Lec9p.SurfaceMicromachining

Lec9p.SurfaceMicromachining - EE 245 Introduction to MEMS...

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Unformatted text preview: EE 245: Introduction to MEMS Lecture 9: Surface Micromachining II/Stiction CTN 9/28/09 Copyright © 2009 Regents of the University of California EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 7 Layout and Masking Layers • At Left : Layout for a folded-beam capacitive comb- driven micromechanical resonator • Masking Layers : 1 st Polysilicon: POLY1(cf) 2 nd Polysilicon: POLY2(cf) Anchor Opening: ANCHOR(df) A A ′ Capacitive comb-drive for linear actuation Folded-beam support structure for stress relief EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 8 Surface-Micromachining Process Flow • Deposit isolation LTO (or PSG): ª Target = 2 μ m ª 1 hr. 40 min. LPCVD @450 o C • Densify the LTO (or PSG) ª Anneal @950 o C for 30 min. • Deposit nitride: ª Target = 100nm ª 22 min. LPCVD @800 o C • Deposit interconnect polySi: ª Target = 300nm ª In-situ Phosphorous-doped ª 1 hr. 30 min. LPCVD @650 o C • Lithography to define poly1 interconnects using the POLY1(cf) mask • RIE polysilicon interconnects: ª CCl 4 /He/O 2 @300W,280mTorr • Remove photoresist in PRS2000 Silicon Substrate Nitride Interconnect Polysilicon Isolation Oxide Silicon Substrate Silicon Substrate Photoresist Cross-sections through A-A ′ EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 9 Surface-Micromachining Process Flow • Deposit sacrificial PSG: ª Target = 2 μ m ª 1 hr. 40 min. LPCVD @450 o C • Densify the PSG ª Anneal @950 o C for 30 min. • Lithography to define anchors using the ANCHOR(df) mask ª Align to the poly1 layer • Etch anchors ª RIE using CHF 3 /CF 4 /He @350W,2.8Torr ª Remove PR in PRS2000 ª Quick wet dip in 10:1 HF to remove native oxide • Deposit structural polySi...
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Lec9p.SurfaceMicromachining - EE 245 Introduction to MEMS...

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