Ion Implantation Energy Filter Layout for Uniform Wafer Doping
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Solution Overview
Problem
Current ion implantation methods for semiconductor wafers face challenges such as mechanical complexity, mechanical stress on energy filters due to vacuum conditions, particle contamination, and high point defect creation, which affect the precision and reliability of doping and defect profiles.
Innovation Solution
The implementation of an ion implantation system that uses an energy filter with a separate vacuum-lockable unit to protect the filter from mechanical and particle contaminants, combined with electrostatic deflection and synchronized mechanical movement of the ion beam and energy filter to ensure uniform irradiation and reduce point defects, and the use of a heatable wafer chuck to optimize implantation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the energy filter is positioned in the implantation chamber to enable ion implantation, then the doping function is achieved, but the filter membrane is exposed to mechanical stress from vacuum pumping and particle contamination from ambient air
Solution Approach 1:
The system is divided into two separate vacuum chambers: a first vacuum chamber for the energy filter and a second vacuum chamber for the implantation process. This segmentation isolates the energy filter from harmful vacuum pumping stresses and particle contamination while maintaining the necessary vacuum environment for ion implantation.
Solution Approach 2:
A transfer mechanism serves as an intermediary between the first vacuum chamber (energy filter) and the second vacuum chamber (implantation chamber). This intermediary enables controlled movement of the energy filter into position for ion beam passage while maintaining vacuum integrity and protecting the filter from harmful environmental factors.
2Area of stationary object
If a rotating wafer wheel with pendulum movement is used for substrate irradiation, then the entire wafer surface can be irradiated, but the mechanical complexity increases
Solution Approach 1:
The complex mechanical wafer wheel with pendulum movement is replaced by a simplified system where the substrate remains stationary on a chuck and the ion beam is steered electronically to scan across the wafer surface. This substitution eliminates the need for complex mechanical movement mechanisms while achieving complete surface irradiation.
Solution Approach 2:
Instead of mechanically moving the wafer, the system uses dynamic control of the ion beam trajectory through electrostatic or magnetic deflection fields. This allows the beam to dynamically scan across the entire wafer surface while the substrate remains stationary, reducing mechanical complexity.
3Manufacturing precision
If conventional ion implantation without energy filter is used, then the process is simpler, but the point defect concentration in the semiconductor material increases
Solution Approach 1:
The energy filter modifies the energy distribution of the ion beam by introducing a controlled energy spread. This parameter change in the ion beam energy distribution allows for reduced point defect concentration while maintaining precise doping profiles, as the energy filtering process modifies how ions interact with the semiconductor lattice.
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 reduced point defect concentration, improved reproducibility, and enhanced activation of semiconductor materials by minimizing mechanical stress and particle exposure, while achieving more precise and uniform doping profiles across the wafer surface.
Implementation Method 1
A basic principle of the energy filter 6 is as follows: A monoenergetic ion beam 2 undergoes a modification of its energy as it passes through the microstructured energy filter component
Implementation Method 2
ion implantation is used to dope or create defect profiles in any material, such as semiconductors
Implementation Method 3
electrostatic deflection and synchronized mechanical movement of the ion beam and energy filter
Data Source
Figure 1~2b
Figure 3a~4
Figure 5~6
AI summary
A device is described comprising a wafer chamber (42) having a wafer holder (20, 45) designed to hold at least one wafer (8) and a filter chamber (36) having a filter holder (44) and a first and second closable opening.