Semiconductor Detector Electrode Structure for High-Sensitivity SEM
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Solution Overview
Problem
Current semiconductor radiation detectors used in scanning electron microscope systems are limited by sensitivity and speed, which affects the accuracy and yield of IC component inspections as feature sizes shrink.
Innovation Solution
A semiconductor detector with a p-n junction and a top electrode featuring a doped layer and a buried portion to reduce series resistance, and an isolation structure to electrically isolate the active area from sidewalls, enhancing detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the active area of the top electrode is increased to improve detection sensitivity, then the detection sensitivity improves, but the series resistance increases reducing bandwidth
Solution Approach 1:
The patent introduces a buried portion of the top electrode that extends vertically beneath the doped layer, transitioning from a two-dimensional surface electrode to a three-dimensional structure. This vertical extension provides additional conduction paths without increasing the horizontal active area footprint, thereby reducing series resistance while maintaining detection sensitivity.
Solution Approach 2:
The buried portion is nested beneath the doped layer of the top electrode, with the buried portion having a smaller horizontal footprint than the doped layer. This nested configuration allows the buried portion to provide electrical conduction pathways underneath the active detection area, reducing series resistance without compromising the active area available for electron detection.
2Measurement precision
If the active area extends close to the sidewalls of the hole to reduce dead areas, then the quantum efficiency improves, but electrical isolation from the sidewalls becomes difficult
Solution Approach 1:
The patent segments the top electrode into functionally distinct regions: a doped layer providing the active detection area and a separately formed buried portion providing electrical conduction. This segmentation allows the doped layer to extend close to the sidewalls for high quantum efficiency while the buried portion can be configured to provide adequate electrical isolation and conduction pathways.
Solution Approach 2:
The patent applies different doping characteristics and geometries to different parts of the top electrode. The doped layer has high doping concentration and extends to the sidewalls for maximum detection area, while the buried portion has tailored doping and geometry optimized for electrical conduction and isolation, allowing each region to perform its specific function optimally.
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 detector improves sensitivity and bandwidth, reducing dead areas and maintaining high quantum efficiency, thus enhancing the accuracy and throughput of IC component inspections.
Implementation Method 1
the buried portion is configured to reduce a series resistance of the top electrode
Implementation Method 2
the isolation structure is configured to electrically isolate the active area from the sidewalls of the hole
Implementation Method 3
the semiconductor structure includes a p-n junction. The detector also has a top electrode for the p-n junction, where the top electrode provides an active area for detecting electrons or electromagnetic radiation
Data Source
AI summary
The present disclosure describes a detector used in critical dimension scanning electron microscopes (CD-SEM) and review SEM systems. In one embodiment, the detector includes a semiconductor structure having a p-n junction and a hole through which a scanning beam is passed to a target. The detector also includes a top electrode for the p-n junction (e.g., anode or cathode) that provides an active area for detecting electrons or electromagnetic radiation (e.g., backscattering from the target). The top electrode has a doped layer and can also have a buried portion beneath the doped layer to reduce a series resistance of the top electrode without changing the active area. In another embodiment, an isolation structure can be formed in the semiconductor structure near sidewalls of the hole to electrically isolate the active area from the sidewalls. A method for forming the buried portion of the top electrode is also described.