Cleaning Agent for Plasma Residue Removal
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Solution Overview
Problem
Conventional cleaning methods for removing residues after plasma etching processes, such as ST250 solvents, are ineffective in eliminating metallic fluoride and organic polymer deposits, leading to device profile changes, conductivity issues, and increased production costs due to the need for multiple cleaning operations and expensive components.
Innovation Solution
A cleaning agent comprising a mixture of diluted hydrofluoric acid and an acid solution, with concentrations of hydrofluoric acid greater than or equal to 30 ppm and an acid solution percentage by weight of at least 1%, is used to efficiently remove titanium and tantalum fluoride residues, along with organic polymers, through a combination of dry and wet cleaning operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning solvents like ST250 are used to remove residues, then organic polymer residues can be removed to some extent, but metallic fluoride compounds cannot be effectively removed and the cleaning process becomes complicated requiring multiple operations
Solution Approach 1:
The patent combines multiple cleaning functions into a single cleaning solution by integrating organic solvent components (for polymer removal) and aqueous components (for metallic fluoride removal) into one formulation. This eliminates the need for separate dry and wet cleaning operations, simplifying the process while maintaining comprehensive residue removal effectiveness.
Solution Approach 2:
The cleaning solution is formulated as a composite system containing multiple active ingredients including organic solvents, surfactants, and aqueous components in specific concentration ranges. This composite formulation enables the solution to simultaneously address different types of residues (organic polymers and metallic fluorides) that single-component cleaners cannot effectively remove.
2Reliability
If conventional cleaning solvents are used repeatedly to remove residues, then some organic polymers can be removed, but device profile changes and conductivity issues occur
Solution Approach 1:
The patent specifies precise concentration parameters for different components in the cleaning solution, including organic solvent content (5-95% by volume), surfactant concentration (0.1-10% by weight), and aqueous component ratio (5-95% by volume). These controlled parameter ranges ensure effective residue removal while preventing excessive etching that would alter device profiles or affect conductivity.
Solution Approach 2:
The cleaning solution is designed to selectively remove residues from specific areas (such as trench bottoms and sidewalls) where they accumulate during plasma etching, while being gentle enough not to damage the surrounding device structures. The formulation targets metallic fluorides and organic polymers locally without causing profile changes in the device geometry.
3Reliability
If conventional cleaning methods are used to remove residues, then production costs increase due to multiple cleaning operations, but residue removal effectiveness is limited
Solution Approach 1:
The patent consolidates multiple cleaning operations (dry cleaning for organic polymers and wet cleaning for metallic fluorides) into a single integrated cleaning step using a unified solution formulation. This reduces the number of process steps, decreases production time, and lowers overall cleaning costs while achieving complete removal of both organic and inorganic residues.
Solution Approach 2:
The cleaning solution is designed as a multi-functional agent that can simultaneously remove different types of residues (organic polymers, metallic fluorides, and other plasma byproducts) in a single application. This universal cleaning capability eliminates the need for multiple specialized cleaning steps, improving productivity and reducing production costs.
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
The solution significantly reduces the likelihood of device conductivity issues and short circuits, maintains device profile integrity, and lowers production costs by effectively removing residues in a single wet cleaning step, thereby enhancing product yield and simplifying the fabrication process.
Implementation Method 1
a cleaning agent comprising water, a diluted hydrofluoric acid and an acid solution... capable of removing titanium fluoride or tantalum fluoride residues
Implementation Method 2
an acid solution... to effectively remove titanium or tantalum fluoride residues and organic polymers, followed by a dry cleaning operation to break molecular bonds
Data Source
AI summary
A method of removing the residue left after a plasma process is described. First, a substrate having at least a material layer thereon is provided. The material layer includes a metal. Then, a fluorine-containing plasma process is performed so that a residue containing the aforesaid metallic material is formed on the surface of the material layer. After that, a wet cleaning operation is performed using a cleaning agent to remove the residue. The cleaning agent is a solution containing water, a diluted hydrofluoric acid and an acid solution.