Back-Supported Photodetector Substrates for Thin BSI Detector Arrays
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Solution Overview
Problem
Backside illuminated photodetector arrays with thinned substrates face fragility issues due to reduced structural integrity, which can lead to breakage during processing, and this affects the efficiency of radiation detection.
Innovation Solution
A back support plate is used to provide structural support for the thinned photodetector substrates, allowing for thinner substrates that reduce substrate absorption and enhance detected quantum efficiency (DQE) by minimizing substrate-induced losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is thinned to reduce substrate absorption, then detected quantum efficiency is improved, but structural integrity deteriorates causing fragility and breakage
Solution Approach 1:
The substrate system is segmented into two functional parts: a thin photodetector substrate (10-30 μm) for optimal radiation detection and a separate thick support substrate (500 μm or more) for structural strength. This segmentation allows each part to be optimized independently - the thin substrate minimizes absorption losses while the thick support substrate prevents breakage during processing and operation.
Solution Approach 2:
A support substrate acts as an intermediary structural element that bears the mechanical loads and stresses, protecting the fragile thinned photodetector substrate from breakage. The support substrate serves as a mediator that provides necessary structural integrity without interfering with the radiation detection function of the thin photodetector substrate.
2Reliability
If the substrate is thinned to minimize substrate-induced losses, then radiation transmission to photodetectors is improved, but manufacturing complexity increases due to handling fragile substrates
Solution Approach 1:
The manufacturing process is segmented into distinct phases: first, the thick support substrate is prepared and processed while it provides structural strength; then the thin photodetector substrate is separately thinned and processed; finally, they are bonded together. This segmentation allows standard manufacturing techniques to be used on the thick support substrate, avoiding the complexity of processing fragile thin substrates throughout the entire manufacturing sequence.
Solution Approach 2:
The support substrate is prepared and processed in advance before the photodetector substrate is thinned. This preliminary action ensures that the structural foundation is established while it still has full structural integrity, simplifying subsequent handling and assembly of the thinned photodetector substrate.
3Loss of energy
If the substrate thickness is reduced to 10 μm or less, then substrate absorption of radiation is minimized, but the substrate becomes extremely fragile and may break during processing
Solution Approach 1:
The system is divided into a thin photodetector substrate (10-30 μm) that minimizes radiation absorption and a thick support substrate (500 μm or more) that provides mechanical stability. This segmentation enables the photodetector substrate to be optimized for energy transmission while the support substrate ensures reliability during processing and operation.
Solution Approach 2:
The detector assembly forms a composite structure combining the thin photodetector substrate material (e.g., silicon) with the thick support substrate material. This composite structure achieves properties that neither component could achieve alone: high radiation transmission from the thin layer and high mechanical strength from the thick layer.
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
The use of a back support plate stabilizes the thinned substrates, reducing substrate absorption and enhancing detected quantum efficiency (DQE) by ensuring more radiation reaches the photodetectors.
Implementation Method 1
The thinned substrate reduces an effect of the substrate on radiation that passes through the substrate to the photodetectors
Data Source
AI summary
Some embodiments include a method, comprising: providing a semiconductor substrate including photodetectors on a first side of the substrate; attaching at least one semiconductor device to the first side of the semiconductor substrate; attaching a back support plate to the semiconductor substrate over the at least one semiconductor device; and thinning the semiconductor substrate.