IGBT Threshold Stabilization With Lifetime Control Regions
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Solution Overview
Problem
In semiconductor devices, particularly insulated gate bipolar transistors (IGBTs), there is a challenge in maintaining uniform threshold values across different transistor cells due to positional variations, leading to instability and increased reverse recovery losses in diode sections.
Innovation Solution
The semiconductor device incorporates a semiconductor substrate with a transistor section and a diode section, featuring a drift region and a base region of opposing conductivity types, along with a lifetime control region and a threshold value adjusting section. The lifetime control region is formed by irradiating a particle beam to introduce crystal defects, and the threshold value adjusting section is created by recovering carrier lifetimes through light irradiation to stabilize the threshold values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a lifetime control region is provided below the base region from the transistor section to the diode section, then reverse recovery losses are reduced, but threshold value differences due to positional variations increase
Solution Approach 1:
The patent applies local quality by providing a lifetime control region with lifetime killers in specific areas (below the base region from the transistor section to the diode section) while excluding certain regions. This creates non-uniform lifetime control that reduces reverse recovery losses in the diode section without adversely affecting threshold value uniformity in the transistor section, thereby resolving the contradiction between energy loss reduction and threshold value uniformity.
2Reliability
If the lifetime control region is extended across the entire semiconductor substrate, then reverse recovery characteristics improve, but manufacturing complexity increases
Solution Approach 1:
The patent segments the lifetime control region into distinct areas: it is provided below the base region from the transistor section to the diode section, but excludes regions below the collector electrode and emitter electrode. This segmentation allows selective application of lifetime control to achieve reverse recovery characteristics while simplifying manufacturing by avoiding uniform treatment across the entire substrate.
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 effectively stabilizes the threshold values across the transistor section, reducing positional variations and minimizing reverse recovery losses in the diode section, thereby enhancing the operational stability and efficiency of the semiconductor device.
Implementation Method 1
the lifetime control region is formed by irradiating a particle beam to introduce crystal defects
Implementation Method 2
the threshold value adjusting section is created by recovering carrier lifetimes through light irradiation
Data Source
AI summary
A method of manufacturing a semiconductor device comprising a transistor section and a diode section each having a drift region of a first conductivity-type inside a semiconductor substrate, and a base region of a second conductivity-type above the drift region. A particle beam is irradiated from an upper surface of the semiconductor substrate forming a lifetime control region including lifetime killers below the base region from at least a part of the transistor section to the diode section. A threshold value adjusting section is formed for adjusting a threshold value of the transistor section, including a thickened portion Wgi of a gate insulating film in a gate trench section adjacent to the base region, the thickened portion having a dielectric constant less than or equal to 0.9 times a remaining portion of the gate insulating film in the gate trench section.