Stacked Semiconductor Devices Using Photosensitive Adhesive Layers

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The challenge in stacked semiconductor devices is the combination of surface protection films and adhesive layers resulting in increased thickness and fabrication issues, particularly when stacking multiple chips, as existing methods fail to ensure reliable adhesion and prevent separation from suction collets during the chip stacking process.

Innovation Solution

A combined surface protection film and adhesive layer with photosensitivity is formed on semiconductor wafers, allowing for single-step processing, exposure, and development to create openings for electrode pads, enabling reliable adhesion between chips and reducing defects by controlling viscosity and surface roughness of the suction collet, ensuring effective bonding and separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a surface protection film and adhesive layer are formed as separate layers, then the protective function and adhesion function are ensured, but the stacked device thickness increases

Engineering Contradiction:

Improveprotective function and adhesion functionVSAvoidstacked device thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent combines the surface protection film and adhesive layer into a single integrated layer that performs both protective and adhesive functions simultaneously, eliminating the need for separate layers and thereby reducing the overall thickness of stacked semiconductor devices while maintaining both protection and adhesion reliability

Inventive Principle:

Principle #5Merging (Combining)

2Length of stationary object

If a combined surface protection film and adhesive layer is used, then the thickness is reduced and processing is simplified, but fabrication issues occur during chip stacking

Engineering Contradiction:

Improvestacked device thicknessVSAvoidfabrication reliability

Core Design Contradiction:

Length of stationary objectVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating a combined protection-adhesive layer with spatially varying properties: the layer has different adhesion strengths at different locations, with stronger adhesion to the circuit side and controlled adhesion to the non-circuit side, enabling reliable chip-to-chip bonding while preventing unwanted adhesion to suction collets during fabrication

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by controlling the adhesion characteristics of the combined layer through material composition and structural parameters, adjusting the adhesion strength to achieve optimal bonding during stacking while preventing separation issues during the fabrication process

Inventive Principle:

Principle #35Parameter changes

3Reliability

If common package stacking process is used with combined protection-adhesive layer, then adhesion reliability between chips is ensured, but separation from suction collet occurs

Engineering Contradiction:

Improveadhesion reliability between chipsVSAvoidseparation from suction collet

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The combined protection-adhesive layer exhibits local quality with differentiated adhesion characteristics: it provides strong adhesion between chip surfaces while maintaining controlled, lower adhesion to the suction collet surface, preventing harmful separation during the stacking process

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

This approach reduces the thickness of stacked semiconductor devices, enhances adhesion reliability between chips, and minimizes defects caused by suction collet separation, improving the overall yield and reliability of the stacking process.

Implementation Method 1

Methodology Applied

Scientific EffectPhotosensitivity: Photopolymerisation

Implementation Method 2

The suction collet has a suction side with lower adhesion to the combined surface protection film and adhesive layer than adhesion between the first semiconductor chip and the second semiconductor chip

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS8796076B2Stacked semiconductor devices and fabrication method/equipment for the same

Publication Date: 2014.08.05 KIOXIA CORP

AI summary

After formation of an opening by exposing and development of the photosensitive surface protection film and adhesive layer which is formed on the circuit side of the semiconductor wafer, the semiconductor chips having a photosensitive surface protection film and adhesive layer thereon is fabricated by cutting individual chips from the semiconductor wafer. After the second semiconductor chip is placed over the first semiconductor chip up by the suction collet, the second semiconductor chip is bonded with the first semiconductor chip by the first surface protection film and adhesive layer. The suction side of the suction collet has lower adhesion to the second semiconductor chip than that between the now bonded semiconductor chips.