Imaging Element Inspection via Integrated Test Electrode Layout
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Solution Overview
Problem
Existing methods for inspecting the quality of photoelectric conversion layers in imaging elements face challenges such as low accuracy due to small current measurements and reduced yield and performance of imaging elements when test structures are used.
Innovation Solution
An inspection method that includes a device with pixel electrodes, a counter electrode, a photoelectric conversion layer, a test electrode, and electrode pads, where a current is measured between the electrode pads by applying a voltage, allowing for effective inspection of the photoelectric conversion layer without reducing the yield of imaging elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test structure is used to inspect the photoelectric conversion layer, then inspection can be performed, but the yield and performance of imaging elements are reduced
Solution Approach 1:
The imaging region serves dual purposes: it functions as both the active imaging area and the test region for inspecting the photoelectric conversion layer. By making the test electrode extend across the entire imaging region rather than being confined to a separate test structure, the same area is utilized for both imaging and inspection functions, thereby eliminating the need to sacrifice imaging element yield for test structure inclusion.
Solution Approach 2:
The patent merges the test electrode with the imaging region structure. Instead of having a separate test structure that would reduce yield, the test electrode is integrated into the existing imaging element architecture, combining the testing function with the imaging function in a unified structure.
2Area of stationary object
If a small test structure is used for inspection, then the chip size can be kept small, but the current measurement area is limited reducing inspection accuracy
Solution Approach 1:
The test electrode is extended in the planar dimension across the entire imaging region, transforming the test area from a small localized structure to a large extended structure. This dimensional extension allows the test to cover a much larger area without increasing the vertical profile or thickness of the device, thereby maintaining a compact chip form factor while significantly improving measurement accuracy through increased current collection area.
3Reliability
If the test electrode is disposed outside the imaging region, then the imaging region is not affected, but the current measurement area is small reducing inspection accuracy
Solution Approach 1:
The imaging region is made to serve dual functions: it remains the active imaging area while simultaneously serving as the test region. The test electrode is positioned to cover the entire imaging region, allowing the same photoelectric conversion layer to be both imaged and tested, thereby achieving both high imaging quality and high inspection accuracy without compromise.
4Measurement precision
If the test electrode extends across the entire imaging region, then the current measurement area increases improving inspection accuracy, but the device complexity increases
Solution Approach 1:
By making the test electrode extend across the entire imaging region, the same structure serves both imaging and testing purposes. This multi-functionality approach actually reduces overall device complexity compared to having separate dedicated test structures, as it eliminates redundant components and simplifies the device architecture while simultaneously improving inspection accuracy through the larger measurement area.
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
This method enhances inspection accuracy by increasing the current measurement area without increasing chip size, thereby maintaining high yield and performance of imaging elements.
Implementation Method 1
a photoelectric conversion layer disposed between the plurality of pixel electrodes and the counter electrode
Data Source
AI summary
An inspection method includes: preparing a device that includes a plurality of pixel electrodes, a counter electrode disposed to face the plurality of pixel electrodes, a photoelectric conversion layer disposed between the plurality of pixel electrodes and the counter electrode, a test electrode disposed to face the counter electrode with the photoelectric conversion layer interposed between the counter electrode and the test electrode, a first electrode pad electrically connected to the counter electrode and exposed to an outside of the device, and a second electrode pad electrically connected to the test electrode and exposed to the outside of the device, the test electrode being disposed between two adjacent pixel electrodes of the plurality of pixel electrodes; and measuring a current that flows between the first electrode pad and the second electrode pad by applying a voltage between the first electrode pad and the second electrode pad.