Dual-Side Illumination Image Sensor Chip Stacking

Solution Overview

Problem

Conventional image sensor chip configurations require two separate cameras and image sensor arrays facing opposite directions, leading to increased thickness and footprint in devices like mobile phones, as each chip needs to maintain a certain distance from the focal lens and have separate signal routing, limiting miniaturization.

Innovation Solution

A Dual-Side Illumination (DSI) image sensor chip is developed by bonding two image sensor chips with shared column readout circuits, allowing them to be stacked and aligned in a way that reduces thickness and footprint, with one chip capturing light from one direction and the other from an opposite direction, and utilizing a Printed Circuit Board (PCB) with transparent windows for signal transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two separate image sensor chips are used to capture images from opposite directions, then full image sensing functionality is achieved, but device thickness increases due to combined chip thicknesses and required separation distances

Engineering Contradiction:

Improveimage sensing functionalityVSAvoiddevice thickness

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

Two image sensor chips are bonded together in a stacked configuration to form a single integrated unit, merging two separate sensing systems into one compact structure that captures images from opposite directions simultaneously

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The solution transitions from a planar arrangement of separate chips to a three-dimensional stacked configuration, utilizing the vertical dimension to reduce the horizontal footprint and overall device thickness

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If two separate image sensor chips are placed on the PCB with separate footprints, then signal routing is simplified, but the device footprint area increases

Engineering Contradiction:

Improvesignal routingVSAvoiddevice footprint

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

Two image sensor chips are bonded together in a stacked configuration to form a single integrated unit, merging two separate sensing systems into one compact structure that captures images from opposite directions simultaneously

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

One image sensor chip is placed on top of the other, creating a nested vertical arrangement where the second chip is positioned within the footprint area of the first chip, dramatically reducing the overall device footprint

Inventive Principle:

Principle #7Nested doll (Nesting)

3Measurement precision

If a certain distance is maintained between image sensor chips and focal lenses, then proper optical focusing is achieved, but the required separation distance increases device thickness

Engineering Contradiction:

Improveoptical focusingVSAvoiddevice thickness

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The solution transitions from a planar arrangement of separate chips to a three-dimensional stacked configuration, utilizing the vertical dimension to reduce the horizontal footprint and overall device thickness

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS9978796B2Methods for forming dual-side illumination image sensor chips

Publication Date: 2018.05.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A Dual-Side Illumination (DSI) image sensor chip includes a first image sensor chip configured to sense light from a first direction, and a second image sensor chip aligned to, and bonded to, the first image sensor chip. The second image sensor chip is configured to sense light from a second direction opposite the first direction.