Semiconductor Cleaning Solution with Controlled Metal Ion Levels
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Solution Overview
Problem
Current cleaning solutions for semiconductor devices after chemical mechanical polishing (CMP) fail to achieve a highly cleaned surface due to residual impurities like sodium, potassium, and iron ions, despite efforts to reduce their content, which affects the electrical characteristics and requires large amounts of ultra-pure water, incurring high costs and environmental burdens.
Innovation Solution
A cleaning solution containing sodium ions, potassium ions, and iron ions at concentrations of 1 ppb to 500 ppb, formulated with a specific ammonium salt of a sulfuric ester, treated with cation and anion exchange resins to reduce impurity levels, and combined with a non-metallic amine-based alkali agent, is used to effectively remove metal ions and enhance cleaning efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning solutions are used to clean the substrate surface after CMP, then the cleaning process can be performed, but residual impurities such as sodium, potassium, and iron ions remain on the surface, affecting electrical characteristics
Solution Approach 1:
The invention changes the chemical composition parameters of the cleaning solution by specifying precise concentrations of ammonium salts of sulfuric esters (0.01-10% by weight), nonionic surfactants (0.1-5% by weight), and controlling metal ion content (sodium, potassium, iron ions each at 10 ppb or less). This parameter optimization enables effective cleaning while minimizing residual impurities that affect electrical characteristics.
Solution Approach 2:
The cleaning solution employs a composite formulation combining multiple functional components: ammonium salts of sulfuric esters (primary cleaning agents), nonionic surfactants (emulsification and stabilization), and controlled amounts of metal ions. This composite approach synergistically enhances cleaning efficacy while maintaining low residual impurity levels.
2Manufacturing precision
If large amounts of ultra-pure water are used for rinsing to remove impurities, then the surface cleanliness is improved, but the cost and environmental burden increase significantly
Solution Approach 1:
The invention extracts and removes harmful metal ion impurities (sodium, potassium, iron ions) from the cleaning solution through careful formulation and control, allowing effective cleaning to be achieved without requiring excessive ultra-pure water for rinsing. The controlled low concentrations of these ions in the final solution minimize the need for extensive water-based rinsing.
Solution Approach 2:
The cleaning solution is designed as a disposable, single-use formulation that achieves complete cleaning function in one application. By optimizing the chemical composition to leave minimal residual impurities, the solution eliminates the need for repeated rinsing with ultra-pure water, reducing both water consumption and associated costs.
3Reliability
If the content of alkali metal ions is reduced in the cleaning solution, then the electrical characteristics are improved, but the cleaning efficacy may be compromised
Solution Approach 1:
The invention introduces ammonium salts of sulfuric esters as intermediary cleaning agents that perform the primary cleaning function without relying on high concentrations of alkali metal ions. These ammonium-based compounds effectively remove contaminants while maintaining low levels of harmful metal ions, thus preserving electrical characteristics.
Solution Approach 2:
The invention changes the cleaning mechanism by shifting from alkali metal ion-based cleaning to ammonium salt-based cleaning. By specifying ammonium salts of sulfuric esters at 0.01-10% by weight and controlling alkali metal ion content to 10 ppb or less, the solution maintains cleaning efficacy through alternative chemical mechanisms that do not compromise electrical characteristics.
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 a highly cleaned semiconductor device surface with reduced impurity levels, using less ultra-pure water and minimizing environmental impact, while maintaining effective detergency and productivity.
Implementation Method 1
treating an aqueous solution containing a sodium ion, a potassium ion, an iron ion, and a sulfuric ester anion with a cation exchange resin and an anion exchange resin, thereby reducing each content of the sodium ion, the potassium ion, and the iron ion
Implementation Method 2
a cleaning solution containing a sodium ion, a potassium ion, an iron ion, an ammonium salt of a sulfuric ester, and water
Implementation Method 3
cleaning the surface obtained by subjecting an object to be polished such as an insulating film to chemical mechanical polishing (CMP)
Data Source
AI summary
A cleaning solution of the present invention contains a sodium ion, a potassium ion, an iron ion, an ammonium salt of a sulfuric ester represented by General Formula (1), and water, and each content of the sodium ion, the potassium ion, and the iron ion is 1 ppb to 500 ppb. ROSO3—(X)+ (1) where R is an alkyl group with a carbon number of 8-22 or an alkenyl group with a carbon number of 8-22, and (X)+ is an ammonium ion.