Auxiliary Leveler Additive Analysis in Acid Copper Plating

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Solution Overview

Problem

Conventional cyclic voltammetric stripping methods are unable to detect the auxiliary leveler additive in acid copper electroplating baths, which is crucial for achieving precise control over copper deposition rates in advanced microelectronic features like through-silicon vias and Damascene processes.

Innovation Solution

The method involves analyzing the auxiliary leveler additive using cyclic voltammetry at a noble metal rotating disk electrode, focusing on the anodic current at very positive potentials in the oxygen evolution region, with a baseline subtraction and charge integration technique to enhance sensitivity, and utilizing an automated apparatus with a computing device for precise measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional cyclic voltammetric stripping methods are used for analysis, then the measurement method is simple and widely applicable, but the auxiliary leveler additive cannot be detected

Engineering Contradiction:

Improvedetection capabilityVSAvoidmeasurement complexity

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent changes the measurement parameters by focusing on the anodic current at very positive potentials (oxygen evolution region) rather than the conventional cathodic stripping peak. By integrating the anodic current over a specific potential range and subtracting a baseline, the method enables detection of the auxiliary leveler additive that is invisible to conventional CVS methods, thus improving measurement precision without excessive complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from measuring cathodic current (conventional dimension) to measuring anodic current in the oxygen evolution region (new dimension). This dimensional shift in the voltammogram allows detection of species that do not produce conventional stripping signals, resolving the contradiction between detection capability and measurement complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the concentration of auxiliary leveler additive is not controlled, then the plating process is simpler, but the deposit quality and leveling characteristics deteriorate

Engineering Contradiction:

Improvedeposit qualityVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual trial-and-error additive control with an automated electrochemical measurement system. The computing device automatically performs cyclic voltammetry, integrates anodic currents, subtracts baselines, and determines additive concentrations, substituting mechanical/manual processes with automated electrochemical analysis to improve deposit quality control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent establishes a feedback loop where the measured auxiliary leveler additive concentration is used to adjust and control the plating bath composition. This feedback mechanism ensures optimal deposit quality and leveling characteristics by maintaining precise control over additive concentrations based on actual measurements rather than estimates

Inventive Principle:

Principle #23Feedback

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 allows for accurate determination of the auxiliary leveler additive concentration, improving the quality of copper deposits and enabling effective control of plating processes for complex microelectronic features, particularly in three-dimensional assembly of integrated circuits.

Implementation Method 1

cycling the potential of an inert electrode (e.g., Pt) in the plating bath between fixed potential limits so that metal is alternately plated on and stripped from the electrode surface

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Implementation Method 2

metal is alternately plated on and stripped from the electrode surface

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Implementation Method 3

analyzing the auxiliary leveler additive using cyclic voltammetry at a noble metal rotating disk electrode, focusing on the anodic current at very positive potentials in the oxygen evolution region

Methodology Applied

Scientific EffectCyclic voltammetry:

Implementation Method 4

anodic current at very positive potentials in the oxygen evolution region

Methodology Applied

Scientific EffectOxygen evolution:

Implementation Method 5

with a baseline subtraction and charge integration technique to enhance sensitivity

Methodology Applied

Scientific EffectCharge integration:

Data Source

PatentUS8535504B2Analysis of an auxiliary leveler additive in an acid copper plating bath

Publication Date: 2013.09.17 KLA CORP

AI summary

An auxiliary leveler additive that cannot be analyzed by conventional CVS methods for acid copper plating baths is analyzed by cyclic voltammetry at a platinum rotating disk electrode from its effect on the anodic current at very positive potentials.