Cylindrical Target Sputtering for Wide-Angle Lens Uniformity
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Solution Overview
Problem
Existing film forming apparatuses are limited in forming uniform film thickness on lens surfaces with large half-aperture angles, particularly failing to achieve uniformity on both concave and convex surfaces.
Innovation Solution
A film forming apparatus with a base material support mechanism and a cylindrical target that rotates about skewed axes, allowing for precise control of film thickness distribution through adjustable magnet positions and plasma emission monitoring, enabling uniform film formation on both concave and convex surfaces with large half-aperture angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a planar target is used in a conventional sputtering apparatus, then the structure is simple, but uniform film thickness cannot be achieved on lens surfaces with large half-aperture angles (40° or greater)
Solution Approach 1:
The patent employs a cylindrical target instead of a conventional planar target. The cylindrical geometry allows the target surface to be curved, enabling sputtered particles to reach lens surfaces with large half-aperture angles more uniformly. This curvature matches the geometric requirements for coating wide-angle lenses, solving the film thickness uniformity problem without requiring complex mechanical adjustment systems.
Solution Approach 2:
The patent introduces rotation of the cylindrical target around its axis, adding a temporal dimension to the sputtering process. By rotating the target, different portions of the cylindrical surface are brought into position to deposit film on different regions of the lens, achieving uniform film thickness across the entire lens surface including edges and corners that would be difficult to reach with a static planar target.
2Area of stationary object
If the target is positioned to cover the entire lens surface, then film formation coverage is improved, but film thickness uniformity deteriorates due to varying distances from target to different lens regions
Solution Approach 1:
The patent makes the target dynamic by enabling rotation around its cylindrical axis. This dynamic motion allows the target to present different surface elements to different regions of the lens during rotation, compensating for the varying distances from the target to different lens regions. The rotation ensures that all areas receive equivalent deposition over time, achieving both full coverage and uniform thickness.
Solution Approach 2:
The periodic rotation of the cylindrical target creates a time-varying deposition pattern. As the target rotates, each region of the lens is exposed to sputtered material from different angular positions, and the periodic nature of this rotation ensures that the cumulative deposition is uniform across the entire lens surface, resolving the contradiction between coverage area and thickness uniformity.
3Manufacturing precision
If a cylindrical target is used to improve film uniformity on wide-angle lenses, then film thickness uniformity is improved, but the device structure becomes more complex
Solution Approach 1:
The cylindrical target structure serves multiple functions simultaneously: it provides the curved surface geometry needed for wide-angle lens coverage, enables rotational motion for uniform deposition, and maintains structural integrity as a single piece. This multi-functionality reduces the need for additional complex components such as multiple planar targets or complex positioning mechanisms, making the overall system more efficient despite the cylindrical geometry.
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 apparatus achieves film thickness uniformity within ±4% on surfaces with half-aperture angles of 40° or greater, regardless of whether the surface is concave or convex, enhancing the efficiency and accuracy of film formation.
Implementation Method 1
a first cathode portion configured to rotate a target in a first cylindrical shape about a second rotation axis; and a second cathode portion configured to rotate a target in a second cylindrical shape about a third rotation axis
Data Source
AI summary
A film forming apparatus includes a base material support mechanism configured to rotate a base material supported by the base material support mechanism about a first axis, and a first cathode portion on which a target in a cylindrical shape containing a film forming material is mounted and configured to rotate the target about a second axis, in a chamber. The second axis is disposed at a position skewed with respect to the first axis.