Three-Side Buttable ROIC Layout for Gap-Free Radiation Detection
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Solution Overview
Problem
Existing radiation detectors face challenges in achieving large continuous detection surfaces with minimal gaps and efficient power management, particularly in CT imaging systems where high photon count rates require advanced signal processing and reduced power dissipation.
Innovation Solution
The development of a radiation detector unit with a three-side buttable read-out integrated circuit (ROIC) and direct mounting of radiation sensors to the ROIC without interposers, utilizing photolithographic stitching for large-scale fabrication and incorporating local control units for data processing and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple radiation sensors are arranged to form a large continuous detection surface, then the detection area is increased, but gaps between sensors and units increase making continuous coverage difficult
Solution Approach 1:
The detector system is divided into modular detector units, each containing multiple radiation sensors arranged in a grid pattern. Each unit can be independently manufactured and then assembled with adjacent units to form a large continuous detection surface, eliminating gaps while maintaining manufacturing precision
Solution Approach 2:
Multiple detector units are combined through precise mechanical coupling and electrical interconnection to form an integrated large-area detector system. The coupling mechanisms ensure continuous mechanical and electrical contact between adjacent units, achieving gap-free coverage across the entire detection surface
2Area of stationary object
If a large number of sensors and circuit blocks are integrated into a single ROIC, then the detection surface area increases, but power dissipation and heat management become problematic
Solution Approach 1:
The read-out integrated circuit is divided into multiple independent core circuit blocks, each serving a specific region of sensors. Each block processes signals locally and independently, distributing power consumption across multiple low-power units rather than concentrating it in a single large circuit, thereby reducing overall power dissipation and heat generation
Solution Approach 2:
The circuit architecture transitions from a planar two-dimensional layout to a three-dimensional stacked configuration, with sensor arrays positioned above the ROIC substrate. This vertical arrangement reduces the footprint and allows for more efficient thermal management by separating heat-generating electronics from the detection surface
3Ease of manufacture
If identical circuit blocks are used for all ROIC regions, then manufacturing simplicity is maintained, but power consumption increases due to redundant circuitry
Solution Approach 1:
The ROIC employs different circuit block configurations in different regions: core circuit blocks with full functionality in regions requiring complete signal processing, and peripheral circuit blocks with reduced functionality at the boundaries. This localized differentiation eliminates redundant circuitry in peripheral areas while maintaining manufacturing simplicity through standardized core block design
Solution Approach 2:
Redundant circuit functions are extracted from peripheral circuit blocks and consolidated into centralized control logic or removed entirely. The peripheral blocks retain only the essential circuits needed for their specific boundary functions, eliminating unnecessary power consumption while maintaining ease of manufacture through modular design
4Area of stationary object
If photolithographic stitching is used to fabricate large-scale ROICs, then manufacturing of large detectors is enabled, but alignment precision and manufacturing complexity increase
Solution Approach 1:
The large-scale ROIC is fabricated by dividing the substrate into multiple smaller regions, each processed through standard photolithography steps. Alignment marks and registration features are incorporated at the boundaries of these regions, enabling precise stitching together of adjacent areas while maintaining the precision capabilities of conventional photolithography equipment
Solution Approach 2:
Alignment marks and registration structures are pre-formed on the substrate before the main photolithography patterning steps. These preliminary features serve as reference points for subsequent stitching operations, ensuring precise alignment between adjacent fabricated regions and reducing the complexity of real-time alignment during manufacturing
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 design enables a continuous detection surface of up to 16 cm in the z-axis direction with reduced power dissipation and improved signal processing capabilities, suitable for cardiac CT scanning and other imaging applications.
Implementation Method 1
a radiation sensor bonded to a front side surface of the ROIC, where each radiation sensor of the plurality of radiation sensors is bonded to a respective core circuit block
Data Source
AI summary
A radiation detector unit includes a read-out integrated circuit (ROIC) including a plurality of core circuit blocks located on a continuous uninterrupted substrate adjacent to one another along a first direction, and a plurality of radiation sensors bonded to a front side surface of the ROIC, where each radiation sensor of the plurality of radiation sensors is bonded to a respective core circuit block of the plurality of core circuit blocks of the ROIC. Additional embodiments include detector modules and detector arrays formed by assembling the detector units, and methods of operating and manufacturing the same.