[Open Manufacturing] Maskless UV lithography for microfabrication, paperdump
Bryan Bishop
I have some papers to share. :-) Here's a quick index of what's
mentioned in this email:
* Maskless photolithography using UV LEDs
* High density nanostructure transfer in soft molding using
polyurethane acrylate molds and polyelectrolyte multilayers
* A photo-polymerization resist for UV nanoimprint lithography
* Polymer Microlenses Added to Micropixelated UV LED (can anyone get
this paper for me?)
* A toner-mediated lithographic technology for rapid prototyping of
glass microchannels
* Design of experiments optimization of PMMA for LIGA applications
* Micromolding of Polymers in Capillaries
* Performing chemical reactions in virtual capillary of surface
tension-confined microfluidic devices
* Patterning Design in Color at the Submicron Scale
* anything by Kahp Y. Suh, Hong H. Lee, or Arun Chattopadhyay :-)
* UV LED oven
* hard disk laser scanner (xy motion from the arm)
* piezo / buzzer for scanning tunneling microscopy
Maskless photolithography using UV LEDs (or, per ##electronics'
suggestion- maybe via an epoxy and blue LEDs?)
http://heybryan.org/books/papers/microfluidics/Maskless%20photolithography%20using%20UV%20LEDs.pdf
Abstract: "A UV light emitting diode (LED) with a maximum output of
372 nm was collimated using a pinhole and a small plastic tube and
focused using a microscope objective onto a substrate for direct
lithographic patterning of the photoresist. Movement of the substrate
with a motorised linear stage (syringe pump) allowed lines in SU-8 to
be pattered with a width down to 35 microns at a linear velocity of 80
m s^-1, while in the dry film resist Ordyl SY 330, features as narrow
as 17 microns were made at a linear velocity of 245 m s^-1. At this
linear velocity, a 75 mm long feature could be patterned in 5 min.
Functional microfluidic devices were made by casting PDMS on a master
made by LED lithography. The results show that UV LEDs are a suitable
light source for direct writing lithography, offering a budget
friendly, and high resolution alternative for rapid prototyping of
features smaller than 20 microns."
High density nanostructure transfer in soft molding using polyurethane
acrylate molds and polyelectrolyte multilayers
http://heybryan.org/books/papers/microfluidics/High%20density%20nanostructure%20transfer%20in%20soft%20molding%20using%20polyurethane%20acrylate%20molds%20and%20polyelectrolyte%20multilayers%20-%20UV%20curing%20-%20HH%20Lee.pdf
Abstract: "Here we present an alternative, new, unconventional
lithographic technique developed to create dense and multilevel
nanostructure pattern transfer using a highly accurate polyurethane
acrylate (PU, MINS101m, Minuta Tech.) mold and a polyelectrolyte
multilayer as the adhesion promotion layer. Specifically, we
demonstrate the pattern transfer of periodic 80 nm lines with 400 nm
height and complex and multilevel nanostructures to a polymer layer on
various substrates, such as Si or SiO2 wafers, glass and flexible
polymer films. This new, unconventional lithographic technique
presented here would open the door to a variety of applications in the
fields of electronic, optical and biological devices."
A photo-polymerization resist for UV nanoimprint lithography
http://heybryan.org/books/papers/A%20photo-polymerization%20resist%20for%20UV%20nanoimprint%20lithography%20-%20PMMA%20-%20MMA.pdf
Abstract: "A novel liquid photo-polymerization resist was prepared for
nanoimprint lithography on transparent flexible plastic substrates.
The resist is a mixture of polymethylmethacrylate (PMMA),
methylmethacrylate (MMA), methacylic acid (MAA) and two
photo-initiators, (2-isopropyl thioxanthone (ITX) and ethyl
4-(dimethylamino)benzoate (EDAB)). The resist can be imprinted at room
temperature with a pressure of 0.25 kg/cm^2, and then exposed from the
transparent substrate side using a broad band UV lamp to obtain nano-
and micro-scale patterns. Replications of high-density line and space
patterns with resolution of 150 nm were obtained on a flexible indium
tin oxide/poly(ethylene terephthalate) (ITO/PET) substrate. The liquid
resist has low viscosity due to the liquid monomers, and low shrinkage
due to the addition of PMMA as a binder."
Design of experiments optimization of PMMA (plexiglass) for LIGA applications
http://heybryan.org/books/papers/Design%20of%20experiments%20optimization%20of%20PMMA%20for%20LIGA%20applications.pdf
Abstract: "The most common resist used for LIGA applications with deep
X-ray lithography is PMMA. It achieves very good resolution of the
mask structures with a typical resist thickness from 200 micrometers
to 2 mm. The resist system employed here is crosslinked on the
substrate after preparation, and this can lead to problems with
internal stresses and resist cracking. To optimize the resist
performance, a design of experiments procedure was implemented. Design
of experiments assists the determination of optimized process
parameters through the use of statistical procedures. The principal
components of the PMMA resist employed in the optimization procedure
were PMMA, adhesion promoter, crosslinker, initiator and accelerator.
The PMMA type employed was kept constant and the concentrations of
adhesion promoter, crosslinker, initiator and accelerator were altered
following a design of experiments methodology. At first 18 resists
compositions were prepared and irradiated to determine preliminary
exposure behavior. A selection was made from this composition on the
basis of the performance, and then these resist composition were
irradiated with standard test structures. This determined the
performance of the resist to stress, its inherent stability and the
inherent resolution that can be achieved. A smaller parameter set was
then implemented in the final optimization of the resist. A design of
experiments procedure has assisted the optimization of the PMMA resist
for LIGA application with deep X-ray lithography. The results obtained
demonstrate the effectiveness of the procedure in quickly attaining
resist compositions suitable for deep X-ray lithography."
