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E241 Fall Term 2017

About E241

This project course focuses on developing processes for ExFab, a shared facility that supports flexible lithography, heterogenous integration, and rapid micro prototyping. Projects for the MOCVD lab are also encouraged. Team projects are approved by the instructor and are mentored by guest experts and SNF staff members. Students will plan and execute experiments and document thin in a final presentation and report, to be made available on the Lab wiki for the benefit of the Stanford research community.

What are the benefits to enrolling? You get:

  • To focus on a project that will benefit YOUR research... and that of others.
  • Equipment use at NO cost to your research project (includes use of support equipment and characterization tools.)
  • Access to the collective expertise of mentors, instructors, staff, and equipment providers.
  • CLASS CREDIT!
  • The satisfaction of supporting the fab community.

How to participate?

  • Enroll!
    • Sooner, rather than later, as enrollment is capped at 20 students.
    • Design a project. Contact a staffer, mentor, or fellow labmembers to discuss possibilities.
  • Mentor!
    • With instructor approval, ANYONE can be a mentor.
  • Support your E241 labmates!
    • E241 benefits the lab community, including YOU!

New ExFab Equipment

As brand new tools, the field is wide open as to possible projects.

Heidelberg MLA 150 Direct Write Lithography System

Who need a mask? The MLA150 can directly expose patterns on photoresist. It can accommodate substrates from < 1cm2 up to 9" X 9" in size. 10W laser enables the tool to expose a 100 mm wafer with full coverage in 7 minutes. The minimum feature size is 1um with a front-side overlay of <0.5 um. Backside alignment is also avalable. At 405nm wavelength, the MLA150 can expose all photoresists currently used at SNF (Shipley 3612, SPR955, SPR220.) Possible projects: gray-scale lithography (subject to software release by Heidelberg), mix-and-match with ASML or Nanoscribe.

Nanoscribe Photonic GT 3D/Additive Printer

The Nanoscribe is a laser writer using two-photon induced photopolymerization to create nanostructures. In the additive manufacturing mode, resolution of 200 nm can be achieved. In the "maskless lithography" 2D writing mode, resolutions of <100 nm can be achieved. A suite of available Nanoscribe-brand photopolymers cover the spectrum of nano- to meso- scale lithography. Special substrates can enable electroplating of your 3D structures. Possible projects: electroplating, mix-and-match with other patterning tools, novel photosensitive materials.

Optomec Aerosol Jet 300 3D/Surface Printer

The Aerosol Jet 300 is used to print "inks" and materials as diverse as nanowires or live cells in suspension onto 3D surfaces. First, the ink as atomized into droplets 1-5 um in size. The aerosol is carried by nitrogen gas to a deposition head where aerodynamic focusing channels stream into a jet which can be as narrow as 10 microns. The particle stream remains focused at a constant width over a distance of up to 5 millimeters, enabling the user to write onto non-uniform and highly topographical substrates. In contrast to inkjetting, the fluid properties of the "inks" in the Optomec don't really matter -- liquids with viscosities from 1 to 1000 cp can be jetted. While this systems is used in production for labeling on shaped substrates or printing flexible electronics, we think this technology opens up lots of possibilities for 3D writing of all sorts of new materials.

Micromist Coater

The Micromist Coater is a research-grade electrostatic coating system, like a mini electrostatic spray painting booth.  You fill an ordinary syringe with just about any liquid (or particles suspended in a liquid) with good dielectric constant, place your substrate on a temperature controlled chuck, and apply voltage between the syringe tip and the chuck.  You program the tip to raster across the chuck to deposit this liquid.  Like electrostatic painting, the advantages are that there is little material waste and the coating is highly conformal.  Materials as diverse as photoresist and chocolate have been demonstrated on this. Possible projects: the field is wide open. This is a new system and despite very impressive demonstrations showing ease of use and flexibility, we have very little information about what is possible with this machine.

Other ExFab Equipment

While these are more "mature" tools and technologies, there are always new ways in which they could be used.

Carbon Nanotube Furnace, Graphene Furnace

These have been the subject of class projects for a few sessions now. Please check out the SNF wiki for previous reports

Raith 150 FBMS

While the Raith 150 is now officially old enough to drive in California (16 years), our system has been retrofitted with the FBMS (Fixed Beam/Moving Stage) software package. This means writing is performed by operating the beam continuously while the stage is programmed to move in any arbitrary pattern, enabling "stitch-free" patterning. If you have an experiment that requires stitch-free structures and would like to put this system through its paces, then this might be the project for you!

Nano Inkjet

The Fujifilm Dimatix printer is capable of inkjetting any of a wide variety of commercial or custom-formulated materials. While the typical use for this system is for flexible electronics, custom inks can be formulated for jetting. Last fall E241 saw Eric Wu inkjetting liquid metal. Possible projects might entail other novel materials, but we'd also be really pleased to see a good, old-fashioned, flexible electronics process documented for this system.

3D Wax Printer

This printer only prints wax, but does it at higher resolution than any commercial printer aside from the Nanoscribe. In contrast to the Nanoscribe prints, the Solidscape wax prints are designed to be sacrificial. Previous project classes have used wax prints as 3D molds for PDMS. Other possible projects: electromolding, lost wax methods.

 

Flip Chip Bonder

Brand new in Fall 2016. Three Fall E241 class projects were built around solder bump bonding, thermocompression, and eutectic bonding of a variety of substrates.

Laser Cutter

The Fusion M2 Laser Cutter has two lasers, a 100 W CO2 laser (10.6 um) and a 100 W fiber laser (1.6 um) which enables engraving and cutting of a wide variety of materials, from silicon to metals, plastics to quartz. The spot size is 75 um. Last Fall, the E241 project examined using this to cut a flexible polymer adhesive to use as a mask for lead solder bump deposition.

AJA Evaporator

The AJA is a load-locked, 8 pocket system. It can accommodate 3 X 4" or one 6" wafer in a pumpdown.

Lesker Sputter System

The Lesker is a load-locked system with 8 possible targets in deposition and reactive sputtering modes. It can accomodate 4" and 6" wafers. Possible projects: TiN or ITO deposition.

Asylum AFM

This new AFM will have an environmental control chamber (glovebox) and an integrated electrical and thermal probe capability (the demo loaner unit is pictured here.)

Aix-CCS GaN MOCVD

While not a part of ExFab, the Aix-CCS is a special/featured capability at SNF. The Aix-CCS system is capable of depositing single- and poly-crystal III-N films, heterostructures, and nanowires, with p- or n- doping. This system can also deposit single crystal GaN on silicon. Previous MOCVD class projects can be seen on the SNF Wiki, under EE412.