Wafer Bonding Material Embedded Rigid Particles

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Solution Overview

Problem

The existing methods for bonding MEMS wafers with a protective lid wafer require additional processing steps to form standoffs, increasing cost and complexity, as the adhesive needs to flow and accommodate variations in wafer surfaces, necessitating pre-fabricated standoffs on the lid wafer.

Innovation Solution

A bonding material with non-melting rigid particles is used, which, when melted or cured, defines the minimum separation between the wafers, eliminating the need for pre-fabricated standoffs by incorporating hard spheres or particles like alumina, silica, or metal into the adhesive substance applied to the wafers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If pre-fabricated standoffs are formed on the lid wafer using additional processing steps, then the minimum separation between wafers is defined, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improveminimum separation definitionVSAvoidprocessing steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the standoff function with the adhesive material itself by embedding rigid particles within the adhesive. This eliminates the need for separate standoff fabrication and application steps, as the rigid particles perform both the separation definition and the adhesive bonding functions simultaneously, thereby reducing manufacturing complexity while maintaining precision

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention uses a composite material consisting of adhesive substance combined with embedded rigid particles. This composite material integrates the properties of both adhesive materials (for bonding) and rigid standoffs (for separation definition), eliminating the need for separate components and processing steps while achieving the required minimum separation between wafers

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If adhesive is applied as liquid to accommodate surface variations, then bonding flexibility is improved, but the adhesive flows outward requiring pre-fabricated standoffs

Engineering Contradiction:

Improvesurface accommodationVSAvoidstandoff fabrication

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the adhesive material with embedded rigid particles in a single application step. The adhesive provides liquid-state flexibility for surface accommodation, while the rigid particles simultaneously define the minimum separation, eliminating the need for separate standoff components and reducing overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The composite material of adhesive with embedded rigid particles allows the adhesive to remain liquid during application for surface adaptation, while the rigid particles prevent excessive flow and define the minimum separation, thereby eliminating the need for pre-fabricated standoffs

Inventive Principle:

Principle #40Composite materials

3Device complexity

If rigid particles are embedded in adhesive, then the manufacturing process is simplified, but the adhesive formulation becomes more complex

Engineering Contradiction:

Improveprocessing stepsVSAvoidadhesive formulation

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent changes the physical parameters of the adhesive formulation by incorporating rigid particles of specific sizes and materials. This allows the adhesive to maintain its liquid state for application while the rigid particles provide structural definition, simplifying the overall manufacturing process despite the enhanced formulation complexity

Inventive Principle:

Principle #35Parameter changes

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 approach simplifies the manufacturing process by eliminating the need for pre-fabricated standoffs, saving time and expense while ensuring a hermetic seal, as the rigid particles maintain their shape and define the necessary separation between the wafers during bonding.

Implementation Method 1

heat is applied to melt or cure the adhesive

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

heat is applied to melt or cure the adhesive

Methodology Applied

Scientific EffectCuring:

Implementation Method 3

the rigid particles maintain their shape and define the necessary separation between the wafers during bonding

Methodology Applied

Scientific EffectShape memory:

Data Source

PatentUS7807547B2Wafer bonding material with embedded rigid particles

Publication Date: 2010.10.05 ATOMICA CORP

AI summary

A material for bonding a lid wafer to a device wafer, which includes an adhesive substance with rigid particles embedded in the adhesive substance. The rigid particles may be particles or spheres of alumina, silica, or diamond, for example. The adhesive substance may be glass frit, epoxy, glue, cement or solder, for example. When the adhesive is applied and melted, and pressure is applied between the lid wafer and the device wafer, the lid wafer approaches the device wafer until a minimum separation is reached, which is defined by the rigid particles.