Ion Beam Generator Grid Distortion Control
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Solution Overview
Problem
Conventional ion beam generators experience thermal distortion in the beam extraction unit, leading to degraded performance in etching or sputtering due to thermal expansion, which affects beam extraction efficiency.
Innovation Solution
The ion beam generator design incorporates a plasma discharge chamber with a mounting platform and extraction electrode assembly, where the thermal expansion coefficients of the sidewall, mounting platform, and grids satisfy the relation αP>αM≧αG, using materials like stainless steel, aluminum, titanium, molybdenum, tungsten, and carbon to minimize grid distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional materials are used for the beam extraction unit, then the structure is simple and easy to manufacture, but thermal distortion occurs during operation leading to degraded beam extraction efficiency
Solution Approach 1:
The patent applies parameter changes by carefully selecting materials with specific thermal expansion coefficients for different components. The sidewall uses material with αP, the mounting platform uses material with αM where αP > αM, and the grids use material with αG where αM ≥ αG. This gradient in thermal expansion parameters allows the structure to accommodate thermal expansion during operation while maintaining grid precision, thereby improving beam extraction efficiency without excessive complexity.
Solution Approach 2:
The patent employs composite materials strategy by using different materials for different components of the beam extraction unit. The sidewall may use stainless steel or aluminum, the mounting platform uses Ti or Mo, and the grids use Mo, W or C. This multi-material approach creates a composite structure that optimizes thermal performance and mechanical properties for each component's specific function, resolving the contradiction between manufacturing precision and device complexity.
2Productivity
If the beam extraction unit operates at high temperature, then ion beam generation is effective, but thermal expansion causes grid distortion and performance degradation
Solution Approach 1:
The patent directly applies the thermal expansion principle by designing a structure where different components have different thermal expansion coefficients. The sidewall (αP) expands more than the mounting platform (αM), which expands more than or equal to the grids (αG). This graduated thermal expansion design allows each component to expand at its own rate during high-temperature operation, preventing grid distortion while maintaining ion beam generation efficiency.
Solution Approach 2:
The patent applies local quality by assigning different material properties to different locations in the beam extraction unit. The sidewall uses materials with higher thermal expansion coefficient, the mounting platform uses intermediate materials, and the grids use materials with lowest thermal expansion coefficient. This spatial variation in material quality ensures that each location has the appropriate thermal and mechanical properties for its specific function, maintaining grid stability during high-temperature operation.
3Weight of moving object
If grids are made thinner to reduce mass, then the structure is lighter, but thermal distortion increases leading to worse beam extraction performance
Solution Approach 1:
The patent uses parameter changes by selecting grid materials with very low thermal expansion coefficients (Mo, W, or C) and optimizing grid thickness to be equal to or larger than 2 mm. This parameter optimization allows the grids to maintain dimensional stability under thermal load while minimizing weight. The low thermal expansion coefficient compensates for the relatively large thickness, achieving a balance between weight and thermal stability that maintains beam extraction efficiency.
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 configuration suppresses grid distortions, ensuring high-quality ion beam production and reducing the time required for etching rate and uniformity stabilization, thereby improving overall process quality and tool utilization.
Implementation Method 1
the sidewall of the plasma discharge chamber which contacts the mounting platform has thermal expansion coefficient TEC=αP, the mounting platform has thermal expansion coefficient TEC=αM and the extraction electrode assembly has thermal expansion coefficient TEC=αG where the αP, αM, αG satisfy the formula: αP>αM≧αG
Data Source
AI summary
[Objection of the invention]An ion beam generator, a thermal distortion in a grid assembly is reduced. [Structure to solve the objection]Thermal expansion coefficients αP, αM and αG, for a sidewall (1A) of a discharge chamber, mounting platform (40) and extraction grid electrode assembly (20) are selected to have a relation: αP>αM≧αG. For example, the material of discharge chamber sidewall is stainless steel o aluminum, the material of grids is Mo, W or C and the material of platform is Ti or Mo.