Plasma-Enhanced Atomic Layer Etching for Semiconductor Precision
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Solution Overview
Problem
Conventional etching technologies face challenges in forming fine, narrow convex-concave patterns and suffer from low etching rate and poor controllability, particularly in double-patterning processes for semiconductor devices, where atomic layer-level etching is required.
Innovation Solution
A method of plasma-enhanced atomic layer etching (PEALE) is developed, where an etching gas is supplied through a mass flow controller with an inert gas, generating a plasma using inert or nitrogen gas, and the etching rate is controlled by adding oxidizing or reducing gases, with temperature maintained between 0° C. to 250° C., allowing for anisotropic or isotropic etching by selecting reactant gases and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional continuous etching using excited reaction species is used, then etching speed is maintained, but manufacturing precision and shape controllability deteriorate due to inability to form fine narrow convex-concave patterns
Solution Approach 1:
The continuous etching process is segmented into discrete atomic layers through sequential pulsed gas supply. The etching gas is supplied in pulses rather than continuously, allowing controlled removal of material layer by layer at atomic precision, thereby achieving both high manufacturing precision and acceptable productivity for fine pattern formation.
Solution Approach 2:
The etching process employs periodic pulsed supply of etching gas combined with continuous inert gas flow. This periodic action enables precise control over etching depth and morphology by adjusting pulse duration and frequency, resolving the contradiction between achieving atomic-level precision and maintaining etching rate.
2Manufacturing precision
If pulsed etching gas supply is used to improve manufacturing precision, then etching rate decreases due to intermittent gas supply
Solution Approach 1:
While the etching gas is supplied in pulses, the inert gas flows continuously throughout the process. This continuous inert gas flow maintains the reactive environment and removes byproducts continuously, ensuring that the useful etching action continues without interruption even when etching gas pulses are momentarily paused, thereby preserving etching rate while achieving atomic layer precision.
3Manufacturing precision
If multiple gas lines and mass flow controllers are used to control etching parameters, then etching controllability improves, but device complexity increases
Solution Approach 1:
The inert gas line serves multiple functions simultaneously: it acts as a carrier gas, a purge gas, and a plasma generation gas. This multi-functionality reduces the need for separate dedicated gas lines and controllers, thereby improving etching controllability while minimizing the increase in device complexity.
Solution Approach 2:
The inert gas acts as an intermediary between the pulsed etching gas supply and the continuous processing requirements. By mediating the interaction between intermittent etching gas pulses and the continuous plasma environment, the inert gas simplifies the overall gas supply control architecture while maintaining precise etching controllability.
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 enhances etching efficiency and controllability, enabling precise formation of micro-patterns with high conformality and directionality, suitable for double-patterning processes, while maintaining a high etching rate and reducing defects.
Implementation Method 1
An etching gas is supplied to a reaction space through a mass flow controller, together with an inert gas, wherein the etching gas and the inert gas converge downstream of the mass flow controller
Implementation Method 2
the inert gas is supplied continuously... Since the inert gas continuously flows, it can function as a purge gas
Implementation Method 3
a plasma is used for etching, wherein an inert gas or nitrogen gas is supplied as an essential reactant gas to the reaction space for generating a plasma therein
Implementation Method 4
etching rate is controlled by selectively adding an oxidizing gas such as oxygen gas
Implementation Method 5
or reducing gas such as hydrogen gas as an additional reactant gas
Implementation Method 6
the process temperature is controlled at 0° C. to 250° C.
Data Source
AI summary
A method for etching a layer on a substrate includes at least one etching cycle, wherein an etching cycle includes: continuously providing an inert gas into the reaction space; providing a pulse of an etching gas into the continuous inert gas flow upstream of the reaction space to chemisorb the etching gas in an unexcited state on a surface of the substrate; and providing a pulse of RF power discharge between electrodes to generate a reactive species of the inert gas in the reaction space so that the layer on the substrate is etched.