Remote Plasma Etch Selectivity for Silicon Nitride
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Solution Overview
Problem
Current dry etch processes have limited selectivity for removing silicon nitride relative to silicon, which is essential for precise patterning in integrated circuits.
Innovation Solution
A remote plasma etch method using a combination of fluorine-containing and oxygen-containing precursors, with an ion suppression element to control the plasma species reaching the substrate, selectively removes silicon nitride at a rate significantly higher than silicon, achieving selectivity of over ten times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry etch processes are used, then etching can be performed on semiconductor substrates, but the selectivity for removing silicon nitride relative to silicon is limited
Solution Approach 1:
The patent changes the chemical parameters of the etch process by using a dual-precursor system (silane and ammonia) instead of conventional single-precursor processes. This chemical parameter change enables selective removal of silicon nitride over silicon by more than 10:1, directly resolving the selectivity limitation of conventional dry etch processes
Solution Approach 2:
The patent employs a composite plasma environment formed from two different precursors (silane and ammonia) that work synergistically. The silane provides silicon-containing species while ammonia provides nitrogen-containing species, creating a composite chemical environment that selectively etches silicon nitride while protecting silicon, thus improving selectivity without sacrificing process versatility
2Object-affected harmful factors
If remote plasma etch processes are used to remove silicon nitride, then material can be gently removed with minimal physical disturbance, but the silicon nitride selectivity relative to silicon has been limited
Solution Approach 1:
The patent modifies the chemical composition parameters of the remote plasma by introducing a dual-precursor system (silane and ammonia) rather than conventional single-precursor gases. This parameter change enables the gentle remote plasma process to achieve high silicon nitride selectivity (>10:1) by creating a chemically selective environment that preferentially reacts with silicon nitride while minimizing damage to other materials
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 allows for precise and selective etching of silicon nitride while minimizing damage to surrounding materials, maintaining high etch selectivity and reducing plasma-induced deformation.
Implementation Method 1
A method of etching exposed silicon-and-nitrogen-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor
Implementation Method 2
Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-and-nitrogen-containing material
Implementation Method 3
The silicon-and-nitrogen-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element reduces or substantially eliminates the number of ionically-charged species that reach the substrate
Data Source
AI summary
A method of etching exposed silicon-and-nitrogen-containing material on patterned heterogeneous structures is described and includes a remote plasma etch formed from a fluorine-containing precursor and an oxygen-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the exposed regions of silicon-and-nitrogen-containing material. The plasmas effluents react with the patterned heterogeneous structures to selectively remove silicon-and-nitrogen-containing material from the exposed silicon-and-nitrogen-containing material regions while very slowly removing other exposed materials. The silicon-and-nitrogen-containing material selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region. The ion suppression element reduces or substantially eliminates the number of ionically-charged species that reach the substrate. The methods may be used to selectively remove silicon-and-nitrogen-containing material at more than twenty times the rate of silicon oxide.