Flip-Chip Memory Modules With Rear Passivation Layer

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Solution Overview

Problem

The existing semiconductor memory modules face limitations in expanding memory capacity to meet increasing user demands, and there is a need for enhanced protection of memory chips mounted using the flip-chip bonding method.

Innovation Solution

The implementation of a passivation layer on the rear surface of memory chips, which can be of a different color from single-crystalline silicon, formed through wafer processes, deposition, or coating methods, including oxide or nitride layers, to protect the chips during flip-chip bonding and provide improved reliability and aesthetic appeal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If memory chips are mounted using flip-chip bonding method, then mounting density and electrical performance are improved, but protection of rear surface of memory chips deteriorates

Engineering Contradiction:

Improvemounting densityVSAvoidprotection of rear surface

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A passivation layer is formed on the rear surface of the memory chip before the flip-chip bonding mounting process. This preliminary protective action ensures that the rear surface is protected from damage during the mounting process and subsequent handling, while still allowing the chip to be mounted with high density using the flip-chip bonding method.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The passivation layer serves as a cushioning protective layer on the rear surface of the memory chip. It absorbs mechanical stress and prevents direct damage to the silicon substrate during the flip-chip bonding process, providing beforehand cushioning against potential damage from the mounting process.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If passivation layer is formed on rear surface of memory chips, then protection and reliability are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveprotection of memory chipsVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The passivation layer formation process is merged with the existing memory chip fabrication process. The same deposition equipment and process conditions used for forming passivation layers on the front surface are utilized for the rear surface, consolidating equipment usage and reducing overall manufacturing complexity despite the additional step.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The passivation layer serves multiple functions simultaneously: it protects the rear surface from mechanical damage, provides electrical insulation, and can serve as a stress management layer. This multi-functionality reduces the need for additional separate protective layers or processes, thereby limiting the increase in manufacturing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If passivation layer is formed by deposition or coating method, then protection is improved, but manufacturing cost and process time increase

Engineering Contradiction:

Improveprotection layer qualityVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The mechanical coating process is replaced with a vapor-phase deposition process. Instead of physically applying coating material through mechanical means, the passivation layer is formed by depositing material from the vapor phase, which is a more efficient and controllable process that integrates better with existing semiconductor fabrication equipment and maintains high manufacturing throughput.

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

This solution allows for the direct mounting of memory chips on module boards with enhanced protection and reliability, meeting user demands for capacity and appearance, while maintaining the high performance of semiconductor memory modules.

Implementation Method 1

the passivation layer may be formed by a deposition method or a coating method

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

the passivation layer may be formed by a deposition method or a coating method

Methodology Applied

Scientific EffectCoating: Coatings

Data Source

PatentUS8866295B2Semiconductor memory modules and methods of fabricating the same

Publication Date: 2014.10.21 SAMSUNG ELECTRONICS CO LTD

AI summary

The inventive concept provides semiconductor memory modules and methods of fabricating the same. The semiconductor memory module may include a module board having a first surface and a second surface opposite to the first surface, and memory chips mounted directly on the module board by a flip-chip bonding method. Each of the memory chips may include a passivation layer disposed on a rear surface of each of the memory chips, and the passivation layer may have a color different from a natural color of single-crystalline silicon.