Flexible Membrane Carrier Head with Annular Flaps for CMP Uniformity
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) processes for 150 mm diameter substrates face challenges in achieving within wafer and wafer-to-wafer uniformity due to form factor difficulties with smaller carrier heads.
Innovation Solution
A flexible membrane carrier head design featuring a main portion, an annular outer portion, and three annular flaps that divide the volume into multiple chambers, allowing for controlled pressure distribution and improved substrate mounting, enhancing uniformity by adjusting the pressure in each chamber independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a smaller carrier head is used for 150 mm diameter substrates, then the device size is reduced, but the within wafer and wafer-to-wafer uniformity deteriorates
Solution Approach 1:
The flexible membrane is divided into multiple chambers by three annular flaps, allowing independent pressure control for different radial zones. This segmentation enables the smaller carrier head to achieve uniform pressure distribution across the 150 mm substrate by adjusting pressure in each zone separately, resolving the contradiction between reduced device size and maintained polishing uniformity.
Solution Approach 2:
Different radial zones of the flexible membrane are given different local properties through the flap structure. The flaps create distinct chambers with independent pressure control, allowing each zone to be optimized for its specific polishing requirements. This local quality adjustment enables uniformity across the entire substrate surface despite the compact carrier head size.
2Manufacturing precision
If multi-zone carrier heads are used for larger substrates, then the within wafer uniformity is improved, but the device complexity increases
Solution Approach 1:
The invention uses a flexible membrane structure with integrated flaps instead of complex rigid multi-zone carrier heads. The flexible membrane naturally conforms to the substrate surface, and the flaps create pressure zones through flexible division rather than rigid segmentation. This approach achieves multi-zone pressure control with reduced structural complexity, as the flexible membrane inherently provides the necessary compliance and adaptation.
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 design improves within wafer and wafer-to-wafer uniformity for 150 mm diameter substrates by enabling precise control of pressure distribution, addressing the form factor limitations of smaller carrier heads and enhancing the CMP process capability.
Implementation Method 1
The three annular flaps include a first annular flap joined to an inner surface of the main portion at a radial position between 75% and 95% of R, a second annular flap joined to the annular outer portion at a position between the lower edge and the upper edge, the second annular flap extending inwardly from the outer annular portion, and a third annular flap joined to the upper edge of the annular outer portion, the third annular flap extending inwardly from the outer annular portion
Data Source
AI summary
A reinforcement ring can be placed in a carrier head to abut an inner surface of a perimeter portion of a flexible membrane. The reinforcement ring has a substantially vertical cylindrical portion, a flange projecting outwardly from the bottom of the cylindrical portion, and a lip projecting outwardly from a top of the cylindrical portion. The flange projects outwardly farther than the lip.