Alpha Ray Shielding Film on Cover Glass for Image Pickup Devices

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Solution Overview

Problem

Existing semiconductor devices face challenges in reducing the influence of alpha rays emitted from cover glasses, which can cause defects and reliability issues, particularly in image pickup devices, due to the complexity and thickness limitations of alpha-ray shielding technologies.

Innovation Solution

A semiconductor device is developed with a cover glass bonded to an image pickup device, featuring a film with a specific gravity and a transparent resin to shield alpha rays, where the film's thickness and resin's thickness are optimized to create a distance that reduces alpha ray influence, and the film is strategically formed only over pixel regions to minimize process time and maintain device thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If an alpha-ray-shielding film is formed on the cover glass and bonded with transparent adhesive, then the alpha ray influence is reduced, but the process time increases due to individual bonding requirements

Engineering Contradiction:

Improvealpha ray influenceVSAvoidprocess time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent segments the cover glass into multiple regions, with alpha-ray-shielding films formed only on specific pixel sections rather than the entire cover glass. This selective segmentation reduces the bonding area and process time while maintaining adequate alpha ray shielding for the functional regions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different properties to different regions of the cover glass: alpha-ray-shielding films are formed only on pixel sections where radiation protection is needed, while other regions maintain original properties. This local quality approach optimizes both shielding effectiveness and manufacturing efficiency.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the transparent adhesive thickness is increased to reduce alpha ray influence, then the shielding effect improves, but warpage increases during thermal history

Engineering Contradiction:

Improvealpha ray influenceVSAvoidwarpage

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The patent creates a composite structure combining the cover glass, alpha-ray-shielding film, transparent adhesive, and image pickup device. This composite design allows the system to achieve adequate alpha ray shielding through the combined thickness and density of multiple layers, rather than relying solely on increased adhesive thickness, thereby reducing warpage during thermal processing.

Inventive Principle:

Principle #40Composite materials

3Productivity

If the image pickup device thickness is reduced to enable WL-CSP production, then manufacturing efficiency improves, but reliability deteriorates due to increased damage susceptibility

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoiddevice reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent incorporates an alpha-ray-shielding film as a protective layer before the image pickup device is diced into individual chips. This beforehand protection shields the device during manufacturing and operation, compensating for the reduced mechanical strength inherent in thinner WL-CSP structures and improving overall reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Object-affected harmful factors

If an oxide film is formed at the image pickup device side for alpha ray shielding, then the shielding function is achieved, but the film thickness is limited due to warpage constraints

Engineering Contradiction:

Improvealpha ray shieldingVSAvoidfilm thickness

Core Design Contradiction:

Object-affected harmful factorsVSLength of stationary object

Solution Approach 1:

Instead of forming the alpha-ray-shielding film on the image pickup device side (which causes warpage), the patent inverts the approach by forming the shielding film on the cover glass side. This inversion eliminates the warpage problem while maintaining effective alpha ray shielding, allowing for greater film thickness without compromising device stability.

Inventive Principle:

Principle #13The other way round (Inversion)

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 effectively reduces alpha ray influence on image pickup devices, enhancing reliability and manufacturing efficiency by optimizing the thickness and placement of the alpha-ray shielding film and transparent resin, while maintaining a thin semiconductor device structure.

Implementation Method 1

a film provided between the image pickup device and the cover glass, the film having a predetermined specific gravity and configured to shield an alpha ray that arises from the cover glass

Methodology Applied

Scientific EffectAlpha ray shielding: Absorption (EM radiation)

Data Source

PatentUS10446598B2Semiconductor device, manufacturing method, and electronic apparatus

Publication Date: 2019.10.15 SONY GROUP CORP

AI summary

A method of manufacturing a semiconductor device includes: forming, on a cover glass, a film having a predetermined specific gravity and configured to shield an alpha ray that arises from the cover glass; and bonding the cover glass on which the film is formed and an image pickup device, by filling a transparent resin between the cover glass and the image pickup device.