AVS 62nd International Symposium & Exhibition
    Additive Manufacturing/3D Printing Focus Topic Thursday Sessions
       Session AM-ThP

Paper AM-ThP3
Novel Deep Si Etching Process for Green IOT

Thursday, October 22, 2015, 6:00 pm, Room Hall 3

Session: Additive Manufacturing/3D Printing Poster Session
Presenter: Takahide Murayama, ULVAC Inc., Japan
Correspondent: Click to Email
TSV (Thru Silicon Via) application for 2.5D silicon interposers and 3D stacked devices is expected to realize a next-generation semiconductor device applied for upcoming IOT world with high packaging density, power saving, and high-speed signal transmission, etc. Generally, SF6 gas has been applied to form TSV in dry etching process because of its useful properties; reasonable cost, chemical safety, and dissociation property which generates a lot of fluorine radicals. Abundant fluorine radicals contribute to achieve higher silicon etching rate, but in the perspective of Global Warming Potential (GWP), SF6 has extremely high potential (GWP = 22200, 100 year base), gives a great impact to greenhouse effect. So, various gases have been offered to alternate SF6. In series SFx (x=0 to 6), there are limited species which have industrial stability, some of them characteristic properties in the points of low GWP and dissociation to generate fluorine radicals. SF4 gas has very low GWP in SFx series . Because SF4 immediately reacts with H2O in atmosphere, generates HF and SOx. GWP for HF and SOx have not been set due to their water-soluble property . In addition to low GWP property, the bond strength in SF4 has unique property. In SF6, SF5-F bond strength is 387 ± 13 kJ/mol. On the other hand, SF3-F bond strength in SF4 is 354 ± 13 kJ/mol . So, there is an expectation that SF4 can generate abundant fluorine radicals compared with SF6. From above properties, SF4 may be one of the SF6 alternative gases for TSV dry etching process.