Semiconductor Buffer Layer Ion Implantation Angle Control
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Solution Overview
Problem
Existing semiconductor device manufacturing methods face inefficiencies in forming thick buffer layers with reduced disorder, as they require lengthy beam adjustments and increased manufacturing steps, and struggle with accurate control of N+ buffer layer distribution.
Innovation Solution
A method involving multiple ion implantation steps with fixed acceleration energy and progressively smaller ion implantation angles to form a thick buffer layer, ensuring uniformity and reducing disorder by implanting ions at deeper positions first and shallower positions subsequently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple cycles of proton irradiation are performed to form a thick buffer layer with reduced disorder, then the buffer layer quality is improved, but the manufacturing time increases due to lengthy beam adjustment between cycles
Solution Approach 1:
The patent changes the ion implantation angle parameter across multiple implantation steps while maintaining fixed acceleration energy. By progressively reducing the ion implantation angle from 45 degrees to 15 degrees in subsequent steps, the patent achieves deeper and more uniform impurity distribution without requiring beam energy re-adjustment, thereby reducing manufacturing time while maintaining buffer layer quality
Solution Approach 2:
The patent performs preliminary ion implantation steps with larger angles to create initial buffer layer structure, then follows with smaller angle implantations to refine and deepen the distribution. This preliminary action approach allows each subsequent step to build upon previous work without requiring full re-adjustment, reducing total manufacturing time
2Manufacturing precision
If oxygen introduction is performed before proton irradiation to form a broad N+ buffer layer distribution, then the buffer layer distribution is improved, but the number of manufacturing steps increases
Solution Approach 1:
The patent achieves broad N+ buffer layer distribution by changing only the ion implantation angle parameter across multiple steps while keeping acceleration energy fixed. This single parameter variation (angle from 45 to 15 degrees) replaces the need for oxygen introduction, reducing manufacturing steps while maintaining distribution quality
Solution Approach 2:
The patent extracts and eliminates the oxygen introduction step from the manufacturing process. By using solely ion implantation with varying angles, the patent achieves the same buffer layer distribution effect without requiring the additional oxygen diffusion step, thereby simplifying the manufacturing process
3Loss of energy
If the substrate is thinned to reduce loss, then the efficiency is improved, but the breakdown voltage characteristics deteriorate and oscillations increase during turn-off operation
Solution Approach 1:
The patent uses ion implantation angle as a control parameter to achieve deep and uniform impurity distribution in the buffer layer. This creates a more effective buffer layer that can support higher breakdown voltages even in thinned substrates, allowing substrate thinning for reduced loss while maintaining reliability through superior impurity distribution
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 allows for the efficient formation of a thick buffer layer with reduced disorder and improved breakdown voltage characteristics, minimizing manufacturing time and steps while maintaining precise control over impurity distribution.
Implementation Method 1
forming a buffer layer by performing a plurality of ion implantation steps, each of the ion implantation steps implanting ions of an impurity of the first conductivity type into a bottom-surface side of the substrate
Data Source
AI summary
A method for manufacturing a semiconductor device includes the steps of forming a layer of a second conductivity type on a top-surface side of a substrate of a first conductivity type, and forming a buffer layer by performing a plurality of ion implantation steps, each of the ion implantation steps implanting ions of an impurity of the first conductivity type into a bottom-surface side of the substrate with an ion implantation angle with respect to a bottom surface of the substrate fixed, the ion implantation angle of a subsequent one of the ion implantation steps being smaller than that of the previous ion implantation step, wherein in the buffer layer formation step, the plurality of ion implantation steps is performed at a fixed acceleration energy.