Through Electrode Head Shape for Wafer Bonding Strength

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Solution Overview

Problem

In 3D and 2.5D semiconductor device integration technologies, achieving adequate bonding strength between the upper surface of a wafer and a supporting substrate is challenging due to the height and shape of the bump or protrusion on the upper surface, leading to potential bonding breakdown during machining of the lower surface.

Innovation Solution

The semiconductor device features a through electrode with a head shape where the perimeter on the lower surface is smaller than on the upper surface, incorporating a depression on the side surface to increase the contact area and adhesion strength using an adhesive, enhancing the bonding strength between the wafer and the supporting substrate through an anchor effect.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a bump or protrusion is formed on the upper surface of the wafer, then subsequent joining functionality is enabled, but bonding strength between the wafer and supporting substrate decreases

Engineering Contradiction:

Improvejoining functionalityVSAvoidbonding strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The through electrode is segmented into two functional parts: a head portion on the upper surface that provides joining functionality, and a body portion extending through the wafer that provides bonding strength. This segmentation allows each part to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution transitions from a two-dimensional surface bump to a three-dimensional through-electrode structure that extends vertically through the wafer. This dimensional change allows the bonding strength to be provided along the vertical axis while the joining functionality is maintained at the upper surface.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the wafer is ground to reduce thickness, then device integration density improves, but bonding breakdown risk increases

Engineering Contradiction:

Improveintegration densityVSAvoidbonding reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The through electrode is formed with an enlarged head portion before the wafer thinning process. This preliminary action ensures that the bonding interface is already strengthened with the anchor effect in place before the wafer is ground to reduce thickness, preventing bonding breakdown during subsequent machining operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The anchor effect created by the depression in the through electrode head provides a cushioning reinforcement to the bonding interface. This beforehand cushioning compensates for the increased stress and risk of bonding breakdown that results from reducing wafer thickness through grinding.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If adhesive contact area is increased, then bonding strength improves, but device structure complexity increases

Engineering Contradiction:

Improvebonding strengthVSAvoidstructure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The through electrode structure merges multiple functions into a single component: it provides electrical connection, mechanical bonding reinforcement through the anchor effect, and structural support. This merging eliminates the need for separate bonding structures, achieving increased adhesive contact area without proportionally increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 configuration increases the bonding strength between the semiconductor device and the supporting substrate by expanding the adhesive contact area and utilizing an anchor effect, ensuring robust bonding even during machining processes.

Implementation Method 1

bonding between the upper surface of the wafer and the supporting substrate is required to have high strength

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

incorporating a depression on the side surface to increase the contact area and adhesion strength using an adhesive, enhancing the bonding strength between the wafer and the supporting substrate through an anchor effect

Methodology Applied

Scientific EffectAnchor effect: Mechanical Fastener

Data Source

PatentUS9881851B2Semiconductor device and method for producing semiconductor device

Publication Date: 2018.01.30 KIOXIA CORP

AI summary

A semiconductor device includes a semiconductor substrate, a device layer located at an upper surface of the semiconductor substrate, an insulating layer located on the device layer, and a through electrode. The through electrode includes a body located in a through hole provided in the insulating layer and a head located on the body and the insulating layer and is electrically connected to an upper-layer wiring in the device layer. A perimeter of the head on a lower surface side thereof is smaller than a perimeter of the head on an upper surface side thereof.