Trench Connector Grounding for Voltage Contrast Defect Inspection
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Solution Overview
Problem
Current defect testing methods for nano-ribbon transistors on wafers are inefficient in identifying electrical defects, particularly in establishing reliable grounding paths for voltage contrast inspection, leading to unreliable detection of shorts and opens in trench contacts.
Innovation Solution
The implementation of electrical connectors that couple multiple trench contacts to a grounding source, providing a robust electrical path for voltage contrast inspection, and the use of P-type epitaxial structures to enhance defect detection through voltage contrast scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If VC inspection technique is implemented to detect electrical defects, then defect detection accuracy is improved, but device complexity increases due to additional grounding structures
Solution Approach 1:
The patent introduces electrical connectors as intermediary elements that provide grounding paths to trench contacts. These connectors act as mediators between the trench contacts and the substrate ground, enabling VC inspection without requiring direct substrate access to each contact. This resolves the contradiction by adding minimal complexity (connector structures) to achieve high measurement precision (defect detection capability).
Solution Approach 2:
The patent segments the grounding function by providing individual grounding paths for each trench contact or group of contacts through electrical connectors. This segmentation allows selective grounding of specific contacts while leaving others floating, enabling targeted defect detection. The segmentation principle resolves the contradiction by creating modular grounding structures that improve detection accuracy without requiring complete restructuring of the entire device.
2Reliability
If multiple electrical connectors are added to ground trench contacts, then reliability of defect detection is improved, but manufacturing complexity increases
Solution Approach 1:
The electrical connectors serve multiple functions: they provide grounding paths for VC inspection, act as electrical interconnects between contacts, and can be integrated with existing interconnect layers. This multi-functionality improves detection reliability while minimizing manufacturing complexity by reusing existing manufacturing capabilities and structures rather than requiring entirely new processes.
Solution Approach 2:
The grounding connectors are formed as part of the interconnect structure during the manufacturing process, before the VC inspection is performed. This preliminary action of pre-establishing grounding paths ensures that the detection system is already in place when needed, improving reliability without adding post-manufacturing complexity. The grounding infrastructure is built in advance as a standard part of device fabrication.
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 approach enables efficient identification of electrical defects by ensuring reliable grounding and enhancing the visibility of defects in voltage contrast scans, improving the accuracy of defect detection in nano-ribbon transistor structures.
Implementation Method 1
VC inspection is a defect inspection technique based on scanning electron microscopy. As an e-beam scans on metal lines, it positively charges the metal in the lines. Any grounded metal lines, for example, which electrically connect to the wafer substrate, emit more electrons and presents as a brighter pattern in e-beam scan images. Any metal lines which are not grounded and which may be isolated from the substrate, which may be referred to as floating metal lines, emit less electrons and look darker in e-beam scan images.
Data Source
AI summary
Embodiments described herein may be related to apparatuses, processes, systems, and/or techniques for electrically coupling components of a transistor structure together in order to perform a voltage contrast test to determine opens and shorts within the transistor structure. In embodiments, trench contacts (TCN) within a transistor structure may be electrically coupled together with an electrical connection that is electrically isolated from a power rail. In other embodiments, TCN may be electrically coupled using P-type epitaxial layers on a P-type substrate. Other embodiments may be described and/or claimed.