# US 12,113,127 B2 · GaN-based high electron mobility transistors and fabrication method thereof

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- Number: US 12,113,127 B2
- Document ID: US12113127B2
- Status: Granted
- Kind: B2
- Application number: 17/719,393
- Filed: 2022-04-13
- Published: 2023-08-24
- Granted: 2024-10-08
- Earliest claimed: 2022-02-21
- Assignees: Nanjing Greenchip Semiconductor Co., Ltd.
- Applicants: Nanjing Greenchip Semiconductor Co., Ltd.
- Inventors: Kuang-Po Hsueh
- Web page: https://patentgrep.com/patent/US12113127B2

## CPC

- H10D 30/475: {having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs}
- H10D 30/015: {of FETs having heterojunction interface channels or heterojunction gate electrodes, e.g. HEMT}
- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 64/254: {for lateral devices wherein the source or drain electrodes extend entirely through the semiconductor bodies, e.g. via-holes for back side contacts}
- H10W 20/42: Vias, e.g. via plugs
- H10W 20/435: {Cross-sectional shapes or dispositions of interconnections}
- H10D 62/343: {Gate regions of field-effect devices having PN junction gates}
- H10D 64/257: {for lateral devices wherein the source or drain electrodes are characterised by top-view geometrical layouts, e.g. interdigitated, semi-circular, annular or L-shaped electrodes (source or drain electrodes of TFTs H10D30/673)}
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A process integration method for connecting the electrode of the normally-off or normally-on GaN-based HEMT to the backside electrode by a deep etching process. Among the three electrodes of each HEMT, a single electrode or multiple electrodes can be connected to the backside electrode. The electrodes to be connected to the backside electrode through an additional deep etching process. Therefore, there is no need to place PADs on various positions as wire bonding electrodes on the upper layer of device, which can reduce the area of the device layout and use the back metal to connect the package frame base island to reduce the wire bonding parasitic effect. A new structure proposed is a design of connecting the electrode and the backside electrode of the normally-off or normally-on GaN-based HEMTs. This process integration technology not only reduce the layout area, but also reduce the parasitic effect of the packaging.

## Claims

### Claim 1

A Gallium Nitride (GaN)-based high electron mobility transistor (HEMT) comprising:
a substrate;
from bottom to top, a n-type Gallium Nitride (GaN) layer, an Aluminum Gallium Nitride (AlGaN) layer and a p-type Gallium Nitride (GaN) layer been formed on one side of said substrate, wherein said n-type GaN layer is used to generate a two-dimensional electron gas therein and used as a channel layer, said p-type GaN layer and said n-type GaN layer form a pn junction to deplete said two-dimensional electron gas in said channel layer;
a backside electrode been formed on other side of said substrate;
a source electrode been formed on said AlGaN layer and making ohmic contact with said AlGaN layer;
a drain electrode been formed on said AlGaN layer not overlapping said source electrode and making ohmic contact with said AlGaN layer; and
a gate electrode been formed on said p-type GaN layer not overlapping said source electrode and said drain electrode;
a protective layer been formed over said AlGaN layer, said source electrode, said drain electrode and said gate electrode;
a plurality of vias been formed in said protective layer to respectively connect said source electrode, said drain electrode and said gate electrode to outside of said protective layer through metal connection; and
a contact via been formed between said outside of said protective layer and said backside electrode, and penetrating through said protective layer, said AlGaN layer, said n-type GaN layer and said substrate to electrically connect one or more electrodes of said source electrode, said drain electrode and said gate electrode to said backside electrode through metal contact.

### Claim 2 (depends on 1)

The GaN-based HEMT of claim 1, wherein material of said substrate includes group consisting of Aluminum Oxide (Al2O3), Silicon Carbide (SiC), Zinc Oxide (ZnO), Silicon substrate (Si), Gallium Nitride (GaN), Aluminum Gallium Nitride (AlxGa1-xN), Indium Gallium Nitride (InxGa1-xN) and Aluminum Indium Gallium Nitride (InxAlyGa1-x-yN), where x, y are the contents (0≤x≤1, 0≤y≤1).

### Claim 3 (depends on 1)

The GaN-based HEMT of claim 1, wherein materials for making said gate electrode, said source electrode and said drain electrode include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 4 (depends on 1)

The GaN-based HEMT of claim 1, wherein materials for making said metal connection include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 5 (depends on 1)

The GaN-based HEMT of claim 1, wherein said other side of said substrate is polished and thinned by a backside polishing process to expose metal contact that filled said contact via before formation of said backside electrode.

### Claim 6 (depends on 1)

The GaN-based HEMT of claim 1, wherein said n-type GaN layer, said p-type GaN layer and said AlGaN layer are formed by molecular beam epitaxy (MBE) or metalorganic vapor phase epitaxy (MOVPE).

