Ion Implanter Velocity Control for Wafer Topology
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Solution Overview
Problem
Current ion implantation processes in semiconductor manufacturing lack three-dimensional control, leading to non-uniform doping profiles and electrical characteristics due to the two-dimensional motion of wafers under constant velocity implants, which fail to account for the wafer's topology.
Innovation Solution
The method involves decomposing dosages into directional components and converting them into velocities to dynamically adjust the movement of the wafer relative to the ion beam, allowing for precise control of dopant implantation across a semiconductor wafer by separating the wafer into cells and using a wafer positioning system to apply these velocities, thereby accounting for the wafer's topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two-dimensional wafer manipulator with constant velocity implant is used, then the implantation process is simple to control, but the doping profile becomes non-uniform due to three-dimensional wafer topology variations
Solution Approach 1:
The patent transitions from constant velocity implantation to dynamically variable velocity implantation. The wafer manipulator adjusts the wafer's velocity dynamically during the implantation process based on real-time position and dosage requirements, allowing the system to compensate for three-dimensional topology variations while maintaining precise control over the doping profile uniformity.
Solution Approach 2:
The patent extends the control system from two-dimensional manipulator motion to three-dimensional dosage control. By incorporating velocity modulation in the time dimension, the system achieves uniform doping profiles across the wafer's three-dimensional topology, effectively adding a temporal dimension to the spatial control problem.
2Productivity
If constant velocity implantation is used across the entire wafer, then the process is efficient and fast, but the electrical characteristics become non-uniform across different regions
Solution Approach 1:
The patent applies local quality control by assigning different velocity parameters to different regions of the wafer. The controller modulates the wafer's velocity based on the specific dosage requirements of each local region, allowing high-speed implantation in some areas while providing precise, slowed-down implantation in regions requiring higher dosage accuracy, thereby achieving uniform electrical characteristics across the entire wafer.
Solution Approach 2:
The patent dynamically changes the velocity parameter during the implantation process. By continuously adjusting the wafer's velocity based on real-time feedback and pre-calculated dosage maps, the system maintains high overall productivity while ensuring that each region receives the precise dosage needed for uniform electrical characteristics.
3Device complexity
If the wafer is swept at constant speed across the ion beam, then the motion control is simple, but the dopant accumulation varies due to overlapping scan paths
Solution Approach 1:
The patent implements a feedback control system where the controller receives information about the wafer's position, the ion beam's location, and the accumulated dosage. Based on this feedback, the controller dynamically adjusts the wafer's velocity to compensate for overlapping scan paths, ensuring uniform dopant concentration while keeping the motion control system relatively simple through algorithmic compensation rather than mechanical complexity.
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 fine-tuning of dopant implantation, ensuring a more uniform dopant profile and improved electrical performance across the wafer by dynamically adjusting velocities in multiple directions to match the desired uniformity.
Implementation Method 1
A typical ion implantation process uses an ion implanter to initially generate ions of the desired dopant and then accelerates these ions to an appropriate energy level. Once accelerated, the ion implanter then transports the ions along an ion beam to impact and implant into a semiconductor wafer.
Data Source
AI summary
A system and method for controlling a dosage profile is disclosed. An embodiment comprises separating a wafer into components of a grid array and assigning each of the grid components a desired dosage profile based upon a test to compensate for topology differences between different regions of the wafer. The desired dosages are decomposed into directional dosage components and the directional dosage components are translated into scanning velocities of the ion beam for an ion implanter. The velocities may be fed into an ion implanter to control the wafer-to-beam velocities and, thereby, control the implantation.