Semiconductor X-ray Detector Bonding for Thermal Stress Reduction
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Solution Overview
Problem
Current semiconductor X-ray detectors face challenges in large-area, high-pixel production due to cumbersome heat management, which limits their effectiveness in applications like medical imaging and cargo scanning.
Innovation Solution
The method involves bonding X-ray absorption layers, made of materials like silicon, germanium, or CdTe, directly to an electronics layer with a redistribution layer and vias, allowing for efficient charge collection and thermal expansion coefficient matching, and using a backing substrate for mechanical support, enabling the creation of large-area detectors without bulky cooling mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If semiconductor X-ray detectors are made with large area and high number of pixels, then detection capability is improved, but heat management becomes cumbersome and production becomes difficult
Solution Approach 1:
The detector is divided into multiple independent pixel regions on the semiconductor substrate, with each pixel having its own readout circuitry. This segmentation allows heat to be distributed across multiple small regions rather than concentrated in a single large detector, making thermal management more manageable while maintaining high detection capability through the combined array of pixels
Solution Approach 2:
A specialized readout integrated circuit (RIC) is introduced as an intermediary component between the semiconductor detector and the external processing system. The RIC handles signal processing and heat dissipation locally, reducing the thermal burden on the main detector substrate and simplifying overall heat management while enabling high-pixel-count operation
2Quantity of substance
If scintillators are used to absorb X-ray, then absorption efficiency is improved, but spatial resolution is reduced due to light spreading
Solution Approach 1:
The scintillator material is completely removed from the detector structure. Instead of using scintillators to convert X-rays to light, the patent employs direct conversion semiconductor detectors where incident X-rays generate electron-hole pairs directly in the semiconductor material. This extraction of the scintillator eliminates the light spreading problem entirely while maintaining high absorption efficiency through optimized semiconductor layer thickness and material selection
Solution Approach 2:
The optical conversion mechanism of scintillators is replaced with direct electrical signal generation in semiconductor materials. X-ray photons directly create charge carriers in the semiconductor, which are then collected by electric fields and readout circuits. This substitution eliminates the intermediate light emission and propagation steps that cause spatial resolution degradation, while the semiconductor's high atomic number materials maintain excellent X-ray absorption
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 approach enhances charge collection efficiency, reduces thermal stress, and allows for the production of large-area, high-resolution X-ray detectors suitable for medical imaging, cargo scanning, and other applications without the need for scintillators, improving spatial resolution and absorption efficiency.
Implementation Method 1
Semiconductor X-ray detectors largely overcome this problem by direct conversion of X-ray into electric signals. A semiconductor X-ray detector may include a semiconductor layer that absorbs X-ray in wavelengths of interest. When an X-ray photon is absorbed in the semiconductor layer, multiple charge carriers (e.g., electrons and holes) are generated and swept under an electric field towards electric contacts on the semiconductor layer.
Implementation Method 2
A semiconductor X-ray detector may include a semiconductor layer that absorbs X-ray in wavelengths of interest. When an X-ray photon is absorbed in the semiconductor layer, multiple charge carriers (e.g., electrons and holes) are generated
Data Source
AI summary
Disclosed herein is a method comprising: obtaining a substrate comprising an electronic system in or on the substrate, and a plurality of electric contacts on a first surface of the substrate, the electronic system being electrically connected to the electric contacts; obtaining a chip comprising an X-ray absorption layer, the X-ray absorption layer comprising an electrode; electrically connecting the electrode to at least one of the electric contacts by bonding the chip to the substrate; and thinning the substrate at a surface opposite the first surface.