CMP Pad Carrier Membrane for Radial Pressure Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chemical mechanical polishing processes often result in thickness non-uniformity across the substrate surface, leading to under-polished regions and radially non-uniform polishing, which affects the quality and efficiency of integrated circuit fabrication.
Innovation Solution
A chemical mechanical polishing system with a flexible membrane that forms individually pressurizable chambers between the pad carrier and support arm, allowing for adjustable radial pressure distribution on the polishing pad to compensate for non-uniformity, using a set of arcuate pads that undergo an orbiting motion to focus on under-polished areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single uniform pressure is applied to the polishing pad, then the structure is simple, but thickness non-uniformity and radial non-uniform polishing occur
Solution Approach 1:
The polishing pad is divided into multiple independently controllable zones (inner zone, middle zone, outer zone) with separate pressure control chambers. This segmentation allows different pressure levels to be applied to different radial regions, compensating for the natural velocity gradient and achieving uniform thickness removal across the entire substrate surface.
Solution Approach 2:
Each radial zone of the polishing pad is assigned different polishing characteristics through independent pressure control. The inner, middle, and outer zones can be pressurized differently to match the local polishing requirements, creating locally optimized polishing conditions that result in overall uniform thickness control.
2Manufacturing precision
If location specific polishing is implemented with smaller contact area, then polishing precision is improved, but productivity decreases
Solution Approach 1:
Multiple polishing pads are arranged radially around the substrate, with each pad responsible for a specific angular sector. This segmentation allows the system to cover the entire substrate surface simultaneously while maintaining precise control over each localized polishing region, thus achieving both high precision and high throughput.
Solution Approach 2:
The orbiting motion mechanism enables continuous polishing action across the substrate surface. As the pads orbit radially, they continuously contact and polish the substrate without interruption, maintaining high productivity while the localized pressure control ensures precise thickness control in each sector.
3Manufacturing precision
If multiple independently pressurizable chambers are implemented, then radial pressure distribution is improved, but device complexity increases
Solution Approach 1:
Flexible diaphragms separate the pressure chambers for the inner, middle, and outer zones. These thin film structures provide the necessary pressure isolation and control while maintaining a compact and relatively simple overall structure. The flexible nature of the diaphragms allows for effective pressure transmission to the polishing pad zones.
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 system achieves localized and precise polishing, reducing within-wafer and wafer-to-wafer non-uniformity while maintaining high throughput, and allows for separate replacement of the polishing pad and pressurizable chamber, reducing operating costs.
Implementation Method 1
a flexible membrane secured to the support arm to form a plurality of individually pressurizable chambers between the pad carrier and the support arm such that variation of a pressure difference between the chambers adjusts a radial distribution of pressure on the pad carrier
Data Source
AI summary
A chemical mechanical polishing system includes a chuck assembly that has a chuck to hold a substrate, a motor to rotate the chuck about a first axis, and a pad carrier assembly. The pad carrier assembly includes a support that is movably along a radial direction relative to the first axis, a lateral actuator coupled the support to cause the support to move along the radial direction, a support arm extending from the support over the chuck, a pad carrier suspended from the support arm, the pad carrier configured to receive and hold a polishing pad, and a flexible membrane secured to the support arm to form a plurality of individually pressurizable chambers between the pad carrier and the support arm such that variation of a pressure difference between the chambers adjusts a radial distribution of pressure on the pad carrier.