Surging Flow Bubble Clearing in Electroplating Vessels
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Solution Overview
Problem
Bubbles in the electroplating bath of semiconductor processing systems interfere with the plating process, causing defects and device failure, as conventional methods struggle to effectively clear bubbles without incurring significant time losses or retrofitting costs.
Innovation Solution
The method involves increasing flow over a weir in the electroplating system to draw bubbles from the surface and into a drain channel, using a combination of central and radial flows through the vessel, with a slotted weir and controlled flow adjustments to minimize bubble retention and facilitate efficient clearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bubble clearing methods are used, then bubble removal is achieved, but significant time losses occur between operations
Solution Approach 1:
The system implements periodic surging flow cycles that alternately draw bubbles from the meniscus into the drain channel and then return fluid to restore operational levels. This periodic action enables rapid bubble clearing (within seconds) without requiring prolonged downtime between electroplating operations, thus resolving the contradiction between clearing effectiveness and time loss.
2Reliability
If increased flow is used to clear bubbles, then bubble clearing effectiveness improves, but system complexity increases
Solution Approach 1:
The system uses the existing electroplating bath fluid circulation infrastructure to perform bubble clearing. The surging flow mechanism leverages the already-present pump, drain channel, and weir components, making the bubble clearing function self-service rather than requiring dedicated external equipment. This maintains reliability while avoiding increased system complexity.
Solution Approach 2:
The existing fluid circulation system serves dual functions: normal electroplating operation and bubble clearing. By controlling flow surges through the existing drain channel and weir structure, the same system components perform both plating fluid circulation and bubble removal, eliminating the need for separate bubble clearing equipment and thus avoiding increased device complexity.
3Reliability
If surfacing flow is increased to draw bubbles into drain channel, then bubble removal improves, but fluid level in drain channel increases
Solution Approach 1:
The system employs periodic surging flow cycles where high flow temporarily draws bubbles into the drain channel and raises fluid level, followed by a return flow phase that restores fluid to the electroplating bath. This periodic action ensures that while bubble removal efficiency is maximized during the surge phase, the fluid level is restored afterward, preventing permanent accumulation in the drain channel.
Solution Approach 2:
The system monitors fluid level in the drain channel and uses this feedback to control the timing and duration of surging flow cycles. When the fluid level reaches a predetermined threshold, the system automatically reduces or reverses the flow surge, preventing excessive fluid accumulation while maintaining effective bubble removal during the surge phase.
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 reduces bubble formation at the meniscus during electroplating, allows for rapid clearing with minimal time loss between operations, and limits the need for additional components or costs, thereby improving plating quality and efficiency.
Implementation Method 1
Electrical current is passed through the electrolyte and the conductive layer. Metal ions in the electrolyte plate out onto the wafer, creating a metal layer on the wafer.
Implementation Method 2
increasing flow to a second drain from the electroplating system. The second drain may be associated with a drain channel from the vessel of the electroplating system. The vessel may include a weir about the vessel, and increasing flow to the second drain may increase flow over the weir into the drain channel
Data Source
AI summary
Exemplary methods of semiconductor processing may include performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system. The methods may include removing the semiconductor substrate from the electroplating bath. The methods may include closing a valve associated with a first drain from the electroplating system. The methods may include increasing flow to a second drain from the electroplating system. The second drain may be associated with a drain channel from the vessel of the electroplating system.