Edinburgh & Piezo 09 Presentation v1

8/6/2019 Edinburgh & Piezo 09 Presentation v1

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Imsat logo

Issues in Manufacturing of Wafer-scale 3DPiezoelectric-on-Silicon Structures.

Manufacturing considerations for 3D Piezo 0nsilicon wafer scale structures.

Edinburgh and Piezo 09

March 2009

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Imsat logo


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Imsat logo

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Loadpoint

European SME since 1963

Manufactures in EC to CE standards

Direct process development service

Consumable support

Over 900 Dicing machines in

operating work wide.

3,700 Dicing Spindles sold, 500 inthe Pacific Rim

45 years experience of electronics

industry

Backgrounds

Imsat


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Imsat logo Wafer scale back ground


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Imsat logo Piezo-on-Siapplications

Medical

NDT

Sonar

Ink jets

Gyroscopes

Micropumps

Pressure sensors

MEMS resonators Microvalves

Accelerometers


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Merging 3D technologies

By permission Yole Developments, Yole News Nov, 2008

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Note mainly silicon


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Imsat logoLessons from 3 D silicon

Semetach August 2008

Their over view on the

advantages for 3D silicon.

This could be applicable to

multi material multi wafer

wafer scale packaging

This is all moving very fast

at the moment


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Imsat logo Wafer scale basics


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Imsat logo Packaging TechnologyPull

ConsumerProducts

Price

Integrate as much as possible to reduce number of external

connections.

Performance / Capability per unit volume

Automobile ProfessionalProducts

Reliability

Durability

Performance / Capability per unit volume

Wafer scale may eliminate 1 level of package, ie BGA QFN etc. This

will be debated as time goes by.

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Imsat logo Concepts in MEMS production

The DRIE-defined structure in

Si

Ti

mes t i

mi

ng reference gets asilicon cap at the wafer level

before being merged w ith a

CMOS structure in its QFN

package

InvenSenses Nasiri-

Fabrication process

simultaneously seals and

interconnects the MEMS

structure to the CMOS ASIC.

Another step removes theexcess silicon on the CMOS to

access the bond pads.

Small Times September, 2007 Author: Randy Frank

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Imsat logo Dicing processes, 2008

Dicing Separation of wafers into

individual die by sawing, lasering

or diamond scribing.

Singulation Separation of moulded frames

into individual packages bysawing. Normally associated withBGA, BGA, QFN

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Imsat logo Background

Supplied dicing machines for airbag pressure sensors to AC Delco,Kokomo in 1978

Dicing street

in s

ilicon 300 m

icron tosuit 200 micron blade needed for

glass

Wafer scale process

This technology still being usedinspecialist sensors

Other package dicing customers /projects include: BT Epic, IBMPowerPC, Nokia Telephones ,Siemens LCD, TI DLP, VTI RadioSonds, Ya Hsin SMD LEDS. SKA

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Imsat logo Silicon 3 D evolution

//

//

//


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Imsat logoTechnologies becoming useful

Planarisation

Thinning of material by grinding or CMP

In this context grinding quickly gives geometry

CMPused to give semiconductor / optical finish Dicing by grinding

Fly cutting now becoming an option

Post operation cleaning critical

Interposers

Vias through silicon, 20 micron 2008, 5 micron 2014

Not just silicon FR3 & FR4 can be considered as well

Rapid via generation needed for glass and other materials.

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Imsat logo Basic silicon Process


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Imsat logo Issues

Table 1. Issues in 3D PZT-Si integration

Issue Description Solutions

1 Standards: there seem to be very few at the moment so each organisation

is developing its own.

SEMI or similar body to undertake.

2 Coefficient of linear expansion, COE Design, thermal vias, pixellation

3 Internal stress build up Design, pixellation

4 Test protocols, procedures and standards Industry

5 Inspection systems and standards Industry and international standards organisations

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Dicing by grinding

Scribe cut silicon wafer thinned to 80 micron

thickness.

Edge chipping was an occasional 2 micron size

defect.

Top photograph shows a wafer just after

machining, the middle an enlargement and the

bottom a cutintersection.

CMP

could be used toimprove f

inish further

ifneeded.

Work performed on PicoAce.

Process good for other materials, i.e.PZT.

