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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). [[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. [[Specific_Process_Knowledge/Lithography/UVExposure#Aligner:_Maskless_01|Aligner: Maskless 01 (MLA1)]] has a 365nm source. Exposure on [[Specific_Process_Knowledge/Lithography/UVExposure#Aligner:_Maskless_02|Aligner: Maskless 02 (MLA2)]] using the 375nm source works, but needs a higher dose, and the resist thickness is limited on this tool. | | The exposure is usually done in near UV-radiation in aligner systems, which blocks wavelengths below the i-line (365nm wavelength). |
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| 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. | | |
| | '''Exposure in mask aligner:'''<br> |
| | Duration of the UV-exposure depends of resist thickness, and if the UV exposure becomes too long, the heating at the interface between the mask and resist can cause formation of "hard skin" at the surface of the SU-8; the so-called T-topping phenomena. The rule of thumb is, that if the exposure dose exceeds 250-300 mJ/cm<sup>2</sup>, it is recommended to do multiple exposures instead, with a waiting time of 15 - 20 s between the exposure steps, to allow the resist cool down. |
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| ==Developing== | | ==Developing== |
