New probe tip fabricated by MEMS (LIGA process) for no ...June 3, 2003 2. 2003 Southwest Test Workshop Background of MEMS probe ... micro spring Low contact force probe tip June 3,

2003 Southwest Test Workshop

New probe tip fabricated by MEMS (LIGA process) for no-cleaning test

Tsuyoshi Tsuyoshi HagaHaga,, K.Okada, J.Yorita, Y.Hirata, S.Shimada*

Harima R&D Department Osaka R&D Laboratories*Analysis Technology Research Center

Sumitomo Electric Industries, LTD.

June 3, 2003 1


OutlineMEMS probe background Introduction of micro contact-probe fabricated using LIGA process

Benefits of no-cleaning test

Analysis of scrubbing motion

Design of cleaning-free shape

Sharpening of LIGA probe tip

Verification of no-cleaning operation

ConclusionsJune 3, 2003 2


Background of MEMS probe<Requirements>

・Fine pitch capability (Down to 50µm or less?)・Multi test (64DUT → 128DUT → wafer level?)・High frequency test (at speed testing GHz)・Low cost testing ・High reliability

・Limit of conventional machiningAccuracy,Shape,etc.

・Increase of conventional machining cost

LIGA(MEMS)LIGA(MEMS)・・High accuracy,high aspect ratio MEMS technologyHigh accuracy,high aspect ratio MEMS technology・・Mass production process based on XMass production process based on X--ray lithographyray lithography

High accuracymicro spring

Low contact force　　 probe tip

June 3, 2003 3

2003 Southwest Test WorkshopAbout LIGA process

<Process flow (LIGA)>(LiLithographie-GGalbvanoformung-AAbformung) <Advantages>

2)Electroforming

Irradiation

Development

Electroforming

Removal of resist

SR(X-ray)

X-ray Mask

Resist

Metal

1)X-ray Lithography

June 3, 2003 4

・High accuracy: ±0.4mm・Good perpendicularly:

0.1µm/100µm・High aspect ratio: 10 or more・High resolution/sharp edge　　　　　　　　　　　Tip R:< 1µm・Multi material

(metal,plastic,ceramics)

・Mass production process


LIGA probePOGO type probe

For array(C4), LCD etc.

Scrub type probe

For Al electrode pad

New material : Ni-Mn alloy Controlled grain size & crystal orientationHigh hardness (HV 600 or more)High toughness

　　　　　　　　　　Ｇｏｏｄ electrical resistivity(1.3x10-7Ωm)

June 3, 2003 5


Benefits of no-cleaning TestIC Test Profile

Yie

ld

Number of Touchdowns

Conventional probe

Cleaning Cleaning Cleaning

Loss

Adhesion and accumulation of debris at the probe tip

No-cleaning

1)1) Improve yield & throughputImprove yield & throughput2)2) Reduce costReduce cost

June 3, 2003 6

Simulation of scrub action2003 Southwest Test Workshop

Why do adhesion and accumulation of debris occur?Al contact wiping action of truncated pyramid tip(Conventional MEMS probe tip fabricated by Si micro machining)

BackwardForward

4µm

Initial adhesion of Al debris occurs at backward scrub actionat backward scrub action.→ Al debris increase the debris adhesion at next contact.

Backward scrub action is useless for electrical contact.June 3, 2003 7


Analysis of scrub motion

1.2mm

1.3m

m

0.06m

m

SEM chamber

Al/Cu coatedSi wafer

Stage(Actuator)

Camera

e-GUN

LIGA probe

Tester

Test condition

Temp. : R.T.Pad material : Al-CuSubstrate : Si

June 3, 2003 8


Basic characteristics of LIGA probe

0 20 40 60 80 100 120 140

Contact force (mN)

140

120

100

80

60

40

20

0

Ove

rdri

ve (S

trok

e) (µ

m) 140

120

100

80

60

40

20

0

Len

gth

of sc

rub

(µm

)

June 3, 2003 9


Analysis of scrub action

Adhesion!!

