Specific Process Knowledge/Lithography/SU-8: Difference between revisions
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Process recommendations: | Process recommendations: | ||
* a standard process consist of spinning, soft bake, exposure, post-exposure bake and development. Please notice that the entire process must be done continuously, meaning that it is not recommendable to spin the resist and then wait until the next day before exposing. | * a standard process consist of spinning, soft bake, exposure, post-exposure bake and development. Please notice that the entire process must be done continuously, meaning that it is not recommendable to spin the resist and then wait until the next day before exposing. | ||
* exposure using radiation above 350 nm is recommended. Aligner | * exposure using radiation above 350 nm is recommended. [[Specific Process Knowledge/Lithography/UVExposure#Aligner-6inch|Aligner-6inch]] uses a long-pass filter which reduces the i-line and blocks shorter wavelengths, while [[Specific Process Knowledge/Lithography/UVExposure#KS Aligner|KS Aligner]] and [[Specific_Process_Knowledge/Lithography/UVExposure#Aligner:_MA6_-_2|Aligner: MA6-2]] both have i-line filters. | ||
* Controlled soft and post-exposure bakes are recommended and must be optimized for the specific application, but baseline parameters which can be used as a starting point will be given. | * Controlled soft and post-exposure bakes are recommended and must be optimized for the specific application, but baseline parameters which can be used as a starting point will be given. | ||
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SU-8 resist is designed to produce low defect coatings over a very broad range of films thickness. | SU-8 resist is designed to produce low defect coatings over a very broad range of films thickness. | ||
Spin Coater: RCD8 is dedicated to spin all SU-8 resist formulations, but Spin Coater: Manual All Resist can also be used. | [[Specific Process Knowledge/Lithography/Coaters#Spin_Coater:_RCD8|Spin Coater: RCD8]] is dedicated to spin all SU-8 resist formulations, but [[Specific_Process_Knowledge/Lithography/Coaters#Manual_Spin_Coaters|Spin Coater: Manual All Resist]] can also be used. | ||
To keep clean room safe and odor free during the spinning please follow the following simple rules: | To keep clean room safe and odor free during the spinning please follow the following simple rules: | ||
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==Exposure== | ==Exposure== | ||
The exposure step is usually done in near UV-radiation at aligners system which blocks the wavelengths below the i-line (365nm wavelength). Aligner | The exposure step is usually done in near UV-radiation at aligners system which blocks the wavelengths below the i-line (365nm wavelength). [[Specific Process Knowledge/Lithography/UVExposure#Aligner-6inch|Aligner-6inch]] uses a long-pass filter which reduces the i-line and blocks shorter wavelengths, while [[Specific Process Knowledge/Lithography/UVExposure#KS Aligner|KS Aligner]] and [[Specific_Process_Knowledge/Lithography/UVExposure#Aligner:_MA6_-_2|Aligner: MA6-2]] both have i-line filters. | ||
Duration of the UV-exposure depends of resist thickness, but notice that if the UV exposure becomes long then the heating at the interface with the mask can cause formation of hard skin at the surface of SU-8 so called T-topping phenomena. The the main rule is if the dose of the exposure exceeds 250-300 mJ/cm2 it is recommended to do a multiple exposure instead and have a waiting time between the steps to allow the resist cool down. | Duration of the UV-exposure depends of resist thickness, but notice that if the UV exposure becomes long then the heating at the interface with the mask can cause formation of hard skin at the surface of SU-8 so called T-topping phenomena. The the main rule is if the dose of the exposure exceeds 250-300 mJ/cm2 it is recommended to do a multiple exposure instead and have a waiting time between the steps to allow the resist cool down. | ||