Specific Process Knowledge/Lithography/CSAR

From LabAdviser


Resist Polarity Manufacturer Comments Technical reports Spinner Developer Rinse Remover Process flows (in docx-format)
CSAR Positive AllResist Standard positive resist, very similar to ZEP520. Allresist_CSAR62_English.pdf‎,, CSAR_62_Abstract_Allresist.pdf‎ Manual Spinner 1 (Laurell), Spin Coater Labspin XAR-600-546, XAR-600-548, N50, MIBK:IPA IPA AR-600-71, 1165 Remover Process Flow CSAR.docx‎


Simple e-beam pattern in this resist has been tested, the results showed on this page. If you have questions to the process or wish to use this e-beam resist, please contact Tine Greibe at tigre@danchip.dtu.dk.


Process Flow

Equipment Process Parameters Comments
Pretreatment
4" Si wafers No Pretreatment
Spin Coat
Spin Coater Manual, LabSpin, A-5 AR-P 6200/2 AllResist E-beam resist

60 sec at various spin speed. Acceleration 4000 s-2, softbake 1 - 5 min at 150 deg Celcius

Disposal pipette used; clean by N2-gun before use. Use approximately 1.5 ml per 4" wafer, never use a pipette twice. Softbake is not a crucial step, see e-mail correspondence with AllResist here.
Characterization
Ellipsometer VASE B-1 9 points measured on 100 mm wafer ZEP program used; measured at 70 deg only
E-beam Exposure
JEOL 9500 E-beam writer, E-1 Dosepattern 15nm - 100nm,

dose 120-350 muC/cm2

Virtual chip mark height detection (CHIPAL V1) used in corner of every dose array
Development
Fumehood, D-3 60 sec in X AR 600-546,

60 sec rinse in IPA, N2 Blow dry

Gentle agitation while developing. After developing, wafer is immersed in beaker with IPA, subsequently blow dried with N2 gun.
Characterization
Zeiss SEM Supra 60VP, D-3 2-3 kV, shortest working distance possible, chip mounted with Al tape For dosepattern SEM inspection: the wafers are diced into smaller pieces and sputter coated with Pt at DTU CEN before SEM inspection; please contact Ramona Valentina Mateiu for further information.


Residues: After a dry etch, residues are very easily observed by SEM inspection. This particular trench was e-beam patterned at a too low dose. Residues are recommended removed by optimising dose and developing, not by plasma ashing, since our plasma ashers in the cleanroom are 'dirty' and most likely generate particles on the substrate.

Spin Curves

The thickness is measured on VASE Ellipsometer using a simple Cauchy model for a transparent polymer on Si. The measurements are performed at one incidence angle (70 degrees) only. 9 points on each 4" wafer has been measured; the standard deviation thus representing the homogeinity of the film on the 4" wafers.

Please be aware that I have experienced a somewhat large thickness deviation (5-8 %) depending on the amount of resist applied to the wafer before spin coating.


Dosepattern has been e-beam exposured and SEM inspected on those wafers marked by silver gray.


AllResist AR-P 6200 (> 2ml per 4" wafer) spinning on Spin Coater: Manual LabSpin A-5, TIGRE, 09-04-2014. Softbake 5 min @ 150 degC.
Spin Speed [rpm] Acceleration [1/s2] Thickness [nm] St Dev
2000 4000 225.98 0.97
3000 4000 194.00 0.6
4000 4000 169.57 0.32
5000 4000 151.47 0.26
6000 4000 142.38 0.41
7000 4000 126.59 0.36


AllResist CSAR (< 2ml per 4" wafer) on Spin Coater: Manual LabSpin A-5, TIGRE, 16-06-2014. Softbake 2 min @ 150 degC.
Spin Speed [rpm] Acceleration [1/s2] Thickness [nm] St Dev
3000 4000 201.61 1.20
4000 4000 173.89 0.64
5000 4000 155.91 0.65


