# US 12,009,247 B2 · Heterogeneous integration of components onto compact devices using moiré based metrology and vacuum based pick-and-place

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- Number: US 12,009,247 B2
- Document ID: US12009247B2
- Status: Granted
- Kind: B2
- Application number: 17/959,932
- Filed: 2022-10-04
- Published: 2023-02-09
- Granted: 2024-06-11
- Earliest claimed: 2016-12-23
- Assignees: Board of Regents, The University of Texas System
- Applicants: Board of Regents, The University of Texas System
- Inventors: Sidlgata V. Sreenivasan; Paras Ajay; Aseem Sayal; Mark McDermott; Shrawan Singhal; Ovadia Abed; Lawrence Dunn; Vipul Goyal; Michael Cullinan
- Web page: https://patentgrep.com/patent/US12009247B2

## CPC

- H10P 72/74: {using temporarily an auxiliary support}
- B81C 99/002: {Apparatus for assembling MEMS, e.g. micromanipulators (micromanipulators per se B25J7/00)}
- G06F 30/392: Floor-planning or layout, e.g. partitioning or placement
- G06F 30/396: Clock trees
- G06F 30/398: Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] (optical proximity correction [OPC] design processes G03F1/36)
- H10P 72/0446: {Apparatus for mounting on conductive members, e.g. leadframes or conductors on insulating substrates}
- H10P 72/78: using vacuum or suction, e.g. Bernoulli chucks
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- G06F 2117/10: Buffer insertion
- H10P 72/7408: {the auxiliary support including alignment aids}
- H10P 72/7414: {the auxiliary support including means facilitating the selective separation of some of a plurality of devices from the auxiliary support}
- H10P 72/7428: {used to support diced chips prior to mounting}
- H10P 72/7434: {used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate}
- H10P 72/744: {Details of chemical or physical process used for separating the auxiliary support from a device or a wafer}
- H10W 46/301: {for alignment}
- H10W 46/601: {for use after dicing}
- H10W 72/0198: {batch processes}
- H10W 90/00: Package configurations
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- 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)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method for assembling heterogeneous components. The assembly process includes using a vacuum based pickup mechanism in conjunction with sub-nm precise moiré alignment techniques resulting in highly accurate, parallel assembly of feedstocks.

## Claims

### Claim 1

A method for assembling components onto a product substrate, the method comprising:
selectively picking one or more elements from a source wafer by a vacuum superstrate attached to said one or more elements;
placing said selectively picked one or more elements onto an adhesive on said product substrate with sub-100 nm placement precision, wherein said adhesive is in a liquid state at a time of said placing which enables said sub-100 nm placement precision, wherein said adhesive is inkjetted or spin-coated onto said product substrate; and
securely attaching said selectively picked one or more elements onto said product substrate by holding onto said one or more elements using said vacuum superstrate until said adhesive reaches its gel point.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein said placement of said selectively picked one or more elements onto said adhesive on said product substrate is arbitrary.

### Claim 3 (depends on 1)

The method as recited in claim 1, wherein said selectively picking and said placing are performed in a massively parallel manner.

### Claim 4 (depends on 1)

The method as recited in claim 1, wherein said one or more elements are fabricated on source wafers with a buried sacrificial layer that is partially or fully removed using a bulk etch process.

### Claim 5 (depends on 4)

The method as recited in claim 4 further comprising:
etching said buried sacrificial layer using an etchant, wherein said etchant comprises vapor hydrofluoric acid.

### Claim 6 (depends on 5)

The method as recited in claim 5, wherein said etching of said buried sacrificial layer using said etchant is timed in such a manner that pillar-like structures remain underneath said one or more elements post-etch.

### Claim 7 (depends on 4)

The method as recited in claim 4 further comprising:
bulk-releasing said one or more elements by etching off an underlying sacrificial layer while holding a vacuum.

### Claim 8 (depends on 7)

The method as recited in claim 7 further comprising:
transferring said one or more elements to an intermediate glass substrate with an ultraviolet-de-tacking adhesive on said intermediate glass substrate.

### Claim 9 (depends on 8)

The method as recited in claim 8 further comprising:
exposing an underside of an element of said one or more elements to selective ultraviolet light to selectively release said element.

### Claim 10 (depends on 1)

The method as recited in claim 1, wherein said one or more elements from said source wafer have access holes to an underlying sacrificial layer.

### Claim 11 (depends on 1)

The method as recited in claim 1, wherein alignment between said vacuum superstrate and said product substrate is achieved using a moiré metrology scheme.

### Claim 12 (depends on 1)

The method as recited in claim 1 further comprising:
performing coarse alignment using stage actuators as said selectively picked one or more elements are brought to said product substrate; and
performing fine alignment after said one or more elements are touching said adhesive on said product substrate in an uncured state.

### Claim 13 (depends on 1)

The method as recited in claim 1, wherein said one or more elements are encapsulated in a chemically inert layer of a particular thickness to protect from chemical damage due to a subsequent material removal process and to mitigate mechanical scratching.

### Claim 14 (depends on 13)

The method as recited in claim 13, wherein said chemically inert layer comprises aluminum oxide or amorphous carbon.

