jeol jbx-9300fs electron beam lithography system · pdf fileelectron beam lithography system...
Post on 06-Mar-2018
233 Views
Preview:
TRANSCRIPT
6/17/09, revision 11 1
JEOL JBX-9300FS Electron Beam Lithography System
Training
6/17/09, revision 11 2
Course Outline•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check–
ALD & Exposure
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 3
Why E-beam Lithography?
•
exceeds patterning capability of optical lithography–
easily pattern sub-micron features
–
MiRC has demonstrated 6.5nm features•
patterns rapidly created from CAD file–
no mask necessary like optical lithography
–
rapid turn around on design modifications, ideal for research
6/17/09, revision 11 4
JBX-9300FS key features•
4nm diameter Gaussian spot electron beam
•
50kV/100kV accelerating voltage•
50pA –
100nA current range
•
50MHz scan speed•
+/-
100um vertical range automatic focus
•
+/-
2mm vertical range manual focus•
ZrO/W thermal field emission source
•
vector scan for beam deflection•
max 300mm (12") wafers with 9" of writing area
•
< 20nm line width writing at 100kV•
< 20nm field stitching accuracy at 100kV
•
< 25nm overlay accuracy at 100kV
6/17/09, revision 11 5
Generic Block DiagramGun Control
Blanking Control
Deflection Control
Electron Optics Control
Pattern Proc.and control
StageControl
Computer
x-interferometer
y-in
terfe
rom
eter
stage
stagemotor
stagemotor
Gun
Ele
ctro
n O
pics
referencemarks
6/17/09, revision 11 6
ColumnElectron gun
ZrO/W emitterSuppressor
First anode
Second anode
Acceleration electrodes
Ground anode
First alignment coil
Second alignment coil
Blanking electrode
Blanking aperture
Secondlens
Thirdlens
Zoom lensesDynamic focus correction electrode
Third alignment coil
Dynamic astigmatism correction electrode
Subsidiary deflector (SUBDEF)
Electromagnetism astigmatism correction electrodeMain deflector (PDEF)
Backscattered electron detector
Objective aperture
Objectivelens
Workpiece
surface
6/17/09, revision 11 7
Beam & Stage Position
Stage position accuracy = λ
/ 1024 = 0.62nm
6/17/09, revision 11 8
PDEF & SUBDEF
50
6/17/09, revision 11 9
Top View of Stage
6/17/09, revision 11 10
Side View
6/17/09, revision 11 11
Stage w/o Cassette
cassette goes here
laser mirrors
6/17/09, revision 11 12
Wafer Cassette
6/17/09, revision 11 13
Field Stitching
500 µm (100kV)
500 µm(100kV)
6/17/09, revision 11 14
Within Field Writing
Vector scan
6/17/09, revision 11 15
4”
Wafer with Chips
2mm
2mm
6/17/09, revision 11 16
Example “Chip”
Chip
Field500um
500um
4um4um
Subfields
beamdiameter
shot pitch
6/17/09, revision 11 17
Objective Aperture
larger aperture = larger beam diameter, more currentsmaller aperture = higher resolution
aperture
beam diameter min resolution
current range3,4,5
4 –
9nm < 20nm
50pA –
2nA6
8 –
14nm
30nm
2nA –
7nA7
30nm
60nm
10nA
Most of the time, the 9300 will be set to aperture #3 and 2nA beam current.
6/17/09, revision 11 18
Beam diameter as a function of current & aperture
6/17/09, revision 11 19
Dose Equation
AtID /)*(=whereD = dose (µC/cm2)I = current (A)t = time (sec)A = exposure area (cm2)
6/17/09, revision 11 20
Job Time Estimate
IADt /)*(=if D = 200 µC/cm2
A = 1 cm2
I = 2nA
then
t = 27 hours 46 min
time calculator at http://nanolithography.gatech.edu/tcalc.php
6/17/09, revision 11 21
Shot Pitch
•
Shot pitch is equivalent to pixel value –
the smaller the shot pitch, the better the feature definition
•
Shot pitch is limited by scanning frequency of the SUBDEF (max = 50MHz)
6/17/09, revision 11 22
Effect of Shot PitchEnergy deposited in resist
x
Consider a line is exposedwith 200uC/cm^2 dose. Dependingon the number of pixels thatthe line-width is divided into, the line edge roughness (LER)and line-width will vary.
The graph at right shows the cross-section of energydeposition profile of a line with1,2,4 and n pixels.
