Ion Implanter Workpiece Tilt and Resolving Aperture
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Solution Overview
Problem
Ion implantation systems face challenges in achieving uniform ion distribution and controlling implantation angles on larger semiconductor wafers, leading to variations in device performance due to increased shadowing and channeling effects as feature sizes shrink and wafer sizes grow.
Innovation Solution
The system tilts the workpiece and moves a resolving aperture with the ion beam as it sweeps across the wafer to maintain a constant implantation angle and block contaminants, ensuring consistent ion implantation across the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer size is increased to allow more devices to be fabricated at the same time, then productivity is improved, but manufacturing precision deteriorates due to increased shadowing and channeling effects
Solution Approach 1:
The system dynamically tilts the workpiece during ion beam sweeping to maintain a constant implantation angle across the wafer surface. This dynamic adjustment compensates for the increased shadowing and channeling effects that occur with larger wafer sizes, ensuring uniform ion implantation while maintaining high productivity
Solution Approach 2:
The control system monitors the beam position and workpiece orientation, automatically adjusting the workpiece tilt angle to maintain the desired implantation angle throughout the sweeping process. This feedback mechanism ensures consistent ion implantation characteristics across the entire wafer surface
2Productivity
If ion beam sweeping is used to cover the entire wafer surface, then productivity is improved, but manufacturing precision deteriorates due to variations in implantation angle
Solution Approach 1:
The workpiece is dynamically tilted during the ion beam sweeping process to compensate for angle variations. As the beam moves across the wafer surface, the workpiece orientation is continuously adjusted to maintain a constant implantation angle, ensuring uniform doping characteristics across the entire wafer
Solution Approach 2:
The workpiece tilt is pre-adjusted based on the expected beam position and sweeping trajectory. This preliminary positioning, combined with real-time adjustments, ensures that the implantation angle remains constant throughout the entire wafer coverage process
3Manufacturing precision
If resolving aperture is moved with the beam to block contaminants, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The resolving aperture serves as an intermediary element that moves synchronously with the ion beam. By positioning the aperture in the beam path and moving it with the beam, the system effectively blocks contaminants while allowing the desired ion beam to pass through, maintaining high ion beam purity
Solution Approach 2:
The motion control of the resolving aperture is merged with the beam sweeping control system. Both the beam position and aperture position are coordinated through a single control mechanism, reducing the need for separate control systems while maintaining effective contaminant blocking
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 ensures consistent and predictable ion implantation, reducing shadowing and channeling effects, and maintaining uniformity in device performance across the wafer, even with increased wafer sizes and tighter feature spacings.
Implementation Method 1
The ion beam is directed at the surface of a semiconductor wafer or workpiece to implant ions therein. The ions penetrate the surface of the wafer to form regions of desired conductivity.
Implementation Method 2
A resolving aperture, or alternatively resolving plates, move with the beam as the beam is swept up and/or down the workpiece. This allows desired ions to impinge on the wafer, but blocks undesirable contaminants.
Data Source
AI summary
A workpiece or semiconductor wafer is tilted as a ribbon beam is swept up and/or down the workpiece. In so doing, the implant angle or the angle of the ion beam relative to the workpiece remains substantially constant across the wafer. This allows devices to be formed substantially consistently on the wafer. Resolving plates move with the beam as the beam is scanned up and/or down. This allows desired ions to impinge on the wafer, but blocks undesirable contaminants.