Power Sense Transistor Trench Segmentation for Current Estimation
Solution Overview
Problem
Current integrated circuits for power applications face challenges in precisely estimating load current due to inaccuracies in sensing the voltage differences between the sense and load paths, leading to potential overload or overcurrent conditions.
Innovation Solution
The design incorporates semiconductor power and sense transistors with specific gate trench structures and termination trenches, along with distinct patterning of interface and main layers, to enhance the accuracy of load current estimation by reducing the spread of sense current and improving area efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power and sense transistor cells are commonly controlled with shared gate structures, then device complexity is reduced and manufacturing is simplified, but measurement precision of load current estimation deteriorates due to inaccurate voltage sensing
Solution Approach 1:
The gate structure is segmented into separate gate electrodes for power transistor cells and sense transistor cells. Each gate electrode can be independently controlled, allowing precise voltage sensing in the sense path while maintaining simplified common control architecture. The gate trenches are also segmented to allow independent gate control for each transistor type.
Solution Approach 2:
Different gate control characteristics are applied to different regions: power transistor gates use one control scheme while sense transistor gates use another. This allows the sense transistors to operate in a regime optimized for precise voltage sensing, while power transistors handle high current switching. The local quality difference enables both simplified control and precise measurement.
2Area of stationary object
If sense transistor cells are integrated in cell arrays with power transistor cells, then area efficiency is improved, but manufacturing precision deteriorates due to difficulties in separately controlling gate structures
Solution Approach 1:
The gate trenches are segmented into first gate trenches for power transistors and second gate trenches for sense transistors. These segmented trenches can be formed using standard CMOS fabrication processes with separate photolithography steps, allowing precise control of each trench's position, depth, and dimensions while maintaining high area efficiency through compact cell array integration.
Solution Approach 2:
The gate trenches extend in a longitudinal direction through the substrate, creating a three-dimensional structure that allows independent control of power and sense transistors within a compact planar footprint. This vertical segmentation in the longitudinal dimension enables precise manufacturing while achieving high area efficiency through dense cell array packing.
3Reliability
If termination trenches are used to electrically connect field electrodes in sense transistor regions, then breakdown voltage stability is improved, but device complexity increases due to additional trench structures
Solution Approach 1:
The termination trenches serve multiple functions: they electrically connect field electrodes in the sense transistor region to ensure proper voltage blocking, they provide mechanical support for the gate structures, and they define the boundaries of the sense transistor cells. This multi-functionality improves breakdown voltage stability without proportionally increasing device complexity.
Solution Approach 2:
The termination trenches create equipotential regions by electrically connecting field electrodes at the same potential. This ensures stable breakdown voltage characteristics in the sense transistor region by preventing potential differences that could lead to premature breakdown or leakage currents.
Data Source
AI summary
An integrated circuit may include a semiconductor portion with a power transistor including first gate trenches that cross a first region and a sense transistor including second gate trenches that cross a second region. Each gate trench extends in a longitudinal direction and comprises a gate electrode and a field electrode. The first and second regions are arranged along the longitudinal direction. A first termination trench intersects at least the second gate trenches in a third region between the first and second regions. The first termination trench includes a first conductive structure that is electrically connected to the field electrodes in the second gate trenches. The characteristics of the sense transistor formed in the second region reliably and precisely replicate the characteristics of the power transistor.