Anolyte Diluent Dosing for Copper Electroplating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing electroplating processes for copper in semiconductor manufacturing face challenges with copper salt precipitation in the anode chamber, leading to anode passivation and high bleed and feed rates, which increase operational costs and risk membrane damage due to electroosmotic effects.
Innovation Solution
An electroplating method and apparatus that control the composition of the anolyte by adding a diluent to the recirculating anolyte, allowing for pre-determined dosing schedules to maintain copper salt concentrations below precipitation levels and compensate for water loss, thereby reducing the need for high bleed and feed rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high bleed and feed rates are used to maintain electrolyte composition, then copper salt precipitation is prevented, but operational costs increase and membrane damage risk increases due to electroosmotic effects
Solution Approach 1:
The system employs a controller that monitors copper ion concentration in the anolyte and automatically adjusts the dosing rate of copper sulfate solution and diluent addition. This closed-loop feedback control maintains copper salt concentration within optimal ranges, preventing precipitation while minimizing unnecessary electrolyte replacement and reducing operational costs.
Solution Approach 2:
The invention dynamically adjusts key parameters including copper sulfate dosing rate, diluent addition rate, and anolyte flow rate based on real-time copper ion concentration measurements. By changing these parameters adaptively rather than using fixed high bleed and feed rates, the system prevents precipitation while reducing energy consumption and membrane damage risk.
2Productivity
If copper salt concentration is maintained high in anolyte, then copper deposition efficiency is improved, but copper salt precipitation occurs leading to anode passivation
Solution Approach 1:
The controller continuously monitors copper ion concentration and adjusts copper sulfate dosing to maintain optimal concentration levels. This feedback mechanism ensures sufficient copper availability for efficient deposition while preventing supersaturation and subsequent precipitation that would cause anode passivation.
Solution Approach 2:
The system transitions from static high concentration maintenance to dynamic concentration control. The copper sulfate dosing rate and diluent addition rate are continuously adjusted based on real-time copper ion concentration, enabling the system to adapt to changing conditions and maintain productivity without precipitation.
3Reliability
If diluent is added to recirculating anolyte to control composition, then copper salt precipitation is prevented, but electrolyte volume increases
Solution Approach 1:
The controller monitors copper ion concentration and adjusts diluent addition rate accordingly. By adding diluent only when and where needed to maintain optimal copper salt concentration, the system prevents precipitation while minimizing unnecessary volume increase compared to continuous high-rate dilution approaches.
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 prevents copper salt precipitation, reduces anode passivation, and minimizes membrane damage, achieving cost-effective and reliable copper electroplating with controlled electrolyte compositions, enhancing the operational efficiency and reliability of the electroplating process.
Implementation Method 1
adding a diluent to the recirculating anolyte, allowing for pre-determined dosing schedules to maintain copper salt concentrations below precipitation levels
Implementation Method 2
separating anodic and cathodic regions of the plating cell by a membrane because processes occurring at the anode and the cathode during electroplating are not always compatible
Implementation Method 3
electrochemically reduce cupric ions at the cathode, resulting in deposition of copper metal on the surface of the wafer seed layer
Implementation Method 4
electrochemically reduce cupric ions at the cathode, resulting in deposition of copper metal
Implementation Method 5
controlling the composition of the anolyte by providing a diluent to the recirculating anolyte
Data Source
AI summary
In a copper electroplating apparatus having separate anolyte and catholyte portions, the concentration of anolyte components (e.g., acid or copper salt) is controlled by providing a diluent to the recirculating anolyte. The dosing of the diluent can be controlled by the user and can follow a pre-determined schedule. For example, the schedule may specify the diluent dosing parameters, so as to prevent precipitation of copper salt in the anolyte. Thus, precipitation-induced anode passivation can be minimized.