Optical Auxiliary Layer for Wafer Levelness Detection
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Solution Overview
Problem
The accuracy of wafer levelness detection in semiconductor manufacturing is limited due to focusing errors and noise signals caused by the height differences between semiconductor substrate surfaces and metal interconnect lines, leading to reduced detection accuracy.
Innovation Solution
A method involving the formation of an optical auxiliary layer that reflects and absorbs levelness-detecting light, reducing noise and improving detection accuracy by preventing light from reaching the substrate and interconnect lines, while allowing alignment-mark-detecting light to pass through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical methods are used to detect wafer levelness by irradiating the substrate surface, then the levelness detection can be performed non-contact, but the detection accuracy is reduced due to focusing errors and noise signals from height differences between substrate surfaces and metal interconnect lines
Solution Approach 1:
An optical auxiliary layer is introduced as an intermediary component between the light source and the substrate surface. This layer selectively reflects levelness-detecting light while allowing alignment-mark-detecting light to pass through, thereby mediating the optical interaction to eliminate focusing errors and noise signals from underlying structures
Solution Approach 2:
The optical auxiliary layer is designed with specific optical properties that cause it to reflect levelness-detecting light while being transparent to alignment-mark-detecting light. This selective optical response based on wavelength characteristics enables differentiation between the two detection functions
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
Enhances the accuracy of wafer levelness detection and reduces noise signals, leading to improved semiconductor structure fabrication by compensating for focusing errors and ensuring high fidelity patterns in the photoresist layer.
Implementation Method 1
forming an optical auxiliary layer configured to reflect a portion of a levelness-detecting light
Implementation Method 2
absorb a portion of the levelness-detecting light transmitting through the optical auxiliary layer
Data Source
AI summary
A method for fabricating a semiconductor structure is provided. The method includes providing a semiconductor substrate; and forming a plurality of semiconductor devices on the semiconductor substrate. The method also includes forming a dielectric layer covering the plurality of the semiconductor devices on the semiconductor substrate; and forming an optical auxiliary layer configured to reflect a portion of a levelness-detecting light and absorb a portion of the levelness detecting light transmitting through the optical auxiliary layer during a levelness-detecting process over the dielectric layer. Further, the method includes forming a photoresist layer over the optical auxiliary layer; and detecting a levelness of the semiconductor substrate and exposing the photoresist layer to form a patterned photoresist layer.