Image Sensor Packaging Groove Structure for Light Reflection Control

Solution Overview

Problem

Conventional wafer level chip size packaging technologies for image sensor chips result in poor imaging quality due to the upper cover substrate disturbing light beams and causing reflection, which interferes with the sensing region.

Innovation Solution

A packaging structure and method that includes a chip unit with a sensing region and an upper cover plate structure featuring a groove structure, where the side wall includes a vertical and inclined wall, reducing the area of the second surface to prevent light reflection into the sensing region, and the height difference is determined based on the thickness of the cover plate, distance between the groove structure, and refraction index to ensure light is incident only on the top surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an upper cover substrate is formed on the sensing region to protect it during packaging, then the sensing region is protected from damage or contamination, but light beams are disturbed and reflected, causing poor imaging quality

Engineering Contradiction:

Improveprotection of sensing regionVSAvoidlight reflection and disturbance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The upper cover plate structure implements local quality by creating a groove structure at specific locations where light reflection would occur. The groove structure is positioned to selectively remove material that causes harmful light reflection while preserving the protective function in other areas. This localized modification allows the cover plate to simultaneously protect the sensing region and maintain optical quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The groove structure converts the harmful effect of light reflection into a beneficial outcome by strategically removing material to create optical pathways. The grooves are designed to redirect or eliminate reflected light beams that would otherwise interfere with imaging, transforming the potential harm of light interaction with the cover plate into improved imaging quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If the area of the second surface of the upper cover plate structure is reduced to prevent light reflection, then imaging quality is improved, but the protective coverage area is reduced

Engineering Contradiction:

Improvelight reflectionVSAvoidprotective coverage area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The upper cover plate structure is segmented into different functional zones: a first surface with larger area that provides extensive protective coverage, and a second surface with reduced area that minimizes light reflection. The groove structure further segments the plate to create specific optical pathways. This segmentation allows different portions of the cover plate to fulfill different functions simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The upper cover plate structure employs asymmetry by having the first surface area differ from the second surface area. This asymmetric design is optimized for its specific function: the larger first surface provides maximum protection during packaging, while the smaller second surface reduces light reflection interference. The groove structure adds further asymmetric features to control light pathways.

Inventive Principle:

Principle #4Asymmetry

3Volume of moving object

If wafer level chip size packaging technology is used to reduce chip size and cost, then miniaturization is achieved, but the upper cover substrate causes light interference in image sensor chips

Engineering Contradiction:

Improvechip sizeVSAvoidlight interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The upper cover plate structure implements local quality by creating a groove structure at specific locations where light reflection would occur. The groove structure is positioned to selectively remove material that causes harmful light reflection while preserving the protective function in other areas. This localized modification allows the cover plate to simultaneously protect the sensing region and maintain optical quality.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The groove structure converts the harmful effect of light reflection into a beneficial outcome by strategically removing material to create optical pathways. The grooves are designed to redirect or eliminate reflected light beams that would otherwise interfere with imaging, transforming the potential harm of light interaction with the cover plate into improved imaging quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 solution improves imaging quality by reducing interfering light beams that enter the sensing region, enhancing the performance of image sensor chips by minimizing light reflection and disturbance.

Implementation Method 1

an angle between the inclined wall and the vertical wall may range from 120° to 150°... determined based on a thickness of the upper cover plate structure, a distance between an inner side wall of the groove structure and the vertical wall of the upper cover plate structure, and a refraction index of the upper cover plate structure

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a height difference between the top of the vertical wall and the second surface of the upper cover plate structure may be determined based on a thickness of the upper cover plate structure, a distance between an inner side wall of the groove structure and the vertical wall of the upper cover plate structure, and a refraction index of the upper cover plate structure

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10490583B2Packaging structure and packaging method

Publication Date: 2019.11.26 CHINA WAFER LEVEL CSP

AI summary

A packaging structure and a packaging method are provided. The packaging structure includes: a chip unit, where a first surface of the chip unit includes a sensing region; and an upper cover plate structure, where a first surface of the upper cover plate structure is provided with a groove structure, the first surface of the chip unit is attached with the first surface of the upper cover plate structure, the sensing region is located within a cavity surrounded by the groove structure and the first surface of the chip unit, the upper cover plate structure further includes a second surface opposite to the first surface, and an area of the second surface of the upper cover plate structure is less than an area of the first surface of the upper cover plate structure.