Specific Process Knowledge/Lithography/SU-8: Difference between revisions

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 ==Baking==
-SU-8 baking can be divided in 2 steps: soft bake step after spinning and post exposure bake after exposure.
+SU-8 baking can be divided in 2 steps:
+#Soft bake step after spinning
+#Post exposure bake after exposure
-The goal of the soft bake step is reducing the amount of solvent in the photoresist layer. The heat application leads to the solvent diffusion to the resist surface and its evaporation. The soft bake step can be done on SU-8 hotplates, marked Hotplates 1 and 2 in LabManager, and usually done in one or two steps with 5-8 deg/min temperature ramp between steps. The soft bake temperature typically is between 20 and 110 C and the soft bake time depends on the film thickness. After soft bake, the resist should be firm to the touch (not sticky) in order to be used in the exposure tools.
-The goal of the post exposure bake is increasing the polymerization reaction even the polymerization can in principle take place at room temperature. The post exposure step can be done at the same hotplates, as the soft bake step, with the temperature range between 20 and 120C and with temperature ramping 5-8 deg/min.
+The goal of the soft bake step is to reduce the amount of solvent in the photoresist layer. The applied heat evaporates the solvent from the resist film. The soft bake step is be done on dedicated SU-8 hotplates, and is usually done in one or two steps with a 5-8 deg/min temperature ramp between the steps.<br>
-It is important to do the post exposure bake immediately after exposure to limit photoinitiator diffusion into non-exposed areas.
+The soft bake temperature is typically between 20°C and 110°C, and the soft bake time depends on the film thickness. After soft bake the resist should be firm to the touch (not sticky), in order to be used in the exposure tools.
+The goal of the post exposure bake is to increase the polymerization reaction (the cross-linking). The post exposure step can be done on the same hotplates as the soft bake step, with the temperature range between 20°C and 120°C, and with temperature ramping of 5-8 deg/min.
+'''NB:''' It is important to do the post exposure bake immediately after exposure to limit photoinitiator diffusion into non-exposed areas.
 ==Exposure==