Difference between revisions of "Soft Lithography"

From Quattrone Nanofabrication Facility
Jump to navigation Jump to search
(adding process image, reformatting)
Line 1: Line 1:
 
[[Category:Lithography]] [[Category:Soft Lithography]]
 
[[Category:Lithography]] [[Category:Soft Lithography]]
 
__NOTOC__  
 
__NOTOC__  
−
 
−
[[File:SoftLitho Protocol Oct2025.PNG|center|800px]] <br>
 
  
 
===About===
 
===About===
Line 9: Line 7:
  
 
===Process Flow===
 
===Process Flow===
 +
[[File: SoftLitho Protocol Oct2025.PNG|thumb|right|upright=1.75|'''Standard QNF Soft Lithography Protocol, Updated May 2025.''' <br>Images from [https://www.fabublox.com/process-editor/70e6195b-900a-48e8-8b05-70dd807d973f "Microfluidics at QNF" Process on Fabublox] ]]
 
*The master used can be fabricated out of photoresist or etched silicon. The most commonly used materials are epoxy-based negative photoresist (SU8 or HARE SQ). For a negative photoresist, the parts exposed to UV become cross-linked, while the remainder of the film remains soluble and can be washed away during development. The height of this structure is determined by the thickness of the resist, which we control through our application method. The length and width of features are patterned through the UV exposure, either by mask or direct write tools.<br>
 
*The master used can be fabricated out of photoresist or etched silicon. The most commonly used materials are epoxy-based negative photoresist (SU8 or HARE SQ). For a negative photoresist, the parts exposed to UV become cross-linked, while the remainder of the film remains soluble and can be washed away during development. The height of this structure is determined by the thickness of the resist, which we control through our application method. The length and width of features are patterned through the UV exposure, either by mask or direct write tools.<br>
 
*For molding success, there are two important components to think about -- master durability and PDMS removal. Etched silicon molds will be more durable than patterned photoresist. However, an O2 plasma treatment under vacuum before applying resist has shown more than sufficient adhesion for patterned HARE SQ in our own tests. To enable easy release of the PDMS from the mold, it can be beneficial to do a silanization treatment before applying the PDMS.<br>
 
*For molding success, there are two important components to think about -- master durability and PDMS removal. Etched silicon molds will be more durable than patterned photoresist. However, an O2 plasma treatment under vacuum before applying resist has shown more than sufficient adhesion for patterned HARE SQ in our own tests. To enable easy release of the PDMS from the mold, it can be beneficial to do a silanization treatment before applying the PDMS.<br>
 
*An O2 plasma step is included if applying the PDMS to glass or another piece of PDMS to make a device.
 
*An O2 plasma step is included if applying the PDMS to glass or another piece of PDMS to make a device.
  
−
=====QNF Example Protocols=====
+
=====QNF Standard Protocols=====
−
* [https://wiki.nano.upenn.edu/wiki/images/c/cf/Microfluidics_Process_Flow.pdf Making a Master: HARE SQ, MA-03]
+
* [https://wiki.nano.upenn.edu/wiki/images/9/9d/SoftLitho_Protocol_Oct2025.PNG Making a Master: HARE SQ, MA-03 - visual overview]
−
* Making a Device: PDMS to PDMS bonding
+
* [https://wiki.nano.upenn.edu/wiki/images/c/cf/Microfluidics_Process_Flow.pdf Making a Master: HARE SQ, MA-03 - detailed instructions]
−
<pdf height="500" width="1100"> File:SOP Microfluidics.pdf</pdf>
+
* [https://wiki.nano.upenn.edu/wiki/images/0/0c/SOP_Microfluidics.pdf Making a Device: PDMS to PDMS bonding]
  
 
=====Videos=====
 
=====Videos=====

Revision as of 13:47, 24 October 2025


About

Soft lithography is the transfer of patterned microstructures with molded elastomer. The most common elastomer used in this technique is PDMS (polydimethylsiloxane), which is soft, low cost and easy to mold. It is also bio-compatible with high thermal stability and high chemical stability, is chemically inert, insulating, transparent to UV and visible light, mechanically flexible and durable, allowing many applications. The most common devices fabricated with this technique are microfluidics.
NOTE: You might hear soft lithography equated to "microfluidics fabrication." However, it is important to remember that not all microfluidic devices are fabricated by soft lithography and not all soft lithography is for microfluidic applications!

Process Flow

Standard QNF Soft Lithography Protocol, Updated May 2025.
Images from "Microfluidics at QNF" Process on Fabublox
  • The master used can be fabricated out of photoresist or etched silicon. The most commonly used materials are epoxy-based negative photoresist (SU8 or HARE SQ). For a negative photoresist, the parts exposed to UV become cross-linked, while the remainder of the film remains soluble and can be washed away during development. The height of this structure is determined by the thickness of the resist, which we control through our application method. The length and width of features are patterned through the UV exposure, either by mask or direct write tools.
  • For molding success, there are two important components to think about -- master durability and PDMS removal. Etched silicon molds will be more durable than patterned photoresist. However, an O2 plasma treatment under vacuum before applying resist has shown more than sufficient adhesion for patterned HARE SQ in our own tests. To enable easy release of the PDMS from the mold, it can be beneficial to do a silanization treatment before applying the PDMS.
  • An O2 plasma step is included if applying the PDMS to glass or another piece of PDMS to make a device.
QNF Standard Protocols
Videos

Equipment at QNF

Soft Materials
Main Cleanroom

Additional Information

Related Wiki Pages
Internal Reports & Presentations

External Resources
Retrieved from "https://wiki.nano.upenn.edu/wiki/index.php?title=Soft_Lithography&oldid=2976"