CdZnTe Radiation Detector Fabrication for Precise Pixel Alignment
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Solution Overview
Problem
Current radiation detectors face challenges in efficiently absorbing and detecting radiation particles at room temperature, particularly for X-rays and γ-rays, due to limitations in material properties and detection efficiency.
Innovation Solution
A method for manufacturing a radiation detector using a semiconductor single crystal, specifically CdZnTe or CdTe, formed by depositing semiconductor particles into a recessed substrate and recrystallizing them to create a high-quality single crystal that absorbs radiation and generates charge carriers, with a substrate of silicon, germanium, or GaAs, and forming electrical contacts for signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used to create pixel electrodes, then manufacturing is simpler, but pixel electrode alignment accuracy deteriorates (3-5 micrometer mismatch)
Solution Approach 1:
The patent applies preliminary action by forming a single continuous electrode layer before dividing it into pixel electrodes through photolithography patterning. This ensures that all pixel electrodes are created simultaneously from one continuous layer, guaranteeing precise alignment (within 1 micrometer) without requiring multiple separate fabrication steps for each electrode layer.
Solution Approach 2:
The patent applies segmentation by dividing the single continuous electrode layer into multiple pixel electrodes through photolithography patterning. This allows the continuous layer to be precisely divided into discrete pixel electrodes while maintaining alignment accuracy, as the division is performed in a single patterning step rather than through multiple alignment-critical steps.
2Manufacturing precision
If multiple separate electrode layers are fabricated, then manufacturing flexibility is higher, but alignment precision deteriorates due to cumulative errors
Solution Approach 1:
The patent applies merging by combining multiple electrode functions into a single continuous electrode layer that is subsequently patterned. This unified approach eliminates the alignment errors that would accumulate from fabricating multiple separate electrode layers, as all pixel electrodes are created from one continuous layer in a single patterning process.
3Measurement precision
If pixel electrodes are made smaller to increase pixel count, then detector resolution improves, but manufacturing precision requirements become more stringent
Solution Approach 1:
The patent applies preliminary action by establishing the precise pixel pattern through photolithography on a single continuous electrode layer before any subsequent processing. This preliminary patterning step defines the exact pixel boundaries and positions with high precision, enabling the fabrication of smaller pixels with tighter spacing while maintaining consistent alignment throughout the array.
Solution Approach 2:
The patent applies segmentation by using photolithography to divide the continuous electrode layer into precisely defined small pixel electrodes. This segmentation approach allows for high-resolution pixel arrays with smaller individual pixel sizes, as the photolithography process can achieve sub-micrometer patterning precision that ensures accurate pixel boundaries and spacing.
4Reliability
If alignment mismatch between pixel electrodes and readout circuits is reduced, then signal loss decreases, but fabrication complexity increases
Solution Approach 1:
The patent applies preliminary action by forming and patterning the pixel electrodes with precise alignment to the readout circuit locations before any subsequent electrode formation or processing steps. This preliminary alignment ensures that the pixel electrodes are correctly positioned relative to the readout circuits from the outset, minimizing signal loss while the single-layer approach keeps the overall fabrication process manageable.
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 method enhances the absorption efficiency and signal-to-noise ratio for radiation detection, enabling effective use in various applications such as medical imaging, industrial testing, and astrophysics by utilizing high-quality semiconductor single crystals and efficient electrical contacts.
Implementation Method 1
forming a melt by melting the semiconductor particles
Implementation Method 2
recrystallizing the melt in the recess
Implementation Method 3
semiconductor single crystal used to absorb radiation particles incident thereon and to generate charge carriers
Data Source
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AI summary
Disclosed herein is a method for making a radiation detector. The method comprises forming a recess into a substrate and forming a semiconductor single crystal in the recess. The semiconductor single crystal may be a cadmium zinc telluride (CdZnTe) single crystal or a cadmium telluride (CdTe) single crystal. The method further comprises forming electrical contacts on the semi conductor single crystal and bonding the substrate to another substrate comprising an electronic system therein or thereon. The electronic system is connected to the electrical contact of the semiconductor single crystal and configured to process an electrical signal generated by the semiconductor single crystal upon absorption of radiation particles.