CMP Conditioning Ring for Full-Radius Pad Uniformity
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Solution Overview
Problem
Conventional pad conditioners in chemical mechanical polishing (CMP) systems face limitations in uniformly conditioning the polishing pad across its entire surface, leading to issues such as reduced performance, non-uniformity, and increased risk of error alarms due to down force at the perimeter, which can cause wafer slip and reduced yield.
Innovation Solution
The use of a conditioning ring with a diameter equal to or greater than the polishing pad radius, allowing simultaneous conditioning from the center to the edge, reducing down force errors, and enhancing uniformity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional pad conditioner is used to condition the polishing pad, then the polishing pad can be conditioned, but the conditioning is non-uniform across the pad surface and causes down force errors at the perimeter
Solution Approach 1:
The conditioner is divided into multiple independent conditioning elements arranged in a circular pattern, each capable of conditioning a specific radial zone of the polishing pad. This segmentation allows uniform conditioning across the entire pad surface while distributing down force evenly, preventing perimeter errors and improving manufacturing precision.
2Manufacturing precision
If the polishing pad is conditioned thoroughly across the entire surface, then uniformity improves, but conditioning time increases
Solution Approach 1:
The circular array of conditioning elements rotates continuously during the conditioning process, maintaining constant contact with the polishing pad surface. This continuous rotational action ensures uniform conditioning across the entire pad surface while completing the process efficiently, improving both uniformity and reducing conditioning time compared to sequential methods.
3Area of stationary object
If down force is applied at the perimeter of the polishing pad during conditioning, then conditioning coverage is improved, but wafer slip occurs and yield reduces
Solution Approach 1:
Each conditioning element in the circular array is positioned to condition a specific radial zone of the polishing pad, with down force locally applied only where needed. This localized conditioning approach achieves comprehensive pad coverage without concentrating excessive down force at the perimeter, preventing wafer slip while maintaining full conditioning coverage.
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 conditioning ring improves polishing pad uniformity, reduces conditioning time, minimizes false alarms, and enhances within-die, within-wafer, and wafer-to-wafer uniformity, leading to improved die yield and increased CMP system throughput.
Implementation Method 1
A pad conditioner is positioned above the polishing pad with a contact surface facing the polishing pad. Both the pad conditioner and polishing pad rotate, and the pad conditioner conditions the surface of the polishing pad.
Implementation Method 2
the pad conditioner conditions the surface of the polishing pad by contacting and rotating against it
Data Source
AI summary
A chemical mechanical polishing (CMP) system includes a polishing pad mounted upon a platen, a wafer carrier configured to hold a substrate on its backside and press the substrate against the polishing pad, and a pad conditioner that includes a conditioner head and a conditioning ring which is held by the conditioner head. The conditioning ring extends from the center of the polishing pad to the edge of the polishing pad, for simultaneous conditioning along the entire radius of the polishing pad. The conditioning ring is better able to remove pad debris. Also described are systems in which one pad conditioner is used for conditioning multiple polishing pads on multiple platens.