Field Stop Layer Doping for Lower IGBT Turn-Off Peak Voltage
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Solution Overview
Problem
Conventional semiconductor devices with field stop layers formed through proton (H+) injection generate excessively high peak voltages in circuits with large parasitic inductance, leading to potential damage to the IGBT or other components.
Innovation Solution
The field stop layer is formed by doping first and second impurity particles, where the first impurity particle with a small size requires low injection energy for deeper penetration, and the second impurity particle with a larger radius has a shallower injection depth and lower annealing temperature requirements, thereby avoiding damage to the MOSFET structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If proton (H+) injection is used to form the field stop layer, then the field stop layer can be formed with appropriate doping density, but the IGBT generates excessively high peak voltage in circuits with large parasitic inductance
Solution Approach 1:
The patent changes the parameters of the impurity particles used for doping - specifically using lighter impurity particles (such as boron) instead of protons (H+). This parameter change in the doping process results in a field stop layer that produces lower peak voltages in circuits with parasitic inductance, while still achieving the required doping density for proper field stopping.
2Length of moving object
If high injection energy is used to form the field stop layer, then deeper penetration is achieved, but damage to the MOSFET structure on the front surface occurs
Solution Approach 1:
The patent changes the mass parameter of the injected particles by using lighter impurity particles instead of protons. This parameter change allows achieving the required injection depth with lower injection energy, thereby preventing damage to the MOSFET structure on the front surface while still forming an effective field stop layer.
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 the peak voltage when the device is turned off, improves IGBT performance, and prevents damage from overvoltage in circuits with large parasitic inductance.
Implementation Method 1
The field stop layer is formed by injecting a first impurity particle from the second surface of the N-type substrate by using first injection energy
Implementation Method 2
a second impurity particle is injected from the second surface of the N-type substrate by using second injection energy that is higher than the first injection energy
Implementation Method 3
a doping density distribution in a direction from the first surface to the second surface of the N-type substrate increases sequentially as an injection depth increases
Data Source
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AI summary
Embodiments of this application disclose a semiconductor device, a related chip, and a preparation method. The semiconductor device includes an N-type drift layer and an N-type field stop layer adjacent to the N-type drift layer. A density of free electrons at the N-type field stop layer is higher than a density of free electrons at the N-type drift layer. The N-type field stop layer includes a first impurity particle and a second impurity particle doped with the first impurity particle, and a radius of the second impurity particle is greater than a radius of the first impurity particle. In the N-type field stop layer, an injection density of the first impurity particle in a region adjacent to the N-type drift layer is higher than an injection density of the first impurity particle in any other region. The foregoing structure is used, to effectively alleviate a situation in which the semiconductor device generates an excessively high peak voltage in a circuit with a large parasitic inductance when the semiconductor device is turned off.