Cost-effective masks for deep x-ray lithography

Heinz-Ulrich Scheunemann; Bernd Loechel; Linke Jian; Daniel Schondelmaier; Yohannes M. Desta; Jost Goettert

doi:10.1117/12.498986

24 April 2003 Cost-effective masks for deep x-ray lithography

Heinz-Ulrich Scheunemann, Bernd Loechel, Linke Jian, Daniel Schondelmaier, Yohannes M. Desta, Jost Goettert

Proceedings Volume 5116, Smart Sensors, Actuators, and MEMS; (2003) https://doi.org/10.1117/12.498986
Event: Microtechnologies for the New Millennium 2003, 2003, Maspalomas, Gran Canaria, Canary Islands, Spain

Abstract

The production of X-ray masks is one of the key techniques for X-ray lithography and the LIGA process. Different ways for the fabrication of X-ray masks has been established. Very sophisticated, difficult and expensive procedures are required to produce high precision and high quality X-ray masks. In order to minimize the cost of an X-ray mask, the mask blank must be inexpensive and readily available. The steps involved in the fabrication process must also be minimal. In the past, thin membranes made of titanium, silicon carbide, silicon nitride (2-5μm) or thick beryllium substrates (500μm) have been used as mask blanks. Thin titanium and silicon compounds have very high transparency for X-rays; therefore, these materials are predestined for use as mask membrane material. However, the handling and fabrication of thin membranes is very difficult, thus expensive. Beryllium is highly transparent to X-rays, but the processing and use of beryllium is risky due to potential toxicity. During the past few years graphite based X-ray masks have been in use at various research centers, but the sidewall quality of the generated resist patterns is in the range of 200-300 nm Ra. We used polished graphite to improve the sidewall roughness, but polished graphite causes other problems in the fabrication of X-ray masks. This paper describes the advantages associated with the use of polished graphite as mask blank as well as the fabrication process for this low cost X-ray mask. Alternative membrane materials will also be discussed.

Citation Download Citation

Heinz-Ulrich Scheunemann, Bernd Loechel, Linke Jian, Daniel Schondelmaier, Yohannes M. Desta, and Jost Goettert "Cost-effective masks for deep x-ray lithography", Proc. SPIE 5116, Smart Sensors, Actuators, and MEMS, (24 April 2003); https://doi.org/10.1117/12.498986

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