CN-122002861-A - Silicon carbide semiconductor device with trench gate structure and shielding region

Abstract

The invention relates to a semiconductor device (500) having a gate structure (150) extending from a first surface (101) into a silicon carbide body (100), wherein a width (w 1) of the gate structure (150) in a first horizontal direction (191) parallel to the first surface (101) is smaller than a vertical extension (v 1) of the gate structure (150) perpendicular to the first surface (101). Contact structures (315) extend from the first surface (101) into the silicon carbide body (100), wherein the gate structures (150) and the contact structures (315) alternate along a first horizontal direction (191). A shielding region (160) in the silicon carbide body (100) is adjacent to a bottom of the contact structure (315) and spaced apart from the gate structure (150) along a first horizontal direction (191).

Inventors

• R. Siminique
• W. BERGNER

Assignees

• 英飞凌科技股份有限公司

Dates

Publication Date

20260508

Application Date

20181130

Priority Date

20171201

Claims (10)

1. 1. A semiconductor device, comprising: A plurality of gate structures extending from the first surface to a first depth in the silicon carbide body, the gate structures having a width along a first horizontal direction parallel to the first surface; a plurality of contact structures extending from a first surface to a second depth in the silicon carbide body, the gate structures and the contact structures alternating along the first horizontal direction; A plurality of shielding regions in the silicon carbide body adjacent to the bottom of the contact structure but not adjacent to the bottom of the gate structure and spaced apart from the gate structure along the first horizontal direction, and A plurality of source regions between the first surface and the body region, Wherein the body region forms a pn-junction with the source region, Wherein the body region includes a main portion adjacent to the gate structure and a contact portion adjacent to the contact structure between the main portion and the contact structure, Wherein the gate structure has a width less than the first depth and the second depth, Wherein each gate structure includes a gate dielectric and a gate electrode, Wherein the gate electrode comprises a first portion of a metal structure adjacent to the gate dielectric, Wherein the contact structure comprises a second portion of the metal structure adjacent to the silicon carbide body.
2. 2. The semiconductor device according to claim 1, wherein The second depth is greater than the first depth.
3. 3. The semiconductor device according to claim 1 or 2, wherein A contact portion of the body region is buried in the silicon carbide body under the source region such that the source region separates the contact portion from the first surface.
4. 4. The semiconductor device according to claim 1 or 2, wherein The gate structure and/or the contact structure are coplanar with the first surface of the silicon carbide body.
5. 5. The semiconductor device according to claim 1 or 2, wherein The contact portion of the body region and the source region are both in contact with sidewalls of the contact structure.
6. 6. The semiconductor device according to claim 1 or 2, wherein The contact portion has a higher doping concentration than the main portion.
7. 7. The semiconductor device according to claim 1 or 2, wherein The width of the shielding region along the first horizontal direction is larger than the width of the contact structure.
8. 8. The semiconductor device according to claim 1 or 2, wherein A mesa portion of the silicon carbide body configured between the gate structure and the contact structure comprises a body region, wherein the body region forms an additional pn junction with a drift structure and wherein the drift structure forms a pn junction with the shielding region.
9. 9. The semiconductor device according to claim 8, wherein The mesa width of the mesa portion along the first horizontal direction is less than at least one of the first depth or the second depth.
10. 10. The semiconductor device according to claim 8, wherein The portion of the contact structure adjacent to the drift structure forms a schottky contact.

Description

Silicon carbide semiconductor device with trench gate structure and shielding region Background Silicon carbide (SiC) based semiconductor devices benefit from the high band gap and high breakdown strength of silicon carbide. But a high number of interface states are formed at the interface between the SiC semiconductor body and the dielectric layer, for example the gate dielectric of a transistor cell of a SiC-MOSFET (SiC metal oxide semiconductor field effect transistor), which can be occupied by more or less carriers depending on the operating state of the SiC-MOSFET. Carriers occupying the interface state affect the mobility and concentration of free carriers that form the channel of the field-controlled transistor in the on-state of the transistor cell. In addition, the high breakdown strength of SiC is often underutilized because the field strength present in the gate dielectric and the reliability of the gate dielectric often limit the compressive strength of SiC-MOSFETs. Technical Field The present application relates to a SiC semiconductor device that can greatly utilize the inherent breakdown electric field strength of silicon carbide. Disclosure of Invention The object of the application is achieved by the subject matter of the independent claims. The dependent claims relate to further embodiments. The present disclosure relates to a semiconductor device having a gate structure, a contact structure, and a shielding region. The gate structure extends from the first surface into the silicon carbide body. The width of the gate structure along a first horizontal direction parallel to the first surface is smaller than a vertical extension of the gate structure perpendicular to the first surface. The contact structure also extends from the first surface into the silicon carbide body. The gate structures and the contact structures alternate along a first horizontal direction. The shielding region is configured in the silicon carbide body adjacent to the bottom of the contact structure and spaced apart from the gate structure along a first horizontal direction. The present disclosure also relates to a semiconductor device having a gate structure and a contact structure extending from a first surface into a silicon carbide body, respectively. The gate structures and the contact structures alternate with each other along a first horizontal direction parallel to the first surface. A body region is configured in the mesa portion of the silicon carbide body between the gate structure and the contact structure. Along the bottom of the contact structure, a shielding region of the conductivity type of the body region is structured and spaced apart from the gate structure along a first horizontal direction. The drift structure with the drift region forms a first pn junction with the body region and forms a schottky contact with the contact structure. The present disclosure also relates to a semiconductor device having a gate structure and a contact structure extending from a first surface into a silicon carbide body, respectively, wherein the gate structure and the contact structure alternate with each other along a first horizontal direction parallel to the first surface. The gate structure has a gate dielectric and a gate electrode, wherein the gate electrode has a first portion of the metal structure adjacent to the gate dielectric. The contact structure has a second portion of the metal structure adjacent the silicon carbide body. A shielding region is configured in the silicon carbide body along a bottom of the contact structure, the shielding region being spaced apart from the gate structure along a first horizontal direction. The present disclosure relates to a method for manufacturing a semiconductor device. A silicon carbide substrate is constructed having a main layer, a bulk layer constructed on a portion of the main layer, and a source layer constructed on a portion of the bulk layer, wherein the bulk layer has a conductivity type opposite to a conductivity type of the source layer and a drift layer constructed in the main layer. Gate trenches and contact trenches are configured extending through the source and body layers and alternating in a first horizontal direction parallel to the first major face of the silicon carbide substrate. A gate dielectric is constructed in the gate trench. A metal structure is constructed having a first portion in the gate trench adjacent to the gate dielectric and a second portion in the contact trench. The second portion is adjacent to the body region formed by the portion of the body layer and the source region formed by the portion of the source layer. A third portion of the metal structure connecting the first portion with the second portion is removed. The present disclosure also relates to a semiconductor device comprising a plurality of gate structures extending from a first surface to a first depth in a silicon carbide body, the gate structures having a width in