Backside Roughness to Frontside Overlay Conversion
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Solution Overview
Problem
Semiconductor device fabrication faces challenges in maintaining tight tolerances for overlay errors due to systematic and stochastic errors, sample geometry-induced errors, and variations, which existing technologies struggle to effectively address.
Innovation Solution
A system and method that measures backside surface roughness using a characterization sub-system and converts this data into overlay values for the frontside surface by generating a vacuum hole map, determining vacuum force distribution, and correlating it with shape data to adjust process tools for improved overlay control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tight tolerances are applied to overlay errors to improve manufacturing precision, then manufacturing precision improves, but measurement precision requirements increase
Solution Approach 1:
The patent uses backside surface roughness as an intermediary parameter to indirectly measure and control frontside overlay errors. Instead of directly measuring frontside overlay with high precision equipment, the system measures backside roughness which correlates to overlay errors, thereby achieving tight overlay control without requiring equally tight measurement precision on the frontside
Solution Approach 2:
The patent replaces direct mechanical/optical measurement systems for frontside overlay with an indirect measurement approach using backside surface roughness characterization. This substitution allows overlay control through roughness measurements that are easier to obtain and process
2Adaptability or versatility
If multiple patterned material layers are added to increase device functionality, then device complexity increases, but overlay control difficulty increases
Solution Approach 1:
The patent performs preliminary measurement of backside surface roughness before frontside patterning and overlay processes. By characterizing the backside roughness early in the process, the system can predict and compensate for potential overlay errors in subsequent layers, preventing compounding of errors as device complexity increases
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 enhances overlay measurement and control by translating backside haze into frontside overlay values, reducing errors and improving surface quality, thereby facilitating more precise semiconductor device fabrication.
Implementation Method 1
a vacuum chuck; generate a vacuum hole map of the vacuum chuck; generate a vacuum force distribution across the sample based on the generated vacuum hole map of the vacuum chuck
Data Source
AI summary
A system for estimating front side overlay on a sample based on shape data is disclosed. The system includes a characterization sub-system and a controller. The controller includes one or more processors configured to: generate a vacuum hole map of a vacuum chuck; generate a vacuum force distribution across a sample based on the generated vacuum hole map of the vacuum chuck; determine shape data of the sample based on the vacuum force distribution and an identified relationship between backside surface roughness and vacuum force of the vacuum chuck; and convert the shape data of the sample to an overlay value of a frontside surface of the sample.