Alkyl Diphosphonic Acid Cleaning Composition 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 pH range of 30-150 parts HEDPA to one million parts water, where 1-hydroxyethane 1,1-diphosphonic acid (HEDPA) does not perform as a chelating agent, and existing methods struggle to maintain efficiency across a wide concentration range.
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 with metal ion-free basic compounds, and optionally including surfactants, effectively removes resist, etching residue, and copper oxide from semiconductor surfaces during manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HEDPA is used in concentrations between 30-150 parts per million, then the solution maintains stability, but the HEDPA does not perform as a chelating agent or corrosion inhibitor (dead zone)
Solution Approach 1:
The patent combines HEDPA with a second acidic compound (such as citric acid, oxalic acid, or sulfamic acid) to create a composite cleaning composition. This composite approach allows the mixture to overcome the dead zone limitation of HEDPA alone, maintaining effective chelating and cleaning performance across a broader concentration range including the previously ineffective 30-150 ppm range.
Solution Approach 2:
The patent modifies the chemical composition parameters by introducing a second acidic compound with different chelating properties and pKa values. This parameter change enables the cleaning solution to maintain effectiveness across varying concentrations, eliminating the dead zone where HEDPA alone fails to perform.
2Reliability
If HEDPA is used at concentrations less than 30 parts per million, then it acts as a corrosion inhibitor, but it does not effectively remove chemical residues and particles
Solution Approach 1:
The composite composition combines HEDPA with a second acidic compound that has strong chelating ability. This allows the mixture to effectively remove chemical residues and particles even at lower concentrations where HEDPA alone would only provide corrosion inhibition, thereby achieving both cleaning effectiveness and corrosion protection simultaneously.
3Reliability
If HEDPA is used at concentrations above 150 parts per million, then it acts as a chelating agent, but it may attack exposed metal surfaces
Solution Approach 1:
The patent adjusts the composition parameters by incorporating a second acidic compound that modulates the chelating strength and pH of the solution. This allows effective chemical residue removal while controlling the aggressiveness toward metal surfaces, preventing excessive attack even when total acid concentration is sufficient for strong chelating action.
4Reliability
If existing cleaning compositions are used, then they can remove some contaminants, but they are ineffective in the pH range corresponding to 30-150 parts HEDPA per million parts water
Solution Approach 1:
The patent creates a composite cleaning system combining HEDPA with a second acidic compound that has complementary chelating properties and pKa characteristics. This composite formulation extends the effective pH and concentration range of the cleaning solution, eliminating the dead zone at pH corresponding to 30-150 ppm HEDPA and providing consistent performance across a broader range.
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 without attacking exposed metal surfaces, maintaining effectiveness across a broad concentration range and avoiding a 'dead zone' in performance, with surfactants enhancing cleaning performance and preventing re-precipitation.
Implementation Method 1
Above 150 parts to million parts water, it acts as a chelating agent
Implementation Method 2
with surfactants enhancing cleaning performance and preventing re-precipitation
Implementation Method 3
achieves complete and rapid dissolution of slurry particle and metal ion remnants
Data Source
AI summary
The compositions and methods herein relate to the method for the removal of residues and contaminants from metal or dielectric surfaces. Particularly, a composition and method of cleaning residues after chemical mechanical polishing of a copper or aluminum surface of the semiconductor substrates. A method of cleaning semiconductor substrates comprising contacting the substrates with a solution of water, and sufficient amount of alkyl diphosphonic acid comprising alkyl diphosphonic acid selected from the group of 1 hydroxyethane 1,1 diphosphonic acid, methylene disphosphonic acid, hydroxymethylene diphosphonic acid, dichloromethylene disphosphonic acid, hydroxycyclohexylmethylene disphosphonic acid, 1-hydroxy-3-aminopropane 1,1 diphosphonic acid, 1-hydroxy-4-aminobutane 1,1 diphosphonic acid mixed with dodecylbenzenesulfonic acid, xylenesulfonic acid, toluenesulfonic acid, phosphonoformic acid, sulfamic acid, 2-amino ethane sulfonic acid, or fluoroboric acid or an organic carboxylic acid and pH is adjusted to from greater than 6 to about 10 with a metal ion free base, and a surfactant.