CMP Membrane Stiffness Zoning for Uniform Edge Pressure
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Solution Overview
Problem
Chemical mechanical planarization (CMP) tools face non-uniform pressure distribution issues due to the rigidity of the membrane, leading to lower removal rates at the edges of substrates and non-planarity problems, which result in reduced yield and increased rework.
Innovation Solution
A CMP membrane with regions of varying malleability and stiffness is developed, where the peripheral region is cured to have a lower stiffness than the central region, allowing for increased expansion and improved contact with the substrate, thereby enhancing pressure uniformity and removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid membrane is used in CMP tools, then structural stability is improved, but pressure distribution uniformity deteriorates
Solution Approach 1:
The membrane is designed with non-uniform physical properties: the peripheral region has lower stiffness and higher malleability compared to the central region. This local differentiation allows the peripheral areas to deform and expand more readily, improving contact with the substrate edges and achieving more uniform pressure distribution across the entire substrate surface while maintaining overall structural stability.
2Ease of manufacture
If a uniform stiffness membrane is used, then manufacturing simplicity is improved, but CMP removal rate uniformity deteriorates
Solution Approach 1:
The membrane incorporates regions with different stiffness characteristics - a stiffer central region and a more compliant peripheral region. This local quality variation ensures that the peripheral areas can adequately contact and apply pressure to the substrate edges, which are typically harder to reach, thereby achieving uniform removal rates across the entire substrate while remaining manufacturable through controlled curing processes.
Solution Approach 2:
The membrane's physical parameters (stiffness and malleability) are deliberately varied across different regions. The peripheral region is formulated or cured to have lower stiffness and higher malleability compared to the central region, allowing it to deform and expand more readily during operation, which improves pressure distribution and removal rate uniformity without significantly complicating the manufacturing process.
3Stress or pressure
If the peripheral region has lower stiffness, then pressure uniformity is improved, but membrane strength deteriorates
Solution Approach 1:
The membrane is designed with spatially varying mechanical properties where the peripheral region has lower stiffness and higher malleability to improve pressure distribution, while the central region maintains higher stiffness for structural support. This local differentiation allows each region to optimize its function without compromising overall membrane integrity or strength.
Solution Approach 2:
The membrane can be constructed as a composite structure with different material compositions or formulations in different regions. The peripheral region uses materials or curing conditions that produce lower stiffness and higher malleability, while the central region uses materials or conditions that produce higher strength and stiffness, creating a functionally optimized composite membrane structure.
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
This approach mitigates pressure non-uniformities, achieving removal rate deviations of less than 15% between the center and edges, significantly improving CMP throughput and reducing rework.
Implementation Method 1
The malleable material is cured to form a membrane, by heating the malleable material within the central region of the membrane mold to a first temperature and heating the malleable material within the peripheral region of the membrane mold to a second temperature that is greater than the first temperature
Implementation Method 2
The lower stiffness of the peripheral region allows the peripheral region of the membrane to expand by a larger amount than the central region of the membrane
Data Source
AI summary
In some embodiments, the present disclosure relates to a chemical mechanical planarization (CMP) tool. The CMP tool includes a carrier and a malleable membrane coupled to the carrier and having a lower surface facing away from the carrier. The lower surface of the malleable membrane includes a first malleable material within a central region of the lower surface and a second malleable material within a peripheral region of the lower surface, which surrounds the central region. The first malleable material provides the central region of the lower surface with a first stiffness and the second malleable material provides the peripheral region of the lower surface with a second stiffness that is different than the first stiffness.