Physical Vapor Deposition Dome Angle Optimization
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Solution Overview
Problem
Existing physical vapor deposition processes face challenges in achieving uniform thickness distribution of material layers on substrates held by a rotating dome, particularly for thick antireflective layers like ZrO2, with substrates near the periphery often having less material than those near the center.
Innovation Solution
A process involving a dome rotation axis with substrates at varying distances, using an energy beam to evaporate material from a target with a specific angle between the dome rotation axis and the main diffusion axis, optimizing the angle between +5° to +40° or -5° to -40° to ensure uniform layer thickness across all substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If substrates are arranged on a rotating dome for physical vapor deposition, then multiple substrates can be coated simultaneously, but the thickness distribution of the material layer becomes non-uniform across substrates at different positions
Solution Approach 1:
The patent applies local quality by adjusting the deposition conditions for different regions of the dome. Specifically, substrates at different radial positions (internal vs external) receive different amounts of material flux by controlling the evaporation geometry and angle, ensuring that each region receives the appropriate material quantity to achieve uniform thickness across all substrates simultaneously
Solution Approach 2:
The patent changes the geometric parameters of the deposition system, specifically the angle between the dome rotation axis and the main diffusion axis of evaporated material (optimized at +5° to +40° or -5° to -40°), and the distance of substrates from the rotation axis. These parameter adjustments compensate for the natural radial variation in material flux during rotation, enabling uniform thickness distribution while maintaining high productivity
2Quantity of substance
If the energy beam evaporates material from the target, then material is deposited on substrates, but thickness homogeneity between interior and exterior substrates cannot be easily obtained for thick layers
Solution Approach 1:
The patent introduces asymmetry in the deposition geometry by positioning the target and substrates at specific asymmetric angles relative to the dome rotation axis. The angle between the dome rotation axis and the main diffusion axis is optimized at +5° to +40° or -5° to -40°, creating an asymmetric material flux distribution that compensates for the radial position differences between internal and external substrates, achieving uniform thickness even for thick layers (≥50nm, particularly for ZrO2)
Solution Approach 2:
The patent adds a angular dimension to the deposition control by varying the angle α between the dome rotation axis and the main diffusion axis. This angular parameter provides an additional degree of freedom to control material distribution, allowing independent optimization of thickness uniformity across different radial positions on the rotating dome
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 process ensures uniform thickness of material layers on both internal and external substrates, as demonstrated by successful deposition of ZrO2 layers on ophthalmic spectacle lenses, achieving satisfactory thickness homogeneity and chromaticity similarity across the dome.
Implementation Method 1
The material to be deposited is vacuum evaporated thanks to an energy beam from a target which is made of said material
Implementation Method 2
Physical Vapor Deposition is a well-known process performed under vacuum in which a target consisting of a material is bombarded with an energy beam. The energy beam causes atoms from the target to transform into the gaseous phase. These atoms then precipitate into solid form, coating simultaneously the plurality of substrates in a vacuum chamber with a layer of the material
Data Source
Figure 1a
Figure 1b~2
Figure 3~4
AI summary
The present invention relates to a process of physical vapor deposition of a material layer on surfaces of a plurality of substrates (11), wherein: - the plurality of substrates (11) are arranged on a dome (12) which rotates according to a dome rotation axis (300); - the material to be deposited is vacuum evaporated thanks to an energy beam from a target (13); - the energy beam interacts with a beam impact surface of the target chosen within the list consisting of a part of a main surface (15) and a part of an edge (14) of the target and wherein the material diffuses from the target to the substrates around a main diffusion axis (100) which intersects the dome (12) at an intersection point, I; and - the angle α between the dome rotation axis (300) and the main diffusion axis (100) is chosen within the ranges of +5° to +40° or -5° to -40°.