Plasma Flood Gun Feedback Control for Filament Contamination
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Solution Overview
Problem
Ion implantation systems face challenges with wafer charging due to the buildup of positive charges during ion implantation, leading to non-uniform doping and arcing defects, which can be mitigated by neutralizing the ion beam with electrons but results in filament contamination and reduced filament life due to increased resistance and temperature.
Innovation Solution
A plasma flood gun is used to inject electrons into the ion beam, with a filament resistance measurement system that adjusts the filament current to maintain a stable operating temperature and reduce contamination, extending the filament's useful life and improving the system's predictability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plasma flood gun is used to neutralize the ion beam with electrons, then wafer charging is mitigated, but filament contamination increases and filament life is reduced
Solution Approach 1:
The system measures filament resistance and uses this feedback to adjust filament current, maintaining stable operating conditions that reduce contamination while preserving the plasma generation function needed for wafer charging neutralization
Solution Approach 2:
The system dynamically adjusts filament current based on measured resistance changes, optimizing the balance between plasma generation efficiency and filament lifespan by modifying operational parameters in real-time
2Quantity of substance
If filament current is increased to maintain plasma generation, then electron supply for neutralization is improved, but filament temperature increases and contamination worsens
Solution Approach 1:
The system adjusts filament current based on resistance measurements to maintain optimal plasma generation while controlling filament temperature and minimizing contamination
Solution Approach 2:
By continuously monitoring filament resistance and adjusting current accordingly, the system maintains stable electron supply for plasma generation without excessive temperature increase
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 plasma flood gun effectively neutralizes wafer charging, reduces contamination, and prolongs the filament's operational life by maintaining a stable resistance, thereby enhancing the ion implantation process's reliability and consistency.
Implementation Method 1
a filament to emit electrons based on a filament current induced in the filament to heat the filament
Implementation Method 2
The plasma flood gun generates and releases electrons, which neutralize at least some of the positively charged ion beam before striking the semiconductor wafer
Data Source
AI summary
A plasma flood gun includes a filament to emit first electrons based on a first filament current induced in the filament to heat the filament to a first temperature at a first time. The first electrons interact with an inert gas in an arc plasma chamber to generate a first plasma. A filament resistance meter measures a first filament resistance of the filament, in-situ, during generation of the first plasma. A filament current source adjusts, based on the first filament resistance, the first filament current induced in the filament at the first time to a second filament current induced in the filament at a second time to generate a second plasma in the arc plasma chamber at the second time.