Embedded structures for high glass strength and robust packaging

Patent metadata

Field	Value
Publication number	US-10189707-B2
Application number	US-201715499381-A
Country	US
Kind code	B2
Filing date	Apr 27, 2017
Priority date	Feb 20, 2015
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A sensor device is constructed to maintain a high glass strength to avoid the glass failure at low burst pressure, resulting from the sawing defects located in the critical high stress area of the glass pedestal as one of the materials used for construction of the sensor. This is achieved by forming polished recess structures in the critical high stress areas of the sawing street area. The sensor device is also constructed to have a robust bonding with the die attach material by creating a plurality of micro-posts on the mounting surface of the glass pedestal.

First claim

What is claimed is:

1. A method for making a pressure sensor, comprising the steps of:
providing a first wafer; and
providing a second wafer;
forming at least one angled recess as part of the first wafer;
forming at least one upper recess as part of the second wafer;
forming at least one lower recess as part of the second wafer;
bonding the first wafer to the second wafer to form a wafer stack having at least one saw street area, such that the at least one angled recess, the at least one upper recess, and the at least one lower recess are partially located in the saw street area;
partitioning the wafer stack in the saw street area to form at least two pressure sensors.

2. The method for making a pressure sensor of claim 1 , further comprising the steps of:
providing a third wafer;
forming at least one outer recess as part of the third wafer, the at least one outer recess located in the saw street area;
bonding the third wafer to the second wafer such that the third wafer is part of the wafer stack, and the at least one saw street area extends through at least part of the third wafer;
partitioning the wafer stack such that a portion of the third wafer is part of each of the at least two pressure sensors.

3. The method for making a pressure sensor of claim 2 , further comprising the steps of:
providing a plurality of smooth areas;
forming a portion of the plurality of smooth areas as part of the at least one angled recess;
forming a portion of the plurality of smooth areas as part of the at least one upper recess;
forming a portion of the plurality of smooth areas as part of the at least one lower recess;
forming a portion of the plurality of smooth areas as part of the at least one outer recess;
partitioning the wafer stack in the saw street area such that each of the plurality of smooth areas retains full structural integrity.

4. The method for making a pressure sensor of claim 2 , further comprising the steps of:
providing at least one pressure sensing element formed as part of the first wafer;
providing at least one pedestal formed as part of the second wafer; and
providing at least one cap formed as part of the third wafer;
as the wafer stack is partitioned such that one of the at least two pressure sensors have the at least one pressure sensing element, the at least one pedestal, and the at least one cap.

5. The method for making a pressure sensor of claim 4 , further comprising the steps of:
providing a cavity formed as part of the at least one pressure sensing element;
providing a cap cavity formed as part of the cap; and
providing an aperture formed as part of the pedestal, the aperture in fluid communication with the cavity;
detecting the pressure applied to the pressure sensing element in the cavity by measuring the pressure sensor output change due to the deflection of at least a portion of the pressure sensing element.

6. The method for making a pressure sensor of claim 2 , further comprising the steps of:
providing a plurality of micro-posts formed on the bottom surface of the third wafer such that a portion of the plurality of micro-posts are part of each of the at least two pressure sensors; and
providing at least one venting area in proximity to at least one of the plurality of micro-posts;
bonding the bottom surface of the third wafer to a housing substrate using a mounting material after the wafer stack has been partitioned;
venting air and vapor away from the at least one venting area as the plurality of micro-posts is attached to a housing substrate.

7. The method for making a pressure sensor of claim 1 , further comprising the steps of:
providing a plurality of rough areas;
forming a portion of the rough areas as the wafer stack is partitioned.

8. The method for making a pressure sensor of claim 7 , further comprising the steps of:
providing at least one first material removal area as part of the saw street area in proximity to the at least one angled recess;
providing at least one second material removal area as part of the saw street area in proximity to the at least one upper at the at least one lower recess;
providing at least one third material removal area as part of the saw street area in proximity to the at least one outer recess;
removing the first material removal area, the second material removal area, and the third material removal area as the wafer stack is partitioned.

9. A method of making a pressure sensor, comprising the steps of:
providing a first wafer having a top surface and a bottom surface;
providing a second wafer having a top surface and a bottom surface;
providing a third wafer having a top surface and a bottom surface;
providing at least one angled recess having at least one angled smooth area formed on the bottom surface as part of the first wafer;
providing at least one upper recess having at least one upper smooth area formed on the top surface as part of the second wafer;
providing at least one lower recess having at least one lower smooth area formed on the bottom surface as part of the second wafer;
providing at least one outer recess having at least one outer smooth area formed on the bottom surface of the third wafer;
bonding the bottom surface of the first wafer to the top surface of the second wafer at a first bonding interface such that the at least one angled recess is located in proximity to the at least one upper recess;
bonding bottom surface of the third wafer to the top surface of the first wafer, at a second bonding interface, and the at least one outer recess is located in proximity to the second bonding interface;
forming a saw street area when the first wafer is bonded to the second wafer, and the third wafer is bonded to the first wafer;
forming a wafer stack when the first wafer is bonded to the second wafer, and the third wafer is bonded to the first wafer;
partitioning the wafer stack in the saw street area to form at least two pressure sensors.

10. The method of making a pressure sensor of claim 9 , further comprising the steps of:
providing a portion of the at least one angled smooth area located outside the saw street area;
providing a portion of the at least one upper smooth area located outside the saw street area;
providing a portion of the at least one lower smooth area located outside the saw street area;
providing a portion of the at least one outer smooth area located outside the saw street area;
partitioning the wafer stack such that each of the portion of the at least one angled smooth area, the portion of the at least one upper smooth area, the portion of the at least one lower smooth area, and the portion of the at least one outer smooth area remain intact after the wafer stack is partitioned.

11. The method of making a pressure sensor of claim 9 , further comprising the steps of:
providing a first material removal area formed as part of the first wafer in proximity to the angled recess and located in the saw street area; and
providing a second material removal area formed as part of the second wafer in proximity to the upper recess and located in the saw street area;
providing a third material removal area formed as part of the third wafer in proximity to the outer recess and located in the saw street area;
removing the first material removal area, the second removal area, and the third material removal area as the wafer stack is partitioned.

12. The method of making a pressure sensor of claim 9 , further comprising the steps of:
providing at least one pressure sensing element formed as part of the first wafer;
providing at least one pedestal formed as part of the second wafer;
providing at least o

Assignees

• Continental automotive systems inc

Inventors

• Ding Xiaoyi
• Nowicki James

Classifications

• G01L19/0654

  against moisture or humidity · CPC title

• B81C2203/032

  Gluing · CPC title

• B81C1/00888 Primary

  Multistep processes involving only mechanical separation, e.g. grooving followed by cleaving · CPC title

• B81C2203/031

  Anodic bondings · CPC title

• B81B7/0019

  Protection against thermal alteration or destruction (B81B7/0083 takes precedence) · CPC title