Cost effective RF MEMS wafer test solution Presto Engineering – Caen, France

E. de Lédinghen, N. Loiseau

Agenda

• Industrial test development cycle

• RF MEMS specifics

• Where are we today ?

• Solution

• Conclusion

Industrial test development cycle (1)

Device

datasheet

Characterization

results

FMEA

Test Specification

Industrial test development cycle (2)

Test

Specification

Volume

estimation

Sales price

target

Implementation choice

RF MEMS specifics

• A New technology = gap to bridge

– More characterization required

– Technology yield & product validation

• A High Volume / Short TTM

– Cellular phones market

• Market competitive ASP

– Competitive mature technology set ref ASP

– ASP must be at least similar, or lower

Test development today

Characterisation

results

Bench test

solution

Test

Specification

Volume test

solution

Test development today

Application bench

Test Production IC Test TOTAL

Labview, Custom

Visual Basic, …

Tester proprietary

language

2 different code

environments to maintain

and correlate

Several discrete

instruments

Rack and stacks, per

testsets

Automatic Test

Equipment

Integrating multi

instrument resources

2 different CAPEX, limiting

re-use of test capabilities

Application board

reference HW

EWS Probe card

FT Loadboard

3 reference HW to be

designed, validated

What if we could merge both at

lower NRE and shortening TTM ?

Our solution

Device

datasheet

Characterization

results

Volume test

solution

More constraints

• RF MEMS switches come with various flavors:

– 3 SPST

– 5 SPST

– Dual: SP5T + SP3T

– SP12T

– Etc…

• More measurement processes:

– Small resistor close to 1Ω

– RF to 6GHz

The tester choice

• PXI backplane

• Test environment open to bench, and flexible

– Same software = Labview + Teststand

– Able to easily connect to more bench instruments

• Fast execution and data transfer

– PXIe able to transfer @ 1Gb/s

– Embedded controller

• Limited or 0 footprint: can be installed on the prober.

• Low CAPEX

PXI: Flexible & low cost for HP-RF

• Single platform can handle characterization + volume

– More different options for characterization

– More parallelism for volume

• Re-usable

– Same software

– TestStand able to quickly switch to parallelism

• Low cost

– 1/10 of standard ATE CAPEX

– Maintenance & operating cost also 1/10 lower

PXI is production friendly for those ICs

• Equivalent throughput

– Standard acquisition + FFT at 1ms

– High end ATE also at 1 or 2ms

• Reduced down time

– Replace full tester instead of single board

– PXI tester price = 2 or 3 ATE boards

• Higher parallelism can be achieved

– PXI can be chained, ATE cannot.

PXI for production

• As a National Instruments Alliance Partner we are also considering the new NI-STS (Semiconductor Test System) as an alternative

Our hardware solution

• Mother board + daughter board

– Flexibility

• Up to 16 MEMS switches

• Any configuration: SPST, SPnT, etc…

– Lower NRE per configuration <2k€

• Mother board connects to standard instrumentation

– 100V high voltage managed locally

– Kelvin resistor measurements local

Hardware solution

16 RF connections

50Ω signal path through 2 PCB

Hardware structure

DUT

RF

src

DC

src

RF

out

A

V

• 16 RF or DC channels

• 16 independent activation signals

Test results

• Capability to watch for low resistance

• Low NRE proved:

– CAPEX of 35 k€ only

– Probe card at < 2 k€ per new pad ring configuration

• Even lower for duplication

• Operation ready for volume:

– Reference probe card exists

• Automatic checker

– Automatic wafer contact detection

0

1

2

3

4

5

6

7

8

9

0.0

E+

00

5.0

E-0

6

1.0

E-0

5

1.5

E-0

5

2.0

E-0

5

2.5

E-0

5

3.0

E-0

5

R (Ω

)

t (s)

Specification / Features

• RF up to 6GHz

• 16 MEMS channels

• Kelvin Resistor measurements at +/- 0.1Ω

• Dynamic R measurement at 4MS/s

• pF Capacitance measurement capability

• Programmable actuation voltage up to 130V

• Programmable actuation shape (AWG)

– Bipolar, bipolar RZ, triangle…

Conclusion

• New system approach

• New answer for new economics

• Target prices already achieved for characterisation

• System ready for volume