6/17/09, revision 11 23
Minimum Shot Pitch Calculation
•
t = D.A/I•
A = area of pixel = a2
•
t = 1/fclk
where fclk
is the maximum scanning frequency of the amplifier
• a = √I/(fclk.D)
6/17/09, revision 11 24
Faraday Cup
6/17/09, revision 11 25
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check–
ALD & Exposure
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 26
Stage
faraday cupAE, BE markSEM sample
6/17/09, revision 11 27
Absorbed Electron Detection
6/17/09, revision 11 28
INITAE
x -
scan y -
scan
ds/dx ds/dy
mark center position
y-scan
metal grid
x-scan
pn
junction
6/17/09, revision 11 29
Backscattered Electron Detection
6/17/09, revision 11 30
INITBE
x -
scan y -
scan
ds/dx ds/dy
Au cross on Si substrate
x-scan
y-scan
mark center position
6/17/09, revision 11 31
PDEFBE, SUBDEFBE, DISTBE mark detection
6/17/09, revision 11 32
PDEFBE & SUBDEFBE500 um
500 um
top
bottom
left right
482um
482um
4 um
4 um
1 2 3
54 6
7 8 9
PDEFBE4 points measured
x & y gain correctionx & y rotation correction
SUBDEFBE9 points measured
x & y gain correctionx & y rotation correction
gain
rotation
shift
6/17/09, revision 11 33
DISTBE Field Distortion Correction
6/17/09, revision 11 34
Height Detection
6/17/09, revision 11 35
HEIMAP
•
measures height across wafer on defined array positions (adjustable by user)
•
takes average height and uses that for focus value for writing everywhere
•
appropriate for 100pA & 1nA current•
not appropriate for 10nA –
use virtual chip
mark height detection
6/17/09, revision 11 36
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check–
ALD & Exposure
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 37
Available Cassettes
•
Wafer–
75mm, 100mm, 150mm, 200mm diameter
–
300mm can be purchased for up to 9”
square writing area
•
Masks–
5”
mask, 6”
mask
•
Pieces–
minimum 3 x 5mm piece
6/17/09, revision 11 38
4”
Wafer Cassette
6/17/09, revision 11 39
Backside of Wafer Cassette
6/17/09, revision 11 40
Global & Chip Mark Detection
6/17/09, revision 11 41
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 42
CAD file conversion
CADENCEfile
AutoCAD.DXF file linkCAD
GDSII file
JEOL01file JBXFILER JEOL52
v3.0 file
or
or
6/17/09, revision 11 43
SCHD execution
specifies1. JEOL52 v3.0 pattern file2. how to arrange on wafer3. shot modulation4. type of calibration 5. beam current
specifies1. wafer cassette window2. calibration file3. base dose4. job deck file(s) to use 5. shot pitch
6/17/09, revision 11 44
Pattern Preparation
6/17/09, revision 11 45
JBXFILER Pattern Preparation
6/17/09, revision 11 46
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 47
Negative/Positive Resist
substrate
exposing e-beam exposing e-beam
NEGATIVE POSITIVE
select appropriate resist for process and to minimize writing time
6/17/09, revision 11 48
resist vs. dose curves
dose
resist thickness
positive negative
dose
resist thickness
lesssensitive
moresensitive
dose
resist thickness
lesscontrast
morecontrast
6/17/09, revision 11 49
Resists on hand at MiRC•
Positive resists–
ZEP520A+
good etch resistance+
fast+
good resolution (~ 10nm)-
expensive ($3/mL)
–
PMMA+
cheap ($1/mL)+
good for liftoff+
high resolution (< 10nm)-
poor etch resistance-
slow
•
Negative resist–
XR-1541 (HSQ)+
good etch resistance (HSQ is basically SiO2)
+
excellent resolution (6.5nm)
-
slow-
expensive ($4/mL)
–
ma-N 2403 (Novolak)+
good etch resistance+
optical DUV exposable+
faster than HSQ±
moderately priced ($2/mL)
-
poor adhesion to quartz
6/17/09, revision 11 50
Resist Comparison
-0.2
0
0.2
0.4
0.6
0.8
1
1.2no
rmal
ized
resi
st th
ickn
ess
100 1000 800 600 500 400 300 200 2000 3000
dose (uC/cm2)
HSQPMMAZEP
resist200 480 1280
6/17/09, revision 11 51
Metal Liftoff
evaporate metal ontopatterned resist
strip resist
6/17/09, revision 11 52
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 53
Electron Solid Interactions
•
electrons forward scatter in resist (alpha)
