Thin-Film Inspection Using Emission Angle and Position Analysis
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Solution Overview
Problem
Existing methods struggle to accurately measure the characteristics, such as thickness, of thin films with a refractive index that varies in the thickness direction, as light is refracted multiple times within the film, making it difficult to predict the emission angle and position of emitted light.
Innovation Solution
A thin film inspection device and method that uses a light source and light-receiving portion positioned on opposite sides of the film, with scale patterns on a substrate, to detect and analyze light emitted at different angles, allowing for the determination of film characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is incident on a thin film with constant refractive index at a constant incident angle, then the thickness can be predicted using the detected position of the light, but this method cannot be applied to thin films with varying refractive index where light is refracted multiple times
Solution Approach 1:
The patent changes the measurement parameters by detecting both the position and angle of emitted light, and by using multiple incident angles. This allows the system to adapt to films with varying refractive indices by capturing enough information to solve for multiple unknowns in the light propagation path.
Solution Approach 2:
The patent transitions from one-dimensional position detection to two-dimensional detection by incorporating angle information. The light-receiving portion detects both where the light hits (position) and at what angle it arrives, adding a dimensional parameter that enables measurement of films with complex refractive index profiles.
2Measurement precision
If the light source and light-receiving portion are positioned on opposite sides of the thin film, then transmission measurement can be performed, but reflection measurement becomes difficult
Solution Approach 1:
The patent designs the inspection device to perform multiple measurement functions. By detecting both position and angle of emitted light, the system can analyze transmission characteristics when light sources are on opposite sides, and potentially analyze reflection characteristics by adjusting the detection geometry, making the device versatile for different measurement modes.
3Measurement precision
If multiple scale patterns are used to detect light position and angle, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent combines multiple scale patterns (first and second scale patterns) into a single integrated measurement system. The first scale pattern detects light position while the second scale pattern detects light angle, and both are processed together to determine film characteristics, merging multiple measurement functions into one cohesive device.
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
Enables precise measurement of thin film characteristics by comparing detected light positions and angles, even with varying refractive indices, providing accurate thickness determination and other properties.
Implementation Method 1
for a thin film with a refractive index that gradually varies, light may be refracted multiple times within the thin film
Implementation Method 2
Some of the thin films may transmit light
Data Source
AI summary
A device for inspecting a thin film with a varying refractive index includes a light source emitting first light toward the thin film on a first surface of the thin film, the first light being incident at a first angle with reference to the first surface on the first surface and a light-receiving portion detecting second light emitted from a second surface of the thin film, the second light being emitted at a second angle with reference to the second surface, where the first surface is one of an upper surface and a lower surface of the thin film, and the second surface is a remaining (the other) one of the upper surface and the lower surface of the thin film.