Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This paper studies spin-on glass (SOG) etching in T-shaped microchannels using hydrofluoric acid (HF). An etching model based on non-first order chemical reaction/steady-state diffusion sacrificial layer etching mechanism is presented to compensate for the etching effect at channel junction. Microchannels are formed on silicon substrate by deep reactive ion etching (DRIE). Samples with channel depth varying from 1μm to 6 μm are prepared by varying exposure time to reactant gas in DRIE chamber. Channel widths prior to the junction are varied from 2 μm to 10 μm while channel width beyond the junction is fixed at 5 μm. The channels are then filled with SOG by multiple spin, bake and cure processes. After etchback planarization using 5% HF solution, the samples are coated with 1.5 μm thick positive photoresist. An etch window is opened at channel fronts to expose underlying SOG. The samples are then time-etched in 5% HF solution and etch front propagation is observed under optical microscope through the transparent photoresist layer. It is observed that SOG etch rate in the microchannels is independent of channel width or channel depth. SOG etch rate at channel's T-junction is 0.67 times lower than etch rate in the straight channels preceding it due to HF concentration variation and etch product transfer rate variation. The proposed model fits experimental data well. Offset crosses vent pattern is determined as a good candidate for removing sacrificial oxide under an enclosed cap structure.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsJ.-C. Chiao, A.S. Dzurak, C. Jagadish, D.V. Thiel
Volume6037
DOIs
Publication statusPublished - 2006
EventDevice and Process Technologies for Microelectronics, MEMS, and Photonics IV - Brisbane, Australia
Duration: 12 Dec 200514 Dec 2005

Other

OtherDevice and Process Technologies for Microelectronics, MEMS, and Photonics IV
CountryAustralia
CityBrisbane
Period12/12/0514/12/05

Fingerprint

Hydrofluoric acid
hydrofluoric acid
microchannels
Microchannels
Etching
etching
Glass
glass
Reactive ion etching
Photoresists
Vents
photoresists
Chemical reactions
Microscopes
Silicon
Oxides
vents
Substrates
optical microscopes
Gases

Keywords

  • Etching model
  • HF etch
  • Microchannels
  • Sacrificial layer
  • Spin-on glass (SOG)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Hamzah, A. A., Yeop Majlis, B., & Ahmad, I. (2006). Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid. In J-C. Chiao, A. S. Dzurak, C. Jagadish, & D. V. Thiel (Eds.), Proceedings of SPIE - The International Society for Optical Engineering (Vol. 6037). [60371O] https://doi.org/10.1117/12.638572

Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid. / Hamzah, Azrul Azlan; Yeop Majlis, Burhanuddin; Ahmad, Ibrahim.

