Atomic Layer Etching for Sub-10 nm Uniformity
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Solution Overview
Problem
Current etch processes in the semiconductor industry, such as reactive ion etching, face challenges in achieving atomic-scale control and uniformity, making them unsuitable for next-generation sub-10 nm technology node devices due to inherent process variability and wafer non-uniformity.
Innovation Solution
The implementation of atomic layer etching (ALE) methods involving a sequence of self-limiting reactions, including surface conversion, ligand exchange, and desorption operations, with thermal energy and plasma applications, to achieve precise and uniform etching of substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reactive ion etching (RIE) is used for etching, then fast etch rates are achieved, but process variability and wafer non-uniformity increase
Solution Approach 1:
The continuous RIE process is segmented into discrete sequential steps: surface conversion, ligand exchange, and desorption. Each step is self-limiting and occurs in separate time intervals, transforming the continuous process into a stepwise sequence that enables atomic-layer precision while maintaining etching efficiency
Solution Approach 2:
The etching process employs periodic cyclic operations where surface conversion, ligand exchange, and desorption steps are repeated in alternating sequences. This periodic action allows controlled removal of material in atomic layers, achieving both fast overall etch rates and minimal process variability through precise cycle control
2Productivity
If reactive ion etching (RIE) is used for etching, then fast etch rates are achieved, but wafer uniformity deteriorates
Solution Approach 1:
The etching process is divided into spatially and temporally separated steps (surface conversion, ligand exchange, desorption) that occur sequentially across the wafer surface. This segmentation ensures uniform exposure and reaction conditions across the entire wafer, eliminating the non-uniformity inherent in continuous RIE while preserving fast etch rates through efficient cycle repetition
Solution Approach 2:
The surface conversion step performs preliminary modification of the wafer surface before etching occurs. This preliminary action creates a uniform reactive state across the entire wafer surface, ensuring that subsequent ligand exchange and desorption steps proceed uniformly, thereby maintaining wafer uniformity throughout the etching process
3Manufacturing precision
If atomic layer etching (ALE) is implemented with sequential self-limiting reactions, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
Each step in the ALE process (surface conversion, ligand exchange, desorption) is self-limiting, automatically terminating when the reactive species are consumed or the surface is saturated. This self-service characteristic eliminates the need for complex external control mechanisms to regulate each step, achieving atomic-scale precision through intrinsic process self-regulation
Solution Approach 2:
The ligand exchange step acts as an intermediary between surface conversion and desorption. This intermediate step facilitates controlled material removal by forming labile surface species that can be easily desorbed, enabling precise atomic-layer etching while maintaining process simplicity through the use of well-defined chemical intermediates
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
ALE provides controlled and consistent etching with atomic-scale precision, reducing variability and enabling the production of sub-10 nm technology node devices by ensuring uniformity and minimal feature size deviation.
Implementation Method 1
the surface conversion reactant adsorbs or chemisorbs on the surface of the substrate and modifies surface species on the surface of the substrate
Implementation Method 2
the surface conversion reactant adsorbs or chemisorbs on the surface of the substrate and modifies surface species on the surface of the substrate
Implementation Method 3
performing a desorption operation that effects removal of surface species from the surface of the substrate; performing the desorption operation includes applying thermal energy to the substrate
Implementation Method 4
performing a desorption operation includes exposing the surface of the substrate to a plasma
Implementation Method 5
performing the desorption operation includes exposing the surface of the substrate to a photon source to effect photolytic desorption
Implementation Method 6
the ligand containing reactant reacts with the modified surface species to form ligand-substituted species that are desorbed from the surface of the substrate
Data Source
AI summary
A method for performing atomic layer etching of a surface of a substrate is provided, including: performing a surface conversion operation by exposing the surface of the substrate to a surface conversion reactant; performing a ligand exchange operation by exposing the surface of the substrate to a ligand containing reactant; performing a desorption operation that effects removal of surface species from the surface of the substrate; performing a purge operation; repeating the surface conversion operation, the ligand exchange operation, the desorption operation, and the purge operation, for a predefined number of cycles.