Vertical Semiconductor Wells Using Angled W-Shaped Doping Profiles
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Solution Overview
Problem
The reduction of cell size in vertical oriented semiconductor devices, such as MOSFETs, is limited by manufacturing accuracy and the required space between body implants, which affects conduction performance and parasitic electric properties.
Innovation Solution
The method involves implanting free charge carriers at multiple acute angles relative to the surface normal of the semiconductor body to create self-aligned W-shaped doping profiles, allowing for smaller pitch semiconductor devices with improved doping profiles and reduced mask count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell size is reduced to increase channel density, then conduction performance is improved, but manufacturing accuracy requirements increase and space between body implants decreases
Solution Approach 1:
The patent transitions from conventional planar doping to three-dimensional angled implantation. By implanting dopants at angles (e.g., 45 degrees) relative to the semiconductor surface, the doping profiles extend in multiple spatial dimensions, creating self-aligned W-shaped regions that define well structures without requiring additional lateral spacing between implants.
Solution Approach 2:
The angled implantation process creates self-aligned doping profiles where the dopant distribution automatically defines the well regions and their spacing. The overlapping angled implantation paths inherently create the required separation between body implants without needing external alignment constraints, allowing the structure to self-organize the appropriate spacing.
2Reliability
If cell size is reduced, then device performance increases, but the required space between body implants decreases leading to pinch off risks
Solution Approach 1:
The patent uses angled implantation to create doping profiles that extend vertically and diagonally into the semiconductor substrate. This three-dimensional approach allows well regions to be defined with adequate separation in the lateral direction while maintaining proper spacing through the depth of the structure, preventing pinch-off even as cell pitch is reduced.
Solution Approach 2:
The angled implantation creates locally optimized doping distributions where the dopant concentration and depth vary systematically with implantation angle. This allows different regions of the semiconductor structure to have tailored doping profiles that ensure adequate body implant spacing and prevent pinch-off in critical areas while maintaining high channel density elsewhere.
3Ease of manufacture
If conventional planar implantation is used, then manufacturing is simpler, but doping profile control and device performance are limited
Solution Approach 1:
The patent employs multiple sequential implantation steps at different angles (e.g., first at +45 degrees, then at -45 degrees). This periodic repetition of the implantation process with varying parameters builds up the complex W-shaped doping profile through controlled accumulation, maintaining manufacturing simplicity while achieving precise three-dimensional dopant 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 enables the manufacturing of small pitch semiconductor devices with enhanced conduction performance and improved dopant profiles, increasing device performance and reducing parasitic electric properties.
Implementation Method 1
implanting free charge carriers of a second conductivity type, said second conductivity type opposite to said first conductivity type, using a mask on said top surface of said semiconductor body
Implementation Method 2
etching said semiconductor material from said top surface to said particular depth such that said W-shaped second conductivity type region is divided into said well regions
Data Source
Figure 1
Figure 2a~2c
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AI summary
A method of manufacturing a vertical oriented semiconductor device, comprising the steps of providing a semiconductor body having a top surface and a current-accommodating region of a first conductivity type, implanting free charge carriers of a second conductivity type, said second conductivity type opposite to said first conductivity type, using a mask on said top surface of said semiconductor body, such that well regions, of the second conductivity type, are provided, said well regions being laterally spaced apart such that the current-accommodating region is provided therein between at a particular depth in said semiconductor material, wherein said implanting is performed under at least two acute angles relative to a surface normal of said top surface such that a W-shaped second conductivity type region is provided in said semiconductor material, etching and/or grinding said semiconductor material from said top surface to said particular depth such that said W-shaped second conductivity region is divided into said well regions having said current-accommodating region therein between.