Atomic Layer Deposition Method for High Quality Thin Film
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Atomic Layer Deposition (ALD) techniques face limitations in achieving high-quality thin films due to low growth-per-cycle rates and impurities from unreacted precursor ligands, particularly in depositing layers thinner than 5 nm, which results in film roughness and localized defects like pinholes.
Innovation Solution
An optimized ALD method involving sequential pulses of precursor gases at specific temperatures, including a first pulse of a halide or oxyhalide precursor and a second pulse of a gas to eliminate ligands, with optional plasma treatment and thermal annealing, to enhance growth-per-cycle and reduce impurities, utilizing a reactor design with temperature control and plasma capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ALD method is used with single temperature processing, then process simplicity is maintained, but growth-per-cycle is limited to 15-20% of monolayer and film quality deteriorates with roughness and pinholes
Solution Approach 1:
The ALD process is segmented into distinct temperature zones: a first temperature zone (100-800°C) for precursor adsorption and reaction, and a second temperature zone (room temperature to 200°C) for ligand elimination. This spatial segmentation allows each zone to be optimized for its specific function, achieving both high growth-per-cycle and high film quality simultaneously
Solution Approach 2:
Different regions of the reactor are assigned different temperature conditions tailored to specific process requirements. The first temperature zone provides thermal energy for complete precursor decomposition and high growth rate, while the second zone provides controlled conditions for impurity removal, ensuring optimal film quality
2Productivity
If higher temperature is used throughout the process, then growth rate increases, but impurity removal efficiency decreases
Solution Approach 1:
The temperature profile is segmented into two distinct zones: a high-temperature zone for rapid deposition and a low-temperature zone for impurity elimination. This allows the process to achieve both high productivity and high purity by performing each function in its optimal temperature environment
Solution Approach 2:
The process employs periodic alternation between high-temperature deposition pulses and low-temperature ligand elimination pulses. This periodic temperature variation enables cyclic accumulation of film material while systematically removing impurities at each cycle
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
The method significantly enhances the growth-per-cycle rate from 15% to 40% of a monolayer and reduces Cl-content by two orders of magnitude, improving film quality and scalability, thereby reducing film roughness and defects.
Implementation Method 1
Atomic Layer Deposition is a thin film deposition technique based on the use of separated chemisorption reactions of at least two gas phase reactants with a substrate
Implementation Method 2
Atomic Layer Deposition is a thin film deposition technique based on the use of separated chemisorption reactions of at least two gas phase reactants with a substrate
Data Source
Figure 1~3
Figure 4~5(b)
Figure 6~7
AI summary
The present invention is related to an ALD method comprising the steps of: a) providing a semiconductor substrate in a reactor, b) providing a pulse of a first precursor gas into the reactor at a first temperature, c) providing a first pulse of a second precursor gas into the reactor at a second temperature, d) providing a second pulse of the second precursor gas at a third temperature lower than the second temperature, and e) optionally repeating at least once step b) through step d) till a desired layer thickness is achieved. It is also related to a reactor suitable to apply the method.