SEM Detector Switching Network With Radiation-Hardened NMOS

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Solution Overview

Problem

Switching elements in detectors of scanning electron microscopes (SEMs) are prone to damage from X-ray exposure, leading to reduced detector lifetime and decreased throughput due to increased resistance and threshold current leakage in transistors.

Innovation Solution

Implement radiation hardened NMOS transistors in the switching network of the detector, positioning them in proximity to sensing elements and potentially separating switching elements onto a different chip from sensing elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If switching elements are used in the detector to activate or deactivate sensing elements, then the detector can adapt to different beam shapes and sizes, but the switching elements get damaged after e-beam exposure, limiting detector lifetime

Engineering Contradiction:

Improvedetector adaptability to different beam shapes and sizesVSAvoiddetector lifetime

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The detector is divided into multiple independently controllable sensing elements arranged in an array. Each sensing element can be individually activated or deactivated, allowing the detector to adapt to different beam shapes and sizes by selectively enabling only the necessary elements, thereby reducing the cumulative radiation exposure to any single switching element and extending overall detector lifetime.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The detector employs dynamic control of sensing elements through switching elements that can activate or deactivate specific elements based on real-time beam position and size. This dynamic adaptation allows the system to optimize performance for varying beam conditions while distributing radiation damage across multiple switching elements over time, mitigating the degradation issue.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If pixelated sensing elements are used to detect beams of unknown sizes and positions, then detection flexibility is improved, but switching elements require more complex control mechanisms

Engineering Contradiction:

Improvedetection flexibility for unknown beam parametersVSAvoidswitching network complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of controlling all sensing elements simultaneously, the system activates only the necessary subset of elements based on the detected beam position and size. This partial action approach maintains detection flexibility for unknown beam parameters while reducing the complexity of the switching network by minimizing the number of active switches at any given time.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The pixelated sensing element array inherently provides the adaptability needed for detecting beams of unknown sizes and positions. Each element independently responds to incident beams, and the readout circuitry automatically identifies which elements are active, reducing the need for complex external control mechanisms and simplifying the overall switching network design.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250316444A1Radiation tolerant detector architecture for charged particle detection

Publication Date: 2025.10.09 ASML NETHERLANDS BV

AI summary

A detector for a scanning electron microscope (SEM) system comprises a semiconductor substrate, and a switching network formed on the semiconductor substrate and comprising a radiation hardened NMOS transistor, the NMOS transistor comprising a first source/drain diffusion region, a second source/drain diffusion region, and a gate patterned on the semiconductor substrate and encircling one of the first and second source/drain diffusion regions.