Solid-Phase Etching of High-Aspect-Ratio Trenches
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Solution Overview
Problem
Conventional etching processes face challenges in selectively removing materials from high-aspect-ratio structures without damaging surrounding materials, particularly due to issues with wet etchants penetrating confined spaces and causing deformation or corrosion, and dry etches potentially damaging substrates with electric arcs.
Innovation Solution
The method involves flowing hydrogen-containing and fluorine-containing precursors into a semiconductor processing chamber to form a spacer with specific layers, allowing for a solid-phase etching process that selectively removes oxygen-containing materials while protecting carbon-containing or nitrogen-containing materials, and maintaining the process plasma-free to minimize damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to remove exposed material, then selectivity towards specific materials is improved, but penetration into constrained trenches is insufficient and deformation of remaining material occurs
Solution Approach 1:
The patent changes the physical state of the etchant from liquid (wet) to gas (dry) form, allowing the etching process to penetrate into high-aspect-ratio trenches and vias that are inaccessible to liquid etchants, while maintaining material selectivity through controlled chemical reactions
Solution Approach 2:
The patent utilizes phase transition by converting the etchant from liquid phase to gas phase, enabling penetration into constrained geometries. The gas-phase etchant can flow into and react within high-aspect-ratio structures, then be removed by pumping, avoiding the deformation issues associated with liquid etchants
2Volume of moving object
If dry etching with local plasma is used to penetrate constrained trenches, then penetration capability is improved, but substrate damage through electric arcs occurs
Solution Approach 1:
The patent extracts the harmful plasma component from the etching process by using non-plasma, gas-phase chemical etching. This removes the source of electric arcs and substrate damage while retaining the ability to etch into constrained trenches through gas flow and chemical reaction
Solution Approach 2:
The patent introduces a photoresist-based mask as an intermediary that enables selective etching without plasma. The photoresist pattern defines the etching regions, allowing material removal through controlled chemical reactions rather than plasma bombardment, thus preventing substrate damage
3Productivity
If conventional etching processes are used on high-aspect-ratio structures, then material removal is achieved, but erosion of surrounding exposed materials and deformation occur
Solution Approach 1:
The patent applies local quality by using photoresist masks with specific patterns that confine the etching action to precise locations. The etchant only reacts with exposed materials in defined regions, preventing erosion of surrounding structures while maintaining high material removal rates in the target areas
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 enables the precise etching of high-aspect-ratio features without eroding other exposed materials, forming airgaps while maintaining the integrity of surrounding structures, and reducing the risk of damage to metal materials like hafnium oxide.
Implementation Method 1
flowing water vapor into a substrate processing region at a temperature below or about 0° C. forming a solid layer of water on a substrate housed in the substrate processing region
Implementation Method 2
flowing water vapor into a substrate processing region at a temperature below or about 0° C. forming a solid layer of water on a substrate
Implementation Method 3
flowing a fluorine-containing precursor into the substrate processing region. permeating the solid layer of water with the fluorine-containing precursor
Data Source
AI summary
Exemplary etching methods may include flowing a hydrogen-containing precursor into a substrate processing region of a semiconductor processing chamber. The methods may include flowing a fluorine-containing precursor into the substrate processing region. The methods may include contacting a substrate housed in the substrate processing region with the hydrogen-containing precursor and the fluorine-containing precursor. The substrate may define a trench. A spacer may be formed along a sidewall of the trench, and the spacer may include a plurality of layers including a first layer of a carbon-containing material, a second layer of an oxygen-containing material, and a third layer of a carbon-containing material. The second layer of the spacer may be disposed between the first layer and third layer of the spacer. The methods may also include removing the oxygen-containing material.