Post-CMP Substrate Cleaning with Compressible Buffing Pad
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Solution Overview
Problem
Conventional cleaning methods after chemical mechanical planarization (CMP) struggle to effectively remove particles and residues from substrates without scratching them, particularly at the edge bevel, due to the difficulty in maintaining contact and applying uniform pressure with existing buffing pads.
Innovation Solution
A post-CMP substrate pre-clean system employing a buffing pad assembly with a compressible sub-pad and a buffing motor, which maintains contact with the substrate by absorbing angular moments and tilting, allowing for controlled buffing with adjustable loads and rotation rates, and the use of a small buffing pad assembly for direct front-side metrology and chemical application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cleaning methods (brush box scrubbing or megasonic tank immersion) are used after CMP, then the cleaning process is simple and easy to operate, but particle removal efficiency is insufficient and some particles and residues remain on the substrate
Solution Approach 1:
The cleaning system is segmented into distinct functional components: a buffing pad assembly with separate buffing pad and sub-pad, a pad holder, and a swing arm mechanism. This segmentation allows each component to perform its specific function optimally while maintaining overall system effectiveness for particle removal.
Solution Approach 2:
A swing arm assembly acts as an intermediary mechanism between the buffing pad assembly and the substrate. It provides controlled movement and positioning, enabling the buffing pad to maintain optimal contact with the substrate surface while allowing for necessary adjustments during the cleaning process.
2Productivity
If a buffing pad assembly is pressed against the substrate to remove particles, then particle removal efficiency improves, but the risk of scratching the substrate increases
Solution Approach 1:
The system allows dynamic adjustment of buffing parameters including pressure applied to the buffing pad, rotation speed of the substrate, and chemistry concentration. These parameter changes enable optimization of particle removal while maintaining safe operating conditions that prevent substrate damage.
Solution Approach 2:
The cleaning system incorporates feedback mechanisms through controlled movement of the swing arm and adjustable pressure systems. This allows real-time adjustment of buffing intensity based on substrate condition, ensuring particles are removed effectively while preventing excessive force that could cause scratching.
3Productivity
If the buffing pad assembly is pressed against the rotating substrate, then cleaning effectiveness improves, but uniform contact and pressure distribution become difficult to maintain
Solution Approach 1:
The system employs dynamic movement through the swing arm assembly that allows the buffing pad assembly to follow the rotation of the substrate. This dynamic adjustment ensures continuous and uniform contact between the buffing pad and substrate surface throughout the cleaning cycle, maintaining consistent pressure distribution.
Solution Approach 2:
The buffing pad and sub-pad are designed with curved surfaces that conform to the substrate geometry. This spherical or curved contact interface ensures uniform distribution of pressure across the substrate surface, preventing localized high-stress areas while maintaining effective cleaning coverage.
4Productivity
If cleaning chemistry is applied during buffing, then particle removal efficiency improves, but chemistry distribution uniformity and control become challenging
Solution Approach 1:
Cleaning chemistry is applied to the substrate surface before the buffing process begins, or is pre-loaded onto the buffing pad assembly. This preliminary action ensures uniform chemistry distribution across the substrate prior to mechanical buffing, allowing the mechanical action to simply activate and enhance the cleaning effect rather than relying on chemistry application during high-speed rotation.
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 ensures effective removal of particles and residues while preventing substrate scratching, extending buff pad life, improving processing efficiency, and reducing chemistry consumption by maintaining uniform pressure and contact, thus enhancing edge defectivity and overall cleaning performance.
Implementation Method 1
a compressible sub-pad coupled to the buff pad
Implementation Method 2
a compressible sub-pad coupled to the buff pad
Implementation Method 3
a buffing motor configured to rotate the buffing pad assembly
Data Source
AI summary
Embodiments of the invention include systems, methods and apparatus for pre-cleaning a substrate after chemical mechanical planarization processing. Embodiments provide a housing; a chuck assembly configured to securely hold a substrate within the housing; and a buffing pad assembly configured to rotate against the substrate while supported within the housing. The buffing pad assembly includes a buff pad, a compressible sub-pad coupled to the buff pad, and a pad holder coupled to the compressible sub-pad and a buffing motor configured to rotate the buffing pad assembly. Numerous additional aspects are disclosed.