Electron Imaging Detector Thermal Layer for Heat and Backscatter
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Solution Overview
Problem
Thinned transmission silicon active pixel sensors in electron imaging detectors face challenges with heat removal due to reduced substrate thickness, which compromises imaging quality and resolution due to backscatter issues, and existing solutions struggle to balance thermal conductivity and electron scatter.
Innovation Solution
A thermal conduction layer with high thermal conductivity and low electron reflectivity is applied to the back-end-of-line layer, allowing for back-illumination and minimizing pre-detection scatter, while also supporting the epitaxial and BEOL layers, enabling the removal of the original substrate for improved electron transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the substrate layer is thinned to reduce backscatter, then electron transmission and imaging quality are improved, but heat removal capability deteriorates
Solution Approach 1:
The device is divided into functionally separate layers: a thinned substrate layer optimized for electron transmission and a dedicated thermal conduction layer optimized for heat removal. This segmentation allows each layer to be optimized for its specific function without compromise.
Solution Approach 2:
A thermal conduction layer is introduced as an intermediary between the thinned substrate and the heat sink. This intermediate layer provides the necessary thermal conductivity to remove heat effectively while allowing the substrate to remain thin for optimal electron transmission.
2Temperature
If a thermal conduction layer is added to improve heat dissipation, then heat removal is improved, but device complexity increases
Solution Approach 1:
The thermal conduction layer serves multiple functions simultaneously: it provides thermal conduction for heat removal, acts as a structural support layer, and can be integrated with existing BEOL processes. This multi-functionality justifies the additional layer by providing multiple benefits from a single addition.
3Measurement precision
If the substrate is completely removed to minimize backscatter, then electron transmission is maximized, but mechanical support is lost
Solution Approach 1:
The substrate is extracted (removed) from its traditional dual role of providing both mechanical support and electron transmission. The mechanical support function is extracted and assigned to a newly introduced thermal conduction layer, while the substrate focuses solely on electron transmission.
Solution Approach 2:
The thermal conduction layer acts as an intermediary that provides the mechanical support previously provided by the substrate, enabling complete substrate removal while maintaining structural integrity.
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 configuration enhances detective quantum efficiency and reduces backscatter, improving imaging resolution and heat dissipation without compromising mechanical support, by using materials with better thermal conductivity and lower electron scattering properties.
Implementation Method 1
A thermal conduction layer with high thermal conductivity and low electron reflectivity is applied to the back-end-of-line layer
Implementation Method 2
minimizing pre-detection scatter, while also supporting the epitaxial and BEOL layers, enabling the removal of the original substrate for improved electron transmission
Data Source
AI summary
A solid state active pixel image sensor for back illumination by an electron beam is described. The image sensor comprises a thermal conduction layer for heat removal. The image sensor may also comprise a thinned silicon substrate on which an epitaxial layer is formed. The substrate may also be completely removed before or after application of the thermal conduction layer. The thermal conduction layer may comprise a metal, a metal compound, silicon, diamond or graphite.