Ohmic Contact Electrode Characterization via Segmented Testing Patterns

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Solution Overview

Problem

Current methods for measuring ohmic contact resistance in semiconductor devices, such as the rectangular transmission line model (TLM) and circular transmission line model (CTLM), face inaccuracies due to edge leakage effects and complex calculations, making them inadequate for high-performance device development.

Innovation Solution

A method involving two sets of testing patterns with concentric circular and annular ohmic electrodes is used to measure resistance values, allowing for a correction formula to accurately calculate the sheet resistance of the ohmic contact area, thereby improving measurement accuracy without complex simulations or large sample areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the rectangular transmission line model (TLM) method is used to measure ohmic contact resistance, then the measurement process is simple, but the measurement accuracy is poor due to edge leakage effects and the assumption that active area sheet resistance equals ohmic area sheet resistance

Engineering Contradiction:

Improvemeasurement process simplicityVSAvoidsheet resistance measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent divides the measurement into two distinct parts: active area sheet resistance measurement and ohmic area sheet resistance measurement. By using separate testing patterns (rectangular for active area, circular for ohmic area) and separate calculation formulas, the method eliminates the erroneous assumption that these two resistances are equal, thereby resolving the accuracy issue while maintaining operational simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary parameter - the active area sheet resistance - that is measured separately using rectangular testing patterns. This intermediary measurement serves as a foundation for subsequently calculating the ohmic area sheet resistance using circular testing patterns and a corrected formula, thereby improving accuracy without significantly complicating the overall process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the circular transmission line model (CTLM) method is used to measure ohmic contact resistance, then the measurement accuracy is improved, but the device complexity increases due to requiring more testing patterns and complex mathematical calculations

Engineering Contradiction:

Improvesheet resistance measurement accuracyVSAvoidtesting pattern and calculation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the measurement process into two distinct parts with dedicated testing patterns: rectangular patterns for active area sheet resistance and circular patterns for ohmic area sheet resistance. This segmentation allows each part to be optimized independently, maintaining accuracy while reducing overall complexity by avoiding the need for multiple circular patterns required by traditional CTLM methods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the geometric parameters of the testing patterns - using rectangular patterns for active area measurement and circular patterns for ohmic area measurement. This parameter change enables the use of simpler calculation formulas for each specific measurement type, reducing mathematical complexity while maintaining high accuracy.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If multiple sets of circular dot electrode testing patterns are used in the CDTLM method, then the measurement accuracy is improved, but the test sample area increases significantly

Engineering Contradiction:

Improvesheet resistance measurement accuracyVSAvoidtest sample area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent segments the measurement requirements by using different testing patterns for different measurement purposes. Rectangular patterns are used for active area sheet resistance measurement, while circular patterns are used for ohmic area sheet resistance measurement. This segmentation eliminates the need for multiple circular patterns, significantly reducing the required test sample area while maintaining measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by using only the necessary number of testing patterns for each specific measurement type. Instead of using multiple circular patterns for both active and ohmic area measurements, the method uses rectangular patterns for active area and circular patterns for ohmic area, reducing the total number of patterns needed and thus the sample area required.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10755990B2Method for characterizing ohmic contact electrode performance of semiconductor device

Publication Date: 2020.08.25 XIDIAN UNIV

AI summary

The present disclosure provides a method for characterizing ohmic contact electrode performance of a semiconductor device. The method comprises: preparing two sets of testing patterns on a semiconductor device; testing resistance values of the two sets of testing patterns respectively; calculating a sheet resistance of an ohmic contact area according to the obtained resistance values; and evaluating the ohmic contact electrode performance of the semiconductor device according to the sheet resistance of the ohmic contact electrode.