# US 11,444,027 B2 · Wafer-scale satellite with integrated propulsion and attitude control

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- Number: US 11,444,027 B2
- Document ID: US11444027B2
- Status: Granted
- Kind: B2
- Application number: 16/875,367
- Filed: 2020-05-15
- Published: 2020-11-19
- Granted: 2022-09-13
- Earliest claimed: 2019-05-15
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Mordechai Rothschild; Sumanth Kaushik; Melissa A. Smith; Livia Racz; Dennis Burianek
- Web page: https://patentgrep.com/patent/US11444027B2

## CPC

- B64G 1/1085: {Swarms and constellations}
- H10W 20/427: {Power or ground buses}
- B64G 1/10: Artificial satellites; Systems of such satellites; Interplanetary vehicles (space shuttles B64G1/14)
- B64G 1/244: {Spacecraft control systems}
- B64G 1/402: {Propellant tanks; Feeding propellants}
- B64G 1/42: Arrangements or adaptations of power supply systems
- B64G 1/428: {Power distribution and management}
- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- H10W 20/20: Interconnections within wafers or substrates, e.g. through-silicon vias [TSV]
- B64G 1/40: Arrangements or adaptations of propulsion systems
- B64G 1/403: {Solid propellant rocket engines}
- B64G 1/411: {Electric propulsion}
- B64G 1/425: {Power storage}
- B64G 1/443: {Photovoltaic cell arrays}
- G01S 19/37: Hardware or software details of the signal processing chain
- B64G: COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A wafer-scale satellite bus and a manner of making the same include using wafer reconstruction techniques to stack functional diced circuits onto each other and bond them. The disclosed techniques allow for a variety of functions in each die, including providing, without limitation: ground-based communications, attitude and propulsion control, fuel tanks and thrusters, and power generation. The wafers are initially manufactured according to a common wafer design that provides electrical and power interconnects, then different wafers are further processed using subsystem-specific techniques. The circuits on differently-processed wafers are reconstructed into a single stack using e.g. wafer bonding. Surface components are mounted, and the circuitry is diced to form the final satellites. Mission-specific functions can be incorporated, illustratively by surface-mounting, to the bus at an appropriate stage of assembly, on-wafer circuitry or instrument packages for performing these functions.

## Claims

### Claim 1

A method of manufacturing a satellite, the method comprising:
forming, on wafers, a plurality of uniform bus dice, each bus die in the plurality of uniform bus dice comprising interconnects for conveying electrical signals and for powering circuitry connected thereto;
processing, on each of a plurality of the wafers, the uniform bus dice according to a respective different function in a plurality of subsystem functions that includes at least control over spatial attitude and propulsion of the satellite in a microgravity environment, wherein processing at least one such uniform bus die includes forming a cavity in the bus die and mounting unpackaged circuitry within the cavity; and
bonding the processed wafers to form the satellite in a stack so as to protect the circuitry mounted within the cavity.

### Claim 2 (depends on 1)

The method according to claim 1, wherein forming on wafers includes forming on wafers of silicon, or glass, or an organic substrate.

### Claim 3 (depends on 1)

The method according to claim 1, wherein forming the plurality of uniform bus dice comprises:
forming, in each of the wafers, through-wafer vias;
forming, in the through-wafer vias, the interconnects for conveying electrical signals; and
forming, on a top surface and a bottom surface of each of the wafers, the interconnects for powering circuitry connected thereto.

### Claim 4 (depends on 1)

The method according to claim 1, wherein processing each of the wafers includes processing the wafer to provide, by the wafer: a communication function, or a fuel storage function, or a propulsive function, or an attitude control function, or a power generation function, or a satellite control function, or any combination thereof.

### Claim 5 (depends on 1)

The method according to claim 1, wherein processing each of the wafers includes forming a through-wafer via, or forming a cavity in the wafer, or surface-mounting circuitry diced from the wafer or from a different wafer, or any combination thereof.

### Claim 6 (depends on 1)

The method according to claim 1, further comprising processing a given wafer according to a mission-specific subsystem function, wherein bonding the stack of the processed wafers includes bonding the stack including the given wafer.

### Claim 7 (depends on 6)

The method according to claim 6, wherein bonding the stack including the given wafer comprises bonding the stack having, in order: a processed wafer having a communication function; the given wafer; a processed wafer having a propulsive function; and a processed wafer having a power generation function.

### Claim 8 (depends on 1)

The method according to claim 1, wherein processing the at least one uniform bus die further includes backfilling a cavity in its wafer, or planarizing the bus die for stacking, or both backfilling and planarizing.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the bonded stack of processed wafers comprises a plurality of satellites, the method further comprising dicing the bonded stack to separate the satellites from each other.

### Claim 10

A satellite comprising:
a plurality of wafers, each wafer comprising a uniform bus die having interconnects for conveying electrical signals and for powering circuitry connected thereto, each wafer further comprising the circuitry connected thereto according to a respective different function in a plurality of subsystem functions that includes at least control over spatial attitude and propulsion of the satellite in a microgravity environment;
wherein at least one wafer in the plurality of wafers comprises a cavity into which an unpackaged circuit has been mounted; and
wherein the plurality of wafers were bonded to form the satellite in a stacked configuration so as to protect the circuit within the cavity.

### Claim 11 (depends on 10)

The satellite according to claim 10, wherein at least one of the plurality of wafers comprises silicon, or glass, or an organic substrate.

### Claim 12 (depends on 10)

The satellite according to claim 10, wherein each uniform bus die comprises one or through-wafer vias having interconnects for conveying the electrical signals.

### Claim 13 (depends on 10)

The satellite according to claim 10, wherein each uniform bus die comprises, on a top surface and a bottom surface of its wafer, the interconnects for powering circuitry connected thereto.

### Claim 14 (depends on 10)

The satellite according to claim 10, wherein the circuitry mounted to each wafer comprises circuitry for providing: a communication function, or a fuel storage function, or a propulsive function, or an attitude control function, or a power generation function, or a satellite control function, or any combination thereof.

### Claim 15 (depends on 10)

The satellite according to claim 10, wherein each of the wafers further includes, according to the respective function of the circuitry connected thereto: a through-wafer via, or a cavity in the wafer, or surface-mounting circuitry diced from the wafer or from a different wafer, or any combination thereof.

### Claim 16 (depends on 10)

The satellite according to claim 10, wherein a given wafer in the plurality of wafers has a mission-specific subsystem function.

### Claim 17 (depends on 16)

The satellite according to claim 16, wherein the stacked configuration has, in order: a processed wafer having a communication function; the given wafer having the mission-specific subsystem function; a processed wafer having a propulsive function; and a processed wafer having a power generation function.

### Claim 18 (depends on 10)

The satellite according to claim 10, further comprising backfill in the cavity.

### Claim 19 (depends on 10)

The satellite according to claim 10, wherein each uniform bus die has been planarized for stacking.

### Claim 20 (depends on 10)

A plurality of satellites according to claim 10, in orbit around the Earth and acting separately, or as a cluster, or as a constellation.