Semiconductor Substrate Super Junction Epitaxial Layer Dopant Control
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Solution Overview
Problem
The existing methods for producing semiconductor substrates with super junction structures face challenges in achieving consistent dopant concentration across epitaxial layers, leading to suboptimal electrical characteristics such as resistivity.
Innovation Solution
A method involving multiple epitaxial layer formation steps with specific dopant gas flow rates and temperatures, ensuring that the dopant concentrations of the second, third, and fourth epitaxial layers differ by no more than ±5%, using chemical vapor deposition and varying the flow rates and temperatures to maintain consistent dopant incorporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If temperature is varied in formation of each epitaxial layer to control dopant concentration, then dopant concentration can be adjusted, but manufacturing precision of uniform dopant concentration across layers deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically varying dopant gas flow rates and temperatures across different epitaxial layer formation steps. Specifically, the first epitaxial layer is formed at a first temperature with a first dopant gas flow rate, the second epitaxial layer is formed at a second temperature (different from the first) with a second dopant gas flow rate (different from the first), and the third epitaxial layer is formed at a third temperature (different from the second) with a third dopant gas flow rate (different from the second). This controlled parameter variation compensates for temperature-induced dopant concentration variations, achieving uniform dopant concentration across layers with different conductivity types.
2Reliability
If multiple epitaxial layers with different conductivity types are formed to create super junction structure, then voltage resistance performance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the semiconductor substrate into multiple epitaxial layers with alternating conductivity types (first conductivity type, second conductivity type, and third conductivity type). These segmented layers form a super junction structure where each layer has a specific function: the first layer provides base conductivity, the second layer creates depletion regions for voltage resistance, and the third layer completes the alternating pattern. This segmentation enables high voltage resistance performance while maintaining manufacturability through systematic process control.
Solution Approach 2:
The patent manages manufacturing complexity by systematically varying parameters (temperature and dopant gas flow rate) across the multiple epitaxial layer formation steps. By establishing a clear parameter progression pattern (first temperature/first flow rate → second temperature/second flow rate → third temperature/third flow rate), the complex multi-step process becomes controllable and repeatable, reducing the practical manufacturing complexity despite the increased number of steps.
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 results in semiconductor substrates with desired electrical characteristics, including high voltage resistance performance and uniform resistivity, suitable for power MOSFETs.
Implementation Method 1
the epitaxial layers are formed by chemical vapor deposition
Data Source
Figure 1~2
Figure 3A~3C
Figure 3D~3E
AI summary
A semiconductor substrate which allows desired electrical characteristics to be more easily acquired, a semiconductor device of the same, and a method of producing the semiconductor substrate. The method of producing this semiconductor substrate is provided with: a first epitaxial layer forming step (S1) of forming a first epitaxial layer; a trench forming step (S2) of forming trenches in the first epitaxial layer; and epitaxial layer forming steps (S3, S4, S5) of forming epitaxial layers on the first epitaxial layer and inside the trenches, using a plurality of growth conditions including differing growth rates, so as to fill the trenches, and keeping the concentration of dopant taken into the epitaxial layers constant in the plurality of growth conditions.