Electroplating System Oxygen Degassing and Oxidation Control

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Solution Overview

Problem

Conventional copper electroplating processes face issues such as air bubble formation, seed layer corrosion, and additive degradation due to high oxygen concentrations in plating solutions, leading to defects and reduced plating solution stability.

Innovation Solution

The method involves degassing the plating solution to reduce oxygen concentrations to 0.1-1 ppm before electroplating and increasing the oxidizing strength of the solution after plating to maintain additive stability and prevent corrosion, using a system comprising a degassing device and an oxidation station.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the oxygen concentration in the plating solution is reduced to improve plating stability and reduce defects, then air bubble formation and seed layer corrosion are reduced, but the oxidizing strength decreases leading to additive degradation

Engineering Contradiction:

Improveplating solution stabilityVSAvoidadditive degradation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The plating system is divided into two distinct functional zones: a degassing zone where oxygen is removed from the plating solution to prevent defects and corrosion, and a separate oxidation zone where oxidizing strength is restored to prevent additive degradation. This spatial segmentation allows both low oxygen concentration and sufficient oxidizing strength to coexist at different locations in the system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediary oxidation station is introduced between the plating cell and the plating solution reservoir. This intermediary component removes oxygen from the plating solution after it leaves the plating cell and before it returns to the reservoir, thereby restoring oxidizing strength without introducing oxygen back into the plating cell where it would cause defects.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional electroplating processes are used with standard oxygen levels, then the process is simple and fast, but air bubble defects and seed layer corrosion occur

Engineering Contradiction:

Improveplating speedVSAvoidair bubble defects

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The degassing device performs preliminary removal of oxygen from the plating solution before the solution enters the plating cell. This preliminary action prevents the formation of air bubbles and seed layer corrosion during the electroplating process, while maintaining fast plating speeds through continuous operation.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If oxygen concentration is maintained at high levels to ensure oxidizing strength, then additive stability is improved, but air bubble formation and corrosion increase

Engineering Contradiction:

Improveadditive stabilityVSAvoidseed layer corrosion

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The system implements local quality by creating different oxygen concentration conditions in different spatial locations: the plating cell maintains low oxygen concentration (0.1-1 ppm) to prevent corrosion and defects, while the oxidation station and reservoir maintain high oxidizing strength to prevent additive degradation. Each location has the specific quality it needs for its function.

Inventive Principle:

Principle #3Local quality

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 reduces air bubble defects, seed layer corrosion, and additive degradation, improving plating solution stability and fill performance while maintaining the desired oxidizing conditions for effective metal deposition.

Implementation Method 1

reducing an oxygen concentration of a plating solution... The oxygen concentration of the plating solution in the plating cell is about 1 part per million or less

Methodology Applied

Scientific EffectDegassing:

Implementation Method 2

A metal is electroplated with the plating solution onto the wafer substrate in the plating cell

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 3

After plating, an oxidizing strength of the plating solution is increased

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS10745817B2Configuration and method of operation of an electrodeposition system for improved process stability and performance

Publication Date: 2020.08.18 NOVELLUS SYSTEMS INC

AI summary

In one aspect, an apparatus includes a plating cell, a degassing device configured to remove oxygen from the plating solution prior to the plating solution flowing into the plating cell; an oxidation station configured to increase an oxidizing strength of the plating solution after the plating solution flows out of the plating cell; and a controller. The controller includes program instructions for causing a process that includes operations of: reducing an oxygen concentration of the plating solution where the plating solution contains a plating accelerator; then, contacting a wafer substrate with the plating solution having reduced oxygen concentration and electroplating a metal such that the electroplating causes a net conversion of the accelerator to a less-oxidized accelerator species within the plating cell; then increasing the oxidizing strength of the plating solution causing a net re-conversion of the less-oxidized accelerator species back to the accelerator outside the plating cell.