Silicon Nitride Metal Covers for Moisture-Resistant Package Interconnects

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Solution Overview

Problem

Semiconductor packages face challenges with corrosion and metal migration due to exposed conductive layers, which can lead to structural and functional integrity issues.

Innovation Solution

A silicon nitride layer with specific thickness and film stress ranges is deposited using vapor deposition techniques to protect metal layers, enhancing moisture resistance and durability, and mitigating migration and corrosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conductive layers are exposed to provide electrical connections, then electrical conductivity is improved, but corrosion and metal migration occur reducing reliability

Engineering Contradiction:

Improveresistance to corrosion and metal migrationVSAvoidexposure to moisture and environmental factors

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A thin film protective layer (50-500 nanometers) is deposited over the exposed conductive layers to provide environmental protection while maintaining electrical functionality. This thin film acts as a barrier against moisture and corrosive elements, preventing degradation of the underlying metal conductors without significantly increasing package thickness.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective structure combines multiple materials with complementary properties: the conductive metal layer provides electrical functionality, while the overlying protective film (such as silicon nitride, silicon oxide, or polymer coatings) provides environmental resistance. This composite structure addresses both electrical and protective requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a protective layer is added to block moisture and corrosion, then reliability is improved, but package thickness increases

Engineering Contradiction:

Improveprotection against corrosion and migrationVSAvoidpackage thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Ultra-thin protective films ranging from 50 to 500 nanometers are applied over the conductive layers. This thickness is sufficient to provide effective barrier protection against moisture and corrosion while adding minimal dimension to the overall package thickness, thus resolving the contradiction between protection and compactness.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective layer thickness is optimized within a specific range (50-500 nm) to achieve the desired balance between protective performance and package thickness. This parameter optimization ensures adequate corrosion resistance while maintaining thin-profile package requirements.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If vapor deposition is used to deposit silicon nitride layer, then moisture resistance is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvemoisture resistanceVSAvoiddeposition process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Vapor deposition techniques (such as chemical vapor deposition or plasma-enhanced chemical vapor deposition) replace traditional liquid coating or physical lamination methods. This substitution provides more uniform film coverage, better adhesion to the substrate, and superior moisture barrier properties, though it requires specialized equipment and process control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 silicon nitride layer effectively blocks moisture and corrosion, reduces metal migration, and maintains package integrity by providing a durable and thin protective layer, facilitating efficient package manufacturing and performance.

Implementation Method 1

using a vapor deposition technique to deposit a silicon nitride layer on the first conductive layer at a pressure lower than 100 Torr

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentUS11876056B2Silicon nitride metal layer covers

Publication Date: 2024.01.16 TEXAS INSTRUMENTS INC

AI summary

In some examples, a semiconductor package includes a semiconductor die; a passivation layer abutting a device side of the semiconductor die; a first conductive layer abutting the device side of the semiconductor die; a second conductive layer abutting the first conductive layer and the passivation layer; a silicon nitride layer abutting the second conductive layer, the silicon nitride layer having a thickness ranging from 300 Angstroms to 3000 Angstroms; and a third conductive layer coupled to the second conductive layer at a gap in the silicon nitride layer, the third conductive layer configured to receive a solder ball.