CMP Pad Configuration for Localized Uniformity Correction
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Solution Overview
Problem
Chemical mechanical polishing (CMP) processes often result in non-uniformity and under-polished regions on substrates, particularly due to bulk polishing methods that fail to address localized non-concentric and angular asymmetry issues.
Innovation Solution
A CMP system employing a small polishing pad that moves in an orbital motion with a fixed angular orientation relative to the substrate, utilizing a substrate support and drive system to maintain precise contact and generate relative motion, ensuring uniform polishing across localized regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large polishing pad is used for bulk polishing, then productivity is improved, but manufacturing precision deteriorates due to non-uniform polishing and inability to address localized under-polished regions
Solution Approach 1:
The invention divides the polishing process into two distinct stages: bulk polishing using a large pad for high productivity, and touch-up polishing using a small precision pad for localized correction. This segmentation allows each stage to optimize for its specific purpose without compromise
Solution Approach 2:
The system dynamically switches between different polishing modes by changing the pad size and motion characteristics. The small pad operates in orbital motion for precision work, while the large pad provides rotational motion for bulk material removal, adapting the polishing approach to the specific needs of each stage
2Manufacturing precision
If a small polishing pad with orbital motion is used for touch-up polishing, then manufacturing precision is improved, but productivity decreases due to limited contact area
Solution Approach 1:
The bulk polishing stage performs preliminary material removal and general planarization before the touch-up stage. This preliminary action removes the majority of material, allowing the subsequent precision stage to focus only on localized corrections rather than entire substrate surfaces
Solution Approach 2:
The small polishing pad concentrates polishing action on specific localized regions of the substrate. By limiting the contact area to only where precision correction is needed, the system achieves high manufacturing precision without requiring prolonged polishing time across the entire substrate
3Productivity
If bulk polishing methods are used, then productivity is improved, but manufacturing precision deteriorates due to non-concentric polishing uniformity and angular asymmetry
Solution Approach 1:
The system uses measurement devices to detect non-uniformity and under-polished regions on the substrate. This feedback information guides the touch-up polishing process, allowing the small pad to target specific problem areas identified by the measurement system, thereby correcting angular asymmetry and non-concentric uniformity issues
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 effectively compensates for non-concentric polishing uniformity, reduces substrate non-uniformity, and improves the flatness and finish of the substrate by focusing on specific under-polished areas with enhanced precision and throughput.
Implementation Method 1
Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate is typically placed against a rotating polishing pad.
Data Source
AI summary
A polishing pad includes and upper portion and one or more lower portions. The upper portion has an upper surface for attachment to a pad carrier and a first lateral dimension. The one or more lower portions project downward from the upper portion. A bottom surface of the one or more lower portions provide a contact surface to contact a substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension that is less than the first lateral dimension. A total surface area of the contact surface from the one or more lower portions is no more than 10% of a surface area of the upper surface.