3D-Printed X-Ray Detector Panels Using Crystallized a-Si Circuits
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Solution Overview
Problem
Current digital X-ray imaging systems using crystalline silicon (c-Si) detectors face high costs, limited dynamic range, and require tiling of smaller panels due to silicon wafer size constraints, leading to complex electrical interconnections and reduced panel size.
Innovation Solution
A method is developed to fabricate light imager panels using amorphous silicon (a-Si) on non-silicon substrates, where a-Si is melted and solidified to form c-Si circuits with field effect transistors, photodiodes, and charge amplifiers, allowing for larger, single-piece panel construction and reduced costs through techniques like selective laser melting or two-photon absorption microfabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline silicon (c-Si) is used to fabricate detector pixels, then electron mobility and image quality are improved, but manufacturing cost increases and panel size is limited
Solution Approach 1:
The patent changes the material state parameter from crystalline silicon to amorphous silicon, which fundamentally alters the manufacturing approach. Amorphous silicon can be deposited using low-cost techniques such as plasma-enhanced chemical vapor deposition (PECVD) directly on large-area substrates, eliminating the need for expensive silicon wafer fabrication processes while maintaining adequate electron mobility for detector operation
Solution Approach 2:
The patent employs amorphous silicon, a cheaper material alternative to crystalline silicon, that can be rapidly deposited and processed. This material substitution enables cost-effective manufacturing of large-area detector panels without requiring the complex and expensive crystalline silicon growth and processing infrastructure
2Reliability
If crystalline silicon (c-Si) is used to fabricate detector pixels, then electron mobility and image quality are improved, but panel size is limited requiring tiling
Solution Approach 1:
The patent changes the substrate material parameter from silicon wafers to large-area glass or metal substrates, enabling the fabrication of monolithic detector panels with areas exceeding 40x30 cm. This parameter change allows direct deposition of amorphous silicon circuits on large substrates, eliminating the tiling requirement while maintaining electron mobility through optimized deposition and annealing processes
Solution Approach 2:
The patent segments the fabrication process into distinct layers: substrate preparation, amorphous silicon deposition, photodiode formation, and readout circuit integration. This segmentation enables independent optimization of each layer, allowing large-area fabrication without compromising the electronic performance of individual pixel elements
3Ease of manufacture
If amorphous silicon (a-Si) is used to fabricate detector pixels, then manufacturing cost is reduced and panel size is increased, but electron mobility decreases
Solution Approach 1:
The patent applies preliminary low-dose ion implantation to amorphous silicon layers before final annealing. This preliminary action creates controlled defects that serve as nucleation sites for crystalline region formation during subsequent thermal processing, thereby enhancing electron mobility in the amorphous silicon structure without requiring full crystallization
Solution Approach 2:
The patent creates a composite structure within the amorphous silicon material by combining crystalline and amorphous phases through controlled ion implantation and annealing. This composite material exhibits enhanced electron mobility compared to pure amorphous silicon while retaining the manufacturing advantages of amorphous silicon deposition techniques
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 reduces costs, increases dynamic range, and enables the construction of large, single-piece X-ray detector panels with improved electron mobility, allowing for smaller feature sizes and reduced electronic noise, while maintaining the benefits of c-Si technology.
Implementation Method 1
amorphous silicon (a-Si) is disposed on a substrate. The a-Si is melted. The a-Si is subsequently solidified to form crystalline silicon (c-Si) circuits on the substrate
Implementation Method 2
The scintillator of the detector converts the higher-energy X-ray radiation to lower-energy light photons that are sensed using photo-sensitive components (e.g., photodiodes or other suitable photodetectors)
Implementation Method 3
The scintillator of the detector converts the higher-energy X-ray radiation to lower-energy light photons that are sensed using photo-sensitive components
Data Source
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AI summary
The present approach relates to the fabrication of radiation detectors. In certain embodiments, additive manufacture techniques, such as 3D metallic printing techniques are employed to fabricate one or more parts of a detector. In an example of one such printing embodiment, amorphous silicon may be initially disposed onto a substrate and a laser may be employed to melt some or all of the amorphous silicon so as to form crystalline silicon circuitry of a light imager panel. Such printing techniques may also be employed to fabricate other aspects of a radiation detector, such as a scintillator layer.