Bubble-Free Flow Control Valve for Electroplating Recirculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor manufacturing, the introduction of bubbles and foam in electroplating processes due to mixed phase fluid circulation leads to inefficiencies and increased costs, particularly in compact stacked module architectures where fluid is recycled and reused, necessitating effective methods to control and prevent gas introduction during fluid return.
Innovation Solution
A system utilizing a level-sensitive feedback flow restriction valve to control the return of electrolyte from an elevated location to a lower elevation with minimal air and liquid mixing, incorporating a float and flow constrictor mechanism to prevent gas passage and ensure a bubble-free flow, along with additional features like baffles and overflow conduits to manage fluid flow and prevent turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluid circulation is used to recycle and reuse operating fluids in stacked module architecture, then productivity and cost efficiency are improved, but bubbles and foam are introduced into the liquid during circulation
Solution Approach 1:
The patent uses the buoyancy of bubbles as a beneficial force by designing a bubble trap that allows bubbles to naturally rise and accumulate at the highest point of the circulation loop, where they can be easily removed. The gas-permeable barrier converts the harmful bubble presence into a manageable separation process, transforming the harm into a benefit by enabling automatic bubble removal without additional energy input.
Solution Approach 2:
The patent introduces a gas-permeable barrier as an intermediary element between the liquid phases at different elevations. This barrier allows gas to pass through while preventing direct mixing of liquid phases, thereby eliminating the harmful effect of bubble generation during fluid transfer while maintaining the circulation necessary for productivity.
2Reliability
If degasser is included in fluid feed line to minimize bubbles, then reliability is improved, but device complexity and implementation cost increase
Solution Approach 1:
The patent implements a self-service bubble removal system where the circulation loop itself provides the conditions for bubble separation. By positioning the feed line inlet at a higher elevation than the reservoir and allowing natural convection and buoyancy to drive bubble accumulation at the highest point, the system eliminates the need for external degassers while maintaining reliable bubble-free flow.
Solution Approach 2:
The patent creates an equipotential circulation loop where the liquid levels and pressure conditions are balanced to allow natural bubble separation. The feed line is positioned at the same elevation as the bubble trap, and the reservoir is positioned lower, creating a balanced system where bubbles naturally accumulate at the highest point without requiring additional energy input or complex control mechanisms.
3Productivity
If mixed phase circulation is used to transfer fluid between elevated and lower locations, then productivity is improved, but gas introduction and turbulence increase
Solution Approach 1:
The patent positions the feed line inlet at the same elevation as the bubble trap and the reservoir at a lower elevation, creating an equipotential system where liquid flow occurs without significant elevation changes that would cause turbulence. This balanced positioning allows efficient fluid transfer while minimizing gas introduction and turbulence during circulation.
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
The solution effectively prevents the introduction of bubbles and foam in the electrolyte return conduit, maintaining a gas-free and stable fluid flow over a range of flow rates, enhancing the efficiency and reliability of electroplating processes while reducing operational costs and defects.
Implementation Method 1
a float and flow constrictor mechanism to prevent gas passage and ensure a bubble-free flow
Implementation Method 2
the gravity driven return flow is mechanically or automatically modulated/controlled by a level sensitive feedback flow restriction valve
Data Source
AI summary
The embodiments disclosed herein relate to methods and apparatus for promoting bubble-free circulation of processing fluids in a recirculation system. Certain disclosed techniques involve passive, mechanical valve designs that promote variable resistance to flow in a drain. Other techniques involve automated flow control schemes that utilize feedback from flow meters, level sensors, etc. to achieve a balanced and bubble-free flow. The disclosed embodiments greatly reduce the incorporation of gas into a processing fluid, in particular as the processing fluid returns from a processing cell to a reservoir.