Remote Plasma Etch Selectivity for Silicon Oxide and Nitride
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Solution Overview
Problem
Current dry etch processes face challenges in achieving high selectivity between silicon oxide and silicon nitride, particularly as linewidths approach and go below ten nanometers, leading to non-negligible loss of silicon nitride.
Innovation Solution
A method involving a remote plasma etch process using a fluorine-containing precursor and an oxygen-containing precursor, combined with water vapor or alcohol, to selectively etch silicon oxide faster than silicon nitride, with the oxygen-containing precursor suppressing the silicon nitride etch rate and enhancing etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry etch processes are used to etch silicon oxide, then etching capability is achieved, but silicon nitride loss increases and etch selectivity decreases
Solution Approach 1:
The patent changes the chemical parameters of the etch process by introducing an oxygen-containing precursor (such as O3, O2, N2O, or NO2) in addition to the fluorine-containing precursor. This parameter change modifies the etch chemistry to achieve higher selectivity between silicon oxide and silicon nitride, with selectivity ratios exceeding 80:1 while minimizing silicon nitride loss.
Solution Approach 2:
The patent uses a composite etch chemistry approach by combining fluorine-containing precursors (providing etching capability) with oxygen-containing precursors (suppressing silicon nitride etching). This composite chemical system creates the selective etching environment needed to resolve the contradiction between etching efficiency and material preservation.
2Productivity
If remote plasma with fluorine-containing precursor is used, then silicon oxide etching is achieved, but silicon nitride etch rate suppression is insufficient
Solution Approach 1:
The patent modifies the plasma chemistry parameters by adding oxygen-containing precursors to the remote plasma system. This changes the plasma composition to include oxygen-bearing species that selectively suppress silicon nitride etching while maintaining silicon oxide etching performance, thereby improving etch selectivity without sacrificing productivity.
Solution Approach 2:
The oxygen-containing precursor acts as an intermediary substance that mediates between the fluorine-containing etchant and the silicon nitride layer. It suppresses the etch rate of silicon nitride through chemical interaction, allowing the fluorine species to continue etching silicon oxide effectively while protecting silicon nitride from excessive removal.
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 achieves unprecedented etch selectivity of silicon oxide to silicon nitride, with etch rates exceeding 80:1, reducing silicon nitride loss and maintaining minimal disturbance to delicate features, and eliminates solid residue production.
Implementation Method 1
The remote plasma excites a fluorine-containing precursor in combination with an oxygen-containing precursor
Implementation Method 2
The combination react with the patterned heterogeneous structures to remove an exposed silicon oxide portion
Implementation Method 3
Plasma effluents within the remote plasma are flowed into a substrate processing region where the plasma effluents combine with water vapor or an alcohol
Implementation Method 4
The inclusion of the oxygen-containing precursor may suppress the silicon nitride etch rate and result in unprecedented silicon oxide etch selectivity
Data Source
AI summary
A method of etching exposed silicon oxide on patterned heterogeneous structures is described and includes a gas phase etch using plasma effluents formed in a remote plasma. The remote plasma excites a fluorine-containing precursor in combination with an oxygen-containing precursor. Plasma effluents within the remote plasma are flowed into a substrate processing region where the plasma effluents combine with water vapor or an alcohol. The combination react with the patterned heterogeneous structures to remove an exposed silicon oxide portion faster than an exposed silicon nitride portion. The inclusion of the oxygen-containing precursor may suppress the silicon nitride etch rate and result in unprecedented silicon oxide etch selectivity.