Copper Plating Electrode Structure for Uniform Current Distribution

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Solution Overview

Problem

Conventional semiconductor devices face challenges in minimizing on-resistance and enabling miniaturization due to uneven current distribution and increased complexity with multiple wires or metal frames, which lead to defects and cost increases.

Innovation Solution

A semiconductor device with an electrode structure featuring a copper plating layer formed by electrolytic plating, covered by a passivation film to prevent oxidation, allowing for flexible bonding portion design and reduced resistance, thereby minimizing uneven operation and enabling miniaturization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple wires are used to connect the source electrode and lead, then current distribution becomes more even, but device complexity and defect risk increase

Engineering Contradiction:

Improvecurrent distribution uniformityVSAvoidnumber of wires

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple wire connections into a single wire by introducing a copper plating layer that provides multiple bonding regions. The copper plating layer with its low in-plane resistance allows current to distribute evenly across multiple operation cells through a single wire connection, eliminating the need for multiple separate wires while maintaining uniform current distribution.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The copper plating layer acts as an intermediary between the source electrode and the wire connection. It provides a low-resistance pathway that distributes current evenly to multiple operation cells, mediating between the single wire connection and the multiple operation cells to achieve uniform current distribution without requiring multiple wires.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a metal frame is used to connect the source electrode and lead, then in-plane resistance is reduced, but manufacturing complexity and alignment difficulty increase

Engineering Contradiction:

Improvein-plane resistanceVSAvoidalignment difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the structural parameter of the connection from a wide metal frame to a thin copper plating layer. The copper plating layer maintains low in-plane resistance while being easily formable through electroplating processes, avoiding the alignment and manufacturing complexities associated with metal frames.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical metal frame structure with an electroplated copper layer. This substitution eliminates the need for complex alignment and mechanical assembly processes, as the copper plating layer can be directly formed on the source electrode through electroplating, significantly simplifying manufacturing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the source electrode covers all operation cells, then current distribution becomes uneven, but miniaturization is limited

Engineering Contradiction:

Improvecurrent distribution uniformityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent applies local quality by creating a copper plating layer with specific properties (low in-plane resistance) at the bonding region. This localized enhancement allows the source electrode to maintain its coverage over all operation cells while the copper plating layer ensures uniform current distribution, enabling both full coverage and miniaturization.

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

The copper plating layer with a passivation film achieves low in-plane resistance, reducing current concentration and allowing for more design flexibility, thereby preventing defects and cost increases while enabling device miniaturization.

Implementation Method 1

a copper plating layer formed on the pad electrode; wherein the copper plating layer and the cap layer are continuously formed by an electrolytic plating method

Methodology Applied

Scientific EffectElectrolytic plating: Electroplating

Implementation Method 2

the copper plating layer is covered by a passivation film on its side surface

Methodology Applied

Scientific EffectOxidation prevention: Oxidation

Data Source

PatentUS8154129B2Electrode structure and semiconductor device

Publication Date: 2012.04.10 SEMICON COMPONENTS IND LLC

AI summary

In a power MOS transistor, for example, a source electrode is formed so as to be commonly connected to a plurality of source regions formed on the front surface. Thus, a current density varies based on in-plane resistance of the source electrode, thereby providing the necessity of increasing the number of wires connecting the sources and a lead. In the invention, an electrode structure includes a copper plating layer 10e formed on a pad electrode 10a by an electrolytic plating method, and a nickel plating layer 10f and a gold plating layer formed so as to cover the upper and side surfaces of the copper plating layer 10e by an electroless plating method.