# US 10,370,243 B2 · Pressure sensor having a bossed diaphragm

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- Number: US 10,370,243 B2
- Document ID: US10370243B2
- Status: Granted
- Kind: B2
- Application number: 15/049,314
- Filed: 2016-02-22
- Published: 2016-09-08
- Granted: 2019-08-06
- Earliest claimed: 2014-01-07
- Assignees: Honeywell International Inc.
- Applicants: Honeywell International Inc.
- Inventors: Carl Stewart; Richard Davis; Gilberto Morales
- Web page: https://patentgrep.com/patent/US10370243B2

## CPC

- B81C 1/00158: {Diaphragms, membranes (manufacture process for semi-permeable inorganic membranes B01D67/0039)}
- B81B 3/0021: {Transducers for transforming electrical into mechanical energy or vice versa (dynamo-electric machines H02K99/00; electrostatic machines H02N1/00; piezoelectric devices H10N30/00)}
- B81B 3/007: {For controlling stiffness, e.g. ribs}
- G01L 7/08: of the flexible-diaphragm type
- G01L 9/0042: {Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms (details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively)}
- G01L 9/0044: {Constructional details of non-semiconductive diaphragms}
- G01L 9/0047: {Diaphragm with non uniform thickness, e.g. with grooves, bosses or continuously varying thickness}
- G01L 9/0054: {integral with a semiconducting diaphragm}
- G01L 9/0055: {bonded on a diaphragm}
- B81B 2201/0264: Pressure sensors
- B81B 2203/0127: Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
- B81C 2201/014: by depositing an etch stop layer, e.g. silicon nitride, silicon oxide, metal
- B81C 2201/0198: for making a masking layer
- B81C 2203/0728: Pre-CMOS, i.e. forming the micromechanical structure before the CMOS circuit
- B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01)
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)

## Abstract

A method includes forming a mask that defines a masked area and an unmasked area on a front side of a substrate, and implanting a buried layer corresponding to the unmasked area on the front side of the substrate. The method also includes forming an epitaxial layer having a back side on the front side of the substrate and on a front side of the buried layer, and creating an opening into a back side of the substrate up to a back side of the epitaxial layer and a back side of the one or portions of the buried layer.

## Claims

### Claim 1

A method comprising:
forming a mask on a front side of a substrate, wherein the mask defines a masked area and an unmasked area;
implanting a buried layer corresponding to the unmasked area on the front side of the substrate;
forming an epitaxial layer on the front side of the substrate and on a front side of the buried layer, wherein the epitaxial layer has a back side; and
creating an opening into a back side of the substrate up to a back side of the epitaxial layer and a back side of the one or portions of the buried layer, wherein creating the opening forms a diaphragm that includes a portion of the silicon epitaxial layer and has a perimeter defined by one or more portions of the buried layer, and the diaphragm carries a boss formed by a portion of the buried layer.

### Claim 2

A method comprising:
forming a mask on a front side of a substrate, wherein the mask defines a masked area and an unmasked area;
implanting a buried layer corresponding to the unmasked area on the front side of the substrate;
forming an epitaxial layer on the front side of the substrate and on a front side of the buried layer, wherein the epitaxial layer has a back side;
creating an opening into a back side of the substrate up to a back side of the epitaxial layer and a back side of the one or portions of the buried layer; and
heating the substrate to diffuse the buried layer in the substrate, wherein edges and corners of the buried layer are rounded or smoothed in response to the heating.

### Claim 3 (depends on 1)

The method of claim 1, wherein creating the opening further forms one or more legs on the epitaxial layer connecting the boss to the one or more portions of the buried layer at the perimeter of the diaphragm.

### Claim 4 (depends on 3)

The method of claim 3, wherein the one or more legs have a minimum width near or at the perimeter of the diaphragm and a maximum width near or at the boss.

### Claim 5 (depends on 4)

The method of claim 4, wherein a ratio of the maximum width to the minimum width is between about 1.1 to about 2.

### Claim 6 (depends on 3)

The method of claim 3, further comprising:
forming one or more piezoresistive sensors on the front side of the epitaxial layer.

### Claim 7 (depends on 6)

The method of claim 6, wherein the one or more piezoresistive sensor are formed over or near the one or more legs.

### Claim 8 (depends on 7)

The method of claim 7, further comprising:
forming electronics in the epitaxial layer laterally adjacent to the diaphragm and connected to the one or more piezoresistive sensors.

### Claim 9 (depends on 1)

The method of claim 1, wherein the substrate comprises a silicon substrate.

### Claim 10 (depends on 1)

The method of claim 1, wherein the epitaxial layer comprises silicon.

### Claim 11 (depends on 1)

The method of claim 1, wherein creating the opening comprises etching the back side of the substrate up to the back side of the epitaxial layer and the back side of the buried layer.

### Claim 12

A method for making a pressure sensor system comprising:
implanting a patterned buried layer, based on a masking, at a front side of a silicon substrate;
heating the substrate to diffuse the buried layer in the substrate to round or smooth edges and corners of the buried layer;
forming a silicon epitaxial layer having a back side on the front side of the silicon substrate and on a front side of the buried layer; and
creating an opening, as defined by masking, into a back side of the substrate up to a back side of the epitaxial layer and a back side of the one or portions of the buried layer.

### Claim 13 (depends on 12)

The method of claim 12, wherein the patterned buried layer reveals in the opening a diaphragm consisting of a portion of the silicon epitaxial layer having a perimeter formed by one or more portions of the buried layer on the epitaxial layer and having a boss formed by a portion of the buried layer, the boss being situated on the diaphragm.

### Claim 14 (depends on 13)

The method of claim 13, wherein the patterned buried layer further reveals in the opening, one or more legs on the epitaxial layer connecting the boss to the one or more portions of the buried layer at the perimeter of the diaphragm.

### Claim 15 (depends on 14)

The method of claim 14, wherein the one or more legs have a minimum width near or at the perimeter of the diaphragm and a maximum width near or at the boss.

### Claim 16 (depends on 14)

The method of claim 14, further comprising:
forming one or more piezoresistive sensors on the diaphragm.

### Claim 17 (depends on 16)

The method of claim 16, further comprising:
forming one or more piezoresistive sensors on the diaphragm, wherein the one or more sensors are situated near or on the one or more legs.

### Claim 18 (depends on 16)

The method of claim 16, further comprising:
forming electronics in the epitaxial layer laterally adjacent to the diaphragm and connected to the one or more piezoresistive sensors.

### Claim 19 (depends on 16)

The method of claim 16, further comprising:
obtaining and amplifying, by the electronics, signals from the one or more piezoresistive sensors indicating magnitudes of deflection of the diaphragm that represent pressures affecting the diaphragm.