Flexible CMP Slurry Injector for Uniform Polishing
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) processes face inefficiencies in slurry utilization, leading to significant waste and contamination due to the reintegration of old slurry and residual water, which affects removal rates and uniformity, as most of the applied slurry is not effectively used between the polishing pad and the wafer.
Innovation Solution
A rectilinear-shaped slurry injector with multiple slots in the top surface and a slit design on the bottom surface, allowing the injector to conform to the polishing pad's profile and ensuring that fresh slurry is introduced as a thin film between the pad and the wafer, while separating used slurry and residual water, thereby minimizing waste and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If slurry is applied at a constant flow rate onto the rotating polishing pad using a simple delivery tube or nozzle, then the slurry application process is simple and easy to operate, but the old slurry reenters the gap between the wafer and polishing pad leading to contamination and defectivity
Solution Approach 1:
The polishing pad surface is segmented into multiple zones (first zone for receiving fresh slurry, second zone for removing old slurry) with distinct functions. The injector device is divided into separate components: a body portion for slurry delivery and a skirt portion for old slurry removal, allowing each segment to perform its specific function independently without interference
Solution Approach 2:
The harmful old slurry is extracted and removed from the system before it can reenter the gap between the wafer and polishing pad. The skirt portion actively sweeps and removes old slurry from the pad surface, separating it from the fresh slurry application zone and preventing contamination
2Area of stationary object
If fresh slurry flows away from the application point under the influence of gravity and centripetal acceleration, then the slurry distribution covers a larger area, but the slurry becomes mixed with used slurry reducing effectiveness
Solution Approach 1:
Different regions of the polishing pad are assigned different qualities and functions: the first zone receives fresh slurry with specific flow characteristics for effective polishing, while the second zone is dedicated to old slurry removal. This local differentiation ensures that fresh and used slurry do not mix, maintaining slurry effectiveness throughout the process
Solution Approach 2:
Old slurry is removed from the pad surface in advance (before it can mix with fresh slurry) through the skirt portion's sweeping action. This preliminary removal prevents contamination of the fresh slurry that will be applied to the first zone, ensuring consistent polishing effectiveness
3Reliability
If the polishing pad surface is continuously roughened by diamond conditioner disks, then the polishing effectiveness is maintained, but the pad surface becomes uneven requiring complex slurry distribution
Solution Approach 1:
The injector device incorporates a flexible skirt portion that can dynamically adapt to the uneven pad surface created by continuous conditioning. The skirt flexes and conforms to the changing pad topology, maintaining effective old slurry removal without requiring a complex rigid mechanical system, thus preserving polishing effectiveness while minimizing device complexity
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 significantly increases the utilization of fresh slurry, reduces waste, and maintains consistent slurry concentration, leading to improved removal rates and uniformity, while also allowing for better control over slurry introduction and separation of contaminants.
Implementation Method 1
The one or more than one bottom surface opening is in fluid communication with the one or more than one top surface opening. A CMP slurry introduced through the one or more than one top surface opening travels through the injector bottom and exits the injector device through the one or more than one bottom surface opening onto the polishing pad top surface.
Implementation Method 2
The injector bottom also includes a leading edge, a trailing edge, and a groove formed in the bottom surface, where the groove extends along a length of the injector bottom between the leading edge and the trailing edge
Data Source
AI summary
Disclosed is an apparatus for injecting slurry onto the polishing pad surface of a chemical mechanical polishing (CMP) tool. The disclosed apparatus includes a rectilinear shaped injector bottom, where multiple slots are created in the top surface of the injector bottom, allowing the injector bottom to flex and to conform to the polishing pad profile. CMP slurry or components thereof are introduced through one or more top surface openings, travel through the injector body, and exit through a slit or bottom surface opening. The slurry is spread into a thin film by the injector, and is introduced at the gap between the surface of the polishing pad and the wafer, along the leading edge of the wafer, in quantities small enough that all or most of the slurry is introduced between the wafer and the polishing pad.