Spatial Tungsten ALD with Controlled WF6-H2 Mixing for Higher Growth Rate
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Solution Overview
Problem
Current spatial Atomic Layer Deposition (ALD) methods for tungsten film growth have growth rates below 0.2 angstroms/cycle, limiting the efficiency of film deposition at substrate temperatures between 200 and 450 degrees Celsius.
Innovation Solution
The method involves exposing a substrate to a first process condition with a constant flow of WF6 and a pulsed flow of H2, with the substrate laterally moved through a gas curtain containing a purge gas stream and/or vacuum region, and then exposed to a second process condition consisting essentially of H2, to enhance film growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional spatial ALD methods are used with spatial separation of precursors, then film deposition is achieved, but growth rates are limited to below 0.2 angstroms/cycle
Solution Approach 1:
The patent merges CVD and ALD process conditions by introducing a first process condition that includes both WF6 and H2 reactive gases simultaneously in a controlled mixture, rather than strictly separating them as in traditional spatial ALD. This combination enables enhanced growth rates (0.2 to 1 angstroms/cycle) while maintaining film quality through controlled precursor mixing and sequential exposure cycles
Solution Approach 2:
The patent implements periodic action through sequential exposure cycles where the substrate alternates between the first process condition (WF6 + H2 mixture) and the second process condition (H2 only). This periodic switching between different gas environments enables controlled film growth with improved rates while maintaining precision through repeatable cycle patterns
2Productivity
If full amount of second reactive gas is used for CVD process, then deposition speed increases, but loss of ALD process control occurs
Solution Approach 1:
The patent applies partial action by introducing the second reactive gas (H2) in less than a full amount required for complete CVD reduction. The H2 is pulsed in controlled quantities during the first process condition to enhance growth rate while maintaining ALD-like control. This partial introduction of reactive gas achieves improved deposition rates without sacrificing process precision
Solution Approach 2:
The patent changes process parameters by controlling the concentration and timing of H2 introduction in the first process condition. By adjusting the amount of H2 (less than full CVD amount) and its pulse timing, the process achieves intermediate behavior between ALD and CVD, enabling enhanced growth rates while maintaining controlled film deposition
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 achieves growth rates greater than 0.2 angstroms/cycle, with deposition rates ranging from 0.2 to 1 angstroms/cycle, while maintaining step coverage and controlled film thickness.
Implementation Method 1
exposing a substrate surface to a first process condition comprising a first reactive gas and a second reactive gas... The first reactive gas and the second reactive gas being spontaneously reactive
Implementation Method 2
The substrate is laterally moved through a gas curtain from the first process region to a second process region of the processing chamber. The gas curtain comprising one or more of a purge gas stream and/or a vacuum region
Data Source
AI summary
Methods of depositing a film by atomic layer deposition are described. The methods comprise exposing a substrate surface to a first process condition comprising a first reactive gas and a second reactive gas and exposing the substrate surface to a second process condition comprising the second reactive gas. The first process condition comprises less than a full amount of the second reactive gas for a CVD process.