 257674-698
• US Class Current: 257/684
• CPC Class Codes: B81B 2207/097 Interconnects arranged on the substrate or the lid, and covered by the package seal
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias

Abstract

A method for providing conductive paths into a hermetically sealed cavity is described. The sealed cavity is formed utilizing a silicon-glass micro-electromechanical structure (MEMS) process and the method includes forming recesses on a glass substrate everywhere that a conductive path is to pass into the cavity, and forming conductive leads in and around the recesses. A glass layer is deposited over the substrate, into the recesses, and over the conductive leads and then planarized to expose portions of the conductive leads. A sealing surface is formed on at least a portion of the glass layer. Silicon is then bonded to the sealing surface of the planarized glass layer, the wafer being configured such that a portion of each lead is within the sealed cavity and a portion of each lead is outside the sealed cavity.

Claims

1. A structure having a hermetically sealed cavity therein, said structure having at least one electrically conductive path passing from outside of the sealed cavity to inside the sealed cavity, said structure comprising:

a glass substrate comprising recesses formed therein where electrical signals are to pass into the sealed cavity;

conductive leads deposited in and around said recesses;

a glass layer deposited over said substrate, said glass layer further deposited over said recesses and said conductive leads, said glass layer planarized to a level of a portion of said conductive leads around said recesses; and

silicon bonded to said planarized glass layer to form a cavity, said silicon fabricated such that a portion of each said conductive lead is within the sealed cavity and a portion of each said conductive lead is outside the sealed cavity.

2. A structure according to claim 1 wherein said recesses comprise etched recesses.

3. A structure according to claim 1 wherein said glass layer is planarized using a chemical-mechanical polishing process.

4. A structure according to claim 1 wherein said silicon comprises a sealing ring bonded to said planarized glass layer, said sealing ring configured to be bonded to a second glass substrate.

5. A structure according to claim 1 wherein said silicon comprises a micro-electromechanical structure (MEMS).

6. A structure according to claim 5 wherein said structure comprises at least one of a MEMS gyroscope and a MEMS accelerometer.

7. A micro electromechanical system (MEMS) gyroscope comprising:

a housing;

gyroscope electronics located within said housing;

a structure defining a hermetically sealed cavity within said housing; and

a tuning fork gyroscope located within the hermetically sealed cavity, said structure comprising;

a plurality of electrical feedthroughs providing electrical connections between said gyroscope electronics and said tuning fork gyroscope;

a glass substrate comprising recesses formed therein, said recesses being where said electrical feedthroughs pass into and out of the hermetically sealed cavity;

a glass layer deposited over said substrate, said glass layer further deposited over said electrical feedthroughs in said recesses, said glass layer planarized to a level of a portion of said electrical feedthroughs around said recesses; and

silicon bonded to said planarized glass layer, said silicon fabricated such that a portion of each said electrical feedthrough is within the hermetically sealed cavity and a portion of each said electrical feedthrough is outside the hermetically sealed cavity.

8. A MEMS gyroscope according to claim 7 wherein said recesses comprise etched recesses.

9. A MEMS gyroscope according to claim 7 wherein said glass layer is planarized using a chemical-mechanical polishing process.

10. A MEMS gyroscope according to claim 7 wherein said silicon wafer comprises a sealing ring bonded to said planarized glass layer, said sealing ring configured to be bonded to a second glass substrate.

11. A structure having a hermetically sealed cavity therein, said structure having at least one electrically conductive path passing from outside of the cavity to the sealed cavity, said structure comprising:

a glass substrate comprising recesses formed therein where electrical signals are to pass into the sealed cavity and an upper surface;

conductive leads deposited on said recesses;

a glass deposit on said conductive leads, said glass deposit comprising an upper surface planarized to a level of said upper surface of said substrate; and

silicon bonded to said upper surface of said glass deposit and said upper surface of said substrate, said silicon fabricated such that a portion of each said conductive lead is within the sealed cavity and a portion of each said conductive lead is outside the sealed cavity.