Cyclic Dry Etching Using Halogen-Containing Film for Uniformity
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Solution Overview
Problem
Conventional atomic layer etching (ALE) techniques suffer from inadequate in-plane uniformity when etching silicon oxide or nitride films, as the etchant gases are adsorbed through physical adsorption rather than chemical adsorption, leading to suboptimal etch rates and uniformity.
Innovation Solution
A method involving the deposition of a halogen-containing etchant film on the target layer, followed by plasma treatment to generate reactive etchant species that etch the film and target layer interface, ensuring a self-limiting etching process with controlled etch rates and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If physical adsorption of etchant gas is used on substrate surface, then etching can be performed, but in-plane uniformity of etching deteriorates
Solution Approach 1:
A fluorocarbon film is introduced as an intermediary layer between the etchant gas and the substrate surface. The etchant gas first forms this film through chemical vapor deposition, and then reactive ion etching removes the film along with a controlled amount of the underlying oxide or nitride film. This intermediary film enables self-limiting etching that achieves atomic layer precision and superior in-plane uniformity compared to direct physical adsorption methods.
2Ease of operation
If conventional ALE with physical adsorption is used, then etching process can be performed, but etch rate per cycle is affected by gas flow rate and pulse duration
Solution Approach 1:
The invention changes the fundamental parameter of adsorption mechanism from physical to chemical adsorption through CVD film formation. This transformation makes the etching process self-limiting, where the etch rate per cycle is determined by the film thickness rather than gas flow rate or pulse duration. The process becomes less sensitive to these parameters, improving controllability and precision.
3Manufacturing precision
If etchant gas is supplied to saturate reactive surface sites, then chemisorption occurs, but this is not achieved with conventional etchant gases on oxide and nitride films
Solution Approach 1:
The fluorocarbon film serves as a mediator that enables chemisorption-like behavior. Although the etchant gas itself does not directly chemisorb on the oxide or nitride surface, the CVD-formed fluorocarbon film creates a self-limiting reaction interface that mimics chemisorption characteristics, achieving saturation behavior and atomic layer precision etching.
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 approach achieves high controllability and operability in etching processes, with etch rates and uniformity improved by limiting the etchant film thickness and exposure time, resulting in consistent etching depths across the target layer.
Implementation Method 1
depositing a halogen-containing film using reactive species on the target layer
Implementation Method 2
etching the halogen-containing film using a plasma of a non-halogen etching gas
Implementation Method 3
generate etchant species at a boundary region of the halogen-containing film and the target layer, thereby etching a portion of the target layer
Data Source
AI summary
A method for etching a target layer on a substrate by a dry etching process includes at least one etching cycle, wherein an etching cycle includes: depositing a halogen-containing film using reactive species on the target layer on the substrate; and etching the halogen-containing film using a plasma of a non-halogen etching gas, which plasma alone does not substantially etch the target layer, to generate etchant species at a boundary region of the halogen-containing film and the target layer, thereby etching a portion of the target layer in the boundary region.