Plating Apparatus Gas Bubble Collector Pleated Channels
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Solution Overview
Problem
Conventional plating apparatuses for ULSI circuit fabrication face issues with non-uniform current density leading to uneven plating rates, gas bubbles causing voids in the plated film, and accumulation of organic additives' break-down products, which affect device reliability and yield.
Innovation Solution
A plating apparatus with a gas bubble collector featuring pleated channels to coalesce and remove small bubbles, an electrolyte flow field control subsystem to manage organic additives and byproducts, and a buffer zone to allow microbubbles to dissolve, ensuring uniform plating and reduced impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas bubbles are present in the electrolyte, then the plating process can proceed, but voids form in the plated film and device yield drops
Solution Approach 1:
The patent extracts and removes gas bubbles from the electrolyte using a de-bubble device with a porous layer. The bubbles are separated from the electrolyte flow path, allowing continuous plating operation without void formation in the plated film, thus maintaining both productivity and device yield.
Solution Approach 2:
The porous layer in the de-bubble device acts as an intermediary element between the electrolyte and the plating surface. It allows electrolyte to pass through while capturing and removing gas bubbles, preventing them from reaching the wafer surface and causing defects.
2Object-affected harmful factors
If a porous layer de-bubble device is used, then gas bubbles can be removed, but small bubbles cannot be effectively moved by buoyancy and adhesion forces
Solution Approach 1:
The patent employs a porous layer as the core component of the de-bubble device. The porous structure provides extensive surface area and capillary action that effectively captures and removes small bubbles from the electrolyte, overcoming the limitation of conventional de-bubble devices that rely solely on buoyancy forces.
Solution Approach 2:
The porous layer creates multiple smaller flow paths and surfaces that replicate and enhance the bubble capture mechanism throughout the electrolyte flow, ensuring comprehensive removal of small bubbles without requiring large-scale structural changes.
3Manufacturing precision
If more organic additives are used in the plating solution, then void-free gapfill is achieved, but break-down products accumulate and degrade gapfill performance
Solution Approach 1:
The patent implements continuous electrolyte circulation and refreshment systems that maintain constant supply of fresh organic additives to the plating surface while continuously removing break-down products. This continuous action ensures sustained gapfill quality without accumulation of harmful byproducts.
Solution Approach 2:
The system discards accumulated break-down products through continuous electrolyte replacement and circulation, while recovering and replenishing fresh organic additives. This maintains the optimal chemical composition in the electrolyte, ensuring consistent plating quality.
4Reliability
If higher bath bleed and feed rate is implemented, then chemical freshness is ensured, but cost increases
Solution Approach 1:
The patent implements dynamic control of electrolyte circulation rates, adjusting feed and bleed rates based on real-time process conditions, bubble presence, and chemical composition. This dynamic adjustment ensures electrolyte freshness is maintained only when necessary, reducing overall consumption and cost.
Solution Approach 2:
The system incorporates monitoring and feedback mechanisms that track electrolyte condition, bubble generation rates, and plating quality. Based on this feedback, the electrolyte circulation system automatically adjusts flow rates to maintain optimal freshness without excessive consumption, balancing quality and cost.
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 achieves uniform plating rates, reduces void formation, and improves device reliability by efficiently removing byproducts and maintaining electrolyte freshness, leading to better gapfill performance and reduced impurities in the plated metal film.
Implementation Method 1
a gas bubble collector (by forced bubbles coalescence)
Implementation Method 2
The pleated channels further creates a large surface area of the bubble collector therefore increasing total electrolyte flow-through area
Implementation Method 3
The buffer zone allows time for micro bubbles that passed the bottom membrane to dissolve before reaching the top membrane
Implementation Method 4
Electrochemical deposition of a metallic layer, usually copper, on a thin resistive substrate—a seed layer—during interconnection formation in ULSI is realized in a plating apparatus
Implementation Method 5
fresh active organic species and break-down byproducts exchange rate in the electrolyte near wafer surface, which is mass transport controlled
Data Source
AI summary
The present invention provides a plating apparatus with multiple anode zones and cathode zones. The electrolyte flow field within each zone is controlled individually with independent flow control devices. A gas bubble collector whose surface is made into pleated channels is implemented for gas removal by collecting small bubbles, coalescing them, and releasing the residual gas. A buffer zone built within the gas bubble collector further allows unstable microscopic bubbles to dissolve.