Semiconductor Wafer Implantation for Uniform Defect-Controlled Doping
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Solution Overview
Problem
The existing methods for semiconductor wafer doping using ion implantation face challenges such as mechanical complexity due to rotational and oscillating movements, mechanical stresses and particle contamination of the energy filter, and the generation of point defects in semiconductor materials, particularly in SiC, which affect the precision and reproducibility of doping profiles.
Innovation Solution
The solution involves a semiconductor wafer processing system where the energy filter is positioned in a separate vacuum-sealable unit to minimize mechanical vibrations and particle exposure, with synchronized electrostatic deflection of the ion beam and mechanical movement of the filter to achieve homogeneous irradiation, and the use of a heatable wafer chuck to reduce point defect concentration and enhance implantation profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If rotational and oscillating movements are used for ion beam scanning, then the ion beam can cover the entire wafer surface, but the mechanical complexity increases
Solution Approach 1:
The patent replaces mechanical rotational and oscillating movements with electrostatic deflection fields to scan the ion beam across the wafer surface. The electrostatic deflectors use electric fields to steer the ion beam without any moving mechanical parts, thereby achieving full wafer surface coverage while eliminating the mechanical complexity of rotational and oscillating mechanisms.
2Reliability
If the energy filter is positioned in the vacuum chamber, then it can filter ions effectively, but mechanical stresses and particle contamination occur
Solution Approach 1:
The patent extracts the energy filter from the vacuum chamber environment and positions it outside the vacuum space. This allows the energy filter to be protected from mechanical stresses and particle contamination that occur within the vacuum chamber during wafer processing, while still maintaining its ion filtering effectiveness through precise positioning in the ion beam path.
Solution Approach 2:
The patent introduces a vacuum window or membrane as an intermediary between the energy filter and the vacuum chamber. This intermediary allows the energy filter to remain outside the vacuum environment (protected from contamination) while still enabling effective ion filtering by transmitting selected ions through the window into the vacuum chamber.
3Ease of manufacture
If ion implantation is performed at room temperature, then the process is simpler, but point defect concentration increases
Solution Approach 1:
The patent changes the temperature parameter during ion implantation by heating the wafer to elevated temperatures (typically 150-450°C). This temperature increase reduces point defect concentration in the implantation area by enhancing defect annealing and improving dopant activation, thereby achieving more precise doping profiles while maintaining process simplicity through integrated heating capabilities.
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 results in reduced point defect concentrations, improved reproducibility, and more controlled doping profiles with reduced mechanical stress and particle contamination, enabling precise and efficient semiconductor wafer processing.
Implementation Method 1
ion implantation is used for doping and for producing defect profiles at predefined depths
Implementation Method 2
An energy filter 6 is well-adapted to ion implantation... the energy filter 6 is structured in such a way that it has areas of different thicknesses
Implementation Method 3
synchronized electrostatic deflection of the ion beam and mechanical movement of the filter
Implementation Method 4
the use of a heatable wafer chuck to reduce point defect concentration and enhance implantation profiles
Data Source
AI summary
A semiconductor wafer includes a first surface and an implantation area adjacent to the first surface and a certain distance away from the first surface, the implantation area including implanted particles and defects. A defect concentration in the implantation area deviates by less than 5% from a maximum defect concentration in the implantation area.