Dual Dresser CMP Pad Conditioning for Asperity Control
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Solution Overview
Problem
The semiconductor industry faces challenges in maintaining the performance of Chemical Mechanical Polishing (CMP) pads due to glazing, which leads to non-uniform asperity configurations on the pads, affecting the polishing of large diameter wafers with nanometer-sized features, and traditional dressing methods often result in warpage and loss of control over superabrasive particle tips.
Innovation Solution
A dual dressing system is introduced, where a deglazing dresser and an asperity-forming dresser are used independently to condition CMP pads, allowing for precise control over the surface by deglazing and forming asperities separately, using smaller diameter tools to minimize warpage and achieve uniform asperity formation with superabrasive particles arranged in a monolayer for optimal polishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional single dresser methods are used to condition CMP pads, then the process is simple and fast, but warpage occurs and control over superabrasive particle tips is lost
Solution Approach 1:
The single dresser is divided into two separate dressers: a deglazing dresser with blade elements for removing glazed layers, and an asperity-forming dresser with superabrasive particles for creating uniform asperities. This segmentation allows each dresser to perform its specific function independently, preventing warpage and maintaining control over particle tips while keeping the overall process efficient
2Area of stationary object
If larger diameter tools are used for dressing CMP pads, then the coverage area is larger, but warpage increases and control is lost
Solution Approach 1:
Instead of using one large diameter dresser that causes warpage, the system uses two smaller diameter dressers. The deglazing dresser and asperity-forming dresser each have smaller diameters that minimize warpage while collectively covering the required area through sequential operation on the rotating CMP pad
Solution Approach 2:
The system transitions from a single-plane dressing approach to a multi-dimensional process where two separate dressers operate at different stages. The deglazing dresser prepares the surface, and the asperity-forming dresser creates the final surface structure, allowing precise control in each dimension of the dressing process
3Productivity
If deglazing and asperity formation are performed simultaneously, then the process is faster, but uniformity of asperity configuration is compromised
Solution Approach 1:
The conditioning process is segmented into two sequential stages: deglazing followed by asperity formation. This separation ensures that asperities are formed on a freshly deglazed surface, guaranteeing uniform asperity configuration while maintaining high productivity through efficient sequential operation
Solution Approach 2:
The deglazing dresser performs preliminary action by removing the glazed layer before the asperity-forming dresser creates asperities. This preliminary preparation ensures that the asperities are formed on a clean, uniform surface, achieving the desired uniformity without sacrificing overall process speed
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 enhances the uniformity and effectiveness of CMP pad conditioning, enabling better polishing of large diameter wafers with nanometer features by maintaining precise control over asperity formation and reducing warpage, thus extending the life of the CMP pads and improving polishing efficiency.
Implementation Method 1
deglazing the working surface of the CMP pad with the deglazing dresser... shaving off a thickness of the working surface of the CMP pad
Implementation Method 2
forming asperities in the working surface of the CMP pad with the asperity-forming dresser
Implementation Method 3
applying a cleansing spray to the working surface during deglazing... the cleansing spray is a water jet
Implementation Method 4
applying a suction to the working surface to remove debris released from the CMP pad during deglazing
Implementation Method 5
vibrating at least one of, or both of, the deglazing dresser and the CMP pad relative to one another during deglazing... the vibrating is ultrasonic vibrating
Data Source
AI summary
Dual dressing systems for conditioning CMP pads, including associated methods, are provided. In one aspect, for example, a method of dressing a CMP pad can include applying a deglazing dresser to a working surface of a CMP pad, deglazing the working surface of the CMP pad with the deglazing dresser, applying an asperity-forming dresser to the working surface of the CMP pad, and forming asperities in the working surface of the CMP pad with the asperity-forming dresser.