>Dear Members:
>     I am new student in MEMS. Now I am concerning to use SU-8
>photoresist for some microstructures. But I do not know how to
>control the depth of the SU-8 layer? Could anyone tell me something
>about that? Thank you for your time and consideration.
>Zeng Yi
>
>
Dear Sir,

It makes now 2.5 years that I am working with SU8 photoepoxy (this material has
partily been developed in our lab at the Swiss Federal Insitute of Technology in
Lausanne in 1996).

I think that what you call depth of the SU8 is the thickness of your layer. This
thickness depends on the viscosity of the SU8 formulation that you are using.
If this is what you are looking for, please give me your fax number and I will
send some graphs with the different spin-coating curves.
The illumination energy that you need is typically 200mJ/cm2 for a 100um thick
layer and 400mJ/cm2 for a 200um thick SU8 layer. There is a linear relation ship
between the illumination dose and the layer thickness.

We are now creating a small company, called SOTEC MICROSYSTEMS, where we will
sell photoepoxy materials and products.

We have the following photoepoxy variations :

SU8 based photoepoxies:
 SM1040 : for thin films  (1-10 microns)
 SM1042 : for thin films, with better properties concerning the dimensions of
the final structure
 SM1060 : for medium size films (10-50 microns)
 SM1062 : for medium films,with better properties concerning the dim. of the
final structure
 SM1070 : for thick layers (20-500 microns)
 SM1072 : for thick films, with better properties concerning the dim. of the
final structure.
Other formulations are possible if required.

other photoepoxies:
  SM2060 and SM2062:    Similar to SM1060/2, but based on other epoxies and
requiring lower softbake temperatures.

All the solutions are filtered trough a 0.4 micron filter.

The prices are the following ones (for every formulation):
                0.5 liter (mimimum quantity)   180 USD or 270,- CHF
                1.0 liter
300 USD or 400,- CHF

The prices exclude package, posting and VAT. The bottles are send by normal post
or airmail. If a fast delivery is requested, they are send by fast-mail such as
FedEX or others, at an additional cost of 50 USD (75,-CHF) per mail. The
delivery time is between 2 and 3 weeks.

We are trying to develop new photoepoxies. A first improvement will be
photoepoxies with better adhesion properities, which are more flexible and which
have lower coefficients of thermal expansions. In a second attempt we will try
to develop photoepoxies based on other epoxies, which have other properties and
which might be used for example at higher temperatures (higher than 350 °C; the
maximum temperature of the SU8-based photoepoxies is about 250 °C).

I hope this helps you. Should you have any more questions about SU8 or related
subjects, please contact me.

Dr Louis J. Guerin


****************************************************
Dr Louis J. Guerin
Institute for Microsystems
EPFL- Swiss Federal Institute of Technology Lausanne
CH-1015 Lausanne
tél: (+41 21) 693 5857
fax: (+41 21) 693 6670
email: louis.guerin@epfl.ch

****************************************************
*          visit our WEB page on URL: http://dmtwww.epfl.ch/ims
*
*
*
*                            visit our SU8 WEB page on URL:
*
* http://dmtwww.epfl.ch/ims/micsys/subtopics/projects/su8/EPON.html     *
****************************************************