YES Equipment Solutions for Imprint Lithography
Chao Liu*, Ken Sautter, Kaushal Singh, Nitin Vaish
Yield Engineering Systems
203-A Lawrence Drive
Livermore, CA 94551
E-mail: CLiu@yieldengineering.com

A successful imprint process begins with surface preparation. High adhesion between thesubstrate and the imprint material is critical to ensure that imprinted film does not delaminate
from the substrate. Low adhesion to the master mold surface is needed when the imprinted film
and mold are separated. YES’s inductively coupled plasma cleaning tools strip contaminantsfrom the surface of the substrate prior to application of vapor-deposited self-assembled
monolayers (SAMs) of a functionalized silane. Currently in widespread use in thesemiconductor industry to promote adhesion of photoresists to Si wafers using Hexa-MethylDi-Silazane (HMDS), all aspects of this process can be tailored to specific material systems.
YES has demonstrated >100 chemical processes for a wide range of purposes.






Alkyl Silane Compounds (such as OTS, OTES, HMDS, etc.)
o Create surfaces with various surface tension to promote adhesion and act asmoisture barrierso Contact Angle: 64 - 107Amino Group (such as APTES, APTMS, etc.)
o Create a positively charged reactive surface. Acts as an adhesion promoter forepoxy-based resist or organic materials such as DNA
o Contact Angle: 50 - 74
Epoxy, Acrylate, Methacrylate Compounds (such as GOPS, Valmat, etc.)
o Create a reactive surface, hydrophilic surface. Epoxy rings are easily reacted toform alcohols or to bindo Contact Angle: 45 - 75
Fluorinated Compounds (such as FDTS, FOTS, etc)
o Create extremely hydrophobic or anti-corrosion coatingso Contact Angle: 100 - 133
Thiol, PEG, or Isocyanate Functional Silane

For imprint materials processed from solution, complete removal of residual solvents is key toachieving repeatable and uniform results. With approximately 1% temperature uniformity overthe volume of the process chamber and automated process controls, YES’s vacuum cure ovens
are effective at removing residual solvents such that imprint material properties are uniform
wafer-to-wafer and lot-to-lot. As shown in Table 1, <1% temperature uniformity (1 sigma)
results in superior film uniformity as indicated by Water Contact Angle (WCA) of APTES (3Amino-Propyl-Tri-Ethoxy-Silane) film on Si wafer.
YES provides equipment ranging from laboratory systems to high volume manufacturingsolutions that leverage the demanding requirements of the semiconductor industry for accuracy
and repeatability to produce resist films that generate the highest fidelity imprints. List ofequipment and main applications has been summarized by the following as well as in Table 2.
 EcoClean Systems: Automated plasma surface cleaning solution.
 EcoCoat Systems: Vapor phase deposition of functionalized silane SAMs foradhesion promotion with excellent repeatability and precision.
 VertaCure System: Vacuum-based, low temperature curing.

Table 1: Temp uniformity of ÉcoCoat and superior film uniformity indicated by WCA of APTES.

Temperature
Average

Temperature
Uniformity(1 sigma)

WCA
Average ofAPTESWCA
Uniformity ofAPTES(1 sigma)

Top shelves

152.6°C

0.36%

60.5

2.24%

Middle shelves

152.2°C

0.29%

60.9

1.69%

Bottom shelves

153.2°C

0.72%

All points

152.7°C

0.53%

60.7

1.90%

Position

Table 2: List of YES Clean, Coat and Cure equipment and representative applications.
Clean

CoatCure

Plasma Clean System
200mm (Manual)

ÉcoCoat / 58TA, 310TA

PB Series Cure System
PB6/PB8/PB12 Vacuum Cure

Plasma Clean

HMDS Vapor
Prime/Image Reversal

Polyimide/BCB/PBO/Low
Temp Polymer Cure

ÉcoClean 200mm Clean
300mm (Automated)

VertaCoat (MonolayerVapor Deposition)

VertaCure 300mm
Vacuum Cure (Panel)

Photoresist
Strip/Clean/Descum

SAMs Silane Prime

Polyimide/BCB/Other
Polymer Cure