A lot of different e-beam resist are availble on the market. The resist you will need depends on your process. Therfore, it is always good to have a little chat about your process and to find out what would be the resist you will need. Here we exposed some resists we are used to work with. Other resist like HSQ, SU-8 and many other were not characterized yet with our e-beam. This is why we do not comment on them here. Of course, you are welcome to setup a new process with some new resists.
Most of the time the processes are divided in two categories. Either you want to dry etch the structures or you want to make a lift-off process to pattern metals. By the way, a lift-off process can also be used to pattern metals which would be used as an etch mask in the case you need to etch deep structures.
Positive e-beam resists:
ZEP520A
High resolution resist with ~35µC/cm2 clearing dose at 20keV and resistant to dry etch similarly to standard photoresistif pre-baked at 180°C for 5min.
ZEP520A is an expensive resist and PMMA should always been considered before juming to it.
Example of a dose test at 20keV:
Courtesy of G. Osowiecki
ZEP7000
High resolution resist with ~12µC/cm2 clearing dose at 20keV and resistant to dry etch similarly to standard photoresist. Specialy developped for lithography mask production. Lower dose needs less exposure time, therefore large areas can be patterned in a shorter time.
ZEP7000 is an expensive resist and PMMA should always be considered before jumping to it.
PMMA 950k
PMMA is a very good e-beam resist. It is very cheap compared to ZEP520A and is an excellent choice for lift-off processes for example. Compared to the ZEP520A it lacks a bit of resistance during dry etching processes. Nevertheless it’s resolution is similar to ZEP520A.
Negative e-beam resists:
ma-N 2400
Is a negative resist used as an alternative to ZEP520A when the exposed areas become too large for positive resist. It is dry etch resistant, it give good results in terms of resolution (down to 30nm) and is easy to remove.
Technical specs:
Spin-curve of ma-N 2403:
