Electron Beam Impedance Imaging for 3D Semiconductor Structures
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Solution Overview
Problem
Existing scanning electron microscope voltage contrast tests provide limited information on the impedance of three-dimensional, microscopic semiconductor structures, necessitating a more comprehensive evaluation of impedance-related values.
Innovation Solution
A charged particle system utilizing an imager and impedance circuit to perform multiple illumination iterations with an electron beam, determining the time difference and charge values to establish a dependency between impedance and image characteristics, allowing for the evaluation of impedance-related values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a single illumination iteration is performed to image the structure, then the measurement process is simple and fast, but the impedance information obtained is limited and insufficient
Solution Approach 1:
The patent applies periodic action by performing multiple illumination iterations with different illumination charges at different time points. The structure is illuminated periodically with varying charge values, and the resulting images are analyzed to extract impedance characteristics. This periodic illumination approach enables comprehensive impedance evaluation while managing process complexity through systematic repetition.
Solution Approach 2:
The patent implements parameter changes by varying the illumination charge values across different illumination iterations. By changing the electrical parameter (illumination charge) and observing the resulting image variations, the system extracts detailed impedance information that would not be obtainable with a single fixed illumination condition.
2Measurement precision
If multiple illumination iterations with varying charges are performed, then comprehensive impedance information is obtained, but the measurement time and process complexity increase
Solution Approach 1:
The patent applies preliminary action by performing a first illumination iteration with a first illumination charge before the second illumination iteration. This preliminary illumination establishes an initial charge state on the structure, which then evolves over time. By capturing images at strategically selected time points, the system efficiently extracts impedance information without requiring continuous monitoring, thus reducing total measurement time while maintaining precision.
Solution Approach 2:
The structure itself serves as the measurement medium by naturally discharging its accumulated charge over time according to its impedance characteristics. The system leverages the structure's inherent electrical properties to generate the measurement signal, eliminating the need for external test equipment or complex measurement circuits, thereby reducing overall system complexity and measurement time.
3Productivity
If the time difference between illumination iterations is minimized, then the measurement process is faster, but the impedance-dependent image variations become less distinguishable
Solution Approach 1:
The system implements feedback by analyzing the image variations resulting from different illumination charges and using this information to determine impedance characteristics. The image data from each illumination iteration provides feedback about the structure's charge state and discharge behavior, which is then used to extract precise impedance measurements. This feedback mechanism enables accurate impedance detection while optimizing the time difference between iterations for efficient measurement.
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
Enables accurate determination of impedance-related values, distinguishing between functional and faulty structures by analyzing image intensity changes over time, enhancing the assessment of semiconductor structures.
Implementation Method 1
perform a first illumination iteration that comprises charging the structure, using an electron beam, with an illumination iteration charge
Implementation Method 2
perform a second illumination iteration that comprises imaging the structure, using the electron beam, to provide an image of the structure
Data Source
AI summary
A method for evaluating an impedance related value of a structure of a sample, the method includes: (i) performing a first illumination iteration that includes charging the structure with an illumination iteration charge; (ii) performing a second illumination iteration that includes imaging the structure to provide an image of the structure; a value of the illumination iteration charge and a value of a time difference between step (i) and step (ii) are determined to introduce a dependency between an impedance of the structure and the image of the structure; wherein steps (i) and (ii) are executed using an electron beam, and (iii) determining the impedance related value of the structure based on the image of the structure. There may be three or more values of the impedance related value.