Thin-Film Phosphor Screen With Lattice Walls for MEMS Imaging
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Solution Overview
Problem
Existing phosphor screens for image intensifiers, particularly those using particle phosphor, face challenges such as undesirable characteristics like pinholes, virtual leaks, and incompatibility with Micro-Electro-Mechanical-Systems (MEMS) due to particle size and scattering issues, which affect reliability and performance.
Innovation Solution
A phosphor screen with a thin film of phosphor deposited on a wafer structure featuring a lattice of interior walls forming cells or pixels, capturing backscattered electrons and minimizing photon scatter, and allowing direct deposition of a reflective metal layer without evaporation processes, resulting in a thinner, more reliable, and MEMS-compatible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particle phosphor is used in phosphor screens, then phosphor conversion is achieved, but manufacturing complexity and reliability deteriorate due to multiple deposition steps, pinholes, and virtual leaks
Solution Approach 1:
The patent changes the physical state of phosphor from discrete particles to a continuous thin film layer. This parameter change eliminates the need for particle deposition processes, sacrificial planarizing materials, and multiple aluminum coating steps, thereby reducing manufacturing complexity and eliminating pinholes and virtual leaks that compromise reliability.
Solution Approach 2:
The patent replaces the mechanical particle deposition and adhesion process with a thin film deposition process. This substitution eliminates the need for adhering materials and temperature bakes, simplifying the manufacturing process and improving reliability by removing steps that introduce defects.
2Adaptability or versatility
If particle phosphor with 2 micron diameter is used, then phosphor conversion is achieved, but compatibility with MEMS wafer scale processing deteriorates
Solution Approach 1:
The patent changes the scale parameter of phosphor from 2 micron particles to a thin film with thickness on the order of nanometers to micrometers. This parameter change makes the phosphor structure compatible with MEMS wafer scale processing, where feature sizes are typically in the micrometer and sub-micrometer range, allowing uniform processing across the entire wafer surface.
3Object-affected harmful factors
If continuous flat aluminum layer is deposited over phosphor particles, then coverage is achieved, but photon scatter and backscattered electron effects worsen
Solution Approach 1:
The patent changes the topography parameter of the phosphor layer from particulate to planar thin film. This change allows the aluminum layer to be deposited as a uniform continuous film without pinholes, eliminating lateral light transfer and preventing backscattered electrons from creating light away from the initial point of contact, thereby reducing photon scatter and improving image fidelity.
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 solution reduces photon scatter, minimizes virtual leaks, and enables smaller, lighter image intensifiers by providing improved image fidelity and compatibility with wafer scale processing, enhancing the performance and reliability of MEMS image intensifiers.
Implementation Method 1
A phosphor screen for a Micro-Electro-Mechanical-Systems (MEMS) image intensifier is presented herein. The phosphor screen includes a thin film of phosphor that is formed (i.e., deposited) on a wafer structure
Implementation Method 2
The cells/pixels include or define open-top depressions or cavities and the phosphor layer is deposited on at least a bottom surface of each depression or cavity
Data Source
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AI summary
A phosphor screen for a Micro-Electro-Mechanical-Systems (MEMS) image intensifier includes a wafer structure, a lattice of interior walls, a thin film phosphor layer, and a reflective metal layer. The wafer structure has a naturally opaque top layer and an active area defined within the naturally opaque top layer. The lattice of interior walls is formed, within the active area, from the naturally opaque top layer. The thin film phosphor layer is disposed in the active area, between the lattice of interior walls. The reflective metal layer that is disposed atop the thin film phosphor layer. In at least some instances, the thin film phosphor layer is a non-particle phosphor layer.