Silicon Carbide Substrate Doping for Uniform Impurity Distribution
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Solution Overview
Problem
Existing methods for manufacturing silicon carbide semiconductor substrates face challenges in achieving uniform p-type impurity concentration, particularly in fine holes, due to differences in doping characteristics between the sidewall and bottom surface, leading to nonuniform p-type silicon carbide semiconductor formation.
Innovation Solution
The method involves forming a p-type silicon carbide semiconductor on a widely exposed surface, followed by creating a hole and filling it with an n-type silicon carbide semiconductor, utilizing epitaxial growth for uniform n-type impurity concentration, and using specific gas sources for p-type impurity incorporation to stabilize p-type semiconductor growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional doping methods are used to form p-type silicon carbide in fine holes, then the doping process can be completed, but the impurity concentration becomes nonuniform due to differences in doping characteristics between sidewall and bottom surface
Solution Approach 1:
The patent applies local quality by forming a p-type silicon carbide semiconductor layer on the widely exposed surface before hole formation, ensuring that p-type impurities are incorporated in regions where epitaxial growth provides uniform distribution. This local application of p-type doping avoids the nonuniformity problem in fine holes while maintaining overall device functionality.
Solution Approach 2:
The patent segments the doping process into two distinct stages: (1) forming p-type silicon carbide on the exposed surface through epitaxial growth with uniform impurity distribution, and (2) forming n-type silicon carbide in the holes through separate epitaxial growth. This segmentation allows each region to be optimized independently, avoiding the nonuniformity issue in fine holes.
2Manufacturing precision
If epitaxial growth is used to form n-type silicon carbide in holes, then uniform n-type impurity concentration is achieved, but the overall substrate formation process becomes more complex
Solution Approach 1:
The patent employs continuous epitaxial growth to form both the p-type silicon carbide layer on the exposed surface and the n-type silicon carbide layer in the holes within a single, uninterrupted growth process. This continuous action ensures uniform impurity concentration throughout the substrate while maintaining process efficiency and reducing the need for separate doping steps.
3Reliability
If specific gas sources are used for p-type impurity incorporation, then stable p-type semiconductor growth is achieved, but the manufacturing process requires more precise gas control
Solution Approach 1:
The patent utilizes parameter changes by selecting specific gas sources (such as silane or methylsilane for silicon supply and ammonia for nitrogen impurity incorporation) and controlling their flow rates, temperatures, and partial pressures to optimize epitaxial growth conditions. These parameter adjustments ensure stable p-type semiconductor growth with uniform impurity distribution while maintaining manufacturability through well-established gas phase epitaxial techniques.
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 enables the stable formation of substrates with uniform impurity concentrations and high carrier concentrations, improving conduction characteristics and productivity while overcoming the difficulties in achieving uniform p-type impurity distribution.
Implementation Method 1
utilizing epitaxial growth for uniform n-type impurity concentration
Implementation Method 2
using specific gas sources for p-type impurity incorporation to stabilize p-type semiconductor growth
Data Source
AI summary
According to one embodiment, a method for manufacturing a substrate is disclosed. The method can include preparing a structure body. The structure body includes a first semiconductor member and a second semiconductor member. The first semiconductor member includes silicon carbide including a first element. The second semiconductor member includes silicon carbide including a second element. The first element includes at least one selected from a first group consisting of N, P, and As. The second element includes at least one selected from a second group consisting of B, Al, and Ga. The method can include forming a hole that extends through the second semiconductor member and reaches the first semiconductor member. In addition, the method can include forming a third semiconductor member in the hole. The third semiconductor member includes silicon carbide including a third element. The third element includes at least one selected from the first group.