Alkyl Diphosphonic Acid Cleaning 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 range of 30-150 parts per million HEDPA to one million parts water, where HEDPA does not perform as a chelating agent, and existing solutions lack a synergistic effect with surfactants to enhance residue dissolving performance.
Innovation Solution
A cleaning solution comprising alkyl diphosphonic acid blended with a second acidic compound at a mole ratio of 1:1 to 10:1, adjusted to a pH of 6 to 10, optionally including surfactants, to effectively remove etching residues and copper oxide from semiconductor surfaces during manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HEDPA is used in the concentration range of 30-150 parts per million, then it cannot perform as a chelating agent, but using higher concentrations increases cost and may cause unwanted side effects
Solution Approach 1:
The patent changes the chemical structure parameter of phosphonic acid from HEDPA to alkyl diphosphonic acids with varying alkyl chain lengths (C1-C8). This structural parameter change enables effective chelating performance across a broader concentration range while avoiding the dead zone experienced by HEDPA
Solution Approach 2:
The patent uses composite cleaning compositions containing alkyl diphosphonic acid combined with surfactants and other cleaning agents. This composite approach creates synergistic effects that enhance chelating performance and residue removal efficiency without requiring excessive phosphonic acid concentrations
2Reliability
If HEDPA is used below 30 parts per million, then it acts as a corrosion inhibitor but loses chelating capability, but increasing concentration to achieve chelating effect increases cost
Solution Approach 1:
The patent modifies the molecular structure by introducing alkyl groups at the phosphonic acid position, creating alkyl diphosphonic acids. This structural parameter change enhances chelating capability while allowing effective performance at lower concentrations compared to conventional HEDPA
Solution Approach 2:
The patent introduces varying alkyl chain lengths (C1-C8) at specific positions of the phosphonic acid molecule. This local structural modification optimizes the balance between chelating capability and concentration requirements, with different alkyl lengths providing different performance characteristics
3Reliability
If conventional cleaning compositions are used, then they lack synergistic effect with surfactants, but modifying composition increases complexity of formulation
Solution Approach 1:
The patent merges alkyl diphosphonic acid with surfactants in a single cleaning composition. This combination creates synergistic effects where the surfactant enhances the residue dissolving performance of the phosphonic acid, and vice versa, achieving superior cleaning results through unified action
Solution Approach 2:
The cleaning composition performs multiple functions simultaneously: alkyl diphosphonic acid provides chelating and corrosion inhibition, while surfactants provide wetting, emulsification, and residue removal. This multi-functional approach simplifies the overall cleaning process despite the complexity of formulation
4Reliability
If cleaning compositions attack metal surfaces to remove residues, then cleaning effectiveness improves, but damage to exposed metal surfaces occurs
Solution Approach 1:
The patent changes the chemical parameters of the cleaning agent by using alkyl diphosphonic acids with controlled chain lengths and structures. These parameter changes enable effective residue removal through chelating action rather than aggressive metal attack, maintaining selectivity between residues and metal surfaces
Solution Approach 2:
The alkyl diphosphonic acid acts as an intermediary that selectively binds to metal ions in residues through chelating, forming soluble complexes that can be rinsed away. This intermediary mechanism removes residues without requiring direct attack on the metal substrate, preventing surface damage
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 achieves complete and rapid dissolution of slurry particle and metal ion remnants on semiconductor substrates without attacking exposed metal surfaces, with a broad concentration range effectiveness and enhanced performance due to the synergistic action with surfactants, eliminating the 'dead zone' in HEDPA's chelating activity.
Implementation Method 1
HEDPA does not perform as a chelating agent... complete and rapid dissolution of slurry particle and metal ion remnants
Implementation Method 2
HEDPA combined with a surfactant produces a synergistic result. The surfactant not only functions as a dispersant but also improves the residue dissolving performance
Implementation Method 3
complete and rapid dissolution of slurry particle and metal ion remnants
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 metal ion free base, and a surfactant. Particularly, a composition and method of cleaning residues after chemical mechanical polishing of a copper or aluminum surface of the semiconductor substrates.