Vapor-Phase HF Etching for Selective Silicon Oxide Removal
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Solution Overview
Problem
Conventional etching processes face challenges in selectively removing silicon oxide from high-aspect-ratio structures without damaging exposed metal materials, particularly due to the use of water-based wet etches that can cause corrosion and deformation.
Innovation Solution
A dry etching method involving a fluorine-containing precursor and a hydrogen-containing precursor, such as an alcohol, is used in a semiconductor processing chamber to create a plasma-free etchant that selectively removes silicon oxide without an incubation period, maintaining the integrity of metal-containing structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wet HF etch is used to remove silicon oxide, then oxide removal efficiency is improved, but metal corrosion and structure deformation occur
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using vapor-phase HF instead of liquid HF, and controlling temperature and pressure parameters to achieve selective oxide removal without metal corrosion. The process operates at specific temperature ranges (e.g., 20-40°C) and pressure conditions to optimize etching selectivity while preventing harmful side effects.
Solution Approach 2:
The patent employs an inert vapor-phase environment using HF vapor rather than liquid water-based etchants. This inert atmospheric approach prevents galvanic corrosion of metal structures while maintaining effective oxide removal capability, as the vapor phase does not create the electrolytic conditions that cause metal degradation in wet etching.
2Productivity
If dry etching with local plasma is used to penetrate constrained trenches, then etching capability is improved, but substrate damage from electric arcs occurs
Solution Approach 1:
The patent replaces the plasma-based dry etching mechanism with a vapor-phase chemical etching process. Instead of using ion bombardment and electric fields that cause arc discharge and substrate damage, the invention uses purely chemical reactions in the vapor phase to achieve oxide removal, eliminating the mechanical and electrical damage associated with plasma processing.
Solution Approach 2:
The patent introduces HF vapor as an intermediary substance that mediates the etching process. Rather than direct ion-substrate interactions that cause damage, the HF vapor molecules act as intermediaries that chemically react with oxide surfaces, enabling gentle yet effective etching without the harmful effects of plasma discharge.
3Reliability
If water-based wet etch is used for oxide removal, then selectivity is improved, but incubation period and process time increase
Solution Approach 1:
The patent achieves continuous etching action from the beginning of the process by using vapor-phase HF that immediately reacts with exposed oxide surfaces. Unlike wet etching that requires an incubation period for pit formation and propagation, the vapor-phase process maintains continuous useful etching action throughout, eliminating idle time and reducing total process duration while preserving selectivity.
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 high-aspect-ratio feature etching without metal corrosion and reduces the need for incubation periods, providing uniform etching results and minimizing substrate deformation.
Implementation Method 1
forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor
Implementation Method 2
condensing the hydrogen-containing precursor on the region of exposed oxide
Data Source
AI summary
Exemplary cleaning or etching methods may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. Methods may include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor. The methods may also include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region, and the substrate may include a region of exposed oxide and a region of exposed metal. Methods may also include providing a hydrogen-containing precursor to the processing region. The methods may further include removing at least a portion of the exposed oxide.