Specific Process Knowledge/Lithography/Espacer

Espacer is a chemical that works as a discharging layer when e-beam writing on a non-conducting wafer; it is spun onto the wafer on top of the resist and easily rinsed off the wafer after e-beam exposure.

All substrates are grounded to the e-beam cassette when properly loaded. On a non-conducting substrate, the accumulation of charges in the substrates will however destroy the e-beam patterning. To avoid this, a charge dissipating layer is added on top of the e-beam resist; this will provide a conducting layer for the electrons to escape, while high-energy electrons will pass through the layer to expose the resist.

We have Espacer in stock and approved for use in the cleanroom. You can find a guideline for a process flow here: Process Flow CSAR + ESPACER.docx‎. Technical information of Espacer can be found here: Espacer_300_Technical_Info.pdf‎, Espacer_catalog.pdf‎.

Espacer is a dirty chemical, so we recommend Electra92, or best Thermal Al eg. 20 nm

Please contact Lithography if you wish to use this material.

Process	No ESPACER	ESPACER
Wafer	Borofloat 4" wafers (JB456), no pretreatment
Resist	AR-P 6200/2 AllResist E-beam resist
Spin Coat	1 min @ 4000 rpm, softbake 2 min @ 150 degC, thickness ~140nm
ESPACER		1 min @ 2000 rpm (no softbake), Spin Coater: Manual All Puropse
E-beam exposure	2 nA, aperture 5, dose 150-310 muC/cm2, SHOT (A,10)
Rinse		Rinsed with hand shower in fumehood, dried with N2 gun
Developing	SX-AR 600-54/6 60 sec, 60 sec IPA rinse
Characterization	Nikon ECLIPSE optical microscope, E-5
All doses
230 muC/cm2
219 muC/cm2
Sputter Coated		<10nm Pt at DTU CEN
Characterization		Zeiss SEM supra 60VP, D-2
230 muC/cm2