Funded by DTI / Eureka as part ofWalpackWSPProject

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Imsat logo 6material stack

Method of build up

Top down or build up

Sub elements that are then

assembled

Dicing, epoxy potting, grinding

usedin various combinations

Molding compound grinds well

Level to level alignment critical

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Imsat logo Material combinations

Possible combination,

Similar structures now being considered for Research applications.

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Level Mater ial Funct ion

1 PZT Sensor / Actuator

2 Ceramic Absorber

3 Silicon Dr iver

4 Silicon Processor

5 Silicon Interposer

6 PCB Connect ion


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Imsat logoStarting point

6 layer Test piece to explore concepts.

There are actually 10if copper and bond layers areincluded. This sample 5.14 mm thick, could go muchthicker, say 30 mm

Interestingideas

Low profile pads, simply etch the copper

Jigged pre-alignment

Not new, 3D Plus have pioneered this approach

Could be applicable for low medium to mediumvolumes

Contractors being developed for high volumes

Suitable for both wafer scale and QFN


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Imsat logoMulti material, how many layers?

FR4

Glass

Silicon

Glass

Silicon

Ceramic

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Copper

FR4

Copper

Epoxy

Glass

Silicon

Glass

Silicon Epoxy

Ceramic


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Materials

Copper

FR4 Copper

Epoxy

Glass

Silicon

Glass

Silicon Epoxy

Ceramic

Multi material, how many processes?

Processes that might be involved

Routing & drilling FR4

Photo-etching Copper

Injection of epoxy

Grinding & CMPglass Iso-static bonding silicon to glass

Grinding & CMPsilicon

Vias in silicon, glass, FR4 and ceramic

Bulk removal, grinding, DRIE of Silicon

Bumping and back fill for bumped wafers

Grinding of epoxy

Lapping, were suitable

Cavity machining

Bonding processes

Planarisation by flycutting

Dicing and profiling of all.


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Imsat logoProcess Sources or development needed

Routing & drilling FR4 PCB Industry

Injection of epoxy Back fill or underfill

Photo-etching Copper or inter-connectmaterial

PCB Industry

Grinding & CMP glass Optical industry

Ink Jet printing of electrical circuits Emerging circuit ink jet printing companies

Iso-static bonding silicon to glass Established bong organisations

Grinding silicon Exists already

CMP silicon Exists already

Vias in silicon, glass, FR4 and ceramic Silicon evolving, glass development needed

Bulk removal by DRIE of Silicon Exists already

Bumping and under fill Exists already

Grinding of epoxy and ceramic Development needed

Lapping, were suitable Exists already some development needed

Cavity machining Moulding, etching, machining

Bonding processes, not iso-static Development needed

Planarisation CMP Evolution outside silicon needed

Planarisation, grinding Needs to be explored

Fly cutting Rapidly emerging development needed

Dicing of all or sub-elements Design of wafers and process critical for this

Inspection 100% of all by X ray or whatever criticsl


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Imsat logoUseful additions

Internal screening, RF - MOD

Islands delineated e

ither by etch

ing or gr

inding

Same idea for cavities

Shapes or curves by milling or etching

What else?


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Imsat logo Dice out

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After final bonding dice out of

whole assembly.

Might only mean only last one or

two layers being diced, critical

point being to maintain

completeness of structure tomaintain position registration


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Imsat logo Points to watch

Tolerances

Silicon +/- 2 micron

Thin film +/- 50 micron

Thick film +/- 75 micron Frame, copper +/- 150 micron

PCB +/- 200 micron

Geometry

Parallelity

Sequence of build up, epoxy does grind quite well Cleaning

Dicing / grinding swarf.

Protection of sensitive structures.

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Material MachiningProducts

PicoAce 300 mm waferNanogrinder & Fly cutter

NanoAce 300 mm wafer dicing machine

MicroAce 150 mm wafer dicing machine

MacroAce 50 mm thickness dicer saw grinder

Washpoint 300 mm after dicing cleaning machine

Disc Point 150 Fly cutting machine

Process development and sub-contract dicing grinding

service

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Thank you

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Full list of references atwww.loadpoint.co.ukfrom the 4th March 2009

Documents

Edinburgh & Piezo 09 Presentation v1