Atomic Layer Etching Selectivity via Precursor Molecular Structure
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Solution Overview
Problem
Current atomic layer etching (ALE) techniques lack the ability to achieve high selectivity and control over etching processes, particularly in advanced semiconductor manufacturing, due to limitations in understanding the impact of precursor chemical composition and structure on etching results.
Innovation Solution
The method involves using hydrofluorocarbon (HFC) and fluorocarbon (FC) precursors in a plasma environment to selectively etch substrates by depositing and removing precursor layers, with precise control over the etching process to achieve high selectivity between different substrate materials, such as SiO2 and Si3N4, through controlled deposition and removal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional steady-state plasma etching is used, then etching speed is maintained, but etch selectivity and pattern transfer fidelity are insufficient
Solution Approach 1:
The continuous plasma etching process is segmented into discrete atomic layer etching cycles, where each cycle deposits a precursor layer followed by selective removal. This segmentation enables precise control over etch depth and selectivity at the angstrom level, resolving the contradiction between precision and speed by allowing optimized parameter settings in each discrete step.
Solution Approach 2:
The patent employs periodic pulsed plasma treatment alternating with precursor deposition cycles. This periodic action creates self-limited etching where the precursor layer formation and removal occur in distinct temporal phases, enabling high selectivity while maintaining overall etching throughput through optimized cycle frequencies and durations.
2Manufacturing precision
If precursor chemical composition is modified to improve selectivity, then etch selectivity increases, but process complexity increases
Solution Approach 1:
The patent systematically varies precursor chemical parameters (composition, molecular structure, deposition temperature, plasma power) to optimize etch selectivity and pattern transfer fidelity. By establishing structure-activity relationships between precursor properties and etching outcomes, the complex parameter space is navigated methodically, improving precision while managing process complexity through data-driven optimization.
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 enables highly selective and controlled etching with minimal loss of non-target materials, achieving angstrom-level precision and improving etch selectivity, as demonstrated by experiments using C4F8, C4F8/H2, and C3H3F3 precursors, which show significant differences in etch stop behavior and surface chemistry evolution.
Implementation Method 1
depositing a chemical precursor on a surface of the substrate to form a chemical precursor layer on the substrate... deposition of the chemical precursor and selective removal of the chemical precursor layer are performed under a plasma environment
Implementation Method 2
selectively removing the chemical precursor layer and at least a part of the first portion of the substrate... performed under a plasma environment
Data Source
AI summary
Provided is a method of selectively etching a substrate comprising at least one cycle of: depositing a chemical precursor on a surface of the substrate to form a chemical precursor layer on the substrate, the substrate comprising a first portion and a second portion, wherein the first and the second portion are of a different composition; selectively removing the chemical precursor layer and at least a part of the first portion of the substrate; and repeating the cycle until the first portion of the substrate is substantially or completely removed, wherein deposition of the chemical precursor and selective removal of the chemical precursor layer and at least a part of the first portion of the substrate are performed under a plasma environment.