SEM Semiconductor Detector Electrode Structure for Low Resistance
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Solution Overview
Problem
Current semiconductor radiation detectors used in scanning electron microscope (SEM) systems face limitations in sensitivity and speed, which affect the accuracy and yield of inspections, especially as IC component features continue to shrink.
Innovation Solution
The development of a semiconductor detector with a p-n junction and a top electrode that includes a doped layer and a buried portion beneath it, configured to reduce series resistance without altering the active detection area, along with an isolation structure to electrically isolate the active area from the detector's sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the top electrode structure is modified to reduce series resistance, then the detector speed and sensitivity improve, but the manufacturing complexity increases
Solution Approach 1:
The top electrode is segmented into two distinct parts: a doped layer that provides the active detection area and a buried portion that extends beneath the doped layer to reduce series resistance. This segmentation allows each part to fulfill its specific function independently, resolving the contradiction between maintaining active area and reducing resistance.
Solution Approach 2:
The electrode structure transitions from a two-dimensional surface layer to a three-dimensional structure by adding the buried portion that extends vertically beneath the doped layer. This dimensional change enables the electrode to reduce series resistance through increased conductive path volume without sacrificing the active detection area on the surface.
2Reliability
If the active area is increased to improve detection sensitivity, then the detector sensitivity improves, but the series resistance increases
Solution Approach 1:
The electrode is divided into a doped layer for active detection and a buried portion for resistance reduction. This segmentation allows the doped layer to maintain large active area for sensitivity while the buried portion provides additional conductive pathways that reduce series resistance, resolving the trade-off between these two parameters.
Solution Approach 2:
The buried portion acts as an intermediary conductive structure that connects to the doped layer and provides additional current pathways. It mediates between the large-area requirement for sensitivity and the low-resistance requirement for energy efficiency, allowing both conditions to be satisfied simultaneously.
3Reliability
If isolation structures are added to electrically isolate the active area from sidewalls, then leakage current is reduced, but the device complexity increases
Solution Approach 1:
The isolation structure is extracted as a separate functional element from the main electrode structure. By positioning the isolation structure near the sidewalls of the hole and separating it from the active detection area, the design achieves electrical isolation to reduce leakage current while keeping the isolation function distinct and manageable.
Solution Approach 2:
The isolation structure serves as an intermediary element between the active area and the sidewalls. It provides electrical isolation without directly interfering with the active detection function, mediating between the need for low leakage current and the need to maintain simple overall device structure.
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 the detector's sensitivity and speed, improving the accuracy and yield of inspections by maintaining the active detection area while reducing series resistance and leakage current.
Implementation Method 1
an element for generating an electrical signal in response to receiving radiation
Implementation Method 2
applying a thermal treatment to drive dopants from the dopant layer into the semiconductor structure and underneath a detecting layer of the top electrode
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.