Specific Process Knowledge/Lithography/CSAR

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.

AllResist AR-P 6200.09 (> 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]
2000	4000	226
3000	4000	194
4000	4000	170
5000	4000	151
6000	4000	142
7000	4000	127

AllResist CSAR 6200.09 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]
2000	4000	84
3000	4000	67
4000	4000	59
5000	4000	53
6000	4000	49

AllResist CSAR 6200.18 (< 2ml per 4" wafer), Spin Coater: Manual Standard Resists, E-5, TIGRE, 15-06-2016. Softbake 2 min @ 180 degC.
Spin Speed [rpm]	Acceleration [1/s2]	Thickness [nm]
2000	2000	1003
3000	2000	809
4000	2000	721
5000	2000	639
6000	2000	586
7000	2000	549

Contrast Curves

100 nm lines in both ~70 nm and ~188 nm thick CSAR has been developed with AR-600-546 (standard CSAR developer) at room temperature.

CSAR Contrast Curve, Processed by TIGRE, FEB-MARCH 2016
Resist	Spin Coat	E-beam exposure	Development	Characterisation
CSAR AR-P6200 AllResist, CSAR AR-P6200 diluted 1:1 in Anisole	08-02-2016, LabSpin E-5, 4000 rpm, 60s, softbaked 60s @ 205 degC	09-02-2016, JBX9500 E-2, 2nA aperture 5, doses 40-600 µC/cm2, 100 nm lines and 300 nm spaces	11-02-2016, Fumehood D-2, AR-600-546, rinsed in IPA 60s.	02-03-2016 AFM Icon, F-2, ScanAsyst in Air

Dark Erosion

Dark erosion has been measured on a un-exposed 4" wafer spin coated with CSAR 6200.18 to a thickness of approximately 549 nm. The resist thickness has been measured by VASE Ellipsometer before development, and after 3 minutes, 13 minutes, and 30 minutes of development in AR 600 546.

The graphs shows the measured thicknesses; the errorbars represents the standard deviations from the ellipsometric measurements. The average etch rate of CSAR is ~0.1 nm/min.

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

	SEM inspection of wafer 6.13, 100 nm exposed pattern, shot pitch 7 nm
300 [muC/cm2]							ACHK NOT READY

	SEM inspection of wafer 6.13, 50 nm exposed pattern, shot pitch 7 nm
270 [muC/cm2]						ACHK NOT READY
300 [muC/cm2]						ACHK NOT READY

	SEM inspection of wafer 6.13, 30 nm exposed pattern, shot pitch 7 nm
270 [muC/cm2]					ACHK NOT READY
300 [muC/cm2]					ACHK NOT READY

	SEM inspection of wafer 6.13, 20 nm exposed pattern, shot pitch 7 nm
270 [muC/cm2]			ACHK NOT READY
300 [muC/cm2]			ACHK NOT READY

	SEM inspection of wafer 4.09, 50 nm exposed pattern, shot pitch 5 nm
230 [muC/cm2]

	SEM inspection of wafer 4.09, 30 nm exposed pattern, shot pitch 5 nm
219 [muC/cm2]
230 [muC/cm2]
242 [muC/cm2]

	SEM inspection of wafer 4.09, 20 nm exposed pattern, shot pitch 5 nm
242 [muC/cm2]
253 [muC/cm2]

	SEM inspection of wafer 3.05, 50 nm exposed pattern, shot pitch 5 nm
219 [muC/cm2]
230 [muC/cm2]
242 [muC/cm2]

	SEM inspection of wafer 3.05, 30 nm exposed pattern, shot pitch 5 nm
219 [muC/cm2]
230 [muC/cm2]
242 [muC/cm2]

	SEM inspection of wafer 3.05, 20 nm exposed pattern, shot pitch 5 nm
230 [muC/cm2]
242 [muC/cm2]
253 [muC/cm2]

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