AllResist CSAR 1:1 in anisole (< 2ml per 4" wafer), Spin Coater: Manual LabSpin A-5, TIGRE, 16-06-2014. Softbake 2 min @ 150 degC.
Spin Speed [rpm] Acceleration [1/s2] Thickness [nm] St Dev
2000 4000 83.48 0.49
3000 4000 67.12 0.41
4000 4000 58.64 0.44
5000 4000 53.13 0.39
6000 4000 48.76 0.38



Contrast Curves

100 nm lines in ~145 nm thick CSAR has been developed with AR-600-546 (standard CSAR developer) with and without agitation at room temperature and at 5 degrees Celsius. Furthermore, same pattern ahs been developed with N50 (standard developer for ZEP520A).

wafer 9.19 Contrast Curve, Processed by TIGRE, Dec-Jan 2014-2015
Resist Spin Coat E-beam exposure Development Characterisation
CSAR AR-P6200 AllResist 19-12-2014, LabSpin A-1, 4000 rpm, 60s, softbaked 60s @ 150degC 19-12-2014, JBX9500 E-2, 2nA aperture 5, doses 60-600 µC/cm2, 100 nm lines and spaces 22-12-2014, 05-01-2015, Fumehood D-2, misc developers, rinsed in IPA 60s. The cold development was performed with developer stored in refrigerator (Cx1), exact temperature was not measured. 23-12-2014, 05-01-2015, Zeiss Supra 60VP, 10kV, Inlens detector, stage at - 4-5 degrees. Samples not coated before inspection.

Dosetests

So far (September 2014) three wafers with CSAR have been e-beam exposed with dosetests and inspected in SEM. Thickness of resist, e-beam dose and development time has been changed somewhat from wafer to wafer:

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Process Equipment Parameters
6.13 4.09 3.05
Resist Fumehood D-3 Resist: AR-P 6200/2 diluted 1:1 in anisole (Bottled opened 16-06-2014 TIGRE) Resist: AR-P 6200/2 diluted 1:1 in anisole (Bottled opened 16-06-2014 TIGRE) Resist: AR-P 6200/2
Spin Coat Spin Coater LabSpin A-5 Spin: 1 min @ 6000 rpm,
softbake: 1 min @ 150 degC,
thickness: ~50nm
(27-08-2014 TIGRE) 		Spin: 1 min @ 5000 rpm,
softbake: 2 min @ 150 degC,
thickness: ~53nm
(16-06-2014 TIGRE) 		Spin: 1 min @ 6000 rpm,
softbake: 5 min @ 150 degC,
thickness: ~143nm
(09-04-2014 TIGRE)
E-beam exposure JEOL 9500 E-2 Condition file: 0.2nA_ap5,
doses: 180-420 muC/cm2,
Shot pitch: 7-27 nm,
PEC: no
(27-08-2014 TIGRE) 		Condition file: 0.2nA_ap5,
doses: 207-242 muC/cm2,
Shot pitch: 5 nm,
PEC: no
(02-07-2014 TIGRE) 		Condition file: 2nA_ap5,
doses: 207-242 muC/cm2,
Shot pitch: 5 nm,
PEC: no
(10-04-2014 TIGRE)
Develop Fumehood D-3 Developer: SX-AR 600-54/6,
time: 30 sec,
Rinse: 30 sec in IPA
(28-08-2014 TIGRE) 		Developer: SX-AR 600-54/6,
time: 60 sec,
Rinse: 30 sec in IPA
(08-07-2014 TIGRE) 		Developer: SX-AR 600-54/6,
time: 60 sec,
Rinse: 60 sec in IPA
(April/May-2014 TIGRE)
Sputter Coat (please contact Ramona Valentina Mateiu for information ) Cressington 208HR, DTU CEN 3-5 nm Pt, sputtering, (29-08-2014 TIGRE) 3-5 nm Pt, sputtering (09-07-2014 TIGRE) 3-5 nm Pt, sputtering (22-05-2014 TIGRE)
Characterization Zeiss SEM Supra 60VP, D-3 Acc voltage: 3 kV, WD: < 4mm,
conducting tape close to pattern (29-08-2014 TIGRE) 		Acc voltage: 3 kV, WD: < 4mm,
conducting tape close to pattern (09-07-2014 TIGRE) 		Acc voltage: 2 kV, WD: < 4mm,
conducting tape close to pattern (06-06-2014 TIGRE)

SEM inspection










Etch Tests

If you have wafers or chips with CSAR you would like to have tested, please send me an [email].

