Single-Crystal Diamond Pad Conditioner for CMP Asperity Control
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Solution Overview
Problem
Conventional diamond pad conditioners face challenges in maintaining uniform tip heights and sharpness, leading to inefficient CMP processes, increased consumption of polishing pads, and reduced wafer yield due to disparities in diamond abrasive particle sizes and shapes.
Innovation Solution
A pad conditioner featuring a pyramid array of single-crystal diamond protrusions with controlled tip heights and spacing, ensuring a balanced distribution for optimal polishing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If diamond abrasive particles of varied sizes are used in the pad conditioner, then the grinding capability is enhanced, but the tip height disparity increases causing uneven asperity distribution and reduced CMP efficiency
Solution Approach 1:
The pad conditioner is segmented into multiple layers with each layer containing diamond abrasive particles of specific size ranges. This segmentation allows different layers to perform different functions: finer particles for precision polishing and coarser particles for faster material removal, thereby maintaining uniform asperity distribution while enhancing overall grinding capability.
Solution Approach 2:
Different regions of the pad conditioner are assigned different particle sizes and hardness characteristics. The local quality variation enables optimized polishing performance in different areas, with finer particles in regions requiring high precision and coarser particles in regions requiring faster material removal, thus resolving the contradiction between grinding capability and asperity uniformity.
2Area of stationary object
If the contact area between wafer and polishing pad is increased, then the polishing coverage is improved, but the polishing rate decreases and CMP efficiency is insufficient
Solution Approach 1:
The pad conditioner dynamically adjusts the contact area through its multi-layer structure with varying particle sizes. During polishing, the system adapts the effective contact area by utilizing particles of different heights and hardness, allowing maintenance of high polishing rate while achieving adequate coverage through optimized asperity distribution.
Solution Approach 2:
The invention changes the physical parameters of the polishing pad surface by controlling the size distribution, hardness, and arrangement of diamond particles in different layers. This parameter optimization enables the system to maintain an optimal balance between contact area and polishing rate, resolving the contradiction between coverage and efficiency.
3Length of stationary object
If the tip height of diamond particles is increased, then the penetration depth into polishing pad increases, but the particle lifespan decreases and wafer yield is reduced due to excessive penetration
Solution Approach 1:
The diamond particles are segmented by size and hardness into multiple layers, with each layer containing particles of controlled tip height. This segmentation ensures that no single layer has excessively high particles that would penetrate too deeply and reduce lifespan, while still providing sufficient penetration depth for effective polishing, thus resolving the contradiction between tip height and particle durability.
Solution Approach 2:
The pad conditioner uses a composite structure combining diamond particles of varying sizes and hardness in layered configurations. This composite material approach allows optimization of tip height distribution to achieve adequate penetration depth while preventing excessive penetration that would reduce particle lifespan and compromise wafer yield.
4Ease of manufacture
If conventional bonding methods are used to attach diamond particles, then the manufacturing process is simplified, but the control over sharpness and tip height becomes challenging
Solution Approach 1:
The diamond particles are pre-sorted and pre-positioned in specific layers before final bonding. This preliminary arrangement allows control over tip height and sharpness distribution, while the bonding process itself remains relatively simple. The pre-organization ensures uniform asperity formation without requiring complex bonding procedures.
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
The solution enhances CMP efficiency, extends pad life, and improves wafer surface planarization by maintaining consistent asperity formation and reducing friction, thereby increasing throughput and reducing downtime and costs.
Implementation Method 1
the contact area and distribution between the wafer and the polishing pad must be controlled
Implementation Method 2
Abrasive particles (such as SiO2 and Al2O3) and chemical reagents; the polishing pad usually contains micropores to adjust the compression ratio and store the refining slurry
Data Source
AI summary
A pad conditioner with pyramids of single-crystal diamond comprises a substrate and a plurality of single crystal diamond sheets provided on the substrate. Each of the single crystal diamond sheets includes a plurality of single crystal diamond protrusions extended upward away from the substrate and have a tip height. A highest tip height is defined in the single crystal diamond sheet. The number of the single crystal diamond protrusions with the tip height greater than 60 μm is more than ten. The number of the single crystal diamond 10 protrusions with a height difference greater than 60 μm compared to the highest tip is more than ten. A spacing between the adjacent single crystal diamond protrusions is at least two times the tip height.