# US 7,610,803 B2 · Robust MEMS flow die with integrated protective flow channel

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- Number: US 7,610,803 B2
- Document ID: US7610803B2
- Status: Granted
- Kind: B2
- Application number: 12/326,539
- Filed: 2008-12-02
- Published: 2009-06-11
- Granted: 2009-11-03
- Earliest claimed: 2007-11-30
- Assignees: Honeywell International Inc.
- Inventors: Lamar F. Ricks
- Web page: https://patentgrep.com/patent/US7610803B2

## CPC

- G01F 1/6845: {Micromachined devices}
- G01F 1/6842: {with means for influencing the fluid flow}
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME

## Abstract

A MEMS flow sensor has a flow channel that avoids wire bond pads and ancillary circuit elements. A fluid can move from the bottom of the sensor substrate, though an inlet hole, over a sensing element on the top of the substrate, and then through an outlet hole. The inlet hole and the outlet hole can pass from the substrate top to the substrate bottom. A top cap can be fixed to the top of the substrate such that it covers the sensing element, the inlet hole, and the outlet hole. The top cap constrains the flow channel and keeps fluid, either gaseous or liquid, from exiting the channel and contacting the wire bond pads or ancillary circuit elements.

## Claims

### Claim 1

A system comprising:
a substrate having a top surface and a bottom surface;
a sensing element electrically connected to a plurality of wire bond pads on the top surface;
an inlet hole and an outlet hole that pass through the substrate from the top surface to the bottom surface; and
a top cap fixed to the top surface wherein the top cap covers the inlet hole, the sensing element, and the outlet hole such that a fluid flowing into the inlet hole flows over the sensing element and out of the outlet hole and wherein the top cap prevents the fluid from contacting the wire bond pads.

### Claim 2 (depends on 1)

The system of claim 1 wherein the top cap is glass.

### Claim 3 (depends on 2)

The system of claim 2 wherein the substrate is silicon.

### Claim 4 (depends on 2)

The system of claim 2 wherein the substrate is quartz.

### Claim 5 (depends on 2)

The system of claim 2 wherein the substrate is glass.

### Claim 6 (depends on 2)

The system of claim 2 wherein the substrate is glass and wherein the top cap is fixed to the substrate by a glass bond such as the glass bond produced by a glass frit process.

### Claim 7 (depends on 1)

The system of claim 1 further comprising an ancillary circuit on the top surface electrically connecting the sensing element to the wire bond pads wherein the ancillary circuit comprises at least one resistor.

### Claim 8 (depends on 7)

The system of claim 7 wherein the top cap prevents the fluid from contacting the at least one resistor.

### Claim 9 (depends on 1)

The system of claim 1 wherein the top cap is silicon.

### Claim 10

A system comprising:
a substrate having a top surface and a bottom surface;
a flow sensing element electrically connected to a multiplicity of wire bond pads on the top surface;
an inlet hole and an outlet hole that pass through the substrate from the top surface to the bottom surface; and
a top cap fixed to the top surface wherein the top cap covers the inlet hole, the flow sensing element, and the outlet hole such that a fluid flowing into the inlet hole flows over the sensing element and out of the outlet hole and wherein the top cap prevents the fluid from contacting the wire bond pads.

### Claim 11 (depends on 10)

The system of claim 10 further comprising an ancillary circuit on the top surface electrically connecting the sensing element to the wire bond pads wherein the ancillary circuit comprises at least one resistor.

### Claim 12 (depends on 11)

The system of claim 11 wherein the top cap is glass.

### Claim 13 (depends on 11)

The system of claim 11 wherein the substrate is quartz.

### Claim 14 (depends on 11)

The system of claim 11 wherein the substrate is silicon.

### Claim 15 (depends on 11)

The system of claim 11 wherein the top cap is sealed to the top surface such that all the fluid entering the inlet hole exits the outlet hole.

### Claim 16 (depends on 10)

The system of claim 10 wherein the top cap is sealed to the top surface such that all the fluid entering the inlet hole exits the outlet hole.

### Claim 17 (depends on 16)

The system of claim 16 wherein the top cap is glass.

### Claim 18 (depends on 16)

The system of claim 16 wherein the substrate is quartz.

### Claim 19 (depends on 16)

The system of claim 16 wherein the substrate is silicon.

### Claim 20 (depends on 16)

The system of claim 16 wherein the substrate is glass.