Dual-Depth Lifetime Control in Semiconductor Trench Structures
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Solution Overview
Problem
Conventional semiconductor devices face challenges in optimizing the trade-off between leakage current and reverse recovery loss, with existing methods often increasing leakage current when attempting to reduce reverse recovery loss, leading to thermal runaway and electrical losses during switching.
Innovation Solution
The semiconductor device incorporates a first lifetime control region formed shallower than a second lifetime control region, with specific depth positions and concentrations of helium ions implanted to reduce reverse recovery loss while minimizing leakage current, thereby improving the trade-off between these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single lifetime control region is used to reduce reverse recovery loss, then reverse recovery loss is reduced, but leakage current increases
Solution Approach 1:
The lifetime control region is divided into two distinct segments: a first lifetime control region with a first depth position and a second lifetime control region with a second depth position. This segmentation allows each region to independently control different aspects of carrier lifetime, enabling reduction of reverse recovery loss while suppressing leakage current simultaneously.
Solution Approach 2:
The invention introduces a depth dimension differentiation by positioning the two lifetime control regions at different depths within the semiconductor substrate. The first lifetime control region is positioned at a first depth position and the second lifetime control region at a second depth position, creating a vertical gradient in lifetime control that resolves the trade-off between reverse recovery loss and leakage current.
2Loss of energy
If helium ion implantation is performed to control carrier lifetime, then reverse recovery loss is reduced, but leakage current increases
Solution Approach 1:
Different regions of the semiconductor substrate are given different lifetime control characteristics through selective helium ion implantation. The first lifetime control region and second lifetime control region have different depth positions and different helium ion concentrations, creating local quality variations that optimize both reverse recovery performance and leakage current suppression in their respective regions.
Solution Approach 2:
The invention changes the parameters of helium ion implantation by performing two separate implantation processes with different conditions. The first helium ion implantation creates the first lifetime control region with specific depth and concentration, while the second helium ion implantation creates the second lifetime control region with different depth and concentration parameters, thereby optimizing both reverse recovery loss and leakage current.
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 effectively reduces reverse recovery loss and leakage current, enhancing the semiconductor device's performance by optimizing the depth positions of the lifetime control regions, which improves the trade-off between electrical losses during switching and thermal stability.
Implementation Method 1
a first lifetime control region and a second lifetime control region in the semiconductor substrate, the first lifetime control region being shallower than the second lifetime control region in the semiconductor substrate in a depth direction from a front surface of the semiconductor substrate
Data Source
AI summary
Provided is a semiconductor device which includes a transistor portion and a diode portion, including: a drift region of a first conductivity type which is provided in a semiconductor substrate; a plurality of trench portions which are provided on a front surface of the semiconductor substrate; a buffer region of the first conductivity type which is provided on a side of a back surface of the semiconductor substrate with respect to the drift region; a first lifetime control region which is provided in the transistor portion; and a second lifetime control region which is provided at a depth different from that of the first lifetime control region in the diode portion.