Background Reading about E-Beam Lithography

Books



A very good book about e-beam lithography technologies is:

SPIE Handbook of Microlithography, Micromachining and Microfabrication, Volume 1: Microlithography.
P. Rai-Choudhury (Editor) (June 1997)
SPIE Press; ISBN: 0819423785

Although it is a little old now, most of the information is still very relevant. The chapter specifically about e-beam lithography is online at this site:
http://www.cnf.cornell.edu/cnf_spietoc.html
I highly recommend you read through this and understand as much as possible. This will speed your learning the specifics of using our JEOL system.


There are many good books that cover microfabrication topics in general, including photolithography. If you are new to microprocessing, I’d also highly recommend you do some background reading on one or more general processing book. If your project will involve other microprocessing steps such as metallization or etching, you will be well-served to have some background knowledge of what is and isn’t possible, and a general sense for the challenges you may encounter.

For any e-beam lithography project, if will also be very useful to be familiar with photolithography processing. In fact, the more you know about photolithography, and the more hands-on experience you personally have doing photolithographic processing on wafers, the better your e-beam work will go. Most principles and challenges of EBL are very similar to photolithography, but often more difficult. There are several reasons why this is true:
  • At the smaller dimensions we typically build with e-beam, most process parameters become far more critical (narrower process latitude)
  • Inspection is more difficult as we typically must use an electron microscope to view structures exposed by EBL (structures too small to see with optical microscope)
  • Inspection is also often more difficult because smaller resist structures are often damaged, sometimes significantly, by the process of SEM inspection (destructive inspection)
  • There are more variables to work with in EBL. While this allows greater flexibility, it also creates greater complexity. For example, in EBL we can manipulate the local exposure dose of each individual shape in a pattern, while in photolithography, the entire mask exposure gets the same single dose value. That said, in EBL we often MUST define multiple dose values within a single pattern to get the intended shapes, thanks to the scattering effects of electron beams, known collectively as “proximity effects”.

Nearly any book on micro-lithography, or microchip fabrication, will contain useful information about lithographic processes for you.


Websites



Other E-beam Sites


An excellent repository of e-beam process information is found at: http://www.cnf.cornell.edu/cnf_process_ebl_resists.html
Lots of useful information is also found at the Georgia Tech website, http://nanolithography.gatech.edu/trdoc.html and http://nanolithography.gatech.edu/processes.html .

Note that these other locations have similar, but not identical EBL systems, and offer similar, but not identical resists and processing capabilities, so not everything is directly relevant, but most of the information from those sites is still very valuable.

Other sites that you may find may refer to low-voltage EBL, possibly using a SEM conversion add-on system, such as a Raith or Nabity system. While some of the information from those systems is still relevant, there are significant differences both in system hardware, capabilities and operation, as well as in process capabilities, so websites describing use of these systems may be less useful.



Companies


Our E-beam is from JEOL: http://www.jeol.com/
Our pattern processing software is from GenISys: http://www.genisys-gmbh.com/