Printable Optical Layer Formulation for Void-Free Grating Filling
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Solution Overview
Problem
Existing manufacturing processes for optical gratings, particularly diffractive gratings used in augmented and mixed reality glasses, face challenges such as incomplete gap filling during deposition, leading to voids and the need for costly chemical mechanical planarization (CMP), which complicates mass production.
Innovation Solution
A formulation comprising metal sulfates, phosphates, oxy sulfates, oxy phosphates, and oxy chlorides, along with a specific chemical compound, is used to create a printable optical layer that can be converted into a metal oxide, enabling efficient gap filling without CMP, ensuring high refractive indices and crack-free layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If physical vapor deposition (PVD) or chemical vapor deposition (CVD) processes are used to fill gaps in optical gratings, then the gaps can be filled with high refractive index material, but incomplete gap filling occurs leading to voids and requiring additional chemical mechanical planarization (CMP) steps
Solution Approach 1:
The patent replaces the mechanical PVD/CVD deposition process with a liquid formulation application process (such as inkjet printing or spin coating) followed by thermal treatment. This substitution eliminates the void formation issue inherent in vapor deposition methods and removes the need for subsequent CMP steps, thereby simplifying the overall manufacturing process while achieving complete gap filling.
Solution Approach 2:
The patent changes the physical state of the filling material from vapor phase (PVD/CVD) to liquid phase (formulation). The liquid formulation can completely fill the gaps without voids, and subsequent thermal treatment converts it to the desired solid optical material. This parameter change fundamentally resolves the incomplete filling problem and eliminates the need for CMP.
2Manufacturing precision
If chemical mechanical planarization (CMP) is performed to remove overburden layers after PVD or CVD, then a flat surface is achieved, but the process becomes time-consuming and costly
Solution Approach 1:
The patent replaces the mechanical CMP process with a controlled liquid formulation application method. By using techniques like inkjet printing or spin coating followed by thermal treatment, the process achieves both complete gap filling and surface flatness in a single integrated step, eliminating the need for separate CMP operations and significantly improving production efficiency.
Solution Approach 2:
The patent performs preliminary action by carefully controlling the formulation application process to deposit material that naturally forms a flat surface without requiring subsequent mechanical planarization. The liquid formulation can be precisely controlled to fill gaps completely while maintaining surface flatness, and thermal treatment solidifies this structure without needing CMP.
3Device complexity
If conventional liquid crystal displays are used in virtual reality glasses, then the device structure is simplified, but diffractive gratings are still required in augmented and mixed reality glasses
Solution Approach 1:
The patent merges the diffractive grating structure directly into the waveguide substrate by using the liquid formulation to fill the gaps of the grating structures. This integration eliminates the need for separate grating components and their associated manufacturing complexities, while maintaining the required optical performance for augmented and mixed reality applications.
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 formulation allows for cost-effective production of optical layers with high refractive indices, dense and crack-free structures, and supports continuous inkjet printing, reducing production costs and time.
Implementation Method 1
applying a thermal treatment to the formulation provided on the surface of the substrate to convert at least a part of the material selected from one or more members of the group consisting of metal sulfates, metal phosphates, metal oxy sulfates, metal oxy phosphates, metal oxy chlorides, hydrated metal sulfates, hydrated metal phosphates, hydrated metal oxy sulfates, hydrated metal oxy phosphates and hydrated metal oxy chlorides of the formulation to a metal oxide
Data Source
AI summary
A formulation for preparing an optical layer that includes a metal oxide includes a material selected from one or more members of the group consisting of metal sulfates, metal phosphates, metal oxy sulfates, metal oxy phosphates, metal oxy chlorides, hydrated metal sulfates, hydrated metal phosphates, hydrated metal oxy sulfates, hydrated metal oxy phosphates and hydrated metal oxy chlorides, and a chemical compound represented by following chemical formula (I) as defined herein.