Wavelength Scan Display Inspection Apparatus for Thin Film Thickness
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Solution Overview
Problem
Existing display inspection apparatuses face challenges in quickly and accurately measuring the thickness of thin films in displays, such as OLED and QLED, especially due to issues like light blocking by partition walls and the inability for real-time inspection with contact-type measurements.
Innovation Solution
A wavelength scan type display inspection apparatus that includes a light irradiator, a filter wheel with multiple filters, a spectrometer, and a controller. This apparatus irradiates light onto a two-dimensional area of the display sample, converts reflected light into wavelength-reflected light, and uses artificial intelligence to determine the thickness of each layer based on the spectrum measured over multiple wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ellipsometry is used to measure thin film thickness, then measurement capability is provided, but light is blocked by partition walls making inspection difficult
Solution Approach 1:
The patent transitions from point-by-point measurement to two-dimensional area measurement by illuminating the entire pixel area simultaneously. The light irradiator emits light that covers the whole pixel region including partition walls, and the imaging sensor captures reflected light from all points in parallel, effectively moving from one-dimensional scanning to two-dimensional simultaneous measurement.
Solution Approach 2:
The patent combines multiple measurement points into a single two-dimensional measurement by capturing reflected light from the entire pixel area at once. Instead of measuring each point separately and combining results, the system merges all spatial information into a single image frame that provides comprehensive thickness data across the pixel area.
2Measurement precision
If contact-type thickness measurement is used, then direct measurement is achieved, but real-time inspection is impossible due to long measurement time and potential film destruction
Solution Approach 1:
The patent replaces contact-type mechanical measurement systems (such as AFM or surface profilers) with a non-contact optical measurement system. By using light reflection and imaging sensors, the system achieves thickness measurement without physical contact, eliminating measurement-induced damage and enabling rapid real-time inspection.
Solution Approach 2:
The patent employs sequential wavelength scanning where the light source emits light at different wavelengths in sequence, and the imaging sensor captures reflected light at each wavelength. This periodic wavelength modulation allows the system to extract thickness information through spectral analysis while maintaining rapid measurement speed for real-time inspection.
3Area of stationary object
If line scan method is used to construct image information, then two-dimensional area information is obtained, but measurement time increases
Solution Approach 1:
The patent simultaneously captures two-dimensional spatial information and wavelength spectral information by using an imaging sensor that records reflected light across the entire pixel area for multiple wavelengths in parallel. This four-dimensional measurement approach (x, y, wavelength, time) eliminates the need for sequential line scanning, dramatically reducing measurement time while providing complete two-dimensional area coverage.
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 apparatus enables rapid measurement of thin film thickness in the nanometer level, predicts the thickness of each layer with a single measurement, reduces measurement time, and minimizes prediction errors, thereby identifying and improving defects due to thickness unevenness.
Implementation Method 1
a filter wheel having a plurality of filters, each filter converting reflected light reflected from the display sample into wavelength-reflected light with a corresponding wavelength
Implementation Method 2
a spectrometer measuring a spectrum for the wavelength-reflected light
Implementation Method 3
a light irradiator irradiating light to the display sample so that the light is incident onto a two-dimensional area of a surface of the display sample
Data Source
AI summary
In an embodiment, a display inspection apparatus of a wavelength scan type includes a display sample having one or more layers; a light irradiator irradiating light to the display sample so that the light is incident onto a two-dimensional area of a surface of the display sample; a filter wheel having a plurality of filters, each filter converting reflected light reflected from the display sample into wavelength-reflected light with a corresponding wavelength; a driver rotating the filter wheel; a spectrometer measuring a spectrum for the wavelength-reflected light; and a controller controlling the driver to change the filter through which the reflected light passes, and determining a thickness of each of the one or more layers based on the spectrum for the two-dimensional area over a plurality of wavelengths according to the change of the filter.