# US 12,218,066 B2 · Monolithic formation of a set of interconnects below active devices

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- Number: US 12,218,066 B2
- Document ID: US12218066B2
- Status: Granted
- Kind: B2
- Application number: 18/458,591
- Filed: 2023-08-30
- Published: 2023-12-21
- Granted: 2025-02-04
- Earliest claimed: 2020-09-30
- Assignees: Tokyo Electron Limited
- Applicants: Tokyo Electron Limited
- Inventors: Daniel Chanemougame; Lars Liebmann; Jeffrey Smith
- Web page: https://patentgrep.com/patent/US12218066B2

## CPC

- H10D 84/0149: {Manufacturing their interconnections or electrodes, e.g. source or drain electrodes}
- H10W 70/611: {for connecting multiple chips together}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10D 84/853: {comprising FinFETs}
- H10W 20/021: {of interconnections within wafers or substrates}
- H10W 20/0696: {by using sacrificial placeholders, e.g. using sacrificial plugs}
- H10W 20/20: Interconnections within wafers or substrates, e.g. through-silicon vias [TSV]
- H10W 20/427: {Power or ground buses}
- H10W 20/481: {on the rear surfaces of the wafers or substrates}
- H10W 70/685: comprising multiple insulating layers
- H10W 72/50: Bond wires
- H10D 84/0158: {the components including FinFETs}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

An additional set of interconnects is created in bulk material, allowing connections to active devices to be made from both above and below. The interconnects below the active devices can form a power distribution network, and the interconnects above the active devices can form a signaling network. Various accommodations can be made to suit different applications, such as encapsulating buried elements, using sacrificial material, and replacing the bulk material with a dielectric. Epitaxial material can be used throughout the formation process, allowing for the creation of a monolithic substrate.

## Claims

### Claim 1

A method of fabrication, the method comprising:
providing a substrate, the substrate comprising bulk semiconductor material;
forming an opening in the bulk semiconductor material patterned for a first wiring structure;
filling the opening in the bulk semiconductor material with a metal such that the first wiring structure is formed at least partially within the bulk semiconductor material;
epitaxially growing active semiconductor material over the first wiring structure so that the bulk semiconductor material and the active semiconductor material are in direct contact with each other, wherein the bulk semiconductor material and the active semiconductor material together form a monocrystalline structure;
forming one or more active devices in the active semiconductor material over the first wiring structure; and
forming a second wiring structure over the one or more active devices.

### Claim 2 (depends on 1)

The method claim 1, further comprising capping the metal with dielectric prior to epitaxially growing the active semiconductor material.

### Claim 3 (depends on 1)

The method of claim 1, wherein the filling the opening comprises:
filling the opening with sacrificial material;
accessing the first wiring structure from a backside of the substrate; and
replacing the sacrificial material with the metal.

### Claim 4 (depends on 1)

The method of claim 1, further comprising replacing the bulk semiconductor material with an insulating material that surrounds the metal.

### Claim 5 (depends on 1)

The method of claim 1, wherein the forming one or more active devices comprises forming one or more of a FINFET device, a CFET device and a side-by-side-nanosheet device in the active semiconductor material.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first wiring structure includes a power delivery network and the second wiring structure includes a signaling network.

### Claim 7 (depends on 1)

The method of claim 1, wherein the bulk semiconductor material is silicon and the active semiconductor material is silicon.

### Claim 8 (depends on 1)

The method of claim 1, wherein the first wiring structure comprises a plurality of wiring layers, the method further comprising:
forming a first layer of the first wiring structure within the bulk semiconductor material;
epitaxially growing additional semiconductor material over the first wiring layer; and
forming a subsequent layer of the first wiring structure within the additional semiconductor material.

### Claim 9 (depends on 8)

The method of claim 8, further comprising repeating steps of epitaxially growing additional semiconductor material and forming a subsequent layer of the first wiring structure within the additional semiconductor material until completing a predetermined number of wiring layers for the first wiring structure.

### Claim 10 (depends on 1)

The method of claim 1, further comprising insulating the openings with dielectric prior to the filling the openings with the metal.

### Claim 11 (depends on 1)

The method of claim 1, further comprising:
forming the first wiring structure as a multilayer fan-in wiring structure; and
forming the second wiring structure as a multilayer fan-out structure.

### Claim 12 (depends on 11)

The method of claim 11, wherein a largest critical dimension within the first and second wiring structures is no greater than 50 nm.

### Claim 13

A method of fabrication, the method comprising:
providing a substrate, the substrate comprising bulk semiconductor material;
forming an opening in the bulk semiconductor material patterned for a first wiring structure;
filling the opening in the bulk semiconductor material with a metal such that the first wiring structure is formed at least partially within the bulk semiconductor material;
epitaxially growing active semiconductor material over the first wiring structure so that the bulk semiconductor material and the active semiconductor material are in direct contact with each other;
forming one or more active devices in the active semiconductor material over the first wiring structure; and
forming a second wiring structure over the one or more active devices, wherein the active semiconductor material and the bulk semiconductor material include a same semiconductor material,
the active semiconductor material is epitaxially grown over the first wiring structure so that the first wiring structure is fully within the same semiconductor material, and
the active semiconductor material is epitaxially grown over the first wiring structure so that the first wiring structure comprises a patterned layer of the metal fully within the same semiconductor material with air gaps above the metal.

### Claim 14 (depends on 13)

The method claim 13, further comprising capping the metal with dielectric prior to epitaxially growing the active semiconductor material.

### Claim 15 (depends on 13)

The method of claim 13, wherein the filling the opening comprises:
filling the opening with sacrificial material;
accessing the first wiring structure from a backside of the substrate; and
replacing the sacrificial material with the metal.

### Claim 16 (depends on 13)

The method of claim 13, further comprising replacing the bulk semiconductor material with an insulating material that surrounds the metal.

### Claim 17 (depends on 13)

The method of claim 13, wherein the forming one or more active devices comprises forming one or more of a FINFET device, a CFET device and a side-by-side-nanosheet device in the active semiconductor material.

### Claim 18 (depends on 13)

The method of claim 13, wherein the first wiring structure includes a power delivery network and the second wiring structure includes a signaling network.

### Claim 19 (depends on 13)

The method of claim 13, wherein the first wiring structure comprises a plurality of wiring layers, the method further comprising:
forming a first layer of the first wiring structure within the bulk semiconductor material;
epitaxially growing additional semiconductor material over the first wiring layer; and
forming a subsequent layer of the first wiring structure within the additional semiconductor material.

### Claim 20 (depends on 13)

The method of claim 13, further comprising:
forming the first wiring structure as a multilayer fan-in wiring structure; and
forming the second wiring structure as a multilayer fan-out structure.