CMP Pad Segmentation for Slurry Distribution
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Solution Overview
Problem
Existing chemical mechanical polishing (CMP) pads suffer from non-uniform slurry distribution and polishing due to centrifugal force, leading to inefficient polishing, particularly at the center of the substrate, as the slurry does not easily move to the center and results in varying polishing speeds.
Innovation Solution
A polishing pad with semi-oval or semicircular curves connected in modified patterns, where the peak of one pattern and the valley of another are sequentially aligned, increasing the slurry's residence time and discharge path, ensuring uniform slurry distribution across the entire area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional polishing pad is used, then the polishing process can be performed, but the slurry distribution becomes non-uniform due to centrifugal force, causing insufficient polishing at the center and excessive polishing at the edge
Solution Approach 1:
The polishing pad surface is segmented into multiple regions with different properties: a central region with first properties (higher friction coefficient) and an outer region with second properties (lower friction coefficient). This segmentation allows different parts of the pad to perform different functions - the center region maintains slurry distribution while the outer region facilitates efficient polishing, resolving the contradiction between uniformity and productivity.
Solution Approach 2:
Different regions of the polishing pad are assigned different local qualities - specifically, different friction coefficients. The central region has a higher friction coefficient to control slurry flow and maintain uniform distribution, while the outer region has a lower friction coefficient to enable efficient polishing. This local differentiation allows the single pad to simultaneously address both uniformity and productivity requirements.
2Productivity
If the polishing pad rotates at high speed to increase polishing rate, then productivity improves, but centrifugal force increases causing non-uniform slurry discharge toward the edge
Solution Approach 1:
The pad is segmented into functional zones with different friction characteristics. The central region with higher friction counteracts the centrifugal force effect, ensuring slurry reaches the center, while the outer region with lower friction allows efficient polishing. This segmentation enables high-speed rotation to maintain both uniform slurry distribution and high polishing rate.
Solution Approach 2:
The friction coefficient parameter is changed across different regions of the pad. By varying the friction coefficient from the center (higher) to the outer region (lower), the pad can operate at high speeds while maintaining uniform slurry distribution. This parameter change allows the system to achieve both high productivity and precise slurry control simultaneously.
3Productivity
If pressure is applied to the film to be polished to improve polishing speed, then productivity increases, but slurry does not easily move to the center causing non-uniform polishing
Solution Approach 1:
The pad applies different local qualities through varying friction coefficients in different regions. The central region's higher friction coefficient resists slurry flow, ensuring slurry reaches the center even under applied pressure, while the outer region's lower friction coefficient allows efficient polishing. This local differentiation enables high polishing speed while maintaining uniformity.
Solution Approach 2:
The pad is segmented into functional regions that handle different aspects of the polishing process. The central region manages slurry distribution under pressure, while the outer region manages polishing efficiency. This segmentation allows the system to achieve both high speed and uniformity by dividing the function across spatial segments with different properties.
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 enhances polishing uniformity and rate by maintaining appropriate slurry residence time and preventing non-uniform polishing, especially at the center, by allowing slurry to move uniformly and be discharged effectively in all directions.
Implementation Method 1
a film to be polished is fixed on a carrier head and disposed so as to be opposite to a rotating polishing pad. The carrier head applies pressure to the rotating polishing pad while the film to be polished is fixed, thus enabling polishing.
Implementation Method 2
In the chemical mechanical polishing process, centrifugal force is generated by the rotation of the polishing pad, and thus the discharge speed of the polishing slurry increases toward the edge of the polishing pad.
Implementation Method 3
a chemical mechanical polishing (CMP) method has been most widely applied for the planarization process. The CMP method is a method wherein a semiconductor substrate is put into contact with a polishing pad of a polishing apparatus and they are relatively moved while supplying a slurry composition including polishing particles and various chemical ingredients between the polishing pad and the semiconductor substrate to mechanically polish a film.
Data Source
AI summary
This disclosure relates to a polishing pad for chemical mechanical polishing, having a shape where 3 or more semi-oval or semicircular curves that connect 2 valleys neighboring on the plane are connected, and including 2 or more modified patterns that are formed to a determined thickness on the polishing pad, wherein a peak of one modified pattern and a valley of another modified pattern neighboring thereto are sequentially located on the same line. The polishing pad may uniformly disperse slurry over the whole area during a polishing process to provide improved polishing uniformity, and appropriately control residence time of the slurry to increase polishing rate.