Trench Shield Electrode Contact Structure for Semiconductor Devices
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Solution Overview
Problem
Current semiconductor devices with shield electrodes face challenges in integrating them effectively with other structures, particularly in non-planar topographies and die area consumption, which affects cost and manufacturability, and there is a need for improved performance and reliability.
Innovation Solution
The semiconductor device incorporates a trench structure with a control electrode layer and a shield electrode layer, where both layers are recessed below the major surface, and contact is made to them within the trench structure, with the shield electrode surrounded by a thick insulator layer, optimizing the integration and performance by reducing gate-to-drain capacitance and enhancing switching characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shield electrodes are integrated with trench structures, then gate-to-drain capacitance is reduced and switching performance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The shield electrode is merged with the trench structure by forming the shield electrode within the trench itself, combining two previously separate components into a single integrated structure. This reduces the number of discrete elements and simplifies the overall device architecture while maintaining the capacitance reduction benefit
Solution Approach 2:
The shield electrode is nested within the trench structure, with the shield electrode positioned inside the trench cavity. This nested arrangement allows the shield electrode to be housed within the existing trench geometry, reducing spatial requirements and simplifying integration without adding external complexity
2Reliability
If shield electrodes are added to reduce capacitance, then switching characteristics are enhanced, but die area consumption increases
Solution Approach 1:
The shield electrode is positioned in the vertical dimension within the trench, rather than expanding horizontally at the surface level. This vertical placement utilizes the third dimension (depth) to accommodate the shield electrode functionality without increasing the two-dimensional die area footprint
3Ease of manufacture
If shield electrodes are integrated into trench structures, then manufacturing processes are simplified, but contact formation difficulty increases due to non-planar topography
Solution Approach 1:
The contact structure is designed to make electrical contact with the shield electrode at the same potential level within the trench, eliminating the need for complex elevated contacts or additional planarization steps. By establishing contact at the equipotential surface, the design simplifies the contact formation process despite the non-planar trench topography
Data Source
AI summary
In one embodiment, a contact structure for a semiconductor device having a trench shield electrode includes a gate electrode contact portion and a shield electrode contact portion within a trench structure. Contact is made to the gate electrode and the shield electrode within or inside of the trench structure. A thick passivating layer surrounds the shield electrode in the contact portion.