Wafer Meniscus Vapor Drying to Reduce CMP Residue Defects
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes leave residues and contaminants on semiconductor substrates, which are difficult to remove, leading to defects and device failures during the drying process, especially with methods like Marangoni drying.
Innovation Solution
A vapor drying method using a mixture of a water miscible organic solvent, a cleaning agent, and an inert gas is applied over the substrate meniscus to reduce residues and contaminants, employing a volatile amine compound as the cleaning agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aqueous cleaning steps are used to remove polishing residue, then cleaning capability is improved, but particle re-attachment and contamination occur
Solution Approach 1:
The patent changes the physical state of the cleaning agent from liquid (aqueous solution) to vapor phase. This parameter change allows the cleaning agent to effectively remove organic residue while preventing particle re-attachment that occurs with liquid aqueous cleaning methods.
Solution Approach 2:
The patent replaces the mechanical/liquid-based aqueous cleaning system with a vapor-based cleaning system. The vapor phase cleaning mechanism substitutes the liquid immersion method, achieving better cleaning results without the harmful side effect of particle re-attachment.
2Manufacturing precision
If Marangoni drying is used to prevent streaking and spotting, then drying quality is improved, but uniform drying is difficult to achieve
Solution Approach 1:
The patent uses a composite vapor mixture containing multiple components (e.g., isopropyl alcohol, water, and inert gas) in specific proportions. This composite vapor composition enables uniform Marangoni drying across the substrate surface, overcoming the difficulty of achieving consistent drying quality.
Solution Approach 2:
The patent optimizes parameters including vapor composition ratios, temperature, and flow rate to achieve uniform drying. By carefully controlling these parameters, the complex Marangoni drying process becomes easier to operate while maintaining high drying quality.
3Shape
If polishing composition is applied to achieve planarization, then surface flatness is improved, but contamination and residue are generated
Solution Approach 1:
The patent extracts and removes the polishing composition and its byproducts from the substrate surface using vapor phase cleaning. The vapor effectively extracts organic residue and contaminants left after polishing, achieving surface flatness without retained contamination.
Solution Approach 2:
The patent employs an inert gas component in the vapor mixture to create an inert cleaning environment. This inert atmosphere prevents additional contamination during the cleaning process while effectively removing polishing residue through the vapor phase action.
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
Significantly reduces defects on polished wafers by minimizing residue reattachment and streaking, improving device yield and performance.
Implementation Method 1
A method known as Marangoni drying (also referred to as surface tension gradient drying or IPA vapor drying) creates a surface tension gradient to induce bath fluid to flow from the substrate
Implementation Method 2
After removal from the rinsing bath, absent use of a drying apparatus, bath fluid may evaporate from the substrate's surface and cause streaking, spotting and/or leave bath residue on the surface
Data Source
AI summary
This disclosure relates to a method that includes applying a polishing composition to a surface of a substrate; bringing a pad into contact with the surface of the substrate and moving the pad in relation to the substrate to create a polished substrate; treating the polished substrate with a rinse solvent; flowing a vapor over a meniscus formed at an interface between air and the rinse solvent on the polished substrate. The vapor includes a first component containing a water miscible organic solvent, a second component containing a cleaning agent, and a third component containing an inert gas.