Voltage Compensation Structure With Sidewall Diffusion Barrier
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Solution Overview
Problem
Conventional methods for manufacturing voltage compensation structures in semiconductor devices are costly, time-consuming, and face limitations in miniaturization due to complex epitaxial processes and doping precision issues, which affect the performance and robustness of the devices.
Innovation Solution
The method involves etching a trench in an epitaxial semiconductor material with n-type and p-type dopant atoms of differing diffusion constants, using a semiconductor or insulating material with a significantly different diffusion constant on the trench sidewalls to facilitate lateral charge separation, and filling the trench with a second semiconductor material to enhance doping efficiency and reduce on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multiple epitaxy process is used to create voltage compensation structures, then the structures can be formed with p-type and n-type column regions, but the manufacturing cost increases significantly and production time is extended
Solution Approach 1:
The patent combines the formation of p-type and n-type column regions into a single epitaxial growth process rather than using multiple separate epitaxy steps. This is achieved by introducing both phosphorus (n-type) and boron (p-type) dopants simultaneously during one continuous epitaxial growth cycle, thereby reducing manufacturing cost and production time while maintaining the voltage compensation functionality.
Solution Approach 2:
The single epitaxial growth process serves multiple functions: it grows the semiconductor layer, introduces both n-type and p-type dopants, and forms the voltage compensation structure with alternating doped regions. This multi-functional approach eliminates the need for separate doping and epitaxial steps, improving productivity without sacrificing structural quality.
2Reliability
If conventional trench etching and compensation with trench filling is used, then the voltage absorbing volume can be isolated on highly doped substrate, but the minimum width of structure is limited due to lateral diffusion
Solution Approach 1:
The patent introduces dopants during the epitaxial growth process itself, before any trench etching or filling operations. By pre-doping the epitaxial layer with both phosphorus and boron in alternating patterns during growth, the structure achieves the desired doping profile without requiring subsequent high-temperature diffusion steps that would cause lateral spreading and limit minimum dimensions.
Solution Approach 2:
The patent changes the doping method from post-growth diffusion to in-situ doping during epitaxial growth. This parameter change allows precise control of dopant concentration and distribution without the thermal diffusion process that causes lateral spreading, thereby enabling smaller minimum structure dimensions while maintaining voltage blocking capability.
3Productivity
If doping is performed during initial epi process with relatively large fluctuations, then cost-performance ratio improves, but the vertical variation of doping profile cannot be controlled and yield losses occur
Solution Approach 1:
The patent employs periodic introduction of dopants during the epitaxial growth process. By alternately introducing phosphorus and boron dopants at controlled intervals during continuous growth, the method achieves both cost efficiency (single growth step) and precise vertical doping profile control (periodic dopant introduction), avoiding the yield losses associated with uncontrolled doping fluctuations.
Solution Approach 2:
The epitaxial growth process incorporates real-time control of dopant introduction based on growth rate monitoring. This feedback mechanism ensures that the alternating n-type and p-type dopant concentrations are precisely controlled during growth, achieving both cost-effectiveness and manufacturing precision by preventing excessive doping variations that would cause yield losses.
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 creation of voltage compensation structures with improved doping precision and reduced on-state resistance without compromising blocking voltage capacity, enabling more efficient and cost-effective manufacturing while enabling smaller dimensions and higher robustness.
Implementation Method 1
diffusing more n-type dopant atoms or p-type dopant atoms from the epitaxial semiconductor material through the first semiconductor or insulating material into the second semiconductor material than the other type of dopant atoms so that a lateral charge separation occurs
Data Source
AI summary
A voltage compensation structure includes a first semiconductor or insulating material disposed along one or more sidewalls of a trench formed in a doped epitaxial semiconductor material. The first semiconductor or insulating material has a dopant diffusion constant which is at least 2× different for n-type dopant atoms than p-type dopant atoms. The voltage compensation structure further includes a doped second semiconductor material disposed in the trench so that the first semiconductor or insulating material is interposed between the doped second semiconductor material and the doped epitaxial semiconductor material. The doped second semiconductor material has a different dopant diffusion constant than the first semiconductor or insulating material so that a lateral charge separation occurs between the doped second semiconductor material and the doped epitaxial semiconductor material.