Specific Process Knowledge/Lithography/LiftOff - Revision history

Jehem at 10:09, 12 January 2026

2026-01-12T10:09:39Z

← Older revision		Revision as of 12:09, 12 January 2026
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	~~=Lift-off at Nanolab=~~		{{:Specific Process Knowledge/Lithography/LiftOff/liftoff_wetbench07}}

	~~==Lift-off wet bench 07==~~
	~~[[Image:Lift_off.jpg\|300x300px\|thumb\|Lift-off wet bench in D-3]]~~

	~~The user manual, and contact information can be found in [http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=384 LabManager] - '''requires login'''~~


	{~~\|border="1" cellspacing="1" cellpadding="10" style="text-align:left;"~~

	~~!colspan="2" border="none" style="background:silver; color:black;" align="center"\|Equipment~~
	~~\|style="background:WhiteSmoke; color:black"; align="center";\|'''Lift-off'''~~
	\|-
	~~!style="background:silver; color:black;"\|Purpose~~
	~~\|style="background:LightGrey; color:black"\|~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	*Lift-off of UV or E-beam resist
	*Resist strip of wafers with metal
	\|-
	~~!style="background:silver; color:black;"\|Bath chemical~~
	~~\|style="background:LightGrey; color:black"\|~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	*NMP (Remover 1165)
	*Rinse in diluted IPA
	\|-
	~~!style="background:silver; color:black" valign="center" rowspan="2"\|Process parameters~~
	~~\|style="background:LightGrey; color:black"\|Process temperature~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	~~Heating of the bath is possible.~~

	~~The heating has been limited to 65°C~~
	\|-
	~~\|style="background:LightGrey; color:black"\|Ultrasonic agitation~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	~~Continuous or pulsed~~

	~~The power may be varied~~
	\|-
	~~!style="background:silver; color:black" valign="center" rowspan="3"\|Substrates~~
	~~\|style="background:LightGrey; color:black"\|Substrate size~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	* 100 mm wafers
	* 150 mm wafers
	\|-
	~~\| style="background:LightGrey; color:black"\|Allowed materials~~
	~~\|style="background:WhiteSmoke; color~~:~~black"\|~~
	~~Silicon or glass wafers~~

	~~Film or patterning of all but Type IV (Pb, Te)~~
	\|-
	~~\|style="background:LightGrey; color:black"\|Batch~~
	~~\|style="background:WhiteSmoke; color:black"\|~~
	~~1 - 25~~
	\|-
	\|}

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	== Process ~~information ==~~
	~~Lift-off is used for lift-off using resists that are soluble in NMP (''N''-Methyl-Pyrrolidone), supplied in the cleanroom as "Remover 1165". Both AZ 5214E and AZ nLOF are soluble in NMP.~~

	~~For information on processing of AZ nLOF, or image reversal of AZ 5214E, see here: [[Specific_Process_Knowledge~~/Lithography/~~Resist~~/~~UVresist\|Resist Overview]].~~

	~~<br clear="all" />~~

	~~==Poor metal (TiPt) adhesion/ Metal delaminating after lift-off==~~

	~~''This experiment was done by Gustav E. Skands(ges@sbtinstruments.com) in May 2024''~~

	This entry details an observed issue with metal adhesion during a Ti/Pt deposition (10/160 nm) and lift-off process within DTU Nanolab. The employed photoresist was TI Spray from MicroChemicals, which is believed (but not confirmed) to share many properties with AZ5214E. The thickness of the resist was approximately 5 µm, and it was spray coated onto the substrate using the Spray Coater.

	~~'''Root cause:'''~~
	The core of the adhesion challenge was linked to the choice of photoresist developer. 2.08% TMAH facilitated excellent resist pattern development, but subsequent metal adhesion during the deposition process was consistently poor, observed across both Wordentec and both Temescal systems. This occurred despite the absence of any visible residues on the substrate surface. Attempts to enhance adhesion, including a descum procedure using 70 mL/min O2 and 70 mL/min N2, 150W, 5 minutes, prior to deposition, were unsuccessful.

	~~'''Solution:'''~~
	Changing the developer to AZ351B (2 minutes development time in beaker) in the process provided significant improvements. Although AZ351B exhibited reduced selectivity in dissolving the soluble vs. insoluble resist, thereby compromising the precision of the resist pattern, it considerably improved the adhesion properties of the deposited metal.

