Plasma Etching Selectivity via Carbon-Rich Deposit Control
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Solution Overview
Problem
Current etching methods face challenges in achieving selective etching of silicon oxide with respect to silicon nitride, particularly in minimizing pattern defects and improving selectivity in miniaturized semiconductor manufacturing.
Innovation Solution
An etching method involving a substrate with a first silicon-containing material region and a second silicon-containing material region, where the first region is etched using plasma generated from a first process gas containing carbon and fluorine atoms, followed by exposure to plasma from an inert gas, with controlled radio-frequency signals and temperature settings to form a carbon-rich deposit that enhances selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a protective film of byproducts (deposit) is formed on the second region to improve selectivity, then the selectivity of silicon oxide to silicon nitride is improved, but the process complexity increases due to multiple alternating plasma exposure steps
Solution Approach 1:
The patent applies periodic action by alternating between exposure to plasma from a first process gas (containing carbon and fluorine atoms) and plasma from a second process gas (containing inert gas). This periodic alternation creates a cyclical pattern of deposit formation and selective etching, allowing the deposit to protect the second region during etching cycles while enabling precise control over the etching depth and selectivity ratio through the number and duration of cycles.
2Manufacturing precision
If radio-frequency signal frequency and substrate temperature are controlled to increase carbon-to-fluorine ratio in the deposit, then the selectivity is improved, but the control precision requirements increase
Solution Approach 1:
The patent applies parameter changes by specifically controlling the radio-frequency signal frequency (60 to 300 MHz) and substrate temperature (100 to 200° C.) during plasma exposure. These parameter adjustments directly influence the composition of the deposit, increasing the carbon-to-fluorine atom ratio. The controlled parameters modify the plasma chemistry to favor carbon-rich deposit formation, which enhances the protective effect on the second region and improves overall etching selectivity.
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
The method improves the selectivity of silicon oxide etching with respect to silicon nitride, reducing faceting and maintaining vertical features, while controlling the carbon-to-fluorine ratio in the deposit to protect the silicon nitride region effectively.
Implementation Method 1
exposes the substrate to plasma generated from a first process gas containing carbon atoms and fluorine atoms using a radio-frequency signal and forming a deposit on the substrate
Implementation Method 2
exposes the substrate to plasma generated from a first process gas containing carbon atoms and fluorine atoms using a radio-frequency signal
Implementation Method 3
exposes the deposit to plasma generated from a second process gas containing an inert gas using a radio-frequency signal and selectively etching the first region with respect to the second region
Data Source
AI summary
An etching method includes: (a) providing, on a support, a substrate having the first region covering the second region and the second region defining a recess receiving the first region, (b) etching the first region until or immediately before the second region is exposed, (c) exposing the substrate to plasma generated from a first process gas containing C and F atoms using a first RF signal and forming a deposit on the substrate, (d) exposing the deposit to plasma generated from a second process gas containing an inert gas using a first RF signal and selectively etching the first region to the second region, and (e) repeating (c) and (d). (c) includes using the RF signal with a frequency of 60 to 300 MHz and/or setting the support to 100 to 200° C. to control a ratio of C to F atoms in the deposit to greater than 1.