The influence of different post exposure bake (PEB) temperature on thermal swelling and the internal stresses of SU-8 photoresist were investigated. Large internal stress of SU-8 layer can result in cracks and deformation. Moreover

the feature width of microchannel will be reduced after electroforming mainly due to the thermal expansion and swelling of patterned SU-8 in electrolyte. The high-aspect-ratio and dimensional precision of micro structure were greatly affected by these two problems. When other parameters were constant

the micro channels’ width at different swelling time were measured under different PEB temperature. Experimental results show that

the swelling deformation of SU-8 became larger when at a lower PEB temperature

and thermal swelling was mainly occurred during the beginning 30 minutes

and then its deforming rate was slow down and tended to be saturated. Internal stress of SU-8 layer was measured after the PEB by the theory of curvature method. It proves that lowering the PEB temperature can greatly reduce the internal stress. Therefore

on consideration of the two effects above

parameters of PEB should be settled by the demand of micro-structure to be made.