Plasma Etching Endpoint Detection via SF6 Gas Modulation
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Solution Overview
Problem
Conventional plasma etching methods require a special area for etching end-point detection patterns on silicon substrates, limiting device integration and equipment configuration, and are not effective in detecting the etching end point without restricting the equipment configuration.
Innovation Solution
A plasma etching method using SF6 gas in two steps: a large-amount supply step for high-speed etching and a small-amount supply step for end-point detection, where the emission intensity of Si or SiFx in the plasma is measured to determine the etching end point, allowing for minimal equipment configuration and enhanced device integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If etching end-point detection patterns are arranged on the silicon substrate, then etching end point can be detected, but device integration is reduced and manufacturing effectiveness decreases
Solution Approach 1:
The invention extracts the end-point detection function from the substrate surface patterns and implements it through plasma emission intensity measurement in the gas phase. By removing the need for detection patterns on the substrate, the device integration area is preserved while maintaining accurate end-point detection capability through optical measurement of plasma emissions.
2Measurement precision
If laser beam oscillating device and image monitoring camera are arranged directly above the silicon substrate, then etching end point can be detected, but equipment configuration is greatly restricted
Solution Approach 1:
The invention introduces plasma emission intensity as an intermediary measurement parameter between the etching process and the detection system. Instead of directly observing the substrate surface with complex optical systems, the measurement is performed on the plasma emissions, which serve as a mediator that simplifies the equipment configuration while maintaining detection accuracy.
3Productivity
If large amount of SF6 gas is supplied for high-speed etching, then etching rate increases, but etching end point detection becomes difficult
Solution Approach 1:
The invention implements periodic switching between large-amount gas supply mode (for high-speed etching) and small-amount gas supply mode (for end-point detection). This periodic action allows the system to alternate between maximizing etching rate and enabling accurate detection, with the detection phase occurring when plasma emission intensity becomes sufficiently distinct to identify the end 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
Enables reliable detection of the etching end point while maintaining high-speed etching, improving device integration and allowing for effective manufacturing without the need for additional detection patterns on the substrate.
Implementation Method 1
The Si film is etched by using etching gas containing SF6 gas
Implementation Method 2
a Si film of a silicon substrate is etched by using etching gas containing SF6 gas
Implementation Method 3
an emission intensity of Si or SiFx in the plasma at the small-amount supply step is measured
Data Source
Figure 1
Figure 2
Figure 3(a)~3(f)
AI summary
The present invention relates to a plasma etching method in which a special area for detecting an end point needs not to be set and an equipment therefor. At an etching step of forming SF6 gas into plasma to etch an etching ground on a Si film, the step is configured by two steps of: a large-amount supply step of supplying a large amount of SF6 gas; and a small-amount supply step of supplying a small amount of SF6 gas. An end-point detecting processor 34 measures an emission intensity of Si or SiFx in the plasma at the small-amount supply step, and determines that an etching end point is reached when the measured emission intensity becomes equal to or less than a previously set reference value.