SiOC Thin-Film PEALD Without Oxygen Plasma for 3D Step Coverage
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Solution Overview
Problem
There is a need for dielectric materials with low dielectric constant (k) values and low acid-based wet etch rates in semiconductor manufacturing, where existing deposition processes for silicon oxycarbide (SiOC) often require oxygen plasma and lack control over step coverage on three-dimensional features.
Innovation Solution
The use of plasma-enhanced atomic layer deposition (PEALD) processes that do not utilize oxygen plasma, employing a silicon precursor with an alkoxy group and an oxygen-free plasma reactant, such as hydrogen plasma, to achieve controlled step coverage and differential etch rates on vertical and horizontal surfaces of three-dimensional features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen plasma is used in deposition processes for silicon oxycarbide, then the film formation is enhanced, but the wet etch rate increases and control over step coverage is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma reactants, specifically using hydrocarbon-based plasmas (methane, ethylene, acetylene) instead of oxygen plasma. This parameter change allows formation of SiOC films with controlled oxygen content while achieving low wet etch rates and improved step coverage control on three-dimensional features
Solution Approach 2:
The patent introduces hydrocarbon-based plasma as an intermediary reactant that mediates between the silicon precursor and the substrate. This intermediary plasma source enables controlled deposition of SiOC films with desirable properties (low k-value, low etch rate, good step coverage) without requiring direct oxygen plasma exposure
2Productivity
If conventional deposition processes are used for silicon oxycarbide, then film deposition is achieved, but selective deposition on different surfaces (horizontal vs vertical) is not possible
Solution Approach 1:
The patent applies local quality by creating different film properties on different surfaces through the use of hydrocarbon plasma. The process achieves selective deposition where horizontal surfaces receive full film coverage while vertical surfaces have reduced or no deposition, enabling surface-specific film formation with the same process conditions
3Productivity
If oxygen plasma is used to deposit SiOC films, then deposition rate is improved, but the dielectric constant and wet etch rate become too high
Solution Approach 1:
The patent changes the plasma chemistry parameters from oxygen-based to hydrocarbon-based (methane, ethylene, acetylene). This parameter change enables deposition of SiOC films with lower dielectric constants and lower wet etch rates while maintaining acceptable deposition rates through the plasma-enhanced ALD process
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 allows for the deposition of SiOC films with step coverage of 20% or greater on three-dimensional features, achieving a wet etch rate ratio of 0.2 to 15 between vertical and horizontal surfaces, enabling selective etching and improved conformality on complex structures.
Implementation Method 1
The SiOC film may be deposited by a PEALD process comprising one or more deposition cycles in which the substrate is contacted with a vapor-phase silicon precursor that comprises oxygen, and subsequently contacted with a second plasma reactant
Implementation Method 2
The second plasma reactant may be generated in a reactant gas at a plasma power of 650 W or less. In some embodiments the second plasma reactant comprises oxygen-free plasma
Data Source
AI summary
Methods for controlling the formation of oxygen containing thin films, such as silicon oxycarbide (SiOC) and silicon oxycarbonitride (SiOCN) thin films, on a substrate in a reaction space are provided. The methods can include at least one plasma enhanced atomic layer deposition (PEALD) cycle including alternately and sequentially contacting the substrate with a silicon precursor that comprises oxygen and a second reactant that does not include oxygen. In some embodiments the plasma power can be selected from a range to achieve a desired step coverage or wet etch rate ratio (WERR) for films deposited on three dimensional features.