	A dual developer approach—using TMAH (3x 60s development in Developer: TMAH UV-lithography followed by a 30 second development step in AZ351B—was therefore implemented. This approach leveraged the high-resolution patterning capability of TMAH and the superior adhesion characteristics provided by AZ351B.

	The different adhesion properties observed with the two developers suggest underlying molecular interactions that may inhibit or promote metal-substrate bonding. It is hypothesized that TMAH may leave molecular residues that, although not detectable through optical inspection, could create a barrier to adhesion at the molecular level. Conversely, AZ351B appears to modify or clear these residues, thereby enhancing adhesion.

	~~A descum step of 70 mL/min O2 and 70 mL/min N2, 150W, 5 minutes, was still performed immediately before deposition. However, it is unknown if this has an effect.~~

	~~Process temperature considerations~~
	The process incorporated a deposition temperature of 50°C, which was maintained without further comparative analysis against room temperature deposition due to the successful outcomes achieved and considerations of operational cost efficiency.

	~~==Poor metal (TiAu) adhesion/ Metal delaminating after lift-off==~~
	~~''This experiment was done by Mathias Zambach (zambach@fysik.dtu.dk) in June 2024''~~

	~~'''Problem:''' Mathias experienced the delamination of TiAu after the lift-off process, see the image.~~

	~~'''Solution:''' Adding a descum step (70 ml/min O2, 70 ml/min N2, 150W, 5 min (Plasma Asher 1)) right before metal depositions.~~

	~~[[File:Delamination of TiAu.jpg\|thumb]]~~

	~~The process flow:~~

	~~1.) 2 um nLOF coating~~

	~~2.) Exposure~~

	~~3.) Development of nLOF~~

	~~'''4.) 5 min descum (70 ml/min O2, 70 ml/min N2, 150W, 5 min in Plasma Asher 1) was done right before TiAu deposition'''~~

	~~5.) 10 nm Ti depositing with 2 A/s by Temescal~~

	~~6.) 200 nm Au depositing with 2 A/s by Temescal~~

	~~7.) Lift-off (approx. 45 min)~~

	~~By adding step 4.) 5 min Descum, the problem with the delamination of metals was solved.~~

Jehem: /* Lift-off Comparison Table */

2026-01-12T10:07:45Z

Lift-off Comparison Table

← Older revision		Revision as of 12:07, 12 January 2026
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	!colspan="2" border="none" style="background:silver; color:black;" align="center"\|Equipment		!colspan="2" border="none" style="background:silver; color:black;" align="center"\|Equipment
	\|style="background:WhiteSmoke; color:black" align="center"\|<b>[[Specific Process Knowledge/Lithography/LiftOff#Lift-off_wet_bench_07\|Lift-off]]</b>		\|style="background:WhiteSmoke; color:black" align="center"\|<b>[[Specific Process Knowledge/Lithography/LiftOff#Lift-off_wet_bench_07\|Lift-off (wet bench 07)]]</b>
	\|style="background:WhiteSmoke; color:black" align="center"\|<b>[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=370 Fume hood 03: Solvents]</b> - '''requires login'''		\|style="background:WhiteSmoke; color:black" align="center"\|<b>[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=370 Fume hood 03: Solvents]</b> - '''requires login'''
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Taran: /* Lift-off wet bench 07 */

2025-06-24T11:44:31Z

Lift-off wet bench 07

← Older revision		Revision as of 13:44, 24 June 2025
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	\|style="background:WhiteSmoke; color:black"\|		\|style="background:WhiteSmoke; color:black"\|
	*NMP (Remover 1165)		*NMP (Remover 1165)
	*Rinse in IPA		*Rinse in diluted IPA
	\|-		\|-
	!style="background:silver; color:black" valign="center" rowspan="2"\|Process parameters		!style="background:silver; color:black" valign="center" rowspan="2"\|Process parameters

Taran: /* Lift-off Comparison Table */

2025-06-24T11:43:48Z

Lift-off Comparison Table

← Older revision		Revision as of 13:43, 24 June 2025
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	\|style="background:WhiteSmoke; color:black"\|		\|style="background:WhiteSmoke; color:black"\|
	NMP (Remover 1165) / Rinse in IPA		Lift-off bath with NMP (Remover 1165)

			Rinse bath with diluted IPA
	\|style="background:WhiteSmoke; color:black"\|		\|style="background:WhiteSmoke; color:black"\|
	User defined		User defined

Taran: /* Poor metal (TiAu) adhesion/ Metal delaminating after lift-off */

2025-02-07T08:32:23Z