Ion Implanter Graphite Surface Saw-Tooth Geometry
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Solution Overview
Problem
Ion implanter components adjacent to the ion beam path, typically made of graphite, suffer from sputtering, leading to material becoming entrained in the beam and causing contamination or damage to semiconductor wafers.
Innovation Solution
Shaping the surfaces of ion implanter components to form a series of angled faces, creating a saw-tooth cross-section that directs sputtered material away from the ion beam path, and applying a surface coating with higher sputtering resistance such as tungsten or tantalum carbide to reduce material entrainment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphite surfaces are used adjacent to the ion beam path, then the components are easy to manufacture and have good thermal properties, but sputtered material becomes entrained in the ion beam causing contamination
Solution Approach 1:
The graphite component surface is shaped with asymmetric angled faces (saw-tooth cross-section) that are not symmetrically arranged. The angled faces are specifically oriented to present surfaces at angles that deflect sputtered material away from the ion beam path, breaking the symmetry that would otherwise cause material to be ejected directly into the beam.
Solution Approach 2:
The solution introduces a new dimensional aspect to the surface geometry by creating angled faces that extend in the direction of ion beam travel. This adds a longitudinal dimension to the surface structure, allowing sputtered material to be ejected at angles that move it out of the beam path rather than directly into it.
2Ease of manufacture
If surfaces are made smooth and flat, then manufacturing is simple, but sputtered material is more likely to be ejected directly into the ion beam path
Solution Approach 1:
Instead of smooth flat surfaces, the invention employs asymmetric angled faces that are deliberately non-uniform in their orientation. The faces are angled relative to each other and to the ion beam path, creating an asymmetric geometry that causes sputtered material to be ejected at varied angles away from the beam rather than in a uniform direction into the beam.
Solution Approach 2:
The invention replaces flat planar surfaces with angled faces that create a more complex, curved-like geometry. While not perfectly spherical, the angled faces introduce curvature and angular variations that deflect material ejection away from straight-line paths that would lead directly into the ion beam.
3Quantity of substance
If material deposits accumulate on surfaces, then the surfaces become contaminated, but this increases the chance of flake formation and particle detachment that become entrained in the beam
Solution Approach 1:
The asymmetric angled face geometry prevents uniform accumulation of deposited material. The varying angles create zones where deposits are less likely to form large continuous flakes, and any flakes that do form are more likely to be oriented or positioned such that they do not detach into the ion beam path.
Solution Approach 2:
By extending the surface geometry in the direction of ion beam travel with angled faces, the invention creates a dimensional structure that prevents deposits from forming large planar flakes. The angled surfaces cause deposits to accumulate in a more distributed, three-dimensional pattern that reduces flake formation and detachment risk.
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
Effectively reduces the amount of sputtered material that becomes entrained in the ion beam, minimizing contamination and extending the life of graphite components by preventing material deposition and flake formation.
Implementation Method 1
If the ion beam strikes such components, material may be sputtered from that surface
Data Source
AI summary
The present invention relates to components in ion implanters having surfaces, such as graphite surfaces, adjacent to the path of the ion beam through the ion implanter. Such surfaces will be prone to sputtering, and sputtered material may become entrained in the ion beam. The present invention sees the use of surfaces that are formed so as to present a series of angled faces that meet at sharp intersections. In this way, any material will be sputtered away from the ion beam.