Trench Drain Transistor Structure for Power Density
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Solution Overview
Problem
Transistors face challenges in increasing power density while maintaining device breakdown voltage and effective heat removal, which limits their performance and efficiency in various applications.
Innovation Solution
The implementation of a trench drain structure in transistors, which includes a trench etched into the n-type layer to enhance current density and voltage breakdown, combined with a fourth electrode and specific doping profiles to reduce field curvature and parasitic capacitance, allows for increased packing density and reduced on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the physical size of the die is reduced to increase power density, then device performance and packing density improve, but device breakdown voltage and heat removal capability deteriorate
Solution Approach 1:
The patent introduces a trench drain structure that extends vertically into the drift region, creating a three-dimensional field management system. This vertical dimension allows for near-planar breakdown characteristics while maintaining reduced die size, as the trench depth controls the electric field distribution without increasing lateral dimensions.
Solution Approach 2:
The trench drain creates localized regions of different doping concentrations and electric field strengths within the drift region. By positioning the trench at specific locations and varying its depth and doping profile, the patent achieves local optimization of both breakdown voltage and power density in different areas of the device.
2Power
If the physical size of the die is reduced to increase power density, then device performance and packing density improve, but heat removal capability deteriorates
Solution Approach 1:
The vertical trench structure provides an additional thermal conduction path from the drain region to the substrate. The trench can be filled with thermally conductive materials or doped regions that enhance heat sinking capability in the vertical direction, compensating for the reduced lateral heat dissipation area in smaller dies.
3Device complexity
If conventional drain structures are used, then device simplicity is maintained, but field curvature and parasitic capacitance increase
Solution Approach 1:
The trench drain transitions the electric field management from a primarily lateral two-dimensional structure to a three-dimensional structure with significant vertical components. This dimensional change reduces the lateral field curvature and associated parasitic capacitances while the trench depth provides control over the vertical field distribution.
4Productivity
If higher power density is achieved through increased packing density, then manufacturing efficiency improves, but device breakdown voltage deteriorates
Solution Approach 1:
The trench drain structure allows different regions of the device to have optimized characteristics for their specific functions. The trench can be positioned to provide breakdown voltage enhancement in critical areas while leaving other areas optimized for current conduction and packing density, enabling both high voltage and high efficiency operation.
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 approach enables higher power density, reduced die size, and improved manufacturing efficiency by achieving near-planar breakdown, thereby enhancing transistor performance and reliability.
Implementation Method 1
a trench etched into the n-type layer to enhance current density and voltage breakdown, combined with a fourth electrode and specific doping profiles to reduce field curvature
Data Source
AI summary
A semiconductor device is formed having a trench adjacent to a current carrying region of the device. The trench is formed having a depth greater than the depth of a tub region of the device. Increasing the trench depth moves a region of higher field strength from the tub region to a region along the trench. The region along the trench does not have a junction and may withstand the higher field strength.