Atomic Layer Etching Bias Waveforms for Single-Gas Uniformity
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Solution Overview
Problem
Conventional ALE processes face challenges in achieving uniformity and consistency across 300 mm wafers due to the unintended introduction of RIE components during the surface modification step, leading to non-uniform layer removal and undesirable etching profiles, particularly in advanced semiconductor manufacturing where minor deviations significantly impact device performance and yield.
Innovation Solution
The method employs a single gas or mixed gas composition throughout the ALE process, combined with optimized timing for surface modification and sputtering steps, and utilizes a tailored waveform generator for precise control of substrate bias, minimizing additional surface modification during the sputtering step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ALE processes use multiple gas compositions with transitions between surface modification and sputtering steps, then etching performance can be optimized, but process complexity and cycle time increase due to gas switching and unintended RIE components introduction
Solution Approach 1:
The patent combines multiple gas functions into a single mixed gas composition containing both reactive species for surface modification and inert species for sputtering. This merging eliminates the need for gas switching between steps, reducing process complexity while maintaining etching uniformity through controlled species ratios and timing.
Solution Approach 2:
The single mixed gas composition serves multiple functions simultaneously: it provides reactive neutrals for surface modification, inert ions for sputtering, and enables precise timing control. This multi-functionality reduces the number of process steps and gas handling complexity while achieving the desired etching precision.
2Manufacturing precision
If gas switching is implemented between surface modification and sputtering steps, then process optimization is achieved, but cycle time increases due to gas transitions
Solution Approach 1:
The patent maintains continuous etching action by using a single mixed gas composition that provides both modification and sputtering species throughout the cycle. This eliminates idle gas switching time and maintains continuous material removal, improving throughput while preserving etching precision through optimized timing and species ratios.
Solution Approach 2:
The mixed gas composition is prepared in advance with optimized ratios of reactive and inert species. The timing of surface modification and sputtering is pre-coordinated within the single gas flow, eliminating the need for real-time gas switching and reducing cycle time while maintaining precision.
3Productivity
If RIE components are introduced during surface modification step, then etching rate can be enhanced, but uniformity and profile control deteriorate
Solution Approach 1:
The patent applies different species concentrations at different times within the ALE cycle using the single mixed gas. During surface modification, reactive neutrals dominate; during sputtering, inert ions dominate. This temporal separation with local species optimization maintains profile uniformity while allowing high etching rates through controlled RIE component presence.
Solution Approach 2:
The patent uses periodic timing within the ALE cycle to control when RIE components are active. Surface modification occurs during periods with higher reactive species concentration, while sputtering occurs during periods with higher ion flux. This periodic action maintains uniformity by limiting RIE effects to specific phases while preserving high etching rates.
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 significantly reduces cycle time and enhances process efficiency and precision, ensuring consistent etching outcomes and improved throughput in semiconductor manufacturing.
Implementation Method 1
a plasma source to generate plasma from the process gas
Implementation Method 2
A radio frequency (RF) power generator, coupled to the ESC, provides a bias for the ions in the plasma
Implementation Method 3
a substrate bias to accelerate ions toward the substrate
Implementation Method 4
The removal step eliminates this modified layer while preserving the underlying substrate... When utilizing energetic ions, the removal is conducted via a sputtering process
Implementation Method 5
an electrostatic chuck (ESC) to feature multiple zones with independently adjustable temperatures
Data Source
AI summary
Disclosed herein is a method and system for atomic layer etching (ALE) that utilizes a single gas or a single mixture of gases throughout the process to enhance efficiency. The method involves designing the step times for surface modification and sputtering, with durations specifically tailored to minimize any additional surface modification during the sputtering step. A key innovation is the use of a tailored waveform generator, which provides rapid and precise control of the substrate bias. This technique significantly reduces ALE cycle time while maintaining high precision in semiconductor fabrication.