Multi-Brush Post-CMP Wafer Cleaning for Uniform Residue Removal
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Solution Overview
Problem
Conventional post-CMP cleaning methods using single brushes can cause over-brushing and corrosion of the center portion of semiconductor wafers due to uneven cleaning and prolonged shear force, especially as device sizes shrink, necessitating improved residue removal techniques that minimize damage and ensure thorough cleaning.
Innovation Solution
The use of multiple brushes with adjustable lengths and locations, along with a pencil-type brush for center cleaning, to distribute cleaning forces more uniformly and prevent over-brushing, combined with synchronized movement and chemical solution application to enhance cleaning efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single brush is used for post-CMP cleaning, then the cleaning process is simple, but the center portion of the wafer suffers from over-brushing and corrosion due to prolonged shear force
Solution Approach 1:
The cleaning apparatus is divided into multiple independent brush modules (at least two brushes) that can be positioned at different locations on the wafer surface. This segmentation allows different regions of the wafer to receive cleaning action from different brushes, preventing any single brush from excessively processing the same area and causing corrosion.
Solution Approach 2:
Different brushes are positioned to target specific regions of the wafer surface, with adjustable lengths and locations to optimize cleaning coverage. The pencil-type brush is specifically designed for center region cleaning, while other brushes handle peripheral areas, ensuring uniform cleaning distribution across the entire wafer surface.
2Object-affected harmful factors
If multiple brushes are used to prevent over-brushing, then wafer damage is reduced, but the cleaning apparatus complexity increases
Solution Approach 1:
The multiple brush modules are designed with universal functionality to clean different regions of the wafer surface. Each brush can be independently controlled and positioned, allowing the same basic brush design to serve multiple cleaning zones, thereby reducing overall system complexity while maintaining effective multi-region cleaning capability.
Solution Approach 2:
The brush modules feature adjustable lengths and positions that can be dynamically configured based on wafer size and cleaning requirements. This dynamic adjustability allows the system to adapt to different cleaning scenarios without requiring completely different apparatus designs, balancing complexity with versatility.
3Ease of operation
If brushes with fixed positions are used, then the apparatus is simple to operate, but uniform cleaning distribution across the wafer surface cannot be achieved
Solution Approach 1:
The brush modules are designed with adjustable positions and orientations that can be configured to achieve uniform cleaning distribution. The ability to dynamically adjust brush locations allows the system to accommodate variations in wafer dimensions and cleaning requirements while maintaining operational simplicity through standardized adjustment 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 approach reduces damage and corrosion by ensuring more uniform brushing, effectively removing residues while maintaining the quality of the cleaning process, even in smaller device generations.
Implementation Method 1
A slurry containing both abrasive particles and reactive chemicals is applied to the polish pad
Implementation Method 2
The surface of the wafer, on which the CMP process has been performed, is cleaned to remove residues. The residues may include organic matters and particles
Implementation Method 3
The relative movement of the polish pad and wafer surface coupled with the reactive chemicals in the slurry allows the CMP process to planarize the wafer surface by means of both physical and chemical forces
Implementation Method 4
In conventional post-CMP cleaning, brushes were used to remove the residues on the wafers
Implementation Method 5
The use of multiple brushes with adjustable lengths and locations, along with a pencil-type brush for center cleaning, to distribute cleaning forces more uniformly
Data Source
AI summary
A method includes performing a first post Chemical Mechanical Polish (CMP) cleaning on a wafer using a first brush. The first brush rotates to clean the wafer. The method further includes performing a second post-CMP cleaning on the wafer using a second brush. The second brush rotates to clean the wafer. The first post-CMP cleaning and the second post-CMP cleaning are performed simultaneously.