Alkyl Diphosphonic Acid Cleaning Solution for Semiconductor Substrates
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Solution Overview
Problem
Current cleaning compositions for semiconductor substrates are ineffective in removing chemical residues and particles, particularly in the presence of copper oxide and low-k dielectric materials, especially after damascene or dual damascene manufacturing processes, due to limitations in pH range and concentration of phosphonic acids.
Innovation Solution
A cleaning solution comprising alkyl diphosphonic acid, a second acidic compound, and a buffering basic compound, with a pH range of 6 to 10, and optionally a surfactant, is applied to semiconductor substrates to effectively remove etching residues, copper oxide, and slurry particles, maintaining performance across a wide concentration range without a 'dead zone'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phosphonic acid compositions are used for cleaning semiconductor substrates, then copper oxide removal is effective, but cleaning performance deteriorates in the presence of low-k dielectric materials and etching residues
Solution Approach 1:
The patent changes the pH parameter range from conventional acidic conditions to a broader range of pH 2-12, with optimal performance at pH 7-12. This parameter change allows the cleaning composition to effectively remove copper oxide and etching residues while being compatible with low-k dielectric materials that are damaged by conventional acidic cleaners
Solution Approach 2:
The patent creates a composite cleaning system combining phosphonic acid (for copper oxide removal), carboxylic acid (for etching residue removal), and surfactant (for particle suspension and low-k material protection). This composite approach synergistically addresses multiple contamination types while protecting sensitive low-k dielectric materials
2Productivity
If high concentration phosphonic acid is used to improve residue removal, then cleaning power increases, but a dead zone appears in the concentration range 30-150 parts per million
Solution Approach 1:
The patent changes the concentration parameter to operate above 150 parts per million phosphonic acid, specifically at 200-500 ppm or higher, which eliminates the dead zone phenomenon. This higher concentration range ensures consistent chelating and cleaning performance across all processing conditions
Solution Approach 2:
The patent introduces carboxylic acid as an intermediary component that works synergistically with phosphonic acid. The carboxylic acid component enhances the overall cleaning mechanism and helps maintain effective performance across varying concentrations, preventing the dead zone effect
3Productivity
If conventional acidic cleaners are used to remove etching residues, then residue removal is effective, but damage occurs to low-k dielectric materials
Solution Approach 1:
The patent changes the pH parameter from conventional acidic conditions (pH 2-4) to a neutral or slightly basic range (pH 7-12). This parameter change eliminates damage to low-k dielectric materials while maintaining effective removal of etching residues through the combined action of phosphonic acid and carboxylic acid
Solution Approach 2:
The patent converts the potential harm of strong cleaning action into benefit by using a neutral to basic pH environment that is inherently gentler on low-k dielectric materials. The cleaning effectiveness is maintained through optimized chemical composition rather than aggressive acidity
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 efficiently removes residues and particles from semiconductor substrates, maintaining effectiveness across varying concentrations and pH levels, ensuring thorough cleaning without attacking exposed metal surfaces, and can be diluted for broader application in semiconductor fabrication processes.
Implementation Method 1
HEDPA combined with a surfactant produces a synergistic result. The surfactant not only functions as a dispersant but also improves the residue dissolving performance of the HEDPA when the HEDPA is used in strength above 150 parts to million parts water.
Implementation Method 2
Phosphonic acid, in particular 1-hydroxyethane 1,1-diphosphonic acid (commonly termed HEDPA) has been in commercial use for many years as a corrosion inhibitor and as a complex agent.
Implementation Method 3
The surfactant not only functions as a dispersant but also improves the residue dissolving performance of the HEDPA
Implementation Method 4
A cleaning solution comprising alkyl diphosphonic acid, a second acidic compound, and a buffering basic compound, with a pH range of 6 to 10
Data Source
AI summary
The compositions and methods for the removal of residues and contaminants from metal or dielectric surfaces comprises at least one alkyl diphosphonic acid, at least one second acidic substance at a mole ratio of about 1:1 to about 10:1 in water, and pH is adjusted to from about 6 to about 10 with a basic compound, and optionally a surfactant. Particularly, a composition and method of cleaning residues after chemical mechanical polishing of a copper or aluminum surface of the semiconductor substrates. One of the embodiment is the method of using the compositions in dilution, wherein the solution may be diluted with DI water at dilution ratios, for example, of up to 1:10, up to 1:50, up to 1:100, up to 1:150, up to 1:250, and up to about 1:500 or any ratios therein.