Permanent Carrier for Wafer Level Imager Module Fabrication

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Solution Overview

Problem

The fabrication of microelectronic imager modules using wafer level techniques faces challenges in protecting the imager array and associated integrated circuits from damage, while also ensuring proper optical and electrical characteristics, reducing electromagnetic interference (EMI) and electrostatic discharge (ESD), and eliminating the debond process associated with temporary carriers.

Innovation Solution

The use of a permanent carrier during wafer level fabrication, which is permanently attached to the imager die to support and attach a lens structure, eliminates the need for a lens standoff and debond process, and incorporates conductive layers for EMI and ESD shielding, without requiring adhesive over the imager array, using materials like semiconductor, glass, or ceramics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a temporary carrier wafer is used during wafer level fabrication, then the imager wafer can be supported during processing, but a debond process is required which risks damaging the imager array and integrated circuits

Engineering Contradiction:

Improveprotection of imager array and integrated circuitsVSAvoiddebond process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the temporary carrier wafer from the fabrication process entirely and replaces it with a permanent carrier that remains attached throughout. This extraction of the temporary carrier eliminates the need for the debond process and associated risks to the imager array and integrated circuits.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The permanent carrier is attached to the imager wafer before any processing steps, providing continuous support and protection throughout the entire fabrication process. This preliminary attachment prevents the need for subsequent debonding operations that could damage sensitive components.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If adhesive is used to attach lens carrier to imager die, then proper optical characteristics can be achieved, but adhesive over the imager array may cause contamination or damage

Engineering Contradiction:

Improveoptical characteristicsVSAvoidcontamination of imager array

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies adhesive only in specific locations around the perimeter of the imager die, rather than over the entire surface. This localized application maintains the necessary mechanical bond and optical characteristics while preventing adhesive contamination of the sensitive imager array surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The bonding process is segmented into discrete bonding pads or regions around the imager die perimeter, separating the adhesive application zones from the imager array area. This segmentation allows independent optimization of bonding strength and contamination prevention.

Inventive Principle:

Principle #1Segmentation

3Reliability

If lens carrier structure is added to protect integrated circuits, then reliability improves, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveprotection of integrated circuitsVSAvoidfabrication process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the lens carrier structure with the permanent carrier into a single integrated component. This combination provides both protection for the integrated circuits and support for the lens element without requiring separate assembly steps, thereby maintaining ease of manufacture while improving reliability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The permanent carrier serves multiple functions simultaneously: it provides mechanical support for the imager wafer during fabrication, protects the integrated circuits, and supports the lens element. This multi-functionality reduces the need for additional protective structures and simplifies the overall manufacturing process.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Object-affected harmful factors

If conductive layers are added for EMI and ESD shielding, then electromagnetic interference protection improves, but device complexity and manufacturing steps increase

Engineering Contradiction:

ImproveEMI and ESD protectionVSAvoidnumber of layers and materials

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The conductive shielding layers are merged with the permanent carrier structure, integrating EMI and ESD protection into the existing carrier rather than adding separate shielding components. This integration provides electromagnetic protection without significantly increasing device complexity or manufacturing steps.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8680634B2Method and apparatus providing an imager module with a permanent carrier

Publication Date: 2014.03.25 MICRON TECHNOLOGY INC

AI summary

Method and apparatus providing a wafer level fabrication of imager modules in which a permanent carrier protects imager devices on an imager wafer and is used to support a lens wafer.