Trench Gate Semiconductor Device With Integrated Diode Contact
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Solution Overview
Problem
Existing power semiconductor switches face challenges in achieving high blocking capability and efficient reverse conducting body diode performance due to limitations in shielding regions and gate dielectric protection under strong electric fields.
Innovation Solution
The semiconductor device incorporates trench structures with gate and contact structures extending into the semiconductor body, forming transistor mesas with specific pn junctions and diode regions that directly adjoin contact structures, enhancing electric field shielding and reducing on-state resistance through increased active channel area and direct vertical connections for the body diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shielding regions are added to protect gate dielectric against strong electric field, then gate dielectric protection is improved, but device complexity increases
Solution Approach 1:
The patent merges the shielding region function with the body diode function into a single structural element. The n-type shielding region serves dual purposes: protecting the gate dielectric from strong electric fields during blocking state while simultaneously forming the body diode for reverse current conduction. This integration eliminates the need for separate shielding structures and body diode structures, thereby reducing device complexity while maintaining reliability.
Solution Approach 2:
The shielding region is designed to perform multiple functions: (1) electric field shielding to protect gate dielectric during blocking state, (2) forming the body diode anode region for reverse conducting capability, and (3) providing a conductive path for reverse current. This multi-functionality approach allows a single structure to address multiple requirements, reducing overall device complexity while improving reliability.
2Reliability
If trench structures with contact structures extending through gate structure are used, then on-state resistance is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The contact structure is formed to extend through the gate structure in advance, establishing direct vertical connections between the n-type shielding region and the n+-type source region before final device operation. This preliminary structural arrangement ensures low on-state resistance by pre-establishing optimal current paths, while the self-aligned nature of the trench formation process helps manage manufacturing precision requirements.
Solution Approach 2:
The patent transitions from planar contact structures to vertical three-dimensional trench structures that extend through the gate structure. This dimensional change creates direct vertical current paths that reduce on-state resistance by shortening current flow paths and increasing effective contact area, while the standardized trench geometry provides clear manufacturing targets for precision control.
3Reliability
If diode regions directly adjoin contact structures, then reverse conducting capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the body diode formation with the contact structure arrangement. The n-type diode regions are positioned to directly adjoin the contact structures that extend through the gate structure, creating an integrated path for reverse current conduction. This integration eliminates the need for separate body diode structures, reducing device complexity while improving reverse conducting capability.
Solution Approach 2:
The contact structures serve dual functions: providing electrical connections during normal transistor operation and serving as electrodes for the body diode during reverse conduction mode. The n-type diode regions directly adjoining these contact structures enable the same structural elements to facilitate both forward transistor current and reverse diode current, achieving multi-functionality without increasing overall device complexity.
Data Source
AI summary
A semiconductor device includes trench structures that extend from a first surface into a semiconductor body. The trench structures include a gate structure and a contact structure that extends through the gate structure, respectively. Transistor mesas are between the trench structures. Each transistor mesa includes a body zone forming a first pn junction with a drift structure and a second pn junction with a source zone. Diode regions directly adjoin one of the contact structures form a third pn junction with the drift structure, respectively.