Tiltable Electroless Plating Chuck for Uniform Wafer Wetting
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Solution Overview
Problem
Conventional electroless plating processes face challenges in achieving uniform material deposition across semiconductor wafers due to variations in plating liquid residence time and surface wetting, particularly in filling high aspect ratio features, which are exacerbated by high chuck rotation speeds and inefficient plating solution usage.
Innovation Solution
A tiltable workpiece chuck and dynamic control of the plating liquid dispensing nozzle position and rotation speed are employed to optimize plating liquid distribution, with the chuck tilted at a few degrees off-level to improve wetting uniformity and residence time, allowing for more efficient plating liquid coverage and reduced residence time variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high chuck rotation speed is used to increase productivity, then deposition speed is improved, but uniformity of plated material thickness deteriorates
Solution Approach 1:
The chuck rotation speed is made dynamically adjustable rather than fixed. The system optimizes rotation speed based on real-time process conditions, allowing slower speeds during critical deposition phases to ensure uniformity, and faster speeds when productivity is the priority. This dynamic control resolves the contradiction by adapting the rotation speed to the specific requirements of each process stage.
Solution Approach 2:
The system changes multiple process parameters simultaneously (chuck rotation speed, nozzle position, plating solution flow rate, chuck tilt angle) to achieve both high productivity and uniform deposition. By coordinating changes in these parameters, the system can maintain uniform plated thickness even at optimized rotation speeds that balance productivity requirements.
2Productivity
If plating liquid dispense flow rate is increased to improve coverage speed, then productivity is improved, but uniformity of surface wetting deteriorates
Solution Approach 1:
The plating liquid dispense flow rate is dynamically controlled based on the chuck rotation speed and nozzle position. As the chuck rotates and the nozzle moves, the system adjusts the flow rate in real-time to maintain optimal wetting conditions across different regions of the wafer, preventing both over-wetting and under-wetting while maintaining high coverage speed.
Solution Approach 2:
The system applies different dispense flow rates to different regions of the wafer surface based on local requirements. The nozzle position and flow rate are coordinated to ensure that areas requiring better wetting uniformity receive optimized liquid distribution, while other areas receive higher flow rates for faster coverage, achieving both productivity and uniformity.
3Manufacturing precision
If chuck rotation speed is reduced to improve wetting uniformity, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The system uses dynamic chuck rotation speed control where the rotation speed varies during the deposition process. During phases requiring excellent wetting uniformity (such as initial plating solution distribution), the rotation speed is reduced. During phases where productivity is more critical, the rotation speed is increased, maintaining overall high productivity while achieving necessary uniformity.
Solution Approach 2:
The system maintains continuous deposition action by coordinating multiple parameters. Even when chuck rotation speed is temporarily reduced to improve wetting uniformity, other parameters (nozzle position, plating solution flow rate, chuck tilt angle) are optimized to ensure deposition continues efficiently, minimizing the impact on overall productivity while achieving the necessary uniformity.
4Loss of substance
If plating solution usage is minimized to reduce cost and environmental impact, then loss of substance is reduced, but uniformity of material deposition deteriorates
Solution Approach 1:
The system applies plating solution selectively to different regions of the wafer based on local deposition requirements. The nozzle position and dispense flow rate are precisely controlled to deliver plating solution only where needed, ensuring uniform material deposition in critical areas while minimizing overall plating solution consumption. This localized approach maintains deposition uniformity while reducing waste.
Solution Approach 2:
The plating solution dispense parameters are dynamically adjusted based on real-time process conditions, chuck rotation speed, and nozzle position. This dynamic control ensures that plating solution is used efficiently - enough to achieve uniform deposition where required, but not excessive amounts that would increase waste. The system optimizes the balance between deposition quality and solution consumption.
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 enhances the uniformity of plated material thickness and reduces plating liquid residence time variations, improving the ability to fill high aspect ratio features while minimizing the cost and environmental impact of plating solution usage.
Implementation Method 1
the chuck tilted at a few degrees off-level to improve wetting uniformity and residence time
Implementation Method 2
a desired material (e.g., a metal such as Ni) is deposited onto a surface by dispensing a plating liquid onto the workpiece
Data Source
AI summary
A single-substrate electroless (EL) plating apparatus including a workpiece chuck that is rotatable about rotation axis and inclinable about an axis of inclination. The chuck inclination may be controlled to a non-zero inclination angle during a dispense of plating solution to improve uniformity in the surface wetting and/or plating solution residence time across the a surface of a workpiece supported by the chuck. The angle of inclination may be only a few degrees off-level with the plating solution dispensed from a nozzle that scans over a high-side of the chuck along a radius of the workpiece while the chuck rotates. The angle of inclination may be actively controlled during dispense of the plating solution. The inclination angle may be larger at commencement of the plating solution dispense than at cessation of the dispense.