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MEMS Design & Fab
Foundry Services: MOSIS as a model
• MOSIS: MOS implementation service, ISI, 1980.
UCB
HP StanfordStartup XMIT
users
Maskmaker Orbit
2um HP0.5um
Dicing and packaging
vendors Chips
Information$$$$$MOSIS
ksjp
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MEMS Design & Fab
Foundry Services and Standard Processes
• MCNC/MUMPS (now by Cronos)• 3 level poly, no electronics• started in 1992, now 6 runs per year
• LIGAMUMPS• single level metal, no electronics
• Sandia• 5 level poly, no electronics• 1 level poly w/ quality CMOS
• CMOS + post-processing• EDP, TMAH, XeF2 (Parameswaran)• Plasma (Fedder)
ksjp
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MEMS Design & Fab
MUMPS process flow
ksjp
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MEMS Design & Fab
MUMPS process flow
ksjp
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1
MEMS Design & Fab
MUMPS process flow
ksjp
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1
MEMS Design & Fab
MUMPS process flow
ksjp
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1
MEMS Design & Fab
MUMPS process flow
ksjp
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MEMS Design & Fab
MicroOptical Bench (Ming Wu, UCLA)
ksjp
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MEMS Design & Fab
MCNC/MUMPS layer thicknesses
Material Layer Thickness (µm) Lithography Level Name
Nitride 0.6 -
Poly 0 0.5 POLY0 (HOLE0)
DIMPLEFirst Oxide 2.0
ANCHOR1
Poly 1 2.0 POLY1 (HOLE1)
POLY1_POLY2_VIASecond Oxide 0.75
ANCHOR2
Poly 2 1.5 POLY2 (HOLE2)
Metal 0.5 METAL (HOLEM)
ksjp
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MEMS Design & Fab
Design “Rules”
• Guidelines for communication between fab people and design people
• Generally not enforced• MUMPS, 2um CMOS: no• HP sub-micron CMOS: yes
• Often desireable to violate• MUMPS: process exploration, new devices, some
previous design rule violations are now encouraged• CMOS: Parameswaran, Fedder style MEMS
depends on design rule violations
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MEMS Design & Fab
• Typically due to • lithographic resolution limits• lithographic alignment repeatability• etching capabilities
• Most important: Line/space• due to lithography or etching• varies from layer to layer• varies near topography• no guarantee of dimensions: the
lines will exist and be distinct.
Design Rules
Line width
... and spacing
ksjp
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MEMS Design & Fab
Design Rules
ksjp
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MEMS Design & Fab
MCNC/MUMPS Design Rules
MnemonicLevel Name
CIFLevelName
GDS LevelNumber
Nominal Line/Space(µm)
Minimum Line(µm)
Minimum Space(µm)
POLY0 CPZ 13 3.0 2.0 2.0
ANCHOR1 COF 43 3.0 3.0 2.0
DIMPLE COS 50 3.0 2.0 3.0
POLY1 CPS 45 3.0 2.0 2.0
POLY1_POLY2_VIA
COT 47 3.0 2.0 2.0
ANCHOR2 COL 52 3.0 3.0 2.0
POLY2 CPT 49 3.0 2.0 2.0
METAL CCM 51 3.0 3.0 3.0
HOLE0 CHZ 41 3.0 2.0 2.0
HOLE1 CHO 0 3.0 2.0 2.0
HOLE2 CHT 1 3.0 2.0 2.0
HOLEM CHM 48 3.0 3.0 3.0
Rules for line/space on all mask layers.
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MEMS Design & Fab
MCNC/MUMPS Design Rules
RuleRule
Letter
Rule
value
POLY1 enclose ANCHOR1 G 4.0
POLY1 enclose DIMPLE N 4.0
POLY1 enclose POLY1_POLY2_VIA H 4.0
POLY1 enclose POLY2 O 4.0
POLY1 space to ANCHOR2 K 3.0
Spacing between lateral etch holes inPOLY1
R <30
RuleRule
Letter
Rule
value
POLY0 space to ANCHOR1 A 4.0
POLY0 enclose ANCHOR1 B 4.0
POLY0 enclose POLY1 C 4.0
POLY0 enclose POLY2 D 5.0
POLY0 enclose ANCHOR2 E 5.0
POLY0 space to ANCHOR2 F 5.0
ksjp
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MEMS Design & Fab
MCNC/MUMPS Design Rules
RuleRule
Letter
Rule
value
POLY2 enclose ANCHOR2 J 5.0
POLY2 enclosePOLY1_POLY2_VIA
L 4.0
POLY2 cut-in POLY1 P 5.0
POLY2 cut-out POLY1 Q 4.0
POLY2 enclose METAL M 3.0
POLY2 space to POLY1 I 3.0
HOLE2 enclose HOLE1 ? T 2.0
HOLEM enclose HOLE2 U 2.0
Spacing between lateral etch holesin POLY1
R <30
Examples for POLY2 frommems.mcnc.org/smumps/mrules
ksjp
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MEMS Design & Fab
Breaking the