### Claim 15 (depends on 1)

The method as recited in claim 1 further comprising:
selectively attaching to said one or more elements using a vacuum based pickup mechanism; and
selectively releasing said one or more elements using an etchant gas or a mechanical pulling approach.

### Claim 16 (depends on 1)

The method as recited in claim 1, wherein said adhesive is cured using ultraviolet light until it reaches said gel point.

### Claim 17 (depends on 1)

The method as recited in claim 1, wherein, once said product substrate has been fully populated with elements, one or more of a material deposition and a coating is performed, followed by a planarization.

### Claim 18 (depends on 17)

The method as recited in claim 17, wherein said planarization utilizes one or more of the following: an inkjet-based planarization and a chemical mechanical polishing.

### Claim 19 (depends on 1)

The method as recited in claim 1, wherein said one or more elements are selectively picked from said source wafer using vacuum-based pickup, wherein valves are used to activate vacuum holes on said vacuum superstrate to enable said vacuum-based pickup.

### Claim 20 (depends on 19)

The method as recited in claim 19, wherein said activation of said vacuum holes is performed in an addressable manner.

### Claim 21 (depends on 19)

The method as recited in claim 19, wherein said vacuum holes are arranged in substantially a same lattice as said product substrate in its final form.

### Claim 22 (depends on 1)

The method as recited in claim 1, wherein a top surface of said one or more elements placed onto said adhesive on said product substrate is at a same height or higher than all previously placed elements on said product substrate.

### Claim 23 (depends on 1)

The method as recited in claim 1, wherein a thickness of said adhesive is varied by using pre-calculated volumes of adhesive drops.

### Claim 24 (depends on 1)

The method as recited in claim 1, wherein said adhesive shrinks by 2-10% by volume upon reaching said gel point.

### Claim 25

A method for assembling components onto a product substrate, the method comprising:
selectively picking one or more elements from a source wafer by a vacuum superstrate attached to said one or more elements;
placing said selectively picked one or more elements onto said product substrate, wherein said placing is performed with sub-100 nm placement precision; and
securely attaching said selectively picked one or more elements onto said product substrate using direct bonding by holding onto said one or more elements using said vacuum superstrate until said attachment occurs.

### Claim 26 (depends on 25)

The method as recited in claim 25, wherein alignment between said vacuum superstrate and said product substrate is achieved using a moiré metrology scheme.

### Claim 27 (depends on 25)

The method as recited in claim 25, wherein a top surface of said one or more elements placed onto said product substrate is at a same height or higher than all previously placed elements on said product substrate.

### Claim 28 (depends on 25)

The method as recited in claim 25, wherein, once said product substrate has been fully populated with elements, one or more of a material deposition and a coating is performed, followed by a planarization.

### Claim 29 (depends on 28)

The method as recited in claim 28, wherein said planarization utilizes one or more of the following: an inkjet-based planarization and a chemical mechanical polishing.

### Claim 30

A method for assembling components onto a product substrate, the method comprising:
selectively picking one or more elements from a source wafer by a vacuum superstrate attached to said one or more elements;
placing said selectively picked one or more elements onto an adhesive on said product substrate, wherein a top surface of said one or more elements being placed onto said adhesive on said product substrate is at a same height or higher than all previously placed elements on said product substrate, wherein said adhesive is in a liquid state at a time of said placing, wherein said adhesive is inkjetted or spin-coated onto said product substrate; and
securely attaching said selectively picked one or more elements onto said product substrate by holding onto said one or more elements using said vacuum superstrate until said adhesive reaches its gel point.

### Claim 31 (depends on 30)

The method as recited in claim 30, wherein a thickness of said adhesive is varied by using pre-calculated volumes of adhesive drops.

### Claim 32 (depends on 30)

The method as recited in claim 30, wherein said adhesive shrinks by 2-10% by volume upon reaching said gel point.

### Claim 33

A method for assembling components onto a product substrate, the method comprising:
selectively picking one or more elements with a distribution from a source wafer by a vacuum superstrate attached to said one or more elements;
placing said selectively picked one or more elements onto said product substrate, wherein said placing is performed with sub-100 nm placement precision, wherein said sub-100 nm placement precision is enabled by in-liquid fine alignment, and
securely attaching said selectively picked one or more elements onto said product substrate by holding onto said one or more elements using said vacuum superstrate until attachment occurs.

### Claim 34 (depends on 33)

The method as recited in claim 33, wherein alignment between said vacuum superstrate and said product substrate is achieved using a moiré metrology scheme.

### Claim 35 (depends on 33)

The method as recited in claim 33, wherein a top surface of said one or more elements placed onto said product substrate is at a same height or higher than all previously placed elements on said product substrate.

### Claim 36 (depends on 33)

The method as recited in claim 33, wherein, once said product substrate has been fully populated with elements, one or more of a material deposition and a coating is performed, followed by a planarization.

### Claim 37 (depends on 36)

The method as recited in claim 36, wherein said planarization utilizes one or more of the following: an inkjet-based planarization and a chemical mechanical polishing.