Polishing Head Multi-Zone Pressure Control for Wafer Edge Flatness
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Solution Overview
Problem
Existing polishing treatment devices face challenges in achieving uniform polishing across the substrate surface, leading to issues like uneven polishing, insufficient polishing, or over-polishing, which affect the edge roll-off amount (ROA) and edge stress-free quadratic range (ESFQR).
Innovation Solution
The polishing head and device incorporate a multi-stage pressure adjustment system, including first, second, third, and fourth pressure adjusting means, to control the processing pressure and compensating pressure applied to the substrate, ensuring uniform contact pressure across the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure chamber is used to apply pressing force to the substrate, then the device structure is simple, but uneven polishing occurs due to stress concentration at the substrate edge
Solution Approach 1:
The single pressure chamber is divided into multiple pressure chambers (first, second, third pressure chambers) with different pressing forces. The first pressure chamber applies higher pressing force to the central region, the second pressure chamber applies moderate pressing force to the intermediate region, and the third pressure chamber applies lower pressing force to the edge region. This segmentation resolves the contradiction by maintaining simple device structure while achieving uniform polishing through distributed pressure zones.
Solution Approach 2:
Different regions of the substrate receive different pressing forces tailored to their specific requirements. The central region receives higher pressure to ensure adequate contact, while the edge region receives lower pressure to prevent stress concentration. This local quality approach maintains simple device structure while achieving uniform polishing across the entire substrate surface.
2Duration of action of stationary object
If the template thickness decreases due to wear, then the template can be used for extended period, but the pressing force becomes excessively high causing uneven polishing
Solution Approach 1:
The pressing force is made dynamically adjustable through the multiple pressure chambers that can be independently controlled. As the template wears and thickness decreases, the system can adjust the pressing forces in different chambers to compensate, maintaining uniform polishing throughout the extended service life of the template.
Solution Approach 2:
The pressing force parameters are changed across different regions and time. The first pressure chamber provides higher pressing force when template thickness is sufficient, while the third pressure chamber provides lower pressing force to the edge region. As the template wears, these parameters can be adjusted to maintain optimal polishing conditions throughout the template's service life.
3Productivity
If high pressing force is applied to ensure adequate contact between substrate and polishing pad, then polishing efficiency increases, but edge stress concentration causes uneven polishing
Solution Approach 1:
The pressing force is segmented into multiple zones with different magnitudes. The first pressure chamber applies high pressing force to the central region for efficient polishing, while the third pressure chamber applies low pressing force to the edge region to prevent stress concentration. This segmentation maintains high polishing efficiency while ensuring edge flatness.
Solution Approach 2:
The pressing force is optimized locally for each region's specific requirements. The central region receives high pressing force to maximize polishing efficiency, while the edge region receives low pressing force to maintain flatness. This local quality approach achieves both high productivity and manufacturing precision simultaneously.
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 solution effectively prevents uneven polishing, improves ESFQR, and maintains high-quality polishing across a large number of substrates by ensuring consistent pressure distribution and compensating for edge stress.
Implementation Method 1
an annular elastic body is arranged on a back surface of the elastic body, and a corrective pressing ring that applies a pressure to an upper surface of the annular elastic body
Implementation Method 2
The retainer ring prevents the flying out of the wafer during polishing by receiving the wafer at the inner circumference thereof
Data Source
AI summary
A polishing head includes a head housing having a first flange part that extends outward from an upper position of a circumferential surface of a cylindrical body and a second flange part that extends outward from a lower position of the circumferential surface, a membrane support ring that is sized to surround an outer circumference of the second flange part and has a third flange part that is formed at an upper end part thereof and located between the first flange part and the second flange part, a membrane that covers a lower end-side opening part of the membrane support ring and holds the wafer with a backing film pasted to a front surface thereof interposed therebetween, a retainer ring formed in a shape to surround an outer circumference of the substrate, and driving means that integrally horizontally rotates the head housing, the membrane support ring, and the retainer ring.