Proceedings of SPIE - The International Society for Optical Engineering. ed. / J.-C. Chiao; A.S. Dzurak; C. Jagadish; D.V. Thiel. Vol. 6037 2006. 60371O.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Hamzah, AA, Yeop Majlis, B & Ahmad, I 2006, Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid. in J-C Chiao, AS Dzurak, C Jagadish & DV Thiel (eds), Proceedings of SPIE - The International Society for Optical Engineering. vol. 6037, 60371O, Device and Process Technologies for Microelectronics, MEMS, and Photonics IV, Brisbane, Australia, 12/12/05. https://doi.org/10.1117/12.638572
Hamzah AA, Yeop Majlis B, Ahmad I. Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid. In Chiao J-C, Dzurak AS, Jagadish C, Thiel DV, editors, Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6037. 2006. 60371O https://doi.org/10.1117/12.638572
Hamzah, Azrul Azlan ; Yeop Majlis, Burhanuddin ; Ahmad, Ibrahim. / Modelling of sacrificial spin-on glass (SOG) etching in non-straight microchannels using hydrofluoric acid. Proceedings of SPIE - The International Society for Optical Engineering. editor / J.-C. Chiao ; A.S. Dzurak ; C. Jagadish ; D.V. Thiel. Vol. 6037 2006.
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abstract = "This paper studies spin-on glass (SOG) etching in T-shaped microchannels using hydrofluoric acid (HF). An etching model based on non-first order chemical reaction/steady-state diffusion sacrificial layer etching mechanism is presented to compensate for the etching effect at channel junction. Microchannels are formed on silicon substrate by deep reactive ion etching (DRIE). Samples with channel depth varying from 1μm to 6 μm are prepared by varying exposure time to reactant gas in DRIE chamber. Channel widths prior to the junction are varied from 2 μm to 10 μm while channel width beyond the junction is fixed at 5 μm. The channels are then filled with SOG by multiple spin, bake and cure processes. After etchback planarization using 5{\%} HF solution, the samples are coated with 1.5 μm thick positive photoresist. An etch window is opened at channel fronts to expose underlying SOG. The samples are then time-etched in 5{\%} HF solution and etch front propagation is observed under optical microscope through the transparent photoresist layer. It is observed that SOG etch rate in the microchannels is independent of channel width or channel depth. SOG etch rate at channel's T-junction is 0.67 times lower than etch rate in the straight channels preceding it due to HF concentration variation and etch product transfer rate variation. The proposed model fits experimental data well. Offset crosses vent pattern is determined as a good candidate for removing sacrificial oxide under an enclosed cap structure.",
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N2 - This paper studies spin-on glass (SOG) etching in T-shaped microchannels using hydrofluoric acid (HF). An etching model based on non-first order chemical reaction/steady-state diffusion sacrificial layer etching mechanism is presented to compensate for the etching effect at channel junction. Microchannels are formed on silicon substrate by deep reactive ion etching (DRIE). Samples with channel depth varying from 1μm to 6 μm are prepared by varying exposure time to reactant gas in DRIE chamber. Channel widths prior to the junction are varied from 2 μm to 10 μm while channel width beyond the junction is fixed at 5 μm. The channels are then filled with SOG by multiple spin, bake and cure processes. After etchback planarization using 5% HF solution, the samples are coated with 1.5 μm thick positive photoresist. An etch window is opened at channel fronts to expose underlying SOG. The samples are then time-etched in 5% HF solution and etch front propagation is observed under optical microscope through the transparent photoresist layer. It is observed that SOG etch rate in the microchannels is independent of channel width or channel depth. SOG etch rate at channel's T-junction is 0.67 times lower than etch rate in the straight channels preceding it due to HF concentration variation and etch product transfer rate variation. The proposed model fits experimental data well. Offset crosses vent pattern is determined as a good candidate for removing sacrificial oxide under an enclosed cap structure.

AB - This paper studies spin-on glass (SOG) etching in T-shaped microchannels using hydrofluoric acid (HF). An etching model based on non-first order chemical reaction/steady-state diffusion sacrificial layer etching mechanism is presented to compensate for the etching effect at channel junction. Microchannels are formed on silicon substrate by deep reactive ion etching (DRIE). Samples with channel depth varying from 1μm to 6 μm are prepared by varying exposure time to reactant gas in DRIE chamber. Channel widths prior to the junction are varied from 2 μm to 10 μm while channel width beyond the junction is fixed at 5 μm. The channels are then filled with SOG by multiple spin, bake and cure processes. After etchback planarization using 5% HF solution, the samples are coated with 1.5 μm thick positive photoresist. An etch window is opened at channel fronts to expose underlying SOG. The samples are then time-etched in 5% HF solution and etch front propagation is observed under optical microscope through the transparent photoresist layer. It is observed that SOG etch rate in the microchannels is independent of channel width or channel depth. SOG etch rate at channel's T-junction is 0.67 times lower than etch rate in the straight channels preceding it due to HF concentration variation and etch product transfer rate variation. The proposed model fits experimental data well. Offset crosses vent pattern is determined as a good candidate for removing sacrificial oxide under an enclosed cap structure.

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