E-test Structure Modification for Scatterometry Compatibility
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Solution Overview
Problem
Current IC fabrication processes face challenges in predicting electrical performance early in the manufacturing process due to the lack of scatterometry compatibility with front-end E-test structures, which are not 'scatterometry friendly', hindering the use of optical metrology for in-line measurements.
Innovation Solution
The method involves modifying E-test structures and surrounding OCD-compatible multiple structures through techniques like multiplication, dummification, and special target design to enable accurate optical scatterometry measurements, establishing correlations between optical and electrical parameters for early performance prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If E-test structures are used for early electrical performance prediction, then prediction capability is improved, but scatterometry compatibility deteriorates because FE E-test structures are not 'scatterometry friendly'
Solution Approach 1:
The patent divides the test structure into two functional parts: the E-test structure for electrical measurements and separate OCD-compatible structures for optical measurements. This segmentation allows each structure to be optimized for its specific measurement type while maintaining spatial proximity for correlation analysis
Solution Approach 2:
The patent introduces OCD-compatible structures as intermediary elements that bridge the gap between E-test structures and scatterometry measurements. These intermediary structures serve as proxies that can be measured optically while correlating to the electrical performance of the E-test structures
2Productivity
If OCD measurements are conducted on E-test structures, then in-line measurement capability is improved, but measurement area requirement deteriorates because E-test structures lack sufficient area for scatterometry spot size
Solution Approach 1:
The patent extends the measurement approach by adding spatial dimension - placing multiple OCD-compatible structures in the vicinity of the E-test structure. This dimensional extension ensures adequate measurement area while maintaining correlation to the original E-test structure's electrical performance
3Measurement precision
If E-test structures are modified for scatterometry compatibility, then optical measurement sensitivity is improved, but structural modification complexity deteriorates
Solution Approach 1:
The patent applies local quality by making modifications only to specific regions - creating OCD-compatible structures in the vicinity of the E-test structure rather than modifying the entire E-test structure. This localized approach maintains electrical performance while enabling optical measurements
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 allows for precise and accurate prediction of IC device performance at early stages, enabling process improvements and activating early in-line predictions in high-volume manufacturing by ensuring scatterometry compatibility and maintaining equivalent performance to the E-test structure.
Implementation Method 1
conducting optical scatterometric (OCD) measurements on said multiple structures
Data Source
AI summary
A test site and method are herein disclosed for predicting E-test structure (in-die structure) and/or device performance. The test site comprises an E-test structure and OCD-compatible multiple structures in the vicinity of the E-test structure to allow optical scatterometry (OCD) measurements. The OCD-compatible multiple structures are modified by at least one modification technique selected from (a) multiplication type modification technique, (b) dummification type modification technique, (c) special Target design type modification technique, and (d) at least one combination of (a), (b) and (c) for having a performance equivalent to the performance of the E-test structure.