Chlorine versus flourine-based etches

We have experienced problems with removal of CSAR after chlorine-based dry etch, see the file File:DryEtchTestsCSAR.pdf. It seems the chlorine etch forms particles of chlorinated CSAR on the surface, and these particles remains on the surface after resist removal with AR-600-71. The C4F8/SF6 etch also forms particles on the surface, but much smaller than those formed in the chlorine etch. It seems these particles are removed after 3 minutes in AR-600-71.

How to mount chips in dry etch tools

All etch rates presented here are measured on chips (i.e. diced 4" wafers) crystal bonded to a carrier. The carrier is either a blank Si wafer, a Si wafer spin coated with resist or a Si wafer coated with ALD grown Al2O3.

Etch Tests of CSAR, recipe 'nano1.42', DRIE PEGASUS, A-1. CSAR thickness measured on Ellipsometer VASE at 70 degrees
Sample CSAR Etch rate nm/min
Full 4" Si wafer with non-patterned ~180 nm CSAR ~56.5 (based on 2 runs)
Full 4" Si wafer with non-patterned ~240 nm CSAR,
postbaked 60 sec @ 130 degC 		~56.5 (based on 2 runs)
1/4 4" Si wafer with non-patterned ~125 nm CSAR,
not crystal bonded to Si carrier 		~83.3 (based on 3 runs)
1/4 4" Si wafer with non-patterned ~125 CSAR,
crystal bonded to 4" Si carrier 		~54 (based on 1 run)

Etch rates and profile inspection

Continous Etches

Recipe nano1.42 on Deep Reactive Ion Etch PEGASUS A-1
Recipe Gasses C4F8 75 sccm, SF6 38 sccm Profiles of lines exposed at 300 µC/cm2, etched 2:30 minutes (150s) with recipe 'nano1.42'
Pressure 4 mTorr,

Strike: 3 secs @ 15 mTorr

Power 800 W Coil Power,

40 W Platen Power

Platen temperature - 20°C
Conditions Conditioning Pre-clean: 10 min oxygen clean

5 min oxygen clean between runs

Etch rates Si

500 nm lines: ~200 nm/min
190 nm lines: ~200 nm/min
102 nm lines: ~190 nm/min
61 nm lines: ~170 nm/min

CSAR ~55 nm/min


Recipe processC on Deep Reactive Ion Etch PEGASUS A-1
Recipe Gasses C4F8 70 sccm, SF6 38 sccm Profiles of lines exposed at 300 µC/cm2, etched 60s with recipe 'ProcessC'
Pressure 4 mTorr,

Strike: secs @ mTorr

Power 450 W Coil Power, 100 W Platen Power
Platen temperature 10°C
Conditions Conditioning Pre-clean: 10 min oxygen clean

5 min oxygen clean between runs

Etch rates Si

500 nm lines: ~300 nm/min
102 nm lines: ~250 nm/min

CSAR 158 nm/min

Bosch Etch

Recipe NBoost01 on Deep Reactive Ion Etch PEGASUS A-1
Recipe Deposition step Duration 2.5 s Profiles of lines exposed at 300 µC/cm2, etched 6:00 minutes with recipe 'NBoost01'
Gasses C4F8 50 sccm, SF6 0 sccm
Pressure 10 mTorr
Powers 500 W Coil
Etch step (boost) Duration 1.5 s
Gasses C4F8 0 sccm, SF6 60 sccm
Pressure 5 mTorr
Powers 400 W Coil, 50 W Platen
Etch step (main) Duration 3.5 s
Gasses C4F8 40 sccm, SF6 60 sccm
Pressure 15 mTorr
Powers 400 W Coil, 20 W Platen
Platen temperature 20 °C
Conditions Conditioning Pre-clean: 10 min oxygen clean

5 min oxygen clean between runs

Etch rates Si

200 nm lines: ~700 nm/min
130 nm lines: ~580 nm/min

CSAR ~18 nm/min
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