Shadow Mask Gradient Thin Film Deposition
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Solution Overview
Problem
Conventional methods for producing high-quality gradient-thickness thin films for optical systems are limited by the difficulty of achieving precise thickness gradients on a wafer-scale, particularly due to the need for large tilt angles and high-production-capacity deposition systems, which can compromise the quality and reproducibility of the films.
Innovation Solution
The use of shadow masks with non-uniform opening densities or moving shadow masks to control the deposition of material flux, allowing for controlled thickness variations along a single direction, enabling the creation of linear or non-linear thickness gradients suitable for optical devices like spectral filters and anti-reflection coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large tilt angle is used to produce a large gradient, then the magnitude of the gradient increases, but the difficulty of producing a high-quality layer increases
Solution Approach 1:
Instead of tilting the substrate to create a gradient, the patent inverts the approach by keeping the substrate flat and tilting the deposition source. This allows the gradient to be formed by the angular distribution of deposited material rather than by substrate orientation, achieving large gradients without compromising layer quality
Solution Approach 2:
The patent changes the geometric parameters of the deposition system by positioning the source at a specific angle (e.g., 45 degrees) relative to the substrate normal and controlling the source-to-substrate distance. This allows independent control of gradient magnitude and layer quality without the constraints imposed by substrate tilt angle
2Manufacturing precision
If the substrate is moved closer to the material source to increase gradient magnitude, then the gradient increases, but the deposition system size increases
Solution Approach 1:
The patent transitions from controlling gradient through one-dimensional substrate tilt to a two-dimensional geometric configuration where both source position and orientation are optimized. By positioning the source at an angle and adjusting the source-to-substrate distance, the system achieves gradient control without requiring excessive system volume
3Manufacturing precision
If a tilted substrate orientation is used to create thickness gradients, then gradient control is achieved, but wafer-scale production capability is limited
Solution Approach 1:
The patent inverts the conventional approach by keeping the substrate flat (parallel to deposition direction) rather than tilted. This enables the entire wafer surface to be uniformly exposed to the deposition flux, allowing wafer-scale production while still achieving thickness gradients through source geometry and position control
4Adaptability or versatility
If conventional deposition methods are used to achieve complex thickness requirements, then multiple components with thickness gradients can be produced, but the formation process is complicated
Solution Approach 1:
The patent applies local quality by creating different thickness gradients at different locations on the substrate through controlled variation in source-to-substrate distance and source angle. Each region of the substrate receives a tailored deposition flux that produces the desired local thickness profile, enabling complex overall patterns through simple local control
Solution Approach 2:
The patent introduces dynamic control by allowing adjustment of source position, source angle, and source-to-substrate distance during the deposition process. This dynamic capability enables the system to produce various thickness profiles (linear gradients, step changes, multiple components) using a single flexible process rather than multiple fixed processes
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
This approach enables the production of high-quality, reproducible thin films with controlled thickness non-uniformity, suitable for a wide range of deposition methods, improving the precision and efficiency of optical thin-film coatings by varying the material flux distribution across the substrate.
Implementation Method 1
a flow of deposition material is projected onto the sample from a material source, such as thermal evaporation, e-beam evaporation, sputter deposition
Data Source
AI summary
The present disclosure is directed toward the simultaneous formation of a plurality of optical elements on a common substrate, where each optical element includes at least one layer having a desired non-uniform-thickness variation. Each such layer is formed such that it includes a plurality of material patterns characterized by the non-uniform thickness variation, where each material pattern is disposed on a different deposition site on the substrate. The material patterns are configured such that adjacent optical elements are separated by a boundary region for facilitating dicing of the substrate into individual optical elements. The non-uniform-thickness layer is formed by direct deposition through a shadow mask that includes a plurality of mask patterns that are either (1) configured to pass material flux in a non-uniform manner or (2) configured to shadow different portions of their respective deposition regions while being moved relative to the substrate.