Printed Pixel Driver IC Layout for Large-Area X-Ray Detectors
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Solution Overview
Problem
Current X-ray detectors face challenges in manufacturing large surface detectors with high image quality and low radiation dose, as TFT processes struggle with forming metal lines at the nanometer level and CMOS processes are limited by silicon wafer size.
Innovation Solution
The X-ray detector employs micro-transfer printing technology to integrate pixel driving microchips on top of a photodiode layer, combining TFT and CMOS processes to maximize fill factor, minimize radiation exposure, and enhance durability by removing insulating substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If TFT process is used to manufacture large surface X-ray detector, then manufacturing cost is reduced, but image quality and metal line precision deteriorate
Solution Approach 1:
The detector is divided into two separately manufactured components: a photodiode layer made by TFT process and pixel driving ICs made by CMOS process. Each component is optimized independently for its respective manufacturing process, then combined through micro-transfer printing. This segmentation allows large surface detectors to be made cost-effectively while maintaining high precision in the pixel driving circuits.
Solution Approach 2:
Micro-transfer printing technology serves as an intermediary method to bond the separately manufactured photodiode layer and pixel driving ICs. This intermediary process enables precise alignment and integration of the two components, achieving high manufacturing precision in metal lines and circuits without requiring the entire detector to be manufactured using the more expensive CMOS process.
2Manufacturing precision
If CMOS process is used to manufacture high image quality X-ray detector, then image quality improves, but manufacturing cost and surface area increase
Solution Approach 1:
The detector is segmented into two parts manufactured by different processes: the photodiode layer is manufactured using cost-effective TFT process for large surface area, while only the pixel driving ICs require precision CMOS process. This segmentation reduces overall manufacturing cost while maintaining high image quality in the critical pixel driving circuits.
Solution Approach 2:
High precision CMOS process is applied locally only to the pixel driving ICs where it is most needed for image quality, while the photodiode layer uses the more cost-effective TFT process. This local application of premium manufacturing processes optimizes the balance between image quality and manufacturing cost.
3Manufacturing precision
If pixel driving ICs are integrated on photodiode layer, then fill factor increases, but device complexity increases
Solution Approach 1:
Micro-transfer printing acts as an intermediary bonding process that simplifies the integration of pixel driving ICs onto the photodiode layer. Instead of complex monolithic integration, the ICs are separately manufactured and then transferred using a standardized bonding process, reducing device complexity while achieving high fill factor through close proximity integration.
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 enables mass production of high-quality X-ray detectors with improved absorption ratios and reduced radiation doses, while maintaining high image quality and durability.
Implementation Method 1
a photodiode layer that is configured to receive X-ray photons that have passed through a target object and to convert the received X-ray photons to electric signals
Implementation Method 2
a plurality of pixel driving integrated chips that are printed on a top of the photodiode layer, using a micro-transfer printing technology
Data Source
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AI summary
Provided are an X-ray detector including a plurality of pixel driving micro integrated chips separately fabricated from a photodiode layer and printed on the photodiode layer and a method for manufacturing the X-ray detector. The X-ray detector may include a photodiode layer and a driver layer. The photodiode layer may include a plurality of photodiodes and be configured to receive X-ray that have passed through a target object and convert the received X-ray to electric signals. The driver layer may be formed on the photodiode layer and include a plurality of micro driving integrated chips each coupled to two or more photodiodes in the photodiode layer. The plurality of pixel driving integrated chips may be manufactured separately from the photodiode layer and printed on the photodiode layer using a micro-transfer printing method.