UV Lithography Mask Holder

Enabling UV lithography off the clean room facility, to provide a wider range of photoactive material possibility, a wider range of substrates, faster work cycles and reduced cost.

Concept[edit | edit source]

The mask holder frame which is an essential part of the lithography process can be printed and used in any lab space equipped with an upright optical microscope and a UV lamp source. The design consist of a frame, a mask holder which slides in and out of the frame, and a costume mount which attaches the frame to the microscope body at a fixed height. Different types of lithography masks such as plastic and chromium masks can be attached to the back side of the mask holder by double-sided tape. The mount and frame can be set at a height where mask level is positioned in focal plane of the objective lens. The substrate can be loaded onto the microscope stage and brought to the same focal plane from below, in almost physical contact with the mask. At this stage, it is possible to align the substrate and mask by moving the stage and controlling via microscope eyepiece. Two paper clips are used to fix the mask and substrate together once alignment achieved. Now the entire stack of holder, mask, substrate and clips can be detached from microscope mount and carried to the UV lamp setup and appropriate exposure can be dosed into the photoactive material on the substrate. It is noteworthy to use a yellow light filter in the microscope light path to prevent pre-exposure by white light during alignment.

Bill of materials[edit | edit source]

1. 3 part modular design, frame, central sliding mask holder, and microscope mount, can be found here: [1]
2. double sided tape
3. paper clips
4. yellow light filter (a piece of yellow Plexi transparent paper can work, e.g.)

Estimated Cost[edit | edit source]

Cleanroom process (excluding training) costs 69 € per hour for lithography in the Micronova clean room at Aalto. [2]

Currently, the optical microscope and UV lamp in the thin film lab in Micronova are free of charge to use. Design weighs around 120 gr with PLA 25$ per kg.

Directions[edit | edit source]

1. Print the part using PLA (non-transparent material, layer thickness 0.050 mm, orientation as shown in the picture below), remove supports
2. Slide the mount to the microscope body to reach a tight fit grip
3. slide the frame into the mount
4. Attach the mask to the mask holder and slide the holder into the frame

Designer[edit | edit source]

Farzin Jahangiri, Department of Chemistry and Materials Science, Aalto University

Parts[edit | edit source]

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  Mask holder

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  Mask holder frame

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  Mount

Images of finished parts[edit | edit source]

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  Mask holder mounted to the microscope

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