Investigating the optimum parameters of a negative photoresist to prepare a V-grooved diffraction grating on Si using photolithography and reactive ion etching techniques

Yas Al-Hadeethi, A. Al-Mujtabi, Fahd M. Al-Marzouki, Alaa Y. Mahmoud, Ahmad Umar, A. M. Abdel-Daiem, Mohammad Shahnawaze Ansari

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


In this study, the deposition parameters of the SU8 2000.5 negative photoresists have been investigated and optimized for the photolithographic technique. Then, applied the inductive coupled plasma reactive ion etching (ICP RIE) to produce V-shaped groove diffraction grating on a silicon substrate. Spin coater (speed: 1000 rpm) was used to coat the photoresist over the Si substrate. The observed photoresist film thickness was measured by ellipsometry and found to be 800 nm. Interestingly, the film exhibited some stability with increasing the spin speed. The thermogravimetric analysis was used to optimize the baking temperature which was found to be ~105 °C. Contrast curves were obtained experimentally and used to optimize the exposure energy along with the images obtained from the field emission scanning electron microscopy (FESEM). The optimized energy fluence was found to be 17 mJ/cm2. It was interesting to observe that the thickness of the photoresists film was increasing with the elevation of the exposure energy fluence. The FESEM images were used to optimize the ICP RIE etching process and the best etching conditions for the Si substrate were ICP power: 150 W, bias power: 100 W, and SF6 gas flow rate: 32 SCCM (standard cubic centimeters per minute), O2 gas flow: 8 SCCM, and Ar gas flow of 8 SCCM. It is worth to mention that well-defined V-shaped grooves were observed with a depth of 2 μm under the same experimental conditions.
Original languageEnglish (US)
Pages (from-to)10705-10715
Number of pages11
JournalCeramics International
Issue number8
StatePublished - Mar 9 2021
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2022-06-14
Acknowledgements: This research was funded by the Deanship of Scientific Research (DSR) at King Abdulaziz University, Jeddah, Saudi Arabia] grant number FP-206-42. Authors also acknowledge with thanks, the contribution of King Abdullah University (KAUST), Saudi Arabia for facilitating the use of their core labs. Special thanks go to the ex-director of core labs Prof. Xixiang Zhange and to Dr. Longqing Chen, Eng. Abdulrazaq Alharbi, Ms. Ohoud Alharbi and Dr. Ping Li. Thanks to Dr. Elsayed Shalaan and to the Clean room staff of the Physics Department, Faculty of Science, and to the nano research center at King Abdulaziz University, Saudi Arabia.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

ASJC Scopus subject areas

  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Electronic, Optical and Magnetic Materials


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