# US 9,041,003 B2 · Semiconductor devices having a recessed electrode structure

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- Number: US 9,041,003 B2
- Document ID: US9041003B2
- Status: Granted
- Kind: B2
- Application number: 13/649,658
- Filed: 2012-10-11
- Published: 2013-04-25
- Granted: 2015-05-26
- Earliest claimed: 2011-10-11
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Tomas Apostol Palacios; Bin Lu; Elison de Nazareth Matioli
- Web page: https://patentgrep.com/patent/US9041003B2

## CPC

- H10D 62/8503: {Nitride Group III-V materials, e.g. AlN or GaN}
- H10D 8/60: Schottky-barrier diodes
- H10D 8/605: {of the trench conductor-insulator-semiconductor barrier type, e.g. trench MOS barrier Schottky rectifiers [TMBS]}
- 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 62/221: {of FETs}
- H10D 64/01358: {the insulator being formed after the semiconductor body, the semiconductor being a Group III-V material}
- H10D 64/117: {Recessed field plates, e.g. trench field plates or buried field plates}
- H10D 64/23: Electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. sources, drains, anodes or cathodes
- H10D 64/411: {for FETs}
- H10D 64/513: {within recesses in the substrate, e.g. trench gates, groove gates or buried gates}
- H10D 64/685: {being perpendicular to the channel plane}
- H10D 64/691: {comprising metallic compounds, e.g. metal oxides or metal silicates (insulators comprising nitrogen H10D64/693)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

## Claims

### Claim 1

A semiconductor structure, comprising:
a semiconductor region including a III-N semiconductor material, the semiconductor region having trenches formed therein;
a conductive electrode, the conductive electrode including conductive regions formed in the trenches of the semiconductor region; and
an insulating region between the semiconductor region and the conductive electrode, the insulating region extending at least partially across an interface between the semiconductor region and the conductive electrode,
wherein the semiconductor region is a first semiconductor region and the III-N semiconductor material is a first III-N semiconductor material, and wherein the semiconductor structure further comprises a second semiconductor region between the first semiconductor region and the conductive electrode, the second semiconductor region including a second III-N semiconductor material,
wherein the first III-N semiconductor material includes GaN, and
wherein the second III-N semiconductor material includes AlInGaN.

### Claim 2 (depends on 1)

The semiconductor structure of claim 1, the semiconductor structure comprising a field effect transistor, the field effect transistor comprising:
a source region; and
a drain region,
wherein the first semiconductor region is between the source region and the drain region, and
wherein the conductive electrode extends, over a channel region of the field effect transistor, no more than a portion of a distance between the source region and the drain region.

### Claim 3 (depends on 2)

The semiconductor structure of claim 2, wherein the conductive electrode forms a gate of the field effect transistor.

### Claim 4 (depends on 2)

The semiconductor structure of claim 2, wherein the conductive electrode forms a field plate of the field effect transistor.

### Claim 5 (depends on 2)

The semiconductor structure of claim 2, wherein the field effect transistor is an enhancement-mode field effect transistor having a normally-off gate region.

### Claim 6 (depends on 2)

The semiconductor structure of claim 2, wherein the field effect transistor is configured to block more than 100 V when the field effect transistor is in an off state.

### Claim 7 (depends on 2)

The semiconductor structure of claim 2, wherein a gate of the field effect transistor has a length of at least 60 nanometers, wherein the length extends along a direction extending between the source and the drain.

### Claim 8 (depends on 2)

The semiconductor structure of claim 2, wherein the trenches are first trenches and the conductive electrode is a first conductive electrode, wherein the first semiconductor region has second trenches formed therein, and wherein the field effect transistor further comprises a second conductive electrode having conductive regions formed in the second trenches.

### Claim 9 (depends on 8)

The semiconductor structure of claim 8, wherein the first conductive electrode forms a gate of the field effect transistor and the second conductive electrode forms a field plate of the field effect transistor.

### Claim 10 (depends on 2)

The semiconductor structure of claim 2, further comprising a diode, wherein the conductive electrode forms an anode of the diode, wherein the anode of the diode is positioned between a gate of the field effect transistor and the drain region and the anode is electrically connected to the source region.

### Claim 11 (depends on 2)

The semiconductor structure of claim 2, wherein the field effect transistor is a normally-off transistor.

### Claim 12 (depends on 1)

The semiconductor structure of claim 1, wherein the first III-N semiconductor material has a different bandgap from that of the second III-N semiconductor material.

### Claim 13 (depends on 1)

The semiconductor structure of claim 1, wherein the first semiconductor region comprises a plurality of semiconductor layers and/or the second semiconductor region comprises a plurality of semiconductor layers.

### Claim 14 (depends on 1)

The semiconductor structure of claim 1, wherein the conductive electrode includes a metal.