Dome-Shaped SnTi Bump Terminal Structure for Semiconductor Modules

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Solution Overview

Problem

Conventional methods for forming bumps on semiconductor electrodes often result in insufficient strength, leading to peeling and breakage issues due to exposed interfaces between the bumps and under bump metal layers.

Innovation Solution

A terminal structure with a dome-shaped bump containing Sn and Ti, where the under bump metal layer is formed with Ni and has an upper surface lower than the insulating covering layer, ensuring the interface between the bump and under bump metal layer is blocked by the inner wall of the insulating covering layer, enhancing strength and reducing profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the bump is formed with the interface between the bump and under bump metal layer exposed outside the opening portion, then the manufacturing process is simpler, but the bump strength is insufficient and peeling occurs easily

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidbump strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The insulating covering layer is formed to extend beyond the opening portion before bump formation, creating a pre-established barrier that will subsequently block the interface between the bump and under bump metal layer. This preliminary structural preparation prevents the interface exposure problem before it occurs during the manufacturing process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The insulating covering layer acts as an intermediary element between the bump and the external environment. By extending this insulating layer beyond the opening, it mediates the interface blocking function, preventing direct exposure of the bump-under bump metal layer interface while maintaining manufacturing feasibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the under bump metal layer is formed higher than the insulating covering layer, then the bump can be formed more easily, but the profile height increases and strength is reduced

Engineering Contradiction:

Improvebump formation easeVSAvoidprofile height

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

The solution shifts the focus from vertical height adjustment to horizontal extension of the insulating covering layer. By extending the insulating layer in the radial direction beyond the opening portion, the interface blocking function is achieved without requiring reduction of the under bump metal layer height, thus maintaining ease of bump formation while reducing profile height.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Strength

If the interface between the bump and under bump metal layer is blocked by the insulating covering layer, then the bump strength is enhanced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvebump strengthVSAvoidinterface blocking precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The insulating covering layer is formed with extended dimensions before the bump formation process begins. This preliminary over-extension creates a built-in tolerance buffer that accommodates manufacturing variations during subsequent steps, reducing the actual precision requirements while ensuring the interface blocking function is achieved.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dimensions of the insulating covering layer are changed to extend beyond the opening portion, creating a dimensional parameter that provides manufacturing tolerance. This parameter change transforms the precision requirement from a tight fit scenario to a more tolerant overlap scenario, enhancing bump strength while easing manufacturing precision demands.

Inventive Principle:

Principle #35Parameter changes

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 terminal structure achieves improved bump strength and reduced breakage by ensuring the interface between the bump and under bump metal layer is not exposed, allowing for more reliable contact and enhanced durability.

Implementation Method 1

electrolytic plating is performed in the order of electrolytic nickel plating and electrolytic solder plating to form under bump metal layers 50 and solder plating layers 60

Methodology Applied

Scientific EffectElectrolytic plating: Electrodeposition

Implementation Method 2

by placing the entire substrate in a reflow furnace and heating it, bumps 65 are formed

Methodology Applied

Scientific EffectReflow heating: Heating

Data Source

PatentUS9257402B2Terminal structure, and semiconductor element and module substrate comprising the same

Publication Date: 2016.02.09 TDK CORP

AI summary

A preferred terminal structure comprises a base material; an electrode formed on the base material; an insulating covering layer formed on the base material and on the electrode and having an opening exposing at least part of the electrode; an under bump metal layer containing Ni, formed in a region in the opening on the electrode so that an upper surface of the metal layer is at a position lower than an upper surface of the insulating covering layer in a peripheral edge portion of the opening; and a dome-shaped bump containing Sn and Ti, formed in a region in the opening on the under bump metal layer, wherein an end portion of a boundary between the under bump metal layer and the bump is in contact with an inner wall of the opening portion in the insulating covering layer.