Semiconductor Device Trench Depth Variation Mitigation
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Solution Overview
Problem
Variations in trench depth cause significant variations in the resistance and current detection precision of trench type IGBTs, making it difficult to detect the main current with high precision.
Innovation Solution
Incorporating a planar gate type element region in the sense cell area of the semiconductor device, which reduces carrier density variations and stabilizes the sense current, while maintaining high integration in the main cell region with trench gate type elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If trench gate type elements are used in the sense cell region, then high integration is achieved, but variations in trench depth cause large variations in sense current and resistance
Solution Approach 1:
The patent applies different gate structures to different regions: trench gate type elements are used in the main cell region for high integration, while planar gate type elements are used in the sense cell region for stable current detection. This local differentiation allows each region to optimize its function without compromising the other.
2Manufacturing precision
If trench depth is reduced, then manufacturing precision is improved, but hole density variations still affect resistance value
Solution Approach 1:
The patent extracts the sense cell region from the main cell region and applies a different gate structure (planar gate) to it. This separation allows the sense cell to be optimized for measurement stability without being constrained by the trench depth requirements of the main cell region.
3Measurement precision
If planar gate type elements are used in the sense cell region, then sense current stability is improved, but device complexity increases
Solution Approach 1:
The patent segments the semiconductor device into main cell region and sense cell region, each with specialized gate structures. This segmentation allows the sense cell to use simpler planar gates for stable measurement while the main cell uses trench gates for high integration, reducing overall system complexity through functional specialization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration inhibits variations in the sense current, stabilizing current detection precision and reducing the impact of trench depth variations, ensuring consistent performance across semiconductor devices.
Implementation Method 1
the gate electrode is applied with a positive voltage. Accordingly, electrons are attracted to the trench gates 904. As a result, in portions of the body region 901 in contact with the trench gates 904, channels inverted to N type are formed.
Implementation Method 2
Electrons are injected through the channels from the emitter regions 905 into the drift region 908. Further, holes are injected from the collector region 903 into the drift region 908.
Implementation Method 3
When holes which are minority carriers are injected into the drift region 908, the density of electrons which are majority carriers increases in order to keep the neutrality condition for carriers in the drift region 908 (so-called conductivity modulation).
Implementation Method 4
Such movement of the electrons and holes results in flow of a main current and a sense current passing from a back surface side (collector region 903 side) toward an upper surface side (emitter region 905 side) of the semiconductor device 900.
Data Source
AI summary
The present teachings provides a bipolar semiconductor device comprising: a main cell region consisting of a trench gate type element region; and a sense cell region including a planar gate type element region.