Flexible Retaining Ring for CMP Substrate Edge Stress
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Solution Overview
Problem
Conventional retaining rings in chemical-mechanical planarization (CMP) systems experience premature wear due to high localized stress from larger substrates and increased polishing pressures, leading to component failure.
Innovation Solution
A flexible inner retaining ring that contours to the substrate's edge, coupled with an inner ring support and optionally an outer retaining ring with a notch, to distribute the side force load over a larger area, reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional rigid retaining ring is used to hold the substrate, then the substrate is securely retained during polishing, but the retaining ring experiences high localized stress and premature wear
Solution Approach 1:
The patent replaces the conventional rigid retaining ring with a flexible retaining ring that can deform elastically under side force loads. This flexibility allows the ring to contour to the substrate edge and distribute contact forces over a larger area, reducing localized stress concentrations that cause premature wear and failure of rigid rings.
Solution Approach 2:
The patent changes the mechanical parameter of the retaining ring from rigid to flexible by selecting materials with appropriate elastic properties. This parameter change allows the ring to dynamically adapt to varying loads and substrate geometries, maintaining reliable retention while reducing stress concentrations that limit service life.
2Productivity
If polishing pressure is increased to improve planarization efficiency, then productivity increases, but side force load on the retaining ring increases causing premature wear
Solution Approach 1:
The flexible retaining ring design allows the system to tolerate higher polishing pressures by distributing the increased side force loads over a larger contact area. The elastic deformation of the flexible ring prevents stress concentration, enabling higher productivity without proportionally increasing wear on the retaining ring.
3Productivity
If substrate size is increased to process larger devices, then productivity improves, but the retaining ring experiences higher loads and premature failure
Solution Approach 1:
The flexible retaining ring can elastically deform to accommodate larger substrate sizes and distribute the increased loads over a larger area. This maintains the strength-to-load ratio and prevents premature failure even when processing larger devices that generate higher side forces.
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 flexible retaining ring design effectively reduces the likelihood of component failure by distributing the side force load, ensuring reliable substrate retention during polishing, even with larger substrates and higher pressures.
Implementation Method 1
a flexible inner retaining ring adapted to contour to an edge of a substrate
Data Source
AI summary
Methods, apparatus, and systems are provided for retaining a substrate in a polishing head of a CMP system. The invention includes a flexible inner retaining ring adapted to contour to an edge of a substrate and an inner ring support coupled to the polishing head. The inner support ring is adapted to contact the flexible inner retaining ring in response to a side force load applied to the flexible inner retaining ring by a substrate being polished. Numerous additional aspects are disclosed.