Boron Ion Beam Current via B2H6-H2-BF3 Dopant Mixture
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Solution Overview
Problem
Current boron ion implantation processes using boron trifluoride (BF3) face limitations in generating high beam current due to reduced ion source life and chemical erosion, leading to unstable beam profiles and shortened equipment lifespan.
Innovation Solution
A dopant gas composition comprising diborane (B2H6) at 0.1%-10% and hydrogen (H2) at 5%-15% with the balance being BF3, which has a higher ionization cross-section than BF3, is used to increase boron ion beam current and extend ion source life by reducing halogen cycle effects and minimizing component erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the energy input to the ion source is increased to increase B+ ion generation, then the beam current increases, but the ion source lifetime is reduced due to increased chemical erosion of chamber walls
Solution Approach 1:
The patent changes the chemical composition parameters of the dopant gas from pure BF3 to a mixture containing B2H6 (0.1-10%) and H2 (5-15%). This parameter change modifies the plasma chemistry to reduce fluorine radical concentration, thereby reducing chemical erosion of tungsten chamber walls while maintaining high B+ ion generation rates and beam current
Solution Approach 2:
The patent uses a composite gas mixture of B2H6, H2, and BF3 instead of a single gas component. This composite approach leverages the beneficial properties of each gas: B2H6 provides high ionization cross-section for B+ generation, H2 suppresses fluorine radical reactivity, and BF3 contributes to the overall boron supply, achieving both high productivity and extended equipment life
2Productivity
If the flow rate of BF3 is increased to increase B+ ion generation, then the beam current increases, but chemical erosion of chamber walls increases leading to shorter ion source life
Solution Approach 1:
The patent introduces H2 as an intermediary substance that mediates the interaction between fluorine radicals and chamber walls. H2 reacts with fluorine radicals to form HF, thereby reducing the concentration of highly reactive F atoms that cause chemical erosion of tungsten walls, while allowing high BF3 flow rates to maintain beam current
3Productivity
If extraction current is increased to increase beam current, then more dopant ions are available for implantation, but the ion source components suffer increased stress and reduced lifetime
Solution Approach 1:
The patent changes the gas composition parameters to create a plasma environment that enables high beam current at lower extraction currents. The B2H6-H2-BF3 mixture provides more efficient ionization and higher B+ ion density in the plasma, allowing increased beam current without proportionally increasing extraction current and associated stress on ion source components
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 composition achieves a sustained increase in boron ion beam current while extending ion source life, reducing beam glitching and maintaining equipment integrity, thus enhancing productivity and throughput in semiconductor manufacturing.
Implementation Method 1
diborane (B2H6) at a level ranging from about 0.1% - 10%, H2 ranging from about 5% - 15% and the balance is BF3. The B2H6 is selected to have an ionization cross-section higher than that of BF3 at an operating arc voltage of an ion source utilized during generation and implantation of active boron ions
Implementation Method 2
The ions produce a plasma environment within the ion chamber
Data Source
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AI summary
A novel composition, system and method thereof for improving beam current during boron ion implantation are provided. The boron ion implant process involves utilizing B2H6, BF3 and H2 at specific ranges of concentrations. The B2H6 is selected to have an ionization cross-section higher than that of the BF3 at an operating arc voltage of an ion source utilized during generation and implantation of active hydrogen ions species. The hydrogen allows higher levels of B2H6 to be introduced into the BF3 without reduction in F ion scavenging. The active boron ions produce an improved beam current characterized by maintaining or increasing the beam current level without incurring degradation of the ion source when compared to a beam current generated from conventional boron precursor materials.