# US 2018/0324938 A1 · Electrostatic microthruster

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- Number: US 2018/0324938 A1
- Document ID: US20180324938A1
- Status: Published application
- Kind: A1
- Application number: 15/586,868
- Filed: 2017-05-04
- Published: 2018-11-08
- Earliest claimed: 2017-05-04
- Assignees: NXP USA, Inc.
- Applicants: NXP USA, Inc.
- Inventors: Andrew Paul Dickens
- Web page: https://patentgrep.com/patent/US20180324938A1

## CPC

- H05H 1/48: using an arc (H05H1/26 takes precedence)
- F03H 1/0093: {Electro-thermal plasma thrusters, i.e. thrusters heating the particles in a plasma (resistojets per se B64G1/415)}
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- F03H: PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR (from combustion products F02K)

## Abstract

Embodiments of the present invention provide for movement of a fluid around a small form-factor device, such as a semiconductor device die or package, through use of a microplasma. Embodiments provide for a microplasma generated in an ambient fluid with a lower power than predicted by a Paschen Curve for that fluid. The ionized molecules of the plasma can be manipulated by further generation of an electric field that can be used, for example, to move the ions in a desired direction. The movement of the ionized fluid generates a fluid flow of neighboring, non-ionized fluid molecules in the desired direction.

## Claims

### Claim 1

A microplasma generator comprising:
a substrate comprising a substrate surface;
a first generation electrode located on the substrate surface; and
a second generation electrode located on the substrate surface, wherein
one of the first and second generation electrode is configured to be a field emitting electrode when a voltage is applied, and
a distance between edges of the first generation electrode and the second generation electrode is such that a plasma can be formed in an ambient gas at a predetermined voltage difference between the first generation electrode and the second generation electrode, wherein the ambient gas is in contact with the substrate surface and at a first pressure;
a first drive electrode located on the substrate surface, wherein the first drive electrode is located closer to the first generation electrode and located external to the region between the first and second generation electrode; and
a second drive electrode located on the substrate surface, wherein
the second drive electrode is located closer to the second generation electrode and located external to the region between the first and second generation electrodes, and
the first and second drive electrodes are located such that an electric field formed between the first and second drive electrodes can attract the plasma to one of the first and second drive electrodes.

### Claim 2 (depends on 1)

The microplasma generator of claim 1 wherein the distance between the edges of the first and second generation electrodes is such that the distance multiplied by the first pressure is at or below a minimum of a Paschen curve for the ambient gas at the first pressure for the predetermined voltage.

### Claim 3 (depends on 1)

The microplasma generator of claim 1 wherein the distance between the edge of the first generation electrode to a nearest edge of the second generation electrode is at or about 0.25 microns.

### Claim 4 (depends on 3)

The microplasma generator of claim 3 wherein the ambient gas comprises air at one atmosphere pressure.

### Claim 5

(canceled)

### Claim 6 (depends on 1)

The microplasma generator of claim 1 wherein a distance between nearest edges of the first drive electrode and the first generation electrode is at or about 2 microns and a distance between nearest edges of the second drive electrode and the second generation electrode is at or about 2 microns.

### Claim 7 (depends on 1)

The microplasma generator of claim 1 wherein
the first drive electrode is formed such that an exposed surface of the first drive electrode is formed at or about 1 micron above the substrate surface, and
the second drive electrode is formed such that an exposed surface of the second drive electrode is formed at or about 1 micron above the substrate surface.

### Claim 8 (depends on 1)

The microplasma generator of claim 1 further comprising:
a third generation electrode located on the substrate surface, wherein the third generation electrode is located closer to the second drive electrode than the first drive electrode, and located external to the region between the first and second drive electrodes; and
a fourth generation electrode located on the substrate surface, wherein
a distance between edges of the third generation electrode and the fourth generation electrode is such that a plasma can be formed in the ambient gas at a predetermined voltage difference between the third generation electrode and the fourth generation electrode.

### Claim 9 (depends on 8)

The microplasma generator of claim 8 further comprising:
a third drive electrode located on the substrate surface, wherein
the third drive electrode is located closer to the fourth generation electrode than the third generation electrode and located external to the region between the third and fourth generation electrodes, and
the second and third drive electrodes are located such that an electric field formed between the second and third drive electrodes can attract the plasma to one of the second and third drive electrodes.

### Claim 10 (depends on 9)

The microplasma generator of claim 9, wherein the first, second, and third drive electrodes are configured to provide a first charge configuration that attracts the plasma to the second drive electrode during a first time period and a second charge configuration that attracts the plasma to the third drive electrode from the second drive electrode during a second time period.

### Claim 11 (depends on 1)

The microplasma generator of claim 1 further comprising:
a second substrate comprising a second substrate surface, wherein the second substrate surface is substantially parallel to the substrate surface;
a third generation electrode formed on the second substrate surface, wherein the third generation electrode is located opposite the first generation electrode across the space between the substrate surface and the second substrate surface;
a fourth generation electrode formed on the second substrate surface, wherein
the fourth generation electrode is located opposite the second generation electrode across the space between the substrate surface and the second substrate surface,
a distance between edges of the third generation electrode and the fourth generation electrode is such that a second plasma can be formed in the ambient gas at a predetermined voltage difference between the third generation electrode and the fourth generation electrode, wherein the ambient gas is in contact with the second substrate surface.

