Silicon Carbide Field Stop Layer Defect Reduction
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Solution Overview
Problem
Existing methods for manufacturing silicon carbide semiconductor devices face challenges in achieving high carrier mobility and reducing crystal defects, leading to degradation of electric properties such as increased loss, conduction resistance, and leak current, particularly when forming n-type field stop layers using proton implantation.
Innovation Solution
A method involving the introduction of impurities, proton implantation, and thermal treatment to form hydrogen-induced donors and reduce crystal defects, where furnace annealing is used to convert protons into donors and laser annealing is applied to activate impurities, thereby forming an n-type field stop layer and reducing disorders in the proton passing-through region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If proton implantation is used to form n-type field stop layer, then doping concentration is improved, but crystal defects are generated leading to degraded carrier mobility
Solution Approach 1:
The patent extracts and removes crystal defects from the proton-implanted region through selective thermal treatment. By applying controlled heating to the specific region containing proton-implanted atoms, the method eliminates harmful crystal defects while preserving the beneficial doping concentration, thereby restoring carrier mobility without sacrificing the field stop layer's doping characteristics.
Solution Approach 2:
The patent changes the thermal parameters (temperature, time, atmosphere) of the semiconductor substrate to transform the state of proton-implanted atoms. By controlling the thermal treatment parameters, the method converts protons into functional donors while simultaneously annealing out crystal defects, thus improving both doping concentration and carrier mobility through parameter optimization.
2Quantity of substance
If thermal treatment is applied to convert protons into donors, then hydrogen induced donors are formed, but crystal defects are generated
Solution Approach 1:
The patent converts the harmful crystal defects generated during thermal treatment into beneficial outcomes by using the same thermal energy that creates donors to simultaneously anneal and remove defects. The controlled thermal treatment transforms the potentially harmful process of defect generation into a beneficial dual-function process that creates donors while eliminating defects.
Solution Approach 2:
The patent optimizes thermal treatment parameters (temperature profile, duration, atmospheric conditions) to achieve the optimal balance between donor formation and defect reduction. By precisely controlling these parameters, the method ensures that the thermal energy sufficient for converting protons to donors does not excessively generate or persist harmful crystal defects.
3Manufacturing precision
If multiple processing steps are used to form field stop layer and reduce defects, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the donor formation process and defect reduction process into a single integrated thermal treatment step. Instead of performing separate operations to convert protons to donors and then separately treating defects, the method combines both functions into one controlled thermal processing step, thereby reducing the total number of processing steps while maintaining high field stop layer quality.
Solution Approach 2:
The patent makes the thermal treatment step multi-functional by designing it to simultaneously achieve donor formation, crystal defect reduction, and carrier mobility improvement. This universal thermal processing step replaces what would traditionally require multiple specialized processing steps, thereby simplifying the overall manufacturing process while maintaining or improving field stop layer quality.
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 stabilizes electric properties by improving carrier mobility and preventing degradation, resulting in an inexpensive silicon carbide semiconductor device with predetermined electric properties and excellent yield.
Implementation Method 1
implanting protons at a position deeper than a position at which the impurity is introduced, from the first principal surface of the n-type semiconductor substrate
Implementation Method 2
forming an n-type field stop layer at a position deeper than the diffusion layer from the first principal surface of the n-type semiconductor substrate by forming hydrogen induced donors by converting the protons into donors
Implementation Method 3
forming an n-type crystal defect reduction region by reducing crystal defects generated in a proton passing-through region from the first principal surface of the n-type semiconductor substrate to a range of the protons
Data Source
AI summary
A method of manufacturing a silicon carbide semiconductor device. The method includes providing an n-type semiconductor substrate having first and second principal surfaces, introducing an impurity from a first principal surface of the semiconductor substrate at a first position, activating the impurity to form a diffusion layer in the semiconductor substrate at a second position, implanting protons at a third position that is deeper from the first principal surface than the first position, the protons generating crystal defects in a region through which the protons pass, converting by thermal treating the protons into hydrogen induced donors to form an n-type field stop layer at a fourth position deeper from the first principal surface than the second position, reducing by the thermal treating the generated crystal defects to form an n-type crystal defect reduction region, and forming an electrode on the second principal surface after implanting the protons.