Post-CMP Substrate Buff Pre-Cleaning with Controlled Force
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Solution Overview
Problem
Conventional cleaning methods after chemical mechanical planarization (CMP) struggle to effectively remove residue and particles from substrates, particularly from the edge bevels, due to their inability to apply targeted and controlled force.
Innovation Solution
A pre-clean buff module with a substrate chuck, a buff pad assembly, and a swing arm that positions and rotates a buff pad with controlled force along the substrate's front side, allowing for targeted buff cleaning using a smaller buff pad and chemical delivery mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods (brush box scrubbing, megasonic tank immersion) are used, then the cleaning process is simple and equipment is basic, but particles and residue remain on the substrate that are difficult to remove
Solution Approach 1:
The cleaning system is segmented into multiple functional zones: a spray zone with chemical delivery for loosening particles, a ultrasonic zone for cavitation cleaning, and a rinse zone. This segmentation allows each zone to perform a specific cleaning function, improving overall cleaning effectiveness while maintaining manageable system complexity through modular design
Solution Approach 2:
A chemical spray is introduced as an intermediary substance between the cleaning mechanisms and the substrate. The chemical agent facilitates particle removal by chemically interacting with the residue, making it easier for subsequent mechanical and ultrasonic cleaning steps to remove difficult particles without requiring excessive mechanical force
2Reliability
If brush box scrubbing is used, then the equipment is simple, but particles at edge bevels are difficult to remove
Solution Approach 1:
The cleaning system applies local quality by directing chemical spray and ultrasonic energy specifically to edge bevel regions where particles are most difficult to remove. The spray nozzles are positioned to target edge areas, and the ultrasonic field is concentrated at the substrate periphery, providing enhanced cleaning effectiveness at critical locations without requiring complex mechanical manipulation
Solution Approach 2:
The system replaces aggressive mechanical brush scrubbing with a combination of chemical spray and ultrasonic cavitation. This substitution eliminates the need for complex mechanical brush mechanisms while achieving superior particle removal at edge bevels through chemical-facilitated cleaning and acoustic cavitation effects
3Reliability
If megasonic tank immersion is used, then the cleaning process is simple, but residue remains that is difficult to remove
Solution Approach 1:
The chemical spray is applied as a preliminary action before the ultrasonic cleaning step. This pre-treatment chemically loosens and facilitates the removal of adhered particles and residue, making them more susceptible to subsequent ultrasonic cavitation. This sequential arrangement of preliminary chemical action followed by physical cleaning enhances residue removal effectiveness without requiring complex simultaneous multi-mode cleaning mechanisms
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
This solution enables efficient removal of difficult-to-clean residues and particles, improving edge defectivity and reducing defect levels near the substrate edges, while optimizing chemical consumption and distribution.
Implementation Method 1
a swing arm coupled to the buff pad and configured to position and rotate the buff pad along the front side of the substrate, and control an amount of force applied by the buff pad against the front side of the substrate during cleaning
Implementation Method 2
buff clean the substrate... efficient removal of difficult-to-clean residues and particles, improving edge defectivity
Implementation Method 3
rotating the substrate using the substrate chuck
Implementation Method 4
a pad conditioning station positioned within the tank and configured to at least one of clean and condition the buff pad
Data Source
AI summary
In some embodiments, an apparatus for cleaning a substrate is provided that includes (1) a substrate chuck configured to support a substrate with a front side of the substrate accessible; (2) a buff pad assembly configured to support a buff pad having a diameter smaller than a diameter of the substrate; and (3) a swing arm coupled to the buff pad and configured to position and rotate the buff pad along the front side of the substrate, and control an amount of force applied by the buff pad against the front side of the substrate during cleaning. The substrate chuck, buff pad assembly and swing arm are configured to buff clean the substrate. Numerous additional aspects are disclosed.