SiC Impurity Implantation Profiles for Precise P-N Region Formation
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Solution Overview
Problem
The challenge in manufacturing semiconductor devices using silicon carbide (SiC) substrates is the difficulty in forming impurity implanted regions with high precision due to the wide diffusion of ions and the lack of thermal diffusion during activation annealing.
Innovation Solution
A method involving two steps of implanting first and second conductivity type impurities into a SiC substrate, with specific concentration distributions and peak values to achieve precise formation of p-type and n-type regions, utilizing a mask to control lateral diffusion and overlapping peak values for precise region definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed into a SiC substrate, then impurity regions can be formed, but the ions diffuse widely making it difficult to form impurity implanted regions with high precision
Solution Approach 1:
The ion implantation process is divided into multiple steps with different acceleration voltages and implantation conditions. First, ions are implanted at a higher acceleration voltage to reach a deeper peak concentration position, then additional ions are implanted at a lower acceleration voltage to create a shallower peak concentration position. This segmentation of the implantation process allows precise control over the impurity distribution profile and limits lateral diffusion effects.
Solution Approach 2:
A mask is formed on the SiC substrate surface before ion implantation to preliminarily define the target region. The mask prevents ions from entering unwanted areas, thereby controlling lateral diffusion and ensuring that impurities are implanted only in the desired regions. This preliminary action of masking is crucial for achieving high precision in impurity implanted region formation.
2Reliability
If activation annealing is performed to activate implanted impurities, then electrical activity is achieved, but thermal diffusion does not occur making it difficult to control impurity distribution
Solution Approach 1:
The activation annealing process uses specific parameter settings (temperature, time, atmosphere) that activate the implanted impurities electrically without causing significant thermal diffusion. By carefully controlling these parameters, the impurities become electrically active while maintaining their implanted spatial distribution, thus achieving both electrical activity and distribution control.
3Manufacturing precision
If a single ion implantation step is used, then the process is simple, but it is difficult to achieve precise concentration distribution with overlapping peak values
Solution Approach 1:
The ion implantation process is divided into multiple steps with different acceleration voltages and implantation conditions. First, ions are implanted at a higher acceleration voltage to reach a deeper peak concentration position, then additional ions are implanted at a lower acceleration voltage to create a shallower peak concentration position. This segmentation of the implantation process allows precise control over the impurity distribution profile and limits lateral diffusion effects.
Solution Approach 2:
Different implantation parameters (acceleration voltage, dose, energy) are used in each step to achieve the desired concentration distribution. By changing these parameters between steps, the patent creates a complex concentration profile with overlapping peaks that cannot be achieved with a single implantation step.
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
Enables the formation of impurity regions with high precision, allowing for smaller and more accurate semiconductor devices, such as MOSFETs, by controlling the expansion of p-type regions and enhancing the accuracy of impurity distribution.
Implementation Method 1
implanting a first conductivity type impurity into a SiC substrate; and implanting a second conductivity type impurity into the SiC substrate
Data Source
AI summary
A method of manufacturing a semiconductor device includes: implanting a first conductivity type impurity into a SiC substrate; and implanting a second conductivity type impurity into the SiC substrate. A concentration distribution of the first conductivity type impurity has a reduction region, in which the concentration of first conductivity type impurity continuously decreases as moving away from a first peak value. A concentration distribution of the second conductivity type impurity has a second peak value. The second peak value overlaps with a specific region within the reduction region that has a first conductivity type impurity concentration that is 10% or more of the first peak value. The position of the first peak value is the first conductivity type region. At least a part of the specific region is the second conductivity type region.