### Claim 12 (depends on 11)

The microplasma generator of claim 11 further comprising:
a third drive electrode formed on the second substrate surface, wherein the third drive electrode is formed closer to the third generation electrode and formed external to the region between the third and fourth generation electrodes; and
a fourth drive electrode formed on the second substrate surface, wherein
the fourth drive electrode is formed closer to the fourth generation electrode and formed external to the region between the third and fourth generation electrodes, and
the third and fourth drive electrodes are formed such that an electric field formed between the third and fourth drive electrodes can attract the second plasma to one of the third and fourth drive electrodes, and
a distance between the substrate surface and the second substrate surface is such that movement of the second plasma can affect movement of non-ionized molecules of the ambient gas near the plasma and movement of the plasma can affect movement of non-ionized molecules of the ambient gas near the second plasma.

### Claim 13

A method for providing a microplasma generator, the method comprising:
providing a first generation electrode on a substrate surface;
providing a second generation electrode on the substrate surface;
providing an ambient gas at a first pressure in contact with the substrate surface and the first and second generation electrodes;
applying a predetermined voltage difference between the first generation electrode and the second generation electrode, wherein one of the first and second generation electrode is configured to be a field emitting electrode when a voltage is applied;
forming a plasma in the ambient gas between the first generation electrode and the second generation electrode, wherein the distance between edges of the first and second generation electrodes is such that the distance multiplied by the first pressure is at or below a minimum of a Paschen curve for the ambient gas at the first pressure for the predetermined voltage;
providing a first drive electrode formed on the substrate surface, wherein the first drive electrode is closer to the first generation electrode and external to the region between the first and second generation electrodes;
providing a second drive electrode formed on the substrate surface,
wherein
the second drive electrode is closer to the second generation electrode and external to the region between the first and second generation electrodes; and
applying a voltage difference to the first and second drive electrodes to attract the plasma to one of the first and second drive electrodes.

### Claim 14 (depends on 13)

The method of claim 13 wherein the distance between the edge of the first generation electrode to the nearest edge of the second generation electrode is about 0.25 microns and the ambient gas comprises air at one atmosphere pressure.

### Claim 15

(canceled)

### Claim 16 (depends on 13)

The method of claim 13 wherein a distance between nearest edges of the first drive electrode and the first generation electrode is at or about 2 microns and a distance between the second drive electrode and the second generation electrode is at or about 2 microns.

### Claim 17

A microplasma generator comprising:
a substrate comprising a substrate surface;
a first generation electrode located on the substrate surface;
a second generation electrode located on the substrate surface, wherein
one of the first and second generation electrode is configured to be a field emitting electrode when a voltage is applied, and
a distance between edges of the first generation electrode and the second generation electrode is such that a plasma can be formed in an ambient gas at a predetermined voltage difference between the first generation electrode and the second generation electrode, wherein the ambient gas is in contact with the substrate surface and at a first pressure;
a first generation bus located in the substrate and coupled to the first generation electrode; and
a second generation bus located in the substrate and coupled to the second generation electrode, wherein the first and second generation busses are configured to provide the predetermined voltage difference to the first and second generation electrodes.

### Claim 18 (depends on 17)

The microplasma generator of claim 17 wherein the distance between the edges of the first and second generation electrodes is such that the distance multiplied by the first pressure is at or below a minimum of a Paschen curve for the ambient gas at the first pressure for the predetermined voltage.

### Claim 19 (depends on 18)

The microplasma generator of claim 18 further comprising:
a first drive electrode located on the substrate surface, wherein the first drive electrode is located closer to the first generation electrode and formed external to the region between the first and second generation electrode;
a second drive electrode located on the substrate surface, wherein
the second drive electrode is located closer to the second generation electrode and formed external to the region between the first and second generation electrodes, and
the first and second drive electrodes are located such that an electric field formed between the first and second drive electrodes can attract the plasma to one of the first and second drive electrodes;
a first drive bus located in the substrate and coupled to the first drive electrode; and
a second drive bus located in the substrate and coupled to the second drive electrode, wherein the first and second drive busses are configured to provide a voltage differential to the first and second drive electrodes sufficient to form the electric field.

### Claim 20 (depends on 19)

The microplasma generator of claim 19 further comprising:
a third generation electrode located on the substrate surface, wherein
the third generation electrode is located closer to the second drive electrode than the first drive electrode, and located external to the region between the first and second drive electrodes, and
the third generation electrode is coupled to the first generation bus;
a fourth generation electrode located on the substrate surface, wherein
a distance between edges of the third generation electrode and the fourth generation electrode is such that a plasma can be formed in the ambient gas at a predetermined voltage difference between the third generation electrode and the fourth generation electrode, and
the fourth generation electrode is coupled to the second generation bus; and
a third drive electrode located on the substrate surface, wherein
the third drive electrode is located closer to the fourth generation electrode than the third generation electrode and located external to the region between the third and fourth generation electrodes, and
the second and third drive electrodes are located such that an electric field formed between the second and third drive electrodes can attract the plasma to one of the second and third drive electrodes, and
the third drive electrode is coupled to the first drive bus.