Micromolding of Polymers in Capillaries
http://heybryan.org/books/papers/microfluidics/Micromolding%20of%20Polymers%20in%20Capillaries%20-%20Saran%20wrap.pdf
Abstract: "This paper describes the use of micromolding in capillaries
(MIMIC) to produce complex polymeric microstructures supported on
different substrates and the applications of these microstructures in
microfabrication. Patterned microstructures of several organic
polymerspolyurethane, polyacrylate, and epoxywere formed by molding in
enclosed, continuous channels formed by conformal contact between a
solid support and an elastomeric mold whose surface had been patterned
with a relief structure having micrometer-scale dimensions. A liquid
prepolymer filled these channels by capillary action and was allowed
to cure photochemically or thermally. The mold was then removed.
Polymeric microstructures formed on films of Saran Wrap could be
folded into different shapes, while these microstructures retained
their forms; they could also be stretched uniaxially to generate
microstructures having distorted forms. The patterned polymeric
microstructures formed on SiO2, glass, and metals (Au, Ag, and Cr)
could be used directly as resists in the selective etching of
underlying substrates. Free-standing polymeric microstructures
fabricated by lift-off were used as disposable masks to generate
patterned microfeatures of metals on the surfaces of both planar and
nonplanar substrates in two different procedures: (a) evaporation of
gold through the polymeric mask supported on a substrate; (b)
formation of patterned self-assembled monolayers (SAMs) by exposure of
a silver film covered by a polymeric mask to hexadecanethiol (HDT) in
vapor, followed by selective etching of the regions that were not
exposed to HDT (that is, the parts of the surface protected by the
mask) in an aqueous solution containing K2S2O3 and
K3Fe(CN)6/K4Fe(CN)6."
Patterning Design in Color at the Submicron Scale
http://heybryan.org/books/papers/microfluidics/Patterning%20Design%20in%20Color%20at%20the%20Submicron%20Scale%20-%20Arun%20Chattopadhyay.pdf
Abstract: "We demonstrate the generation of patterns on overhead
projector paper (OHP) and glass slides with the dimension at the
submicron scale and in various colors. We have used the commercially
available permanent marker pen to write lines on the surface of OHPs
and glass slides and transferred the patterns of a compact disk (CD)
onto the line. Observation under an optical microscope exhibited
various color patterns on the film as per the design of the mold. When
the mold was pressed twice on the same parent line in perpendicular
geometry, cross patterns could be observed."
(Also, if anyone knows any information about using CDs or DVDs as
masks for lithography, I'd like to hear about it. The ideal of burning
an ISO image and then using it as a mask is simply awesome.)
UV LED oven:
http://synth-diy.blogspot.com/2008/10/making-of-uv-oven.html
Hard disk laser scanner: XY motion of a mirror to write patterns with
a laser (this is actually for 'laser shows'- but I found it while
thinking about maskless UV (or now blue?) LED lithography)
http://heybryan.org/mediawiki/index.php/Hard_disk_laser_scanner
So, the arm works in an arc motion over the hard disk in a hard drive,
so depending on the size of the disk, that's the range of motion that
the arm is set up for, and some simple driver hacking could lead to
utilization of that range of motion. It would be better to use it to
hold a small mirror to write on a (distant) surface with a
point-source of light- either a blue laser, or UV from an LED, etc.
This way you can draw over a greater distance (see inverse square
law).
piezo / buzzer for scanning tunneling microscopy
http://heybryan.org/instrumentation/instru.html
http://www.geocities.com/spm_stm/
piezo scanner description:
http://www.geocities.com/spm_stm/Disk_Scanner_Exp.html
how to make a disk scanner: http://www.geocities.com/spm_stm/disk_scanner.html
mechanical approach mechanism (screw-actuated):
http://www.geocities.com/spm_stm/Mechanical_Approach.html
electronics: http://www.geocities.com/spm_stm/Schematic_Print.html and
a BOM: http://www.geocities.com/spm_stm/STM_BOM.htm
Essentially, the project involves cutting up a piezo or buzzer into
four sections for +x, -x, +y, -y, and using this to control the motion
of a cut metal wire with a sharp tip to serve as the tip for the
scanning tunneling microscopy. The range of motion isn't going to be
that much because of the maximum amount of voltage and maximum amount
of movement that the piezo can generate, and it seems to be 0.17 mm
per volt, so getting small motions is possible, but overall the range
of motion is going to be bounded. Still, for a simple control
mechanism, I think it wins the cake (or the internet).
I have not been able to find this paper- can anyone get it for me?
* Polymer Microlenses Added to Micropixelated UV LED
Other stuff you should know about:
* A toner-mediated lithographic technology for rapid prototyping of
glass microchannels
* Capillary force lithography
* Adhesive force lithography
* STM/AFM lithography
I have a (partial) bibliography of microfluidics paper here- in a
terrible format on a wiki-
http://heybryan.org/mediawiki/index.php/Microfluidics (more available
upon request)
.. but still, actuation is somewhat an issue. Jonathan and I were
complaining to each other about this yesterday. Maybe there's some way
we can solve this by using a screw to increase internal pressure, or a
piezoelectric buzzer to modulate internal pressure with some simple
electronics (which is simpler than building an entire microheater
array).