Localized Pressure Control for CMP Substrate Planarization
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Solution Overview
Problem
Chemical mechanical polishing systems face challenges in finely controlling pressure distribution on substrates due to high substrate stiffness, making it difficult to correct small-scale peaks or valleys on the polished surface.
Innovation Solution
A polishing system with a pressure applicator that applies localized pressure to the back surface of the polishing pad, allowing for precise control of pressure distribution on the substrate surface without dispersion, using pressure control pads or flexible rings to modify substrate thickness at specific locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If backside pressure is applied to the substrate to achieve planarization, then the substrate surface can be polished, but the high stiffness of the substrate causes pressure dispersion to a larger area, making it difficult to finely control pressure distribution
Solution Approach 1:
A flexible polishing pad is introduced as an intermediary between the pressure applicator and the substrate. The pad transmits localized pressure from the applicator to the substrate surface without the pressure dispersion that occurs when applying pressure directly to the stiff substrate backside. This enables precise localized thickness modification.
Solution Approach 2:
Instead of applying pressure to the backside of the substrate (conventional approach), the invention applies pressure to the front surface of the substrate through the polishing pad. This inversion of the pressure application approach allows for localized pressure control because the stiff substrate does not disperse the pressure when pressure is applied from the front surface through a flexible medium.
2Manufacturing precision
If uniform pressure is applied across the substrate for bulk polishing, then overall planarization is achieved, but small-scale peaks or valleys in specific zones cannot be corrected
Solution Approach 1:
The pressure applicator is designed to apply pressure to localized regions of the polishing pad rather than uniformly across the entire pad. This enables different zones of the substrate to receive different pressure levels, allowing correction of small-scale peaks or valleys in specific zones while maintaining overall planarization.
Solution Approach 2:
The polishing process is divided into bulk polishing (for overall planarization) and localized correction (for small-scale imperfections). The pressure applicator can selectively apply pressure to specific regions of the polishing pad, segmenting the pressure distribution to address different surface defects in different zones.
3Productivity
If the polishing pad spans the entire substrate surface for bulk polishing, then overall planarization is achieved, but localized pressure control becomes difficult
Solution Approach 1:
The pressure applicator applies pressure to selected regions of the polishing pad rather than uniformly across the entire pad. This allows the polishing pad to maintain its function for bulk polishing while enabling localized pressure control in specific zones where thickness modification is needed.
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
Enables precise and localized thickness modification of substrates, improving the ability to correct small-scale imperfections and achieving uniformity in substrate surfaces by controlling pressure distribution directly on the polishing pad.
Implementation Method 1
a pressure applicator to apply pressure at a selected region of a back surface of the polishing pad
Implementation Method 2
an actuator and a body configured to be moved by the actuator into and out of contact with the selected region of the back surface of the polishing pad
Implementation Method 3
generating relative motion between the substrate and polishing pad to cause polishing of the one or more underpolished regions
Implementation Method 4
Chemical mechanical polishing (CMP) is one accepted method of planarization
Data Source
AI summary
A polishing system include a support to hold a substrate having a substrate surface to be polished, a carrier to hold a polishing pad in contact with the substrate surface, and a pressure applicator to apply pressure at a selected region of a back surface of the polishing pad. The back surface is opposite to the polishing surface. The pressure applicator includes an actuator and a body configured to be moved by the actuator into and out of contact with the selected region of the back surface of the polishing pad.