### Claim 7

A Gallium Nitride (GaN)-based high electron mobility transistor (HEMT) comprising:
a n-type Gallium Nitride (GaN) layer;
an Aluminum Gallium Nitride (AlGaN) layer been formed on one side of said n-type GaN layer; and
a p-type Gallium Nitride (GaN) layer been formed on said AlGaN layer, wherein said n-type GaN layer is used to generate a two-dimensional electron gas therein and used as a channel layer, said p-type GaN layer and said n-type GaN layer form a pn junction to deplete said two-dimensional electron gas in said channel layer;
a backside electrode been formed on other side of said n-type GaN layer;
a source electrode been formed on said AlGaN layer and making ohmic contact with said AlGaN layer;
a drain electrode been formed on said AlGaN layer not overlapping said source electrode and making ohmic contact with said AlGaN layer; and
a gate electrode been formed on said p-type GaN layer not overlapping said source electrode and said drain electrode;
a protective layer been formed over said AlGaN layer, said source electrode, said drain electrode and said gate electrode;
a plurality of vias been formed in said protective layer to respectively connect said source electrode, said drain electrode and said gate electrode to outside of said protective layer through metal connection; and
a contact via been formed between said outside of said protective layer and said backside electrode, and penetrating through said protective layer, said AlGaN layer and said n-type GaN layer to electrically connect one or more electrodes of said source electrode, said drain electrode and said gate electrode to said backside electrode through metal contact.

### Claim 8 (depends on 7)

The GaN-based HEMT of claim 7, wherein materials for making said gate electrode, said source electrode and said drain electrode include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 9 (depends on 7)

The GaN-based HEMT of claim 7, wherein materials for making said metal connection include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 10 (depends on 7)

The GaN-based HEMT of claim 7, wherein said n-type GaN layer, said p-type GaN layer and said AlGaN layer are formed by molecular beam epitaxy (MBE) or metalorganic vapor phase epitaxy (MOVPE).

### Claim 11

A Gallium Nitride (GaN)-based high electron mobility transistor (HEMT) comprising:
a substrate;
from bottom to top, a n-type Gallium Nitride (GaN) layer and an Aluminum Gallium Nitride (AlGaN) layer been formed on one side of said substrate, wherein said n-type GaN layer is used to generate a two-dimensional electron gas therein and used as a channel layer;
a backside electrode been formed on other side of said substrate;
a source electrode been formed on said AlGaN layer and making ohmic contact with said AlGaN layer;
a drain electrode been formed on said AlGaN layer not overlapping said source electrode and making ohmic contact with said AlGaN layer; and
a gate electrode been formed on said AlGaN layer not overlapping said source electrode and said drain electrode;
a protective layer been formed over said AlGaN layer, said source electrode, said drain electrode and said gate electrode;
a plurality of vias been formed in said protective layer to respectively connect said source electrode, said drain electrode and said gate electrode to outside of said protective layer through metal connection; and
a contact via been formed between said outside of said protective layer and said backside electrode, and penetrating through said protective layer, said AlGaN layer, said n-type GaN layer and said substrate to electrically connect one or more electrodes of said source electrode, said drain electrode and said gate electrode to said backside electrode through metal contact.

### Claim 12 (depends on 11)

The GaN-based HEMT of claim 11, wherein material of said substrate includes group consisting of Aluminum Oxide (Al2O3), Silicon Carbide (SiC), Zinc Oxide (ZnO), Silicon substrate (Si), Gallium Nitride (GaN), Aluminum Gallium Nitride (AlxGa1-xN), Indium Gallium Nitride (InxGa1-xN) and Aluminum Indium Gallium Nitride (InxAlyGa1-x-yN), where x, y are the contents (0≤x≤1, 0≤y≤1).

### Claim 13 (depends on 11)

The GaN-based HEMT of claim 11, wherein materials for making said gate electrode, said source electrode and said drain electrode include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 14 (depends on 11)

The GaN-based HEMT of claim 11, wherein materials for making said metal connection include Au, Pt/Ti/Pt/Au, Ti/Al/Ti/Au, Ti/Au, Cr/Au, Pd/Au, Ti/Pd/Au Pd/Ti/Au, Cr, Pt/Au, Ni/Au, Ta/Ti, Ti/Pt/Au, Ti/Cr/Au, W/Au, W/Cu, Cu or Pt/Ru.

### Claim 15 (depends on 11)

The GaN-based HEMT of claim 11, wherein said n-type GaN layer and said AlGaN layer are formed by molecular beam epitaxy (MBE) or metalorganic vapor phase epitaxy (MOVPE).

### Claim 16 (depends on 11)

The GaN-based HEMT of claim 11, wherein said other side of said substrate is polished and thinned by a backside polishing process to expose metal contact that filled said contact via before formation of said backside electrode.