Ion Implanter Beam Control Circuit for Particle Contamination Reduction
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Solution Overview
Problem
Ion implantation systems face significant challenges in minimizing particle contamination due to beam strikes on electrodes and beamline components, which leads to non-uniformity and reduced yield in semiconductor fabrication, especially with larger wafers where contamination can render entire wafers unusable.
Innovation Solution
A beam control circuit utilizing high voltage high speed (HVHS) switches is introduced to minimize particle contamination by controlling the duty factor of the ion beam, with switches connected in series between the power supply and electrodes to initiate or terminate the ion beam, thereby reducing the duration of beam strikes and associated contamination. This circuit includes protection mechanisms to manage overvoltages and synchronize switch operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ion beam is continuously applied during ion implantation, then the implantation process can be maintained without interruption, but particle contamination increases due to beam strikes on electrodes and beamline components
Solution Approach 1:
The patent applies periodic action by switching the ion beam between ON and OFF states. The beam is turned OFF during wafer loading/unloading and turned ON during implantation, creating a periodic duty cycle that reduces beam strikes and particle contamination while maintaining productive implantation time
Solution Approach 2:
The patent implements dynamic control of the ion beam through a beam control circuit that adjusts the beam duty factor in real-time. The system dynamically switches the beam state based on process requirements, optimizing between continuity and contamination reduction
2Object-affected harmful factors
If the ion beam duty factor is reduced to minimize beam strikes, then particle contamination decreases, but the total implantation time increases
Solution Approach 1:
The periodic switching of the ion beam creates optimized duty cycles where the beam is OFF only during necessary non-implantation activities (wafer loading/unloading) and ON during productive implantation, minimizing both contamination and time loss
Solution Approach 2:
The beam control circuit performs preliminary actions by pre-cooling electrodes and preparing the beamline before turning the beam ON, and by turning the beam OFF immediately after implantation completes, optimizing the transition periods to minimize both contamination and time loss
3Object-affected harmful factors
If high voltage switches are added to control the ion beam duty factor, then particle contamination is reduced, but the system complexity increases
Solution Approach 1:
The patent introduces high voltage switches as intermediary components between the power supply and the ion source electrodes. These switches act as mediators that control beam generation by interrupting or enabling voltage application, providing clean ON/OFF control without direct mechanical intervention
Solution Approach 2:
The patent replaces mechanical beam control methods with electrical switching. Instead of mechanical choppers or physical beam blocking, the system uses high voltage electronic switches to control beam generation electrically, reducing mechanical complexity and improving reliability
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
The solution effectively reduces particle contamination by minimizing the ion beam's on-time, thereby increasing its useful application on wafers and reducing peripheral contamination, enhancing the quality and yield of semiconductor devices by ensuring more precise control over the implantation process.
Implementation Method 1
a high voltage switch connected in series with a power supply and an element associated with an ion source portion of the ion implantation system, wherein the switch is operable to interrupt or reestablish a connection between the power supply and the electrode
Implementation Method 2
an ion source ionizes a desired dopant element, and the ionized impurity is extracted from the ion source as a beam of ions
Data Source
AI summary
The present invention is directed to a beam control circuit and method used to minimize particle contamination in an ion implantation system by reducing the duty factor of the ion beam. In one embodiment the beam control circuit comprises a high voltage switch connected in series with a power supply and an ion source portion of the ion implantation system, wherein the switch is operable to interrupt or reestablish a connection between the power supply and an electrode of the ion source including electrodes for plasma production. The beam control circuit also comprises a switch controller operable to control the duty factor of the ion beam by controlling the switch to close before a start of ion implantation and to open after a completion of implantation or at other times when the beam is not needed, thereby minimizing beam duty and particle contamination. The beam control technique may be applied to wafer doping implantation and duty factor reduction. Protection circuits for the high voltage switch absorb energy from reactive components and clamp any overvoltages.