Lec11p.BulkMicromachining

Lec11p.BulkMicromachining - EE 245: Introduction to MEMS...

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Unformatted text preview: EE 245: Introduction to MEMS Lecture 11: Bulk Micromachining CTN 10/1/09 Copyright 2009 Regents of the University of California EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 47 Foundry MEMS: The MUMPS Process EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 48 MUMPS: M ulti U ser M EMS P roces S Originally created by the Microelectronics Center of North Carolina (MCNC) now owned by MEMSCAP in France Three-level polysilicon surface micromachining process for prototyping and foundry services Designed to service as many users as possible; basically an attempt to provide a universal MEMS process 8 photomasks $4,900 for 1 cm 2 dies Micromotor fabricated via MUMPS EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 49 MUMPS: M ulti U ser M EMS P roces S Micromotor Example EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 50 Masks in polyMUMPS Field type: Light (or clear) field (cf) : in layout, boxes represent features that will stay through fabrication Dark field (df) : in layout, boxes represent holes to be cut out Minimum set of masks that must be used in MUMPS Minimum set of masks that must be used in MUMPS Extra masks for more flexibility & ease of release Extra masks for more flexibility & ease of release EE 245: Introduction to MEMS Lecture 11: Bulk Micromachining CTN 10/1/09 Copyright 2009 Regents of the University of California EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 51 MUMPS Process Flow Deposit PSG on the starting n- type (100) wafers Anneal to heavily dope the wafers Remove the PSG LPCVD 600 nm of low stress nitride LPCVD 500 nm of polysilicon Lithography using the POLY0(cf) mask and RIE etching to pattern the poly0 ground plane layer LPCVD 2 m of PSG as the 1 st sacrificial layer Lithography using the DIMPLE(df) mask (align to poly0) RIE 750 nm deep to form dimple vias Lithography using the ANCHOR1 (df) mask (align to poly0) RIE anchor vias down to the nitride surface EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 52 MUMPS Process Flow (cont.) LPCVD 2 m undoped polysilicon LPCVD 200 nm of PSG Anneal for 1 hr. @ 1050 o C This both dopes the polysilicon and reduces its residual stress Lithography using the POLY1(cf) mask to define structures (align to anchor1) RIE the PSG to create a hard mask first, then RIE the polysilicon LPCVD 750 nm of PSG Lithography using the P1_P2_VIA (df) mask to define contacts to the poly1 layer (align to poly1) EE C245 : Introduction to MEMS Design LecM 5 C. Nguyen 8/20/09 53 MUMPS Process Flow (cont.) Recoat with photoresist and do lithography using the ANCHOR2(df) mask to define openings where poly2 contacts nitride or poly0 (align to poly0) RIE the PSG at ANCHOR2 openings LPCVD 1.5 m undoped polysilicon LPCVD 200 nm PSG as a hard mask and doping source Anneal for 1 hr @ 1050...
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This note was uploaded on 10/31/2010 for the course C 218 taught by Professor Clarknguyen during the Fall '09 term at University of California, Berkeley.

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Lec11p.BulkMicromachining - EE 245: Introduction to MEMS...

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