Dry Etching Endpoint Detection via Multi-Wavelength Plasma Monitoring
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Solution Overview
Problem
The miniaturization of semiconductor products makes it difficult to accurately detect the end point of via hole etching in interlayer insulating films, leading to defects such as conduction or high-resistance issues due to incomplete etching or over-etching through barrier metals.
Innovation Solution
Monitoring the emission intensities of CO, CN, and AlF during dry etching of interlayer insulating films, with secondary differential operations on these wavelengths to accurately determine the end point, preventing penetration of the barrier metal and ensuring complete etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the opening area of via hole is reduced with miniaturization, then the semiconductor product size is reduced, but the accuracy of end point detection deteriorates
Solution Approach 1:
The patent divides the end point detection into multiple stages by monitoring different emission components: first detecting the inflection point using CO emission from SiO2 etching, then detecting the second inflection point using AlF emission when barrier metal is reached. This segmented approach allows accurate detection even with reduced via hole opening areas.
Solution Approach 2:
The patent transitions from monitoring a single emission wavelength to monitoring multiple wavelengths (CO at 226nm and AlF at 396nm) simultaneously. By adding the wavelength dimension, the system can detect different chemical reactions at different etching stages, maintaining detection accuracy despite reduced via hole size.
2Device complexity
If single wavelength emission monitoring is used, then the detection system is simple, but the accuracy of detecting both SiO2 etching end and barrier metal penetration is insufficient
Solution Approach 1:
The patent makes the emission monitoring system multi-functional by simultaneously detecting multiple wavelengths. The same optical detection system monitors both CO emission (226nm) for SiO2 etching detection and AlF emission (396nm) for barrier metal penetration detection, eliminating the need for separate detection systems while achieving dual-stage accuracy.
Solution Approach 2:
The patent changes the monitoring parameter from a single wavelength to multiple wavelengths. By monitoring emission intensity at different wavelengths (226nm for CO, 396nm for AlF) simultaneously, the system can distinguish between different etching reactions and accurately detect both the SiO2 etching end point and barrier metal penetration point.
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 method improves the manufacturing yield and reliability of semiconductor devices by accurately forming via holes and preventing high-resistance defects, allowing for early detection of abnormal processing.
Implementation Method 1
the end point of etching is detected by monitoring changes in the emission intensity of an etching gas component that emits light in plasma
Implementation Method 2
monitoring changes in the emission intensity of an etching gas component that emits light in plasma or in the emission intensity of a reaction product generated in plasma
Data Source
AI summary
A via hole is accurately formed in an interlayer insulating film over a metal wiring. Of emission spectra of plasma to be used for dry etching of the interlayer insulating film, the emission intensities of at least CO, CN, and AlF are monitored such that an end point of the dry etching of the interlayer insulating film is detected based on the emission intensities thereof.