⑥⑤Backward ④

③

Electric contact

②Forward ①

Probe Tip : Pillar-shaped structure imitated truncated pyramid tip

June 3, 2003 10

Simulation of no-cleaning shape2003 Southwest Test Workshop

New Type Probe Tip

Forward

Backward

June 3, 2003 11

Design of no-cleaning shape2003 Southwest Test Workshop

55°

55°

R10 µm

R2 µm

R5 µm 45°

22.5°59.35°

June 3, 2003 12


No-cleaning shape Fabricated by LIGA

Tip shape

June 3, 2003 13

Sharpening of LIGA probe tip2003 Southwest Test Workshop

Probe Tip

Discharge electrode

Oil

Combination of LIGA and Micro Electro Discharge Machining

Forward

20µm

48µm

Shaving

Scrub Mark

Probe tip

SEM micrograph of discharge scarJune 3, 2003 14


Hardness variation of the EDMed surfaces EDMed surface profile

Element density in the depth direction of the recast layer (the recast layer )：Ｃ，：Ｎｉ，：Ｗ， ×：Ｔｉ，：Ｏ

C Ni

Spattering time (min.)

Inte

nsity

(%)

Depth

(1µm)

Discharge voltage60V

AnnealingAnnealing Carburizing Carburizing

June 3, 2003

672±96

After machining(60V)

540±68

After machining(110V)

616±20

Before machining

Hardness(HV)

(Discharge Voltage)

Verification of no-cleaning operation2003 Southwest Test Workshop

Forward ① ③②

Backward ④ ⑤ ⑥

Probe Tip : No cleaning shape

June 3, 2003 16

Verification of no-cleaning operation2003 Southwest Test Workshop

After 10,000 touchdownsBefore touchdownForward side Backward side

Accumulated aluminum

Conventional(trapezoidal) tip

Newly designed(no-cleaning) tipsharpened by µ-EDM

June 3, 2003 17


Conclusions

Micro contact probe fabricated by LIGA process (MEMS).

Probe tip sharpening using the LIGA and µ-EDM combination.

New probe tip shape for cleaning free test.

To realize cleaning-free test:

Aluminum debris generation phenomena were analyzed by dynamic SEM.

The scrub simulation technology by applying cutting simulation technology was developed.

June 3, 2003 18


Spare

June 3, 2003 19

Cutting tool simulation technology2003 Southwest Test Workshop

3D Machining simulation

Cutting Tool

Tool

IGETARROY

3mm

ToolDebris(Shaving)

For cutting tool shape design & cｕｔｔｉｎｇ condition analysis

Scrub simulationScrub simulation20June 3, 2003


Basic characteristics of LIGA probe

Four terminal method

Substrate

Test ConditionTemp. : R.T.Pad : Al-Cu

0

1

2

3

4

0 20 40 60 80 100 120 140

Con

tact

resi

stan

ce (Ω

)

0

25

50

75

100

Scr

ub le

ngth

(µm

)

ResistanceScrub

OD (µm)

June 3, 2003 21


Grain　TEM photographNi Grain Size Control

１μｍ

Conventional Material

Miniaturization of grain sizeHigh hardness: up to Hv600

Good uniformity

Grain size uniformity along thickness

XRD Measurement（Wilson method）

New Material

０．１μｍ

New Material

Hardness:Hv620

Ave

rage

gra

in si

ze (n

m)

Seed layer side Thickness (µm) Top

Hardness:Hv400-500

June 3, 2003 22


Crystal orientation controlCrystal orientation distribution

New material Old material

Seed layer side Thickness (µm) Top Seed layer side Thickness (µm) Top

Control of the seed layerFitting current condition and additive agent

Good uniformity of grain size and crystal orientation along thicGood uniformity of grain size and crystal orientation along thicknessknessJune 3, 2003 23


Alloy design

High heat resistance Ni alloySuppress NiS,SOx generation

Ni + S → NiS (Very brittle)S + O2 →　SOx (brittle)

Sulfur

20nm20nm

NiS,SOxNiS,SOx

Sの添加量を減らす

Sの析出をトラップする

Sulfur

Mn (Trap)

　　

Mn + S → MnS

June 3, 2003 24


1

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

トラップ材に求められる機能トラップ材に求められる機能

Niより強いSとの結合

電析可能である

0

NaMg

Al Ti

MnMn

Mo NiCu

FeSn

Ag

Co

-200 -150 -100 -50

Sta

ndar

d el

ectro

de p

oten

tial (

V)

Electrolysis of water

Electroforming is possible

Free Energy of metal sulfide⊿G(Kcal/gmolS2)

25June 3, 2003

Documents

New probe tip fabricated by MEMS (LIGA process) for no ...June 3, 2003 2. 2003 Southwest Test Workshop Background of MEMS probe ... micro spring Low contact force probe tip June 3,