Alkaline Wet Cleaning Solution for Semiconductor Etch Residue Removal
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Solution Overview
Problem
Dry etching in semiconductor fabrication leaves nonvolatile and thermally stable etch residues that, if not removed, can degrade or fail semiconductor devices, while existing wet solutions often damage patterned features on substrates during residue removal.
Innovation Solution
An alkaline wet solution comprising water, ammonium hydroxide, quaternary organic ammonium or phosphonium hydroxide, and dissolved silica forms a protective coating on metal oxide features, allowing for etch residue removal without damaging the features, and an inhibitor like azole compounds can protect metallization layers from etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing wet solutions are used to remove etch residues, then etch residues are removed, but patterned features on substrates are damaged
Solution Approach 1:
The patent introduces an intermediary substance (protective coating formed from the alkaline wet solution containing dissolved silica) that mediates between the etch residue removal process and the patterned features. This coating acts as a protective barrier that allows aggressive cleaning to occur while preventing damage to sensitive features, effectively decoupling the harmful effect from the useful effect.
Solution Approach 2:
The patent changes the chemical parameters of the wet solution by using a specific alkaline composition with dissolved silica that forms a protective coating. The solution contains controlled concentrations of ammonia, hydrogen peroxide, and dissolved silica, creating a chemical environment that selectively removes etch residues while preserving features through in-situ coating formation.
2Productivity
If aggressive wet cleaning is performed to remove nonvolatile etch residues, then etch residues are removed, but metal oxide features are etched or damaged
Solution Approach 1:
The patent applies preliminary action by forming the protective coating on metal oxide features before the actual etch residue removal occurs. The alkaline wet solution with dissolved silica creates this protective layer in advance, preparing the features for subsequent aggressive cleaning without damage, ensuring both high removal efficiency and precision preservation.
Solution Approach 2:
The protective coating serves as an intermediary layer between the aggressive wet cleaning solution and the metal oxide features. This coating enables the use of strong cleaning agents to remove nonvolatile residues while the coating itself absorbs the chemical attack, preventing direct contact with and damage to the metal oxide features.
3Object-generated harmful factors
If alkaline wet solution is used to remove etch residues, then residues are removed, but metallization layers are etched
Solution Approach 1:
The patent uses an intermediary inhibitor substance that selectively protects metallization layers from the alkaline wet solution. This inhibitor forms a protective complex with the metal surfaces, allowing the alkaline solution to remove etch residues without attacking the metallization layers, thus separating the cleaning function from the harmful etching effect.
Solution Approach 2:
The patent applies local quality by introducing selective inhibitors that provide different levels of protection to different materials on the substrate. The inhibitor concentration and type are optimized to provide specific protection to metallization layers while allowing the alkaline solution to effectively remove etch residues from other areas, creating spatially selective chemical resistance.
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
Effectively removes etch residues without damaging metal oxide features or metallization layers, ensuring the integrity of semiconductor devices by forming a protective coating and preventing undesirable surface reactions.
Implementation Method 1
performing a treatment process that exposes the patterned substrate to an alkaline wet solution that forms a protective coating on the metal oxide feature
Implementation Method 2
performing a wet cleaning process that removes the etch residue but not the metal oxide feature that is protected by the protective coating
Data Source
AI summary
An alkaline wet solution for protecting features on a patterned substrate and a substrate processing method using the alkaline wet solution are described. The method includes providing a patterned substrate containing a low-k material, a metal oxide feature, and an etch residue, performing a treatment process that exposes the patterned substrate to an alkaline wet solution that forms a protective coating on the metal oxide feature, the alkaline wet solution containing a mixture of 1) water, 2) ammonium hydroxide, a quaternary organic ammonium hydroxide, or a quaternary organic phosphonium hydroxide, and 3) dissolved silica, and performing a wet cleaning process that removes the etch residue but not the metal oxide feature that is protected by the protective coating. The patterned substrate can further include a metallization layer and the alkaline wet solution can further contain 4) an inhibitor that protects the metallization layer from etching by the alkaline wet solution.