Superjunction Transistor Sidewall Doping for Reduced Pitch
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Solution Overview
Problem
Current methods for producing superjunction devices with a drift region in vertical superjunction transistors face challenges in achieving a small pitch for the alternating n-type and p-type regions, which affects the device's performance.
Innovation Solution
A method involving the implantation of dopant atoms of different doping types into the sidewalls of trenches in a semiconductor layer, followed by diffusion to form regions of specific doping types, where the dopant atoms with a smaller diffusion coefficient create regions that are partially embedded within those with higher diffusion, allowing for a reduced pitch by quartering the initial pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional implantation methods are used to form alternating doped regions, then the manufacturing process is simple, but the pitch between regions cannot be reduced sufficiently
Solution Approach 1:
The manufacturing process is divided into separate implantation steps for different dopant types (first doping type and second doping type), allowing independent control of each region's formation. This segmentation enables precise pitch control by treating the formation of alternating n-type and p-type regions as distinct operations rather than a single complex process
Solution Approach 2:
The patent transitions from forming regions in a single lateral dimension to utilizing vertical depth dimension as well. By implanting dopants at different depths and using selective diffusion, the pitch is reduced by quartering the initial pitch through three-dimensional dopant distribution control, not just lateral positioning
2Manufacturing precision
If dopant atoms with larger diffusion coefficient are used, then diffusion is faster and more efficient, but the doping regions overlap excessively and cannot form the desired spaced-apart structure
Solution Approach 1:
Different dopant types are selected with different diffusion coefficients tailored to specific regional requirements. The first dopant type has a smaller diffusion coefficient for precise, localized region formation, while the second dopant type has a larger diffusion coefficient for broader coverage. This local optimization of dopant properties enables both precise spacing and efficient diffusion where needed
Solution Approach 2:
Dopant atoms are implanted into the semiconductor layer before the actual diffusion process begins. This preliminary implantation establishes the initial dopant distribution and concentration profiles, allowing subsequent diffusion to proceed in a controlled manner that achieves the desired spaced-apart region structure without excessive overlap
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 effectively reduces the pitch between alternating regions, enhancing the performance of superjunction devices by optimizing the arrangement and diffusion of dopant atoms, thereby improving the device's structure and functionality.
Implementation Method 1
diffusing the dopant atoms of the first doping type and the dopant atoms of the second doping type in a first diffusion process
Implementation Method 2
implanting dopant atoms of a first doping type and dopant atoms of a second doping type in a first implantation process into opposite sidewalls
Data Source
AI summary
A method for forming a transistor device includes: implanting dopant atoms of a first doping type and dopant atoms of a second doping type into opposite sidewalls of each of a plurality of trenches of a first semiconductor layer having a basic doping of the first doping type, the dopant atoms of the first doping type having a smaller diffusion coefficient than the dopant atoms of the second doping type; filling each trench with a second semiconductor layer of the first doping type; and diffusing the dopant atoms of the first doping type and the dopant atoms of the second doping type such that a plurality of first regions of the first doping type and a plurality of second regions of the second doping type are formed. The second regions are spaced apart from each other. Each first region is at least partially arranged within a respective second region.