Negative Hydrogen Ion Beam Generation via Charge Exchange Optimization
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Solution Overview
Problem
Conventional ion implanters face challenges in producing high energy hydrogen ion beams with sufficient current for high energy implantation, particularly in semiconductor manufacturing, due to low ion current limitations.
Innovation Solution
The method involves generating positive hydrogen ions and adjusting their extraction voltage to maximize negative ion current yield through a charge exchange process using a charge exchange cell, optimizing the energy and species of hydrogen ions such as H+, H2+, and H3+ to achieve higher negative hydrogen ion currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional ion implanters use tandem acceleration to generate high energy hydrogen ions, then ion energy can be increased to desired levels, but ion current remains relatively low which limits substrate throughput
Solution Approach 1:
The invention changes the extraction voltage parameter to optimize the product of extraction efficiency and charge exchange efficiency. By adjusting extraction voltage, the system maximizes negative ion current yield while maintaining high ion energy, thereby resolving the contradiction between energy and throughput
Solution Approach 2:
The invention introduces a charge exchange cell as an intermediary component between the ion source and the accelerator. This cell converts positive molecular hydrogen ions to negative hydrogen ions through charge exchange with cesium atoms, enabling high current negative ion beams that can be accelerated to high energies without the current limitations of conventional direct acceleration
2Quantity of substance
If extraction voltage is increased to improve ion current, then more ions can be extracted, but charge exchange efficiency decreases reducing negative ion yield
Solution Approach 1:
The invention optimizes extraction voltage as a critical parameter to achieve the maximum product of extraction efficiency and charge exchange efficiency. Rather than simply increasing extraction voltage to maximize ion current, the system finds the optimal voltage point where both extraction efficiency and charge exchange efficiency are balanced to maximize negative ion yield
Solution Approach 2:
The system employs feedback through efficiency measurements to determine the optimal extraction voltage. By monitoring both extraction efficiency and charge exchange efficiency, the system can adjust operating parameters to maintain optimal negative ion current yield
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 significantly increases negative hydrogen ion current, enabling higher proton currents at the substrate, thereby enhancing the throughput and efficiency of high energy ion implantation processes.
Implementation Method 1
a charge exchange cell comprising charge exchange species to convert the extracted positive molecular hydrogen ions to negative hydrogen ions
Data Source
AI summary
An apparatus to generate negative hydrogen ions includes an ion source operative to generate positive hydrogen ions, a first component to adjust positive molecular hydrogen ion species in the ion source, a second component to adjust extraction voltage for extraction of the positive molecular hydrogen ions from the ion source, and a charge exchange cell comprising charge exchange species to convert the extracted positive molecular hydrogen ions to negative hydrogen ions. The adjusted extraction voltage is effective to generate an ion energy to maximize negative ion current yield in the charge exchange cell based upon a product of extraction efficiency of the positive molecular hydrogen ions and a peak in charge exchange efficiency for converting a species of the positive molecular hydrogen ions to negative hydrogen ions through charge exchange between the extracted hydrogen ions and charge exchange species.