Wafer Mapping Tools Bulk Microdefect Analyzer for imaging of · Wafer Mapping Tools for high speed, high resolution whole wafer mapping of defects and/or contaminants Deep Level Spectrometer

1st RD50 Workshop 1

SEMICONDUCTOR CHARACTERIZATIONSYSTEMS

Wafer Mapping Tools for high speed, high resolution whole wafer mapping of defects and/or contaminants

Deep Level Spectrometer for identification of electrically active point defects

Bulk Microdefect Analyzer for imaging of extended defects (from 20nm to several micron)

1st RD50 Workshop 2

WAFER MAPPING TOOLS

WT-2000 Wafer Testermonitoring defects and contamination both in the bulk and in the surface region of silicon wafers

Applied measurement techniques:

µ-PCD for bulk SiCharge-PCD for bare wafers

EpiTest for epi wafers

Temperature dependent µ-PCD:for Si and compound materials

SPV for bulk Si

Kelvin Probe for oxide characterization

Eddy current for resistivity mapping

LBIC for solar cell characterization

1st RD50 Workshop 3

WT-2000 µ-PCD TOOL

µ-PCD (microwave photoconductive decay) technique for mapping crystal growth andprocess induced defects and heavy metal contamination in bulk silicon wafers

APPLICATIONSCRYSTAL GROWTH DEFECTS

PROCESS INDUCED DEFECTS/Fe MAPPING

Laser

Microwave

wafer

I = I0 e-t/τ Slip lines Oxygen striations OSF ring

Contaminated hot chuck Fe detectionBoat contamination

Fe

Fe

Fe

1st RD50 Workshop 4

WT-2000 SPV TOOL

Surface Photovoltage (SPV) technique for mapping heavy metal contamination and crystaldefects in the bulk silicon wafer

IRON CONCENTRATIONMAPPING

FeSPV µ-PCD

oxygen Fe

12

34

1/α

Φ/VSPV

L

ΦVSPV

= C(L+1/α )

Fe AND O2 MONITORING BYCOMBINED µ-PCD AND SPVTECHNIQUES

Life

time,

µs

0.01

0.1

1

Injection level, 1/cm31.E+11 1.E+13 1.E+15 1.E+17

SPV µ-PCD

Fe-B pairO2 prec.NFe = C ( )

1Lafter

21

Lbefore2

-

1st RD50 Workshop 5

WT-2000 Charge-PCD

Laser

Microwave

waferCharging

Charging1

1τmeas

1τbulk

=1

τdiff τsurf++

Semilab’s patented new surface passivation method applying controlled charge deposition on to the wafer surface during lifetime mapping provides a highly efficient, reproducible and homogeneous surface recombination elimination on bare wafers.

without charging with charging

Surface /interface characterization

Interface recombination velocity map of an oxidized wafer calculated from the lifetime map measured with and without charging on the same wafer

τaverage=15.7 µs τaverage=268 µs

Lifetime map measured

1st RD50 Workshop 6

WT-2000 MCTTEMPERATURE DEPENDENT LIFETIME

Temperature dependent carrier lifetime measurements

50 100 150 200 2500.01

0.1

1

sample 1 sample 2

Temperature [K]

Life

time

[µs]

50 100 150 200 250

0.1

0.2

0.3

0.4

0.5

Temperature [K]

Life

time

[µs]

sample #2sample #4

HgCdTe InSb

Monitoring minority carrier lifetime as a function of temperature in narrow band gapsemiconductors (InSb, HgCdTe, etc.)

Two measurement strategies:• whole wafer mapping at a preselected stabilized temperature

between 85K and 300K• single point lifetime plot as a function of temperature

between 85K and 300K

1st RD50 Workshop 7

WT-2000 EPITEST

Improved µ-PCD (microwave photoconductive decay) technique for the characterizationof recombination processes in epi structures.

Light excitation

Oxide or passivation.

Microwave

Green laser532nm

Epi layer

p+ or n+ substrate

Ssurface

Sinterface

τepi

τsubstrate

Lifetime map Fe concentration map

13.8µs 14.8µs 5 E91/cm3

3 E101/cm3

1st RD50 Workshop 8

WT-2000 V-Q TOOL

Plasma damage monitoring and oxide/interface characterization by non-contact V-Q curve measurement using Kelvin Probe with additional high intensity illumination and controlledcorona charging

Charge

.. .........

... . .

Light/Kelvin probe

Plasma damagemonitoring

by oxide charge mapNon-contact V-Q

Charge, nC/cm2

SP

V,

V

0

0.5

1

-0.5

Theoritical

Dark -corrected bright

0100 100

Tox Electrical oxide thickness

Qeff Effective charge

Vfb Flatband voltage

Vt Threshold voltage

Vox Oxide voltage

Dit Density of interface traps

1st RD50 Workshop 9

WT-2000 RESITIVITY MAPPER

Controlelectronics

High frequency coil

Headheightcontrol

Non-contact whole wafer resistivity mapping based on the eddy current technique for thedetermination of bulk resistivity distribution in silicon wafers

Resistivity map

Single crystal8” CZ wafer

Multi-crystallinePV material

1st RD50 Workshop 10

SIRM-300BULK MICRODEFECT ANALYZER

Non-contact, non-destructive method based on reflection mode confocal microscopyfor detection and analysis of bulk microdefects

Dislocations Stacking fault

laser

beamsplitter

Z scanning

X-Y scanning

detector

wafer

Denuded zone determination

depth

1st RD50 Workshop 11

DLS-83DDEEP LEVEL SPECTROMETER

Detection and identification of trace level of impurities in concentrations down to 109 atoms/cm3

CRYOSTATSIN DIFFERENT TEMPERATURE RANGES

• Closed Cycle He-cryostat from 20K to 300K• LN2 cryostats from 77K to 450K:

simple bath type LN2 cryostatautomatic LN2 cryostat with controlled LN2 flow

SAMPLE HOLDERwith motor driven positioning

in n-type FZ silicon

Cs-Sii-Cs Ps-Ci(1)Vac-Vac

Ps-Ci(2)

P-Vac

Vac-O

Vac-Vac

Vac-?

?

Cs-Oi

C-O-V2

or

Ci

in p-type FZ siliconRadiation defects

Influence of annealingon Fe-B pairs

Fe-B pair

Fe-interstitial

Molybdenum

1st RD50 Workshop 12

MICRO-LBIC

Very high, 1µm resolution mapping capability to measure at low temperaturesMajor application: HgCdTe devices

LBIC=Light Beam Induced Current