CMP Retainer Ring Slurry Inlets for Wafer Edge Polishing
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Solution Overview
Problem
As the number of layers in semiconductor devices increases, achieving uniform planarization of material layers on wafers during manufacturing remains a challenge, particularly in controlling the polishing rate between the central and edge portions of the wafer during chemical mechanical polishing (CMP) processes.
Innovation Solution
The CMP apparatus incorporates a retainer ring with additional polishing slurry feeding inlets to locally adjust the polishing rate at the edge of the wafer, using a combination of first and second polishing slurries with adjustable compositions to minimize the difference in polishing rates between the center and edge portions, thereby enhancing polishing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single polishing slurry is used for the entire wafer surface, then the polishing process is simple, but the polishing uniformity between center and edge portions deteriorates
Solution Approach 1:
The polishing slurry application is segmented into multiple zones: a first polishing slurry is applied to the center portion of the wafer through a first feeding line, while a second polishing slurry is applied to the edge portion through a second feeding line. This spatial segmentation allows different slurry compositions to be used in different regions, improving polishing uniformity across the wafer surface.
Solution Approach 2:
Different polishing slurries with tailored compositions are used for different regions of the wafer. The first polishing slurry is optimized for the center portion while the second polishing slurry is optimized for the edge portion, allowing local optimization of polishing characteristics to achieve overall uniformity.
2Manufacturing precision
If multiple polishing slurries are used to improve polishing uniformity, then the polishing precision improves, but the device complexity increases
Solution Approach 1:
The retainer ring serves multiple functions: it retains the wafer during polishing, provides structural support for the polishing head, and acts as a distribution manifold for delivering both the first and second polishing slurries to different regions of the wafer. This multi-functionality reduces the need for separate components for each slurry delivery system.
Solution Approach 2:
The first and second polishing slurry feeding lines are merged into a single retainer ring structure that distributes both slurries simultaneously. This integration consolidates what could be separate complex delivery systems into one unified component, reducing overall device complexity while maintaining the capability to deliver multiple slurries.
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 effectively reduces the difference in polishing rates between the central and edge portions of the wafer, improving overall polishing uniformity and ensuring consistent material layer removal across the entire surface.
Implementation Method 1
chemical mechanical polishing (CMP) apparatus capable of controlling the polishing uniformity
Data Source
AI summary
A chemical mechanical polishing (CMP) apparatus includes a polishing pad on a polishing platen, a polishing head on the polishing pad, the polishing head having a membrane to hold a wafer on the polishing pad, and a polishing slurry feeding line to feed a polishing slurry, and a retainer ring around the membrane and in contact with the polishing pad to prevent detachment of the wafer, the retainer ring including a polishing slurry feeding inlet connected to the polishing slurry feeding line to feed the polishing slurry onto the polishing pad.