Silicon-Coated Dose Cup Assembly for Low-Particle Ion Implanting
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Solution Overview
Problem
The formation of brittle films on dose cup assemblies in ion implanters due to ion beam exposure leads to particle formation, increasing preventive maintenance and reducing throughput.
Innovation Solution
A dose cup assembly with components made of silicon or coated with silicon carbide, featuring a unique geometry that minimizes film formation by altering the angle of ion incidence and interaction, thereby reducing particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the dose cup assembly is exposed to the ion beam to monitor beam current, then beam current measurement is enabled, but film formation occurs on the dose cup assembly which leads to particle generation
Solution Approach 1:
A silicon-coated shield is introduced as an intermediary component between the ion beam and the dose cup assembly. This shield intercepts the ion beam exposure, preventing direct interaction between the beam and the dose cup surfaces. The silicon coating acts as a sacrificial layer that protects the underlying metal surfaces from film formation, thereby eliminating particle generation while allowing the dose cup assembly to maintain its beam current measurement function
Solution Approach 2:
The harmful effect of ion beam exposure causing film formation is converted into a beneficial outcome by applying a silicon coating. The ion beam that would otherwise damage the dose cup assembly is instead used to deposit or modify the silicon coating, creating a protective layer. This transforms the harmful radiation into a tool for surface engineering that prevents the very film formation it initially causes
2Strength
If the dose cup assembly components are made from graphite or metal, then structural integrity is maintained, but brittle film forms on the exposed surfaces due to ion beam interaction
Solution Approach 1:
The dose cup assembly components are constructed as composite structures with a metal or graphite substrate providing structural integrity and a silicon coating providing surface stability. The silicon layer serves as a protective barrier that prevents the formation of brittle films on the underlying structural materials. This composite approach allows the assembly to maintain its mechanical strength while resisting the chemical changes caused by ion beam exposure
3Reliability
If the dose cup assembly is positioned to protect current sensors, then sensor protection is achieved, but the assembly itself is exposed to ion beam and generates particles
Solution Approach 1:
A silicon-coated shield is positioned between the ion beam and the dose cup assembly, serving as an intermediary protective element. This shield maintains the spatial arrangement needed to protect current sensors while intercepting the ion beam before it reaches the dose cup surfaces. The silicon coating on the shield prevents film formation and particle generation, allowing the dose cup assembly to fulfill its protective function without becoming a source of contamination
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 redesigned dose cup assembly significantly reduces film formation and particle generation, enhancing the operational reliability and throughput of ion implanters.
Implementation Method 1
A dose cup assembly with components made of silicon or coated with silicon carbide, featuring a unique geometry that minimizes film formation by altering the angle of ion incidence and interaction
Data Source
AI summary
A dose cup assembly that results in less particles in a process chamber is disclosed. The dose cup assembly includes a faceplate attached to a back wall of the process chamber, and having an opening; an aperture plate defining a plurality of slots; and a tunnel having walls and sidewalls and having a proximal end and a distal end, located between the faceplate and the aperture plate, such that the proximal end is nearer to the faceplate and the distal end is nearer to the aperture plate; wherein at least one of the faceplate, the walls, the sidewalls or the aperture plate has one or more exposed outer surfaces that comprise silicon. The exposed outer surfaces may be silicon. In some embodiments, the faceplate, the walls, the sidewalls or the aperture plate may be graphite, aluminum, or stainless steel which is coated with silicon or silicon carbide.