A new method is presented,which can obtain high aspect ratio in SU8 structures.Instead that the top of the photo resist layers are exposed to UV light through masks in conventional lithography,the new method utilizes ...A new method is presented,which can obtain high aspect ratio in SU8 structures.Instead that the top of the photo resist layers are exposed to UV light through masks in conventional lithography,the new method utilizes a mask-back exposure technique,i.e.the SU8 resist layer coated on a mask surface (metal patterns on a glass plate),is irradiated by UV light through the back of the mask.So a desired exposure dose on the bottom of the resist layer can be easily achieved without over-exposing from its top.This has a two-fold effect,i.e.proper dose on the bottom of the resist and less internal stress.Initial experimental results show that compared to an aspect ratio of 18 obtained by conventional method,a higher aspect ratio of 32 in the SU8 structures can be achieved by this new method.展开更多
Over the past few decades,polydimethylsiloxane(PDMS)has become the material of choice for a variety of microsystem applications,including microfluidics,imprint lithography,and soft microrobotics.For most of these appl...Over the past few decades,polydimethylsiloxane(PDMS)has become the material of choice for a variety of microsystem applications,including microfluidics,imprint lithography,and soft microrobotics.For most of these applications,PDMS is processed by replication molding;however,new applications would greatly benefit from the ability to pattern PDMS films using lithography and etching.Metal hardmasks,in conjunction with reactive ion etching(RIE),have been reported as a method for patterning PDMS;however,this approach suffers from a high surface roughness because of metal redeposition and limited etch thickness due to poor etch selectivity.We found that a combination of LOR and SU8 photoresists enables the patterning of thick PDMS layers by RIE without redeposition problems.We demonstrate the ability to etch 1.5-μm pillars in PDMS with a selectivity of 3.4.Furthermore,we use this process to lithographically process flexible fluidic microactuators without any manual transfer or cutting step.The actuator achieves a bidirectional rotation of 50°at a pressure of 200 kPa.This process provides a unique opportunity to scale down these actuators as well as other PDMS-based devices.展开更多
文摘A new method is presented,which can obtain high aspect ratio in SU8 structures.Instead that the top of the photo resist layers are exposed to UV light through masks in conventional lithography,the new method utilizes a mask-back exposure technique,i.e.the SU8 resist layer coated on a mask surface (metal patterns on a glass plate),is irradiated by UV light through the back of the mask.So a desired exposure dose on the bottom of the resist layer can be easily achieved without over-exposing from its top.This has a two-fold effect,i.e.proper dose on the bottom of the resist and less internal stress.Initial experimental results show that compared to an aspect ratio of 18 obtained by conventional method,a higher aspect ratio of 32 in the SU8 structures can be achieved by this new method.
基金Supported by the National Natural Science Foundation of China(No.61474130 and No.51572172)the Scientific Development Project ofUniversity of Shanghai for Science and Technology(16KJFZ011)Chinese Academy of Sciences via Hundred Talents Program
基金BG is a Doctoral Fellow of the Research Foundation—Flanders(F.W.O.),Belgium.MDV acknowledges support from the ERC starting grant HIENA(no.337739).
文摘Over the past few decades,polydimethylsiloxane(PDMS)has become the material of choice for a variety of microsystem applications,including microfluidics,imprint lithography,and soft microrobotics.For most of these applications,PDMS is processed by replication molding;however,new applications would greatly benefit from the ability to pattern PDMS films using lithography and etching.Metal hardmasks,in conjunction with reactive ion etching(RIE),have been reported as a method for patterning PDMS;however,this approach suffers from a high surface roughness because of metal redeposition and limited etch thickness due to poor etch selectivity.We found that a combination of LOR and SU8 photoresists enables the patterning of thick PDMS layers by RIE without redeposition problems.We demonstrate the ability to etch 1.5-μm pillars in PDMS with a selectivity of 3.4.Furthermore,we use this process to lithographically process flexible fluidic microactuators without any manual transfer or cutting step.The actuator achieves a bidirectional rotation of 50°at a pressure of 200 kPa.This process provides a unique opportunity to scale down these actuators as well as other PDMS-based devices.
