CMP Apparatus with Magnetic Asperity Control
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Solution Overview
Problem
Conventional chemical mechanical polishing (CMP) techniques struggle to achieve controlled asperities on polishing pads, leading to uniform removing effects that do not account for varying topography on semiconductor wafers, resulting in inadequate planarization and increased defects.
Innovation Solution
A CMP apparatus and slurry system utilizing a counterface with a first electromagnet array and magnetic polymer beads, where the polarity of electromagnets is controlled to create controllable asperities corresponding to specific wafer or die profiles, allowing for non-uniform removing events based on topography information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CMP techniques are used with uniform polishing pads, then the polishing process is simple and easy to operate, but the removing effect is uniform and does not account for varying topography on semiconductor wafers, resulting in inadequate planarization
Solution Approach 1:
The polishing pad is divided into multiple regions with different asperity characteristics. Each region has specifically engineered asperities (protrusions) with different densities, heights, or distributions to address local topography variations on the wafer surface. This allows different parts of the wafer to receive customized polishing action, improving overall planarization precision while maintaining a relatively simple uniform pad structure.
Solution Approach 2:
The polishing pad incorporates adjustable or adaptive asperity structures that can modify their characteristics during the polishing process. This dynamic adjustment allows the pad to respond to varying wafer topography in real-time, enhancing planarization precision without requiring a completely complex multi-component system.
2Reliability
If conventional CMP techniques are used, then the polishing process is straightforward, but defects increase due to inadequate planarization
Solution Approach 1:
By engineering specific asperity patterns in different regions of the polishing pad, the system targets defect-prone areas with customized polishing action. Regions with higher asperity density or greater protrusion height are applied where the wafer surface has larger irregularities, thereby reducing defects in those specific locations while maintaining overall process reliability.
Solution Approach 2:
The polishing pad is pre-configured with asperities designed based on anticipated or measured wafer topography variations. This preliminary structuring of the pad allows the system to proactively address potential defect formation before it occurs during polishing, improving reliability without adding complex real-time control systems.
3Manufacturing precision
If uniform removing effects are applied across the wafer, then the polishing process is simple to control, but planarization is inadequate for highly irregular surfaces
Solution Approach 1:
The polishing pad features region-specific asperity configurations that create localized variations in removing rates. By concentrating asperities in certain areas or varying their characteristics across different zones, the system achieves non-uniform removing effects that match the wafer's topography variations, improving surface uniformity while maintaining relatively simple operational control through fixed pad design.
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 enables precise control over the polishing process, increasing removal events where needed and reducing them where not, thereby improving planarization and reducing defects on semiconductor wafers.
Implementation Method 1
a first electromagnet array under the first surface
Implementation Method 2
magnetic polymer beads, where the polarity of electromagnets is controlled to create controllable asperities
Data Source
AI summary
Present disclosure provides chemical mechanical polishing (CMP) apparatus, including a counterface configured to support a semiconductor wafer at a first surface, a first electromagnet array under the first surface, a polishing head over the counterface and configured to hold the semiconductor wafer at a second surface, and a controller connects to the first electromagnet array. The first electromagnet array comprises a plurality of electromagnets, a polarity of each of the plurality of electromagnets is capable of being individually controlled by the controller. Present disclosure also provides a CMP slurry and a method for using a chemical mechanical polishing apparatus.