Semiconductor Sample Preparation for Charge-Stable Beam Imaging
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Solution Overview
Problem
Charging effects during charged particle beam inspection of semiconductor samples, particularly in multi-layer stacks, lead to image quality deterioration and measurement inaccuracies due to charge accumulation in isolated conducting structures, causing local electrical fields and lateral field gradients.
Innovation Solution
Providing an electrical connection to electrically isolated regions within the semiconductor sample to allow charge dissipation, which can be achieved by identifying these regions using design data and forming connections with conducting materials like platinum or tungsten in trenches using focused ion beam milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion beam milling is performed to create slanted cross-section surfaces for 3D imaging, then the ability to inspect high aspect ratio structures is improved, but electrically isolated regions form that accumulate charge and deteriorate image quality
Solution Approach 1:
The patent applies preliminary action by forming conductive connections to electrically isolated regions before performing charged particle beam inspection. The method identifies isolated regions using design data, creates conductive paths through ion beam milling and material deposition, and establishes electrical connections prior to imaging to prevent charge accumulation during inspection
Solution Approach 2:
The patent uses an intermediary approach by introducing conductive materials (such as platinum or tungsten) as mediators between the electrically isolated regions and the sample holder or ground. These conductive materials act as intermediaries to provide charge dissipation paths without interfering with the inspection of the isolated regions themselves
2Productivity
If multiple cross-section surfaces are milled and inspected to generate 3D volume images, then inspection throughput is improved, but charge accumulation in isolated regions worsens due to repeated beam exposure
Solution Approach 1:
The patent performs preliminary action by establishing conductive connections to all electrically isolated regions before beginning the multi-step cross-section milling and inspection process. This ensures that charge dissipation paths are in place before repeated beam exposure begins, maintaining measurement accuracy throughout the high-throughput inspection process
Solution Approach 2:
The patent enables continuity of useful action by ensuring uninterrupted charge dissipation throughout the entire 3D imaging process. The conductive connections maintain continuous charge dissipation paths during repeated ion beam milling and electron beam inspection cycles, preventing image quality deterioration even during extended inspection sequences
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
Reduces charging effects, resulting in improved image quality and measurement accuracy by balancing local electrical fields and mitigating charge accumulation, thereby enhancing the inspection process.
Implementation Method 1
ion beam milling the semiconductor structure sample to form a slanted surface under an angle with respect to a surface of the semiconductor structure sample
Implementation Method 2
providing an electrical connection to the at least one electrically isolated region... allow charge dissipation
Data Source
AI summary
A method of preparing a sample for charged particle beam inspection comprises providing a semiconductor structure sample and identifying electrically isolated regions in an area of the sample to be examined. The method further comprises providing an electrical connection to the at least one electrically isolated region.