Substrate Etch Selectivity via Plasma Densified Mask
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Solution Overview
Problem
Current substrate processing methods face limitations in achieving sufficient etch selectivity for thin films on 3D patterned structures without increasing RF power, which can lead to damage in reactor components due to high ion bombardment.
Innovation Solution
A method involving the formation of a first thin film on a structure, followed by a second material layer with different etch resistance properties, using directional plasma to densify or weaken the second layer, and subsequent isotropic etching to expose and remove portions of the first thin film, allowing for selective deposition without photolithography and without increasing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If higher RF power is applied to increase etch selectivity, then etch selectivity of thin films on pattern structure is improved, but damage to reactor components occurs due to high ion bombardment
Solution Approach 1:
The patent changes the chemical composition parameters of the plasma process gas to achieve selective etching. By using a process gas containing oxygen and at least one of nitrogen, sulfur, or fluorine, the etch selectivity is improved through chemical affinity differences rather than increasing ion bombardment energy, thus avoiding damage to reactor components.
Solution Approach 2:
The patent replaces the mechanical/physical approach of increasing ion bombardment energy (RF power) with a chemical approach using reactive plasma species. The etch selectivity is achieved through chemical reactions between plasma species and thin film materials, substituting the need for high-power ion bombardment that causes reactor component damage.
2Manufacturing precision
If plasma is applied to increase etch selectivity, then thin films on top and bottom of pattern structure are densified, but thin films on side of pattern structure become less dense and require wet etching
Solution Approach 1:
The patent modifies the plasma process gas composition to include oxygen and reactive elements (nitrogen, sulfur, or fluorine), which change the etching mechanism from purely physical ion bombardment to chemical reaction-based etching. This creates more uniform thin film removal across different surfaces including sides, tops, and bottoms of pattern structures.
Solution Approach 2:
The patent uses a composite plasma environment combining oxygen with reactive elements (nitrogen, sulfur, or fluorine) to create a multi-functional plasma chemistry that achieves both selective etching and uniform thin film density maintenance across complex 3D pattern structures.
3Manufacturing precision
If photolithography process is used for selective deposition, then deposition selectivity is achieved, but process complexity increases
Solution Approach 1:
The patent extracts and removes the photolithography process from the selective deposition sequence by using plasma-based selective etching to directly create the desired pattern. This eliminates the need for separate photolithography, resist coating, and pattern transfer steps, significantly reducing process complexity.
Solution Approach 2:
The patent introduces a plasma process with specific gas composition as an intermediary mechanism that directly achieves selective deposition/etching without requiring photolithography. The plasma acts as a mediator that provides both the selectivity and the patterning function in a single integrated 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 enhances etch selectivity for thin films on 3D structures by using a second material layer with altered properties to act as an etch mask, reducing the need for higher RF power and preventing damage to reactor components, thereby improving the selective deposition process.
Implementation Method 1
first plasma may be applied during the supplying of the second gas, and second plasma may be applied during the forming of the second material layer
Implementation Method 2
Due to the straightness and ion bombardment effect of radicals generated by plasma application, thin films on the top and bottom of the pattern structure in a direction perpendicular to a traveling direction of the radicals may be densified
Implementation Method 3
the second plasma may include directional plasma, and properties of the second material layer may be partially changed by the second plasma
Implementation Method 4
the removing of a portion of the second material layer and the removing of the exposed portion of the first thin film may be performed by isotropic etching
Data Source
AI summary
A substrate processing method capable of improving etch selectivity without increasing the power includes: forming a first thin film on a structure; forming a material layer having wet etch resistance greater than that of the first thin film on the first thin film; removing a portion of the material layer using wet etching to expose a portion of the first thin film; and removing the exposed portion of the first thin film.