Direct Attach Radiation Detector Structures with Varying Pitch
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Solution Overview
Problem
Existing radiation detector systems face challenges in efficiently coupling pixelated radiation sensors with ASICs due to differences in pitch and layout, leading to increased noise charge and power consumption, particularly when using indirect attach configurations with interposers.
Innovation Solution
A direct attach configuration where the radiation sensor is mounted directly to the ASIC with bonding material portions extending between pixel detectors and the ASIC, allowing for reduced input node capacitance and lower power consumption, and a redistribution layer on the ASIC to accommodate varying pixel detector pitches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If indirect attach configuration with interposers is used to couple pixelated radiation sensors with ASICs, then compatibility with different pitch layouts is improved, but equivalent noise charge and power consumption increase
Solution Approach 1:
The patent employs an interposer as an intermediary component between the radiation sensor and ASIC. The interposer includes a first surface facing the radiation sensor with bonding pads arranged in a first pitch, and a second surface facing the ASIC with bonding pads arranged in a second pitch. This intermediary structure enables compatibility between components with different pitch layouts while maintaining low noise charge and power consumption by providing direct electrical connections without requiring complex routing through the ASIC substrate.
2Adaptability or versatility
If indirect attach configuration with interposers is used to couple pixelated radiation sensors with ASICs, then compatibility with different pitch layouts is improved, but power consumption increases
Solution Approach 1:
The interposer serves as a dedicated mediator for pitch adaptation, preventing the need for long signal paths through the ASIC substrate. By placing bonding pads on both surfaces of the interposer with different pitches, it enables direct coupling between sensors and ASICs with mismatched layouts, thereby reducing the electrical path length and associated power consumption while maintaining pitch compatibility.
Solution Approach 2:
The solution transitions from a planar coupling approach to a three-dimensional structure by introducing the interposer as a separate layer between the sensor and ASIC. This vertical stacking arrangement allows independent pitch optimizations on each interface (sensor-interposer and interposer-ASIC) without compromising the other, enabling pitch transformation in the vertical dimension while reducing lateral signal path lengths and power consumption.
3Measurement precision
If direct attach configuration is used to couple radiation sensors with ASICs, then equivalent noise charge and power consumption are reduced, but compatibility with non-uniform pixel layouts is limited
Solution Approach 1:
The interposer implements local quality by allowing different pitch configurations at different locations and interfaces. The first surface can be customized with bonding pads arranged in a first pitch to match the sensor layout, while the second surface has bonding pads arranged in a second pitch to match the ASIC layout. This localized adaptation at each interface enables compatibility with non-uniform pixel layouts while maintaining the low noise and power consumption benefits of direct attachment.
Data Source
AI summary
Direct attach radiation detector structures include an application specific integrated circuit (ASIC) including an array of unit cells including signal processing channel circuitry and at least one radiation sensor including an array of pixel detectors located over a front surface of the ASIC. In various embodiments, an ASIC having a fixed layout of unit cells may accommodate different radiation sensors having varying layouts of pixel detectors. In some embodiments, a redistribution layer on the front surface of the ASIC may route detection signals from pixel detectors to the corresponding unit cells. Alternatively, or in addition, a subset of the unit cells of the ASIC may be active unit cells that are electrically coupled to a pixel detector. The remaining unit cells may be inactive unit cells that may be powered down.