Camera Module Optical Coating to Minimize Dot Defects
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Solution Overview
Problem
Current optical coating processes, such as vacuum thermal evaporation and magnetron sputtering, fail to effectively control the formation of dot defects in camera modules, leading to imaging quality issues due to large particle deposition on substrate surfaces.
Innovation Solution
A chemical vapor deposition (CVD) method involving the alternate deposition of low- and high-refractive-index layers on a substrate, using specific precursors and gases, to form multilayer film structures that minimize dot defects by avoiding evaporation and sputtering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum thermal evaporation or magnetron sputtering is used for optical coating, then coating efficiency and film formation are achieved, but large particle dots are deposited on substrate surface causing imaging quality degradation
Solution Approach 1:
The patent changes the fundamental deposition parameters by switching from physical vapor deposition (evaporation/sputtering) to chemical vapor deposition. This involves changing the deposition mechanism from direct physical deposition to chemical reaction-based deposition, where precursors decompose and react to form films, fundamentally altering how material is deposited and eliminating the particle dot problem inherent in physical methods
Solution Approach 2:
The patent replaces the mechanical/physical deposition processes (thermal evaporation and magnetron sputtering) with a chemical process (CVD). Instead of using physical energy (heat, electromagnetic fields) to deposit material directly, the system uses chemical reactions of gas-phase precursors to form the optical film, substituting a mechanical system with a chemical one that inherently produces finer, more uniform deposits without large particles
2Manufacturing precision
If conventional optical coating processes are used, then multilayer film structures can be formed, but dot defects with size exceeding 5 μm are generated affecting imaging quality
Solution Approach 1:
The patent changes the deposition mechanism from physical to chemical, using precursor decomposition and reaction to form films. This fundamental parameter change in the deposition process eliminates the generation of large particle dots while maintaining the ability to form precise multilayer structures with controlled thickness and refractive indices
Solution Approach 2:
The CVD process operates in a controlled gas atmosphere using inert or reactive gases as carriers and reactants. This controlled chemical environment allows for precise film formation through chemical reactions, contrasting with the vacuum-based physical methods that generate particle contamination, thereby eliminating dot defects while maintaining manufacturing precision
3Ease of manufacture
If thermal energy conversion methods are used to vaporize coating material, then film deposition is achieved, but large droplets and particles are generated causing uncontrollable dot defects
Solution Approach 1:
The patent replaces thermal vaporization methods with chemical vapor deposition. Instead of heating materials to vaporize them (which creates large droplets and particles), the system introduces gas-phase precursors that decompose and react chemically on the substrate surface, forming films through controlled chemical reactions rather than physical phase changes, thereby eliminating large particle generation
Solution Approach 2:
The patent fundamentally changes the deposition parameter from thermal energy-driven physical vaporization to chemically-driven decomposition and reaction. This parameter change transforms the deposition mechanism to one where material is delivered as gas-phase precursors that react on the substrate, avoiding the large droplet and particle formation inherent in thermal vaporization methods
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 CVD method significantly reduces the occurrence of dot defects, enhancing imaging quality, improving the smoothness and firmness of optical coatings, and meeting stringent size requirements for high-quality camera modules.
Implementation Method 1
a chemical vapor deposition (CVD) method... involving the alternate deposition of low- and high-refractive-index layers on a substrate... to form multilayer film structures that minimize dot defects by avoiding evaporation and sputtering processes
Data Source
AI summary
A CVD preparation method for minimizing camera module dot defects includes: performing ultrasonic cleaning and drying on a base substrate to obtain a pre-treated base substrate; placing the pre-treated base substrate into a reaction chamber, evacuating, and introducing nitrogen or inert gas to slightly positive pressure; simultaneously introducing precursor I and precursor II at a temperature of 500-700° C. to deposit a low-refractive-index L layer on the base substrate; halting introduction of the precursor I and the precursor II, and purging the reaction chamber with nitrogen or the inert gas; introducing raw gas precursor III and precursor IV at a temperature of 600-800° C. to deposit a high-refractive-index H layer on the low-refractive-index L layer; and halting introduction of the precursor III and precursor IV, and purging the reaction chamber with nitrogen or inert gas; and cooling to room temperature to obtain an optical element with coating films having different refractive indices.