Grayscale lithography for metal-insulator-metal color filters
Pietilä, Jesse (2023)
2023
Teknis-luonnontieteellinen DI-ohjelma - Master's Programme in Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2023-12-18
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2023111810058
https://urn.fi/URN:NBN:fi:tuni-2023111810058
Tiivistelmä
This thesis studies the possibility of utilizing grayscale lithography to create metal-insulator-metal (MIM) color filter arrays for snapshot hyperspectral camera applications. MIM structures are optical cavities made from parallel layers of metals and insulator materials. They can be used to achieve controlled light transmittance by changing the thickness of the insulator layer. These structures are instrumental in photonics and semiconductor technology as they can be utilized in microchips, lens applications, and color filters. In this study, we aim to build a multi-pixel color filter that can be utilized in snapshot hyperspectral imaging. The transmittance spectrum of the color filter is measured and compared with simulated values to determine if the filter works as designed.
One way to build these multi-pixel color filters is to use different lithography methods. In this thesis, the primary focus is on grayscale lithography, where the exposure dose and the choice of material easily control the insulator thickness.
The thesis consists of two parts. The first part is a literature review that explains the use of metal-insulator-metal layers as color filters, the different lithography methods that can be used for creating such structures, and lastly, the basics of color filters in hyperspectral imaging. The second part focuses on experiments where metal-insulator-metal color filters are created with two different direct writing lithography methods. Different photoresist materials, such as AZ-3012, AZ-3027, ARN-7520.17, and PMMA, are investigated to study which works best as a grayscale photoresist. Silver is used as the main material for the metal layers, and gold is used as an encapsulation layer. Ultimately, the transmittance spectrum is measured from the finished samples, and the results are analyzed and compared with simulation values.
One way to build these multi-pixel color filters is to use different lithography methods. In this thesis, the primary focus is on grayscale lithography, where the exposure dose and the choice of material easily control the insulator thickness.
The thesis consists of two parts. The first part is a literature review that explains the use of metal-insulator-metal layers as color filters, the different lithography methods that can be used for creating such structures, and lastly, the basics of color filters in hyperspectral imaging. The second part focuses on experiments where metal-insulator-metal color filters are created with two different direct writing lithography methods. Different photoresist materials, such as AZ-3012, AZ-3027, ARN-7520.17, and PMMA, are investigated to study which works best as a grayscale photoresist. Silver is used as the main material for the metal layers, and gold is used as an encapsulation layer. Ultimately, the transmittance spectrum is measured from the finished samples, and the results are analyzed and compared with simulation values.