Multi-Point Probe for Electrical Property Measurement
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Solution Overview
Problem
Current methods for determining electrical properties of test samples, particularly those with non-conductive and conductive areas, face challenges in accurately measuring properties like sheet resistance and carrier mobility due to limitations in traditional characterization techniques and probe designs.
Innovation Solution
A method utilizing the Hall effect with a test probe having multiple conductive tips and a magnetic field to measure electrical properties by varying the distance between tips and a boundary, allowing for precise calculations of sheet resistance and carrier mobility, especially suitable for thin films and ultra-shallow junctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional characterization techniques are used, then measurement simplicity is maintained, but measurement precision deteriorates due to inability to accurately measure sheet resistance and carrier mobility in mixed conductive/non-conductive areas
Solution Approach 1:
The probe is divided into multiple independently controllable conductive tips arranged in specific patterns (e.g., 4-point, 6-point configurations). Each tip can be independently positioned and controlled, allowing selective contact with different regions of the test sample. This segmentation enables precise measurement of electrical properties in specific areas while avoiding adjacent non-conductive regions, thereby resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The probe design transitions from traditional single-point or simple linear contact to multi-dimensional spatial arrangement of multiple tips. The tips are positioned in two-dimensional patterns (e.g., rectangular arrays, radial configurations) that allow simultaneous multi-point contact with the test sample. This dimensional change enables accurate measurement of sheet resistance and carrier mobility by establishing multiple current and voltage measurement paths, overcoming the limitations of traditional techniques while maintaining manageable device complexity through systematic geometric arrangements.
2Measurement precision
If traditional probes are used, then device simplicity is maintained, but measurement precision deteriorates due to probe penetration and junction leakage current
Solution Approach 1:
The measurement method uses partial contact where only specific subsets of the multiple probe tips make contact with the test sample at any given time. By selectively activating only the necessary tips for a particular measurement configuration, the method achieves accurate carrier mobility measurement without requiring full probe engagement. This partial action reduces the total contact area and measurement points involved, thereby minimizing junction leakage current while maintaining measurement precision.
Solution Approach 2:
The multiple conductive tips act as intermediaries between the measurement system and the test sample. Instead of using a single large contact point that causes probe penetration and leakage, the current is distributed across multiple smaller tip contacts. This intermediary approach allows precise control of current flow paths, enabling accurate electrical property measurement while reducing harmful effects like junction leakage and probe penetration damage to ultra-shallow junctions.
3Measurement precision
If multiple conductive tips are used, then measurement precision improves, but device complexity increases
Solution Approach 1:
The multi-tip probe structure is designed to perform multiple measurement functions using the same physical hardware. The same array of conductive tips can be configured for different measurement modes (e.g., 4-point probe for sheet resistance, Hall effect measurements for carrier mobility, resistance anisotropy measurements). This multi-functionality allows the probe to achieve high measurement precision across various electrical property characterizations without requiring separate specialized probes for each measurement type, thereby managing device complexity while maintaining versatility and accuracy.
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 and precise measurements of electrical properties with high spatial resolution, reducing junction leakage current and avoiding probe penetration, thus improving the characterization of ultra-shallow junctions and highly doped materials.
Implementation Method 1
A first aspect of the present invention relates to a method of determining an electrical property of a test sample by utilising the so-called Hall effect
Data Source
AI summary
A method of obtaining an electrical property of a test sample, comprising a non-conductive area and a conductive or semi-conductive test area, by performing multiple measurements using a multi-point probe. The method comprising the steps of providing a magnetic field having field lines passing perpendicularly through the test area, bringing the probe into a first position on the test area, the conductive tips of the probe being in contact with the test area, determining a position for each tip relative to the boundary between the non-conductive area and the test area, determining distances between each tip, selecting one tip to be a current source positioned between conductive tips being used for determining a voltage in the test sample, performing a first measurement, moving the probe and performing a second measurement, calculating on the basis of the first and second measurement the electrical property of the test area.