Inspection Tool Field-of-View Setting for Process Margin Sampling
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Solution Overview
Problem
Obtaining accurate metrology data over the entire surface of a substrate requires a prohibitively long time, making it difficult to determine control parameters for semiconductor manufacturing processes, especially for features smaller than the classical resolution limit of lithographic projection apparatuses.
Innovation Solution
A method for determining a field of view (FOV) setting for an inspection tool, involving obtaining a process margin distribution, identifying regions based on a threshold value, and configuring the FOV setting to optimize sampling schemes for efficient measurement, considering factors like FOV size, location, and density to reduce overall measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metrology data is collected over the entire substrate surface using conventional inspection methods, then measurement accuracy is improved, but measurement time becomes prohibitively long
Solution Approach 1:
The substrate surface is divided into multiple regions with different process margin characteristics. Inspection regions are selectively identified based on process margin distribution, allowing metrology data collection to be segmented into critical and non-critical areas. This segmentation enables accurate measurement of critical regions while reducing or skipping measurements in non-critical regions, thereby resolving the contradiction between comprehensive coverage and measurement time.
Solution Approach 2:
Different inspection strategies are applied to different regions of the substrate based on their process margin characteristics. Regions with low process margins (high variability) receive intensive inspection with smaller FOV settings, while regions with high process margins receive reduced inspection or are skipped entirely. This local differentiation maintains measurement accuracy for critical features while reducing overall measurement time.
2Measurement precision
If a small field of view (FOV) is used for inspection to increase measurement density, then measurement precision is improved, but the number of inspection locations increases, extending measurement time
Solution Approach 1:
Instead of applying uniform high-density inspection (small FOV) across the entire substrate, the method applies partial action by selectively using small FOV settings only in regions where process margins indicate high variability or criticality. In regions with adequate process margins, larger FOV settings are used or inspection is skipped, thereby achieving necessary measurement precision where needed while avoiding excessive measurements that would extend inspection time.
3Manufacturing precision
If process variability is reduced to improve feature reproduction precision, then manufacturing precision is improved, but the ability to handle diverse process conditions decreases
Solution Approach 1:
The inspection system dynamically adapts its FOV settings and sampling density based on real-time process margin distribution data. Rather than using fixed inspection parameters, the system adjusts inspection intensity and FOV size according to the specific process conditions and variability characteristics of different substrate regions. This dynamic approach maintains high manufacturing precision for critical features while adapting to diverse process conditions and variability patterns.
Data Source
AI summary
A method of determining a field of view setting for an inspection tool having a configurable field of view, the method including: obtaining a process margin distribution of features on at least part of a substrate; obtaining a threshold value; identifying, in dependence on the obtained process margin distribution and the threshold value, one or more regions on at least part of the substrate; and determining the field of view setting in dependence on the identified one or more regions.