Imaging Element Test Pad Insulating Film for Bonding Damage Prevention

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Solution Overview

Problem

Conventional imaging elements are damaged during the bonding process due to the penetration of test probes through the oxide film on semiconductor chips, leading to reduced yield and potential signal leakage.

Innovation Solution

The imaging element incorporates a second pad with a protrusion in the wiring region, covered by an insulating film of at least 650 nm thickness, to protect the surface during bonding, preventing damage from test probe contact and ensuring proper alignment of pads during bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If test probes contact test pads with high needle pressure to penetrate oxide film and reduce electrical resistance, then electrical connection is improved, but the front surface of test pads becomes uneven causing damage to opposite semiconductor chip during bonding

Engineering Contradiction:

Improveelectrical connectionVSAvoidsurface unevenness damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an insulating film as an intermediary layer between the test pad and the bonding interface. This mediator allows the test probe to contact the test pad through the insulating film without directly exposing the metal surface, thereby maintaining electrical connection while preventing surface unevenness from damaging the opposite chip during bonding

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating film is formed on the test pad before the bonding process. This preliminary action prepares the surface by creating a protective layer that prevents future damage during bonding, while still allowing electrical testing to be performed through the film

Inventive Principle:

Principle #10Preliminary action

2Productivity

If semiconductor chips are bonded together after electrical testing, then productivity is improved, but the imaging element is damaged due to uneven test pad surfaces

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidproduct quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The insulating film serves as a mediator that enables both electrical testing and subsequent bonding without damage. It allows the manufacturing process to proceed efficiently while protecting the test pad surface from causing defects during the bonding of semiconductor chips

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the oxide film on test pads is penetrated to reduce electrical resistance, then electrical conductivity is improved, but the test pad surface becomes uneven leading to signal leakage

Engineering Contradiction:

Improveelectrical conductivityVSAvoidsignal leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The insulating film acts as a mediator that allows electrical conduction through its structure while maintaining a smooth surface. This prevents the surface unevenness that would otherwise cause signal leakage, while still enabling the necessary electrical connection for testing and operation

Inventive Principle:

Principle #24Intermediary (Mediator)

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 prevents damage to the imaging element by protecting the test pads with an insulating film, ensuring reliable bonding and reducing signal leakage, thereby improving the yield and performance of the imaging element.

Implementation Method 1

an insulating film disposed between the second pad and the surface for bonding, the second pad being formed with a protrusion toward the surface for bonding

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

one of the plurality of semiconductor chips being disposed with a photoelectric conversion unit that performs photoelectric conversion of incident light

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Implementation Method 3

surfaces of the wiring regions of the two semiconductor chips being bonded together, the first pads being disposed on the respective surfaces of the wiring regions and being joined to each other when the surfaces are bonded

Methodology Applied

Scientific EffectWafer bonding:

Data Source

PatentUS20230117629A1Imaging element and method for manufacturing imaging element

Publication Date: 2023.04.20 SONY SEMICON SOLUTIONS CORP

AI summary

An imaging element including a plurality of semiconductor chips which are bonded together is prevented from being damaged._The imaging element includes the plurality of semiconductor chips each including a semiconductor substrate and a wiring region. One of the plurality of semiconductor chips is disposed with a photoelectric conversion unit that performs photoelectric conversion of incident light. Two of the plurality of semiconductor chips each includes a first pad, surfaces of the wiring regions of the two semiconductor chips being bonded together, the first pads being disposed on the respective surfaces of the wiring regions and being joined to each other. At least one of the two semiconductor chips further includes a second pad disposed in the wiring region and an insulating film disposed between the second pad and the surface for bonding, the second pad being formed with a protrusion toward the surface for bonding.