US 12,477,771 B2
Semiconductor device
Yusuke Kanda, Toyama (JP); and Jun Shimizu, Toyama (JP)
Assigned to NUVOTON TECHNOLOGY CORPORATION JAPAN, Kyoto (JP)
Appl. No. 18/848,769
Filed by Nuvoton Technology Corporation Japan, Kyoto (JP)
PCT Filed Feb. 20, 2023, PCT No. PCT/JP2023/006048
§ 371(c)(1), (2) Date Sep. 19, 2024,
PCT Pub. No. WO2023/181749, PCT Pub. Date Sep. 28, 2023.
Claims priority of provisional application 63/323,736, filed on Mar. 25, 2022.
Prior Publication US 2025/0113526 A1, Apr. 3, 2025
Int. Cl. H10D 30/47 (2025.01); H10D 62/85 (2025.01); H10D 64/23 (2025.01); H10D 64/60 (2025.01)
CPC H10D 30/475 (2025.01) [H10D 62/8503 (2025.01); H10D 64/251 (2025.01); H10D 64/602 (2025.01)] 11 Claims
OG exemplary drawing
 
1. A semiconductor device comprising:
a substrate;
a back-barrier layer that is provided above the substrate and includes a group-III nitride semiconductor;
a channel layer that is provided above the back-barrier layer, includes a gallium nitride semiconductor, and has a band gap smaller than a band gap of the back-barrier layer;
a first barrier layer that is provided above the channel layer, includes a group-III nitride semiconductor containing Al, and has a band gap larger than the band gap of the channel layer;
a second barrier layer that is provided to fill a first recessed portion provided in an upper face of the channel layer, includes a group-III nitride semiconductor containing Al, and has a band gap larger than the band gap of the channel layer;
a two-dimensional electron gas that is generated on a channel layer side of an interface between the channel layer and the first barrier layer or the second barrier layer;
a source electrode and a drain electrode that are provided above the first barrier layer, spaced apart from each other, and each electrically connected to the two-dimensional electron gas; and
a gate electrode that is provided above the second barrier layer and spaced apart from the source electrode and the drain electrode, wherein:
an In composition ratio of the first barrier layer is greater than or equal to 0 and less than an In composition ratio of the second barrier layer,
the In composition ratio of the first barrier layer is represented by a ratio of a total number of In atoms to a total number of all of group-III elements included in the first barrier layer,
the In composition ratio of the second barrier layer is represented by a ratio of a total number of In atoms to a total number of all of group-III elements included in the second barrier layer,
an Al composition ratio of the first barrier layer is greater than or equal to an Al composition ratio of the second barrier layers,
the Al composition ratio of the first barrier layer is represented by a ratio of a total number of Al atoms to the total number of all of the group-III elements included in the first barrier layer,
the Al composition ratio of the second barrier layer is represented by a ratio of a total number of Al atoms to the total number of all of the group-III elements included in the second barrier layer, and
the first barrier layer covers and is in direct contact with at least part of an upper face of the second barrier layer, which is opposite to a lower face of the second barrier layer facing the upper face of the channel layer.