Electrodeposited Gold Electrode Surface State Control

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Solution Overview

Problem

Anomalous appearance reports in semiconductor devices due to false detection of gold precipitates as foreign substances during electrolytic gold plating, caused by surface state changes from rough to smooth due to aging variations in the plating solution composition, leading to increased manufacturing costs and reduced yield.

Innovation Solution

A method of forming an electrodeposited gold electrode by alternately repeating energization and no energization between anode and cathode electrodes during the electrolytic gold plating process, using a plating apparatus with a stirrer or jet to maintain a rough surface state and prevent false reports by controlling the energization ON and OFF times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If continuous energization is applied during electrolytic gold plating, then plating efficiency is improved, but surface state varies from rough to smooth due to aging in plating solution

Engineering Contradiction:

Improveplating efficiencyVSAvoidsurface state stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies periodic action by alternately repeating energization and no-energization periods during electrolytic gold plating. This periodic cycling prevents the continuous crystal growth that causes surface smoothing, thereby maintaining surface roughness while still achieving plating formation. The method divides continuous plating into discrete cycles, allowing surface state stabilization without sacrificing overall plating efficiency.

Inventive Principle:

Principle #19Periodic action

2Quantity of substance

If plating solution composition changes with aging, then surface state changes from rough to smooth, but false detection of foreign substances increases

Engineering Contradiction:

Improveplating solution composition stabilityVSAvoidappearance inspection accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

By implementing periodic energization and no-energization cycles, the patent maintains consistent surface roughness throughout the plating process even as plating solution composition ages. This consistency prevents the surface state changes that lead to false foreign substance detections during appearance inspection, thereby improving measurement precision without requiring frequent plating solution replacement.

Inventive Principle:

Principle #19Periodic action

3Stability of the object's composition

If plating solution is replaced frequently to maintain composition, then surface state stability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvesurface state consistencyVSAvoidmanufacturing cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The periodic energization method allows the plating solution to be used for extended periods without replacement while maintaining surface state consistency. By controlling crystal growth through cyclic energization, the patent eliminates the need for frequent solution changes, thereby reducing manufacturing costs while preserving surface roughness stability throughout the plating solution's service life.

Inventive Principle:

Principle #19Periodic action

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 method effectively suppresses surface state variations of the electrodeposited gold electrode, reducing false reports in appearance inspections and maintaining a rough surface state, thereby decreasing manufacturing costs and improving yield.

Implementation Method 1

an electrodeposited gold electrode is formed by an electrolytic gold plating process

Methodology Applied

Scientific EffectElectrolysis: Electrolysis

Implementation Method 2

forming a gold bump electrode by an electrolytic gold plating technique

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Implementation Method 3

performing energization between an anode electrode and a cathode electrode provided in a treatment cup of a plating apparatus to cause crystal growth of a electrodeposited gold layer

Methodology Applied

Scientific EffectCrystal growth: Crystallisation

Data Source

PatentUS9735017B2Method of manufacturing semiconductor device

Publication Date: 2017.08.15 RENESAS ELECTRONICS CORP

AI summary

A false report on appearance inspection of a semiconductor device is prevented by suppressing variation in surface state of an electrodeposited gold electrode. In formation of an electrodeposited gold electrode, an electrodeposited gold electrode comprised of a plurality of electrodeposited gold layers in the stack is formed by alternately repeating a step of performing energization between an anode electrode and a cathode electrode provided in a treatment cup of a plating apparatus to cause crystal growth of an electrodeposited gold layer (energization ON), and a step of performing no energization between the anode electrode and the cathode electrode (energization OFF). Consequently, even if aging variation occurs in composition of the plating solution, variation in surface state of the electrodeposited gold electrode is suppressed, and a surface state with a surface roughness of, for example, about 0.025 rad can be maintained.