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Distributed Feedback Laser
Published in Kenichi Iga, Yasuo Kokubun, Encyclopedic Handbook of Integrated Optics, 2018
As an example, Figure 7 depicts a negative and a positive (nega-posi) photoresist method, which is a simple and promising method for fabricating of λ/4 shifted corrugation [7,10]. The process is as follows: Nonexposed positive photoresist stripe of typically 400 Å thickness and 500 μm width is formed by a conventional photolithography.70 Å thick SiNx film is deposited by ECR plasma deposition technique at room temperature as an intermediate layer which prevents from the mixing of the negative and the positive photoresists. Then the negative photoresist of 300 Å thickness is spin coated.Two beam holographic exposure is carried out using He–Cd laser (λ = 3250 Å).The negative photoresist is developed.The SiNx film is etched by buffered HF.Surface damaging layer of the positive photoresist is removed by O2 plasma ashing.The positive photoresist is developed.InP is etched by an HBr + HNO3 solution.
Wet Chemical and Plasma Etching
Published in Andrew Sarangan, Nanofabrication, 2016
To act as an effective etch mask, the photoresist needs to survive as long as possible in a plasma etch process. It is interesting to note that the original plasma etching systems were developed for exactly the opposite purpose—to more effectively strip photoresists from wafers compared to using liquid hydrocarbons such as acetone [45]. Oxygen plasma can selectively etch organic photoresists without affecting any of the inorganic films and substrates. In this process, also known as plasma ashing, oxygen radicals react with the carbon and hydrogen atoms in the photoresist to produce volatile CO2 and H2O.
High Temperature Superconductor Films: Processing Techniques
Published in David A. Cardwell, David C. Larbalestier, Aleksander I. Braginski, Handbook of Superconductivity, 2023
Multilayer structures were applied for integrated SQUIDs where the magnetometer or gradiometer antenna are in a higher layer very near to the SQUID loop, see e.g. Adachi et al., 2011. For patterning of each layer they used photolithography and dry ion etching. The residual resist was removed by plasma ashing. Important improvement was obtained by surface cleaning before the final annealing of the SmBCO layer. Similar multilayer techniques were used by Wakana et al., 2005 and Nakayama et al., 2005 to prepare SFQ circuits with high reproducibility and small parameter spreads.
Occurrence of water within different rank coals: a review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Shilin Liu, Dengfeng Zhang, Zengmin Lun, Chunpeng Zhao, Haitao Wang
In summary, both the oxygen-containing functional groups and the minerals contribute to H2O occurrence in coals. However, how to distinguish the contribution of the aforementioned two factors is still a challenge. In this paper, the pretreatment method, i.e., low-temperature plasma ashing, is recommended. The low-temperature plasma ashing can excite low-pressure oxygen into highly active oxygen plasma through high-frequency electric field, which triggers deep oxidation and decomposition of organic matters. Compared with conventional ashing method at a higher temperature of 815 ± 10°C, the low-temperature plasma ashing can remove organic matters from coals at the extremely low temperature of 100–200°C, which can maintain the mineral structure of coals (Jin 1989). Therefore, the low-temperature ashing is predictive to further distinguish the effects of organic and inorganic substances in coals on H2O occurrence, respectively.