Plasma ALD Oxide Film Growth Selective to Boron-Containing Films
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Solution Overview
Problem
Existing film forming methods struggle to selectively form oxide films on substrates with varying surface materials, particularly where a boron-containing film and a film made of a different material are involved, as existing methods often result in non-selective film formation due to the reactivity of halide gases with both types of films.
Innovation Solution
A film forming method involving a substrate with a boron-containing first film and a second film of a different material, where a halogen-containing raw material gas and a plasmarized oxygen-containing reaction gas are alternately supplied to selectively form an oxide film on the second film while minimizing reaction on the first film, utilizing plasma atomic layer deposition (ALD) to control the adsorption and desorption of gases and achieve selective film growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halide gas is supplied to form oxide film, then film formation speed is improved, but selectivity between different film materials deteriorates
Solution Approach 1:
The patent segments the film formation process into two distinct alternating steps: (1) supplying halide-containing raw material gas to adsorb halide on the substrate surface, and (2) supplying oxygen-containing reaction gas to oxidize the adsorbed halide and form oxide film. This segmentation allows the process to achieve high formation speed during oxidation while maintaining selectivity during the adsorption step, as the halide gas only adsorbs on specific film surfaces that have appropriate affinity for halide species.
Solution Approach 2:
The patent employs periodic action by alternately supplying the halide-containing raw material gas and the oxygen-containing reaction gas in repeated cycles. Each cycle consists of a halide adsorption phase followed by an oxidation phase. This periodic alternation enables precise control over film thickness and composition while maintaining high formation speed, as each period contributes a controlled amount of oxide material to the growing film.
2Productivity
If halide gas reacts with substrate surface, then film formation is accelerated, but unwanted reactions with boron-containing film occur
Solution Approach 1:
The patent applies local quality by exploiting the different chemical properties of different film surfaces. The halide-containing raw material gas selectively adsorbs on the second film surface that has appropriate affinity for halide species, while the first boron-containing film surface does not adsorb the halide gas effectively. This local difference in surface quality ensures that subsequent oxidation occurs only on the desired film regions, preventing unwanted reactions on the boron-containing film.
Solution Approach 2:
The patent uses the adsorbed halide species as an intermediary that mediates between the raw material gas and the substrate surface. The halide gas first adsorbs on the substrate surface to form an intermediate layer, and then the oxygen-containing reaction gas reacts with this adsorbed halide to form the oxide film. This intermediary mechanism allows controlled film formation on specific surfaces while preventing direct unwanted reactions between the oxygen gas and the boron-containing film.
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 method allows for the selective formation of an oxide film on the second film relative to the boron-containing first film, enhancing control over film thickness and pattern formation, including filling recesses and confining voids, while maintaining the integrity of the first film.
Implementation Method 1
a reaction gas containing oxygen is plasmarized and supplied to the surface of the substrate
Implementation Method 2
the adsorbed halide is oxidized to form a third film which is an oxide film of the element X
Implementation Method 3
a raw material gas containing halide and an element X other than halide is supplied to the surface of the substrate
Data Source
AI summary
A film forming method includes: preparing a substrate having a surface on which a first film containing boron and a second film made of a material different from that of the first film are formed; supplying a raw material gas, which contains halogen and an element X other than halogen, to the surface of the substrate; and supplying a plasmarized reaction gas, which contains oxygen, to the surface of the substrate, wherein a third film as an oxide film of the element X is selectively formed on the second film with respect to the first film by alternately supplying the raw material gas and the plasmarized reaction gas.