Semiconductor Drift Zone Doping for Low On Resistance
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Solution Overview
Problem
Current semiconductor devices with epitaxially grown semiconductor material face challenges in minimizing on resistance due to lateral diffusion of charge compensation zones, which complicates the manufacturing process and makes it difficult to achieve the desired breakdown voltage, especially when increasing doping levels to reduce on resistance.
Innovation Solution
The semiconductor device employs a method where 20 to 80 atomic % of doping material is homogeneously distributed in epitaxial growth phases, with the remaining 80 to 20 atomic % introduced near the surface by ion implantation, and selective ion implantation is used to limit the widening of charge compensation zones, allowing for higher doping of drift zones and reduced on resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the level of doping material in drift zones and charge compensation zones is increased to reduce on resistance, then on resistance decreases, but the geometrical period must be reduced further to ensure complete depletion of charge carriers
Solution Approach 1:
The patent changes the doping concentration parameter by introducing a maximum doping concentration of 1×10^16 to 1×10^18 atoms/cm³ in the drift zone and charge compensation zone. This controlled parameter change allows achieving low on resistance while maintaining adequate geometrical period through precise doping level optimization rather than geometric scaling.
2Reliability
If masked or selective ion implantation is used to introduce charge compensation zones, then charge compensation zones are formed, but major widening of the columns or strips of charge compensation zone material occurs due to lateral diffusion
Solution Approach 1:
The patent applies preliminary low-energy ion implantation to introduce dopants into the charge compensation zones before subsequent high-temperature processing steps. This preliminary doping establishes the dopant distribution early, and the low energy minimizes initial diffusion, preventing excessive widening during later processing.
Solution Approach 2:
The patent replaces conventional high-energy ion implantation with low-energy ion implantation methodology. This substitution changes the implantation mechanism to reduce dopant penetration depth and minimize lateral diffusion during the implantation process itself, thereby maintaining charge compensation zone dimensional precision.
3Manufacturing precision
If non-doped epitaxial layers are grown to reduce lateral diffusion widening, then widening is reduced, but initially high-impedance layers are generated and on resistance cannot be reduced as desired
Solution Approach 1:
The patent applies local quality by introducing doping materials at specific locations and depths within the semiconductor structure. Dopants are implanted selectively into drift zones and charge compensation zones with different doping concentrations and profiles, creating locally optimized electrical properties rather than uniform doping throughout the structure.
Solution Approach 2:
The patent performs preliminary low-energy ion implantation to establish dopant distributions in charge compensation zones before subsequent processing. This preliminary doping action ensures adequate carrier concentration is present early in the fabrication sequence, preventing high-impedance conditions while still allowing lateral diffusion control through the low-energy implantation methodology.
4Loss of energy
If a high level of doping material is introduced to reduce on resistance, then on resistance decreases, but breakdown voltage becomes highly dependent on wrong doping and fluctuations increase
Solution Approach 1:
The patent optimizes the doping concentration parameter within a specific range of 1×10^16 to 1×10^18 atoms/cm³, avoiding both too-low and excessively high doping levels. This parameter optimization achieves an balance between low on resistance and stable breakdown voltage by preventing doping-induced fluctuations that occur at extreme doping concentrations.
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 minimizes on resistance and concentration fluctuations, enabling smaller step sizes between charge compensation zones and drift zones, thus achieving a more stable and efficient semiconductor device with improved breakdown voltage control.
Implementation Method 1
a laterally limited charge compensation zone doping, which is introduced into the epitaxially grown semiconductor material
Implementation Method 2
The regions of a complementary conduction type for the charge compensation zones, which are introduced by masked or selective ion implantation and typically doped with boron, have to diffuse together through the epitaxial growth phases of finite thickness
Implementation Method 3
In multiple epitaxy, epitaxial growth phases are interspersed with unmasked large-area and masked selective implantation processes for doping materials
Data Source
AI summary
A semiconductor device with a semiconductor body and method for its production is disclosed. The semiconductor body includes drift zones of epitaxially grown semiconductor material of a first conduction type. The semiconductor body further includes charge compensation zones of a second conduction type complementing the first conduction type, which are arranged laterally adjacent to the drift zones. The charge compensation zones are provided with a laterally limited charge compensation zone doping, which is introduced into the epitaxially grown semiconductor material. The epitaxially grown semiconductor material includes 20 to 80 atomic % of the doping material of the drift zones and a doping material balance of 80 to 20 atomic % introduced by ion implantation and diffusion.