Grid Assembly Positioning Holes for Ion Beam Etching
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Solution Overview
Problem
The existing grid assembly for ion beam etching apparatuses is difficult to assemble and prone to manufacturing errors, leading to misalignment and deformation, which affects the uniformity of the ion beam distribution and etching rate on semiconductor substrates, especially as substrate size increases.
Innovation Solution
A grid assembly design featuring positioning holes and fixing holes with protrusion portions and passing-through members that allow for precise alignment and easy assembly, reducing the risk of misalignment and deformation by separating the positioning and fixing processes, and incorporating a configuration that accommodates thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of through-holes is reduced to simplify assembly, then ease of manufacture is improved, but positioning precision deteriorates
Solution Approach 1:
The through-holes are segmented into two distinct types: positioning through-holes (with smaller diameter) and fixing through-holes (with larger diameter). This segmentation allows each type of hole to serve its specific function optimally - positioning holes provide precise alignment while fixing holes accommodate larger fastening elements, thereby maintaining positioning precision while simplifying the overall assembly process.
Solution Approach 2:
Positioning through-holes are provided in advance before the actual fixing operation. These pre-positioned holes enable accurate alignment of the grids relative to each other and to the chamber wall before the fixing bolts are installed, ensuring positioning precision is achieved without requiring complex assembly procedures.
2Ease of manufacture
If loose fitting tolerance is used to facilitate assembly, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The fitting tolerance is segmented and differentiated between positioning through-holes and fixing through-holes. Positioning through-holes use tighter tolerances to ensure precise alignment, while fixing through-holes can use looser tolerances to facilitate easier assembly. This segmented approach to tolerance specification allows the system to achieve both precise alignment and ease of assembly.
3Manufacturing precision
If close fitting tolerance is used to suppress misalignment, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The close fitting tolerance is applied selectively only to the positioning through-holes, not to all through-holes. This segmentation allows precise alignment to be achieved where needed (at the positioning holes) while other areas (fixing holes) can use more generous tolerances to maintain ease of assembly.
4Reliability
If forced fixing is applied to ensure assembly, then reliability is improved, but manufacturing precision deteriorates
Solution Approach 1:
The fixing process is segmented into two stages: first, positioning through-holes are used to align the grids precisely without applying significant force; second, fixing through-holes are used to install larger diameter bolts that provide reliable mechanical fastening. This segmented approach ensures that the grids are positioned accurately before fixing, and the reliable fixing is achieved through properly sized fastening elements rather than forced assembly, thereby preventing deformation.
Data Source
AI summary
An object of the invention is to provide a grid assembly which is easy to assemble and is high in assembly reproducibility, and an ion beam etching apparatus including it. A grid assembly is constructed of three grids each in the shape of a circular plate, which are stacked one on top of another. The grid assembly includes three fixing holes for fixing the three grids, and three positioning holes for positioning the three grids. In assembly, the three grids are stacked one on top of another on a first ring so that positioning pins provided on the first ring are inserted into the positioning holes. Then, a second ring is stacked on top of the three grids, and bolts are inserted into the fixing holes. Thus, positioning is performed by using the fixed positioning pins and thereafter the fixing can be performed, which facilitates the assembly.