•
electrons backscatter off substrate (beta)
•
Causes dose to spread away from where you want it to go, and expose areas you don’t want to be exposed
6/17/09, revision 11 54
Forward Scattering (α)
•
as electrons enter resist, they experience small angle scattering, effectively broadening the initial beam diameter
•
forward scattering is minimized by using the thinnest possible resist and highest accelerating voltage
5.1)/(9.0 btf VRd =df
= effective beam diameter (nm)Rt
= resist thickness (nm)Vb
= acceleration voltage (kV)
6/17/09, revision 11 55
Backscattering (β)•
as electrons pass thru resist and enter substrate, many will undergo large angle scattering events
•
these electrons may return back into the resist at a significant distance from the incident beam, causing additional resist exposure → this is called the proximity effect
6/17/09, revision 11 56
Electron Solid Interaction
Source: SPIE Handbook of Microlithography, Section 2.3 Electron-Solid Interactions
6/17/09, revision 11 57
Simulated Electron Energy Profile
Source: SPIE Handbook of Microlithography, Section 2.3 Electron-Solid Interactions
6/17/09, revision 11 58
Alpha & Beta (for 0.5um resist on Si substrate)
Beam energy (keV)
α
(um) β
(um) η
5 1.33 [0.18] [0.74]10 0.39 [0.60] [0.74]20 0.12 2.0 0.7450 0.024 9.5 0.74100 0.007 31.2 0.74
backscattered electrons have large range at 100kV!!!
6/17/09, revision 11 59
Influence of Proximity Effect on Pattern Generation
6/17/09, revision 11 60
Line Edge Deviations due to Proximity Effect
6/17/09, revision 11 61
Proximity Effect Correction by Dose Modulation
6/17/09, revision 11 62
Proximity Effect Correction by Shape Modulation
original CAD pattern
simulated doseprofilecalculated shape
modification to achieve desired
line
6/17/09, revision 11 63
Dose Dependencies
pattern size
pattern density
required dose
required dose
resist thickness required dose
acceleration voltage required dose
substrate AMU required dose
6/17/09, revision 11 64
Example of Proximity Effectlarge exposed area next to small lines
causes overexposure
6/17/09, revision 11 65
How to correct in my CAD file?•
separate small features from large features by placing on different layers in AutoCAD
•
then assign a different datatype
to each layer in linkCAD
•
then assign different doses (shot modulation) to each datatype–
try a wide range of doses on your first exposure
•
use SEM image to make careful dimension measurements
•
adjust dose as necessary and repeat exposure
6/17/09, revision 11 66
Test Pattern
1000nm
500nm
200nm
100nm
50nm
20nm
10nm
2nm
50 x 50um
1 x line 2 x line 10 x line 10um 20um 30um 40um 50um
line width
space width(exception: 2nm line group has same spacing as 10nm line group)
3 x line 4 x line 5 x line
6/17/09, revision 11 67
1um lines in ZEP at various pitch
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
line
wid
th (u
m)
100 200 300 400 500 600 700 800 900 1000 1100
actual dose (uC/cm2)
"1:01""1:02""1:03""1:04""1:05""1:10""1:20""1:30""1:40""1:50"
line:space ratio
6/17/09, revision 11 68
Required dose for 1um line in ZEP as a function of grating
0
1000
2000
3000
4000
50001u
m d
ose
(uC
/cm
2)
0 10 20 30 40 50 60
space/line ratio
1um dose (uC/cm2) = 98.318479 + 85.290888 space/line ratio
6/17/09, revision 11 69
•
Explain hardware–
column, lenses, amplifiers–
field, chip, subfield–
shot pitch, beam diameter–
D = (I * t)/A•
Calibration–
AE & BE marks–
INITAE, INITBE, PDEFBE, SUBDEFBE, DISTBE–
HEIMAP•
Substrate–
various cassettes–
global & chip mark alignment–
virtual chip mark height detection•
Pattern Preparation–
CAD file preparation–
linkCAD
conversion–
file transfer–
JBXFiler–
Job Deck & Schedule File–
Schd
and Array check
•
Resist Exposure & development–
positive & negative resists–
contrast–
liftoff, etching•
Proximity Effect•
Website
6/17/09, revision 11 70
Website
•http://nanolithography.gatech.edu
top related