Transcript Dark field detection

Surfscan
Operations and
Overview Course
KLA-Tencor
660 Alder Drive
Milpitas, CA 95035
TBI
SP1
Surfscan 6XY0
The Surfscan SP1TBI is
the newest in a series
of Surfscan tools. It’s
optics and capabilities
are the next generation
for the Surfscan 6000
family.
Unpatterned Surfscan
Product Mix
6420
6220
•
•
•
•
488nm, 30mW Ar laser
0.09µm sensitivity*
smooth surfaces
surface quality
•
•
•
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488nm, 30mW Ar laser
0.10µm sensitivity
rough surfaces
varying film thickness
6100
•
•
•
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633n m, 5mW HeNe laser
0.15µm sensitivity
smooth surfaces
surface quality
*All sensitivities refer to latex spheres on well-polished bare silicon
How does the Surfscan work?
•
Illuminates wafer with scanning laser
•
Uses normal incidence for 62X0 (SP1)
•
Grazing-angle incidence for 64X0
•
Collects scattered light from particles
•
Sizes and counts particles
•
Accepts or rejects and then sorts wafers
•
Displays information and writes information to file
(SP1TBI)
Dark field and bright field
basic definitions
• Dark field detection: refers to the
collection and registration of
scattered radiation.
• Bright field detection: refers to
operations performed on the
reflected light.
Inspection System
Substrate
Raster Scanning the Wafer
Wafer Motion
85mm
Raster Motion
LPDs & Haze
Particles are High Amplitude & High Frequency
Haze is Low Amplitude & Low Frequency
PMT Output Signal
Particles
Haze
Time/Position
Dark Field (Normal)
Fundamentals of Light
Scattering
•
Light from laser illuminates particles on
wafer and surrounding surface
•
Particles and surface scatter light
simultaneously
•
Maximize detection of particle scatter and
minimize detection of surface scatter
Laser
SP1TBI Optics & measurement
principle
Detector
 Static Optics
Wafer
:
Translation
Rotation
 Moving Sample
Scanning principles
The wafer is transferred
underneath the beam
in a spiral motion
Dark Field vs. Bright Field
(Scattered Light vs. Reflected Light)
Scattered Light
(Dark Field)
Scattered Light
(Dark Field)
Two Dark Field detection
channels increase sensitivity and
dynamic range
SP1 Dark-field optics optimized for
detection uniformity
fy µm
-1
2.3
SP1
6220
1.0
-2.0
1.
0
-1.0
-1.0
-2.3
2.0
fx µm
-1
Surface scattering (haze) limits ability to detect
particles on unpatterned wafers.
200
Threshold level
Photo150
electrons
from PMT
photocathode
Particle signal
Noise
100
Background (100 photoelectrons)
50
0
0
2000
4000
6000
8000
10000 12000 14000
Position in mm
Rotational collection symmetry is
insensitive to defect orientation
Amplitude
Amplitude
Signal response WITH
rotational symmetry
Amplitude
time
time
Amplitude
Signal response WITHOUT
rotational symmetry
time
Light Scattering Inspection Process
Detector
Point Defect
Collector
Surface Information
Dark Field / Bright Field
Scan
Surface Data Display
Defect Display
LPDs & Areas scatter light into
different polar angles
narrow
collector
wide
collector
small PSL sphere
Scattering
Intensity
large PSL sphere
Si Surface
0
20
40
60
Scattering Polar Angle [degree]
80
Different defect types scatter light into different
polar angles ...
… allowing distinction of defect types
(particle)
(crystal defect)
Distinction of Defects with multiple
DF-Collectors
DFW vs DFN Size
3000
2500
DFN Size
2000
1500
1000
500
0
0
200
400
600
800
1000
1200
1400
1600
DFW Size
DFN/DFW Defect Distribution
20
18
16
12
10
8
6
4
2
DFN/DFW ratio []
5.8
5.4
5.0
4.7
4.3
4.0
3.6
3.2
2.9
2.5
2.2
1.8
1.4
1.1
0.7
0.4
0
0.0
Frequency [#]
14
No Particles
Dark Field (Oblique)
TBI Optics Layout
Dark Field
Wide PMT
Normal
Incidence
Beam
Oblique
Incidence
Beam
ND, polarizers
Dark Field
Narrow PMT
Apertures
Beam
Deflection
Wedge
Lens
Collector
Beam Position
CCD
Ellipsoidal
Collector
Wafer
Scattering Cross-Section
LSE diameter and geometric diameter are not the same.
All of these particles have LSE diameters of 100 nm on a Surfscan 6200.
Si
Index 3.88
LSE
72 nm
Cu
1.14-2.52i
72 nm
Al
0.75-5.75i
75 nm
Si3N4
2.04
90 nm
PSL
1.60*
100 nm
*bulk refractive
index at 488 nm
LSE : Laboratory scale enclosure
SiO2
1.47
105 nm
PSL
Full deposition
Spot deposition
PSL Wafer Standards are used to calibrate the size response curves of
Scanning Surface Inspection Systems (SSIS) manufactured by KLA-Tencor,
Topcon, ADE and Hitachi. PSL Wafer Standards are also used to evaluate
how well the SSIS performs a uniform surface scan across the wafer.
최근 관련 기사
KLA-Tencor사는 자사의 결함검출 툴인 Surfscan SP1 제품군에 결함의 검
출, 분석과 공정 감시 기능을 추가했다.
Monitor eXpert(MX 4.0)라는 명칭의 소프트웨어 옵션 모음은 이 툴이 추가
적인 비용을 들이지 않고도 단일 주사로 공정 감시 정보와 벤치마크 결함 검
출 기능을 제공할 수 있게 한다.
웨이퍼와 IC 제조자는 Surfscan SP1에 MX 4.0을 사용하면 표면 거칠기, 낮
은 k 유전체의 유공률 수준, 방식제와 박막 두께의 균일화, 화학 기계 연마
(CMP) 패드의 상태조절과 연마 균일성, 구리의 전자화학식 증착(ECD)을 하는
동안 용액의 화학적 성분 변경을 비롯하여 동시에 다양한 경과 특성에 대한 결
함을 검출하고 필수적인 통찰력을 확보할 수 있다.
MX 4.0의 웨이퍼 탁도 감시 기능은 정상 조작 창의 바깥으로 벗어나기 시작
하는 공정에 대해 조기에 검출 경보를 제공한다. 이 소프트웨어의 업그레이
드 판에는 검사를 하는 동안 비정상적인 탁도 패턴을 찾아내고 사용자가 공
정 기술자를 위해 이것들을 이전에는 탐색 및 관측이 불가능하던 결함으로
판별할 수 있게 하는 새로운 탁도 분석 기능도 포함되어 있다.