Riding the 3rd Wave: Reducing Cost of Test for MEMS Sensors · Wave: Reducing Cost of Test for MEMS Sensors 16 th. April 2015. Contents – MEMS Sensor Overview ... 6 Axis Inertial

Riding the 3rd Wave:Reducing Cost of Test for MEMS Sensors16th April 2015

Contents

– MEMS Sensor Overview– The “Third Wave” of MEMS Sensors– MEMS Calibration and Test – Steps to Minimize MEMS Cost of Test– Conclusion and Future Challenges

16 April 2015Confidential 2

MEMS Sensors and Applications


Sensor type Application examples

Accelerometer high G - air bag sensors

Accelerometer 3 axis low g

- gaming- position detection

Gyroscope - navigation- automotive ESP

Pressure & Gas Sensors - tyre pressure - barometric applications (navigation)- differential pressure - gas detection (CO, CO2, Alcohol …..)

Electro-Magnetic - navigation- angular measurements- turn count

Microphone - mobile phones, tablets

Humidity - air conditions- environmental applications

Optics - gesture sensors- health (body temp., blood oxygen level)

MEMS Devices are entering the “3rd Wave” of growth

Sources: Gartner, IDC, Strategy Analytics, Machina Research, company filings,BII estimates, Bosch

IoT will grow to be thelargest end application market

Integration of sensor technologywill introduce new challenges


MEMS Industry Trends – Combo Devices Proliferate


MEMS Industry Trends – Increasing Integration

– Integration of one or more MEMS functions with MCU (and possibly Radio interface)


MEMS Industry Trends - Package Size Evolution


MEMS Industry Trends – Overall Conclusions?

Source: ATREG Inc


How can this be improved?

Why is Calibration and Test Required for MEMS?

• Errors inherent in MEMS manufacturing process produce variations in the sensor performance

• Calibration during test is required to compensate for these variations.


MEMS Wafer Fabrication

MEMS Assembly /Packaging

MEMS Calibration

MEMS Final Test Verification

Over-EtchingUnder-EtchingNon-Uniform Geometries

Device Misalignment Package Stresses

Device Error Corrections Made to Meet Final Device Performance Specifications

Verification Testing of Calibrated Device Final Test Pass/Fail Binning

MEMS Manufacturing Process MEMS Manufacturing Errors

LSL USLUncompensated Errors

Compensated ErrorsLSL USL

MEMS Parametric Variations

LSL: Lower Spec Limit USL: Upper Spec Limit

Challenges with Cost of MEMS Calibration and Test

– Using traditional solutions, MEMS Calibration and Test represents up to 30% or more of device cost• MEMS test equipment capital is expensive• Calibration + test times are long• Test cells are not scalable from low volume to high volume • Test cells are not scalable across different MEMS product types• Test cell maintenance is costly

– Challenge: Provide innovative, scalable test cells that minimize CoT for both the high-volume, price-driven Consumer market and the low-medium volume, performance -driven markets (Automotive / Aerospace…)


What’s in a MEMS Test Cell

Handler- Handle different DUT package types- Support multiple input/output media types- Multi-temp control- Manage Pass/Fail binning

MEMS Stimulus Module- Provides physical stimulus for DUT- Reference sensor calibration

SOC ATE- Electrical test of DUT- Control physical stimulus- Communicate with handler

Handler-Tester Interface- Soft or hard dock, determined

by application- Handler-tester communication


Test Cell Opportunities to Reduce MEMS Cost of Test

– Single vendor approach is typically limited to capex, throughput and some variable costs

– Test cell-approach allows all elements of the CoTmodel to be addressed

Lifetime

Yield Utilization Throughput (UPH)* *

Capital CostsVariable Costs +

CoT+

=

Overhead


Test Cell Opportunities to Reduce MEMS Cost of Test

Lifetime

Yield Utilization Throughput (UPH)* *

Capital CostsVariable Costs +

CoT+

=

Overhead


Smaller test cell footprint

Re-usable, flexible platform

•Simplified conversion kits•Low maintenance platforms

Flexible test cell base with optional MEMS modules

•Contacting accuracy and repeatability•Temperature stability

Higher uptime, through standardised handling of multiple package types

•Faster tester-handler communication

•More contact sites•Higher multisite efficiency•Faster test and index times•Larger soak capacity

Four Steps to Minimize MEMS CoT


Flexible Platforms with Modular Options

Standardised Handling

High Parallelism

Optimized Test Cell Throughput

1234

Flexible Handler Platforms and Modular MEMS Stimulus OptionsSingulated Package Test

Low/Med Volume (Automotive, Industrial...)Strip Test / Test inCarrierHigh Volume (Consumer)

handler platform Gravity Gravity P&P Striptube

x4tube

x4 / x8tray

x4 / x8 / x16strip

x42 / x72 / x144

Accelerometers 20g/ 50g /100g X, Y, Z, 45° Y, Z, X+Y on request

3 axis low gZ+X, Z+Y on request 3DOF Accelerometer;

6DOF Accel. + Magnetometer

GyroscopesYZ = 5DOF Z sinusoidal; XYZ =

6DOFZ sinusoidal;

XYZ = 6DOF (9DOF on request)

6DOF Accel. + Gyro9 DOF Accel + Gyro +

Magnetometer

Pressure / Gasup to 20 bar absolute

Gas detectionBarometric abs.& rel.(on

request)Gas detection

Pressure (20bar abs.+ gas detect.)

Barometric absolute

MagnetometerZ = 1DOF, MRS XY =

2DOF, XYZ = 5 (8) DOF

MRS XY = 2DOF, XYZ = 3DOF

MRS XY = 2DOF, XYZ = 3/6DOF (9DOF

on requ.)

6DOF Accel. + Magnetometer

9 DOF Accel + Gyro + Magnet

Microphone Audio stimulus

Humidity humidity MEMS Humidity stimulus

Optical Sensors specific solutions available

specific solutions available Light /IR stimulus

Oscillators temp. calibr. up to +/-0.2°K

on request on request

application


Standardisation and Modularity

– Multiple applications use the same base handling system

– New sensor applications require only changes in the sensor test modules

faster time to market– Ease of operation /

maintenance - similar to standard process

– Leverage skills / lower additional training

Pressure Sensors

Accel. / Mag. / Gyro:3/6/9DOF

Base Strip HandlerAccelerometer / Magnetometer:

3/6DOF

Audio Microphones


Modularity: Multi DOF Test in One Insertion


• Requires Sensor Stimulus Equipment to fully support multi-axis / combo sensors

Example: 9 DOF Test Setup

>Multiple actuations in ONE insertion

> Increases UPH for Combo Sensors

>Reduces manufacturing process complexity

Cost of Test Advantages

9DOF Combo Sensor Test Example:6 Axis Inertial MEMS Test = 3 Axis Gyroscope + 3 Axis low g Accelerometerwith non-magnetic contact environment for passive 3 DOF Magnetometer test



Sensor Test Equipment is combined with Strip-Like Test Equipment and Carrier Loading / Unloading

>High throughput: up to x256 parallel test

>Supports smallest packages and WLCSP, with high reliability and uptime

>Full device traceability maintained through multiple test insertions

Example: InCarrier

Cost of Test Advantages:

• Leverages advantages of strip test for singulated packages• Addresses the concern of MEMS output changes after singulation



Singulated IC Test InStrip® IC Test

InCarrierTM IC Test

Patented

InCarrier: Combined advantages of Singulated Test and InStrip Test

InCarrier Examples

WLPin InCarrier

BGA 64 in InCarrier

LGA 2x2 in InCarrier InCarrier in standard

slotted strip cassette(cassette is shown open)

SO Device in InCarrier


Examples of Magnetometer on Strip

– >3000 DUTs per strip– Tested at >200 sites in parallel!


SOC ATE Parallelism vs. PXI Implementation

576 Channels3648 Channels

High volume manufacturing bonus15 Times advantage in channel density


Example of Test Cell Throughput Optimization: Magnetic Coil Stimulus


Analog stimulus Power to Coils

• 200ms settling using conventional GPIB-controlled bench-top supply to drive magnetic field coils

• <10ms settling using V/I amplifier to drive coils, based on analog stimulus from ATE system

GPIBcommands Power to Coils

I

t

I

t

MEMS Test Cell Features for CoT Reduction

Strip Test Handler- Standardised Strip or Carrier handling- Up to 256 sites tested in parallel- High reliability handling of small and WLCSP

packages- Multi-temp. support with high accuracy

MEMS Stimulus Module- Modular physical stimulus, with

integrated reference sensor feedback loop

- Multiple DOF options

SOC ATE- Modular testhead supporting

full parallelism of strip handler - High MSE for best throughput- Low cost, high-density digital

for efficient register read/write

Handler-Tester Interface- Performance-optimized

interfacing- High throughput communication

link for stimulus control and sensor readback


Challenges for Future Integrated Smart Sensors

• RF test solutions available today for:– Low-cost connectivity and high-performance

mobility applications

• Limitations with existing solutions– At very high site counts, RF sub-system will drive ATE CapEx

• Economic RF test solution required for massive parallelism!


Four Steps to Minimize MEMS CoT


Flexible Platforms with Modular Options


High Parallelism

Optimized Test Cell Throughput

1234

Thank you !

Documents

Riding the 3rd Wave: Reducing Cost of Test for MEMS Sensors · Wave: Reducing Cost of Test for MEMS Sensors 16 th. April 2015. Contents – MEMS Sensor Overview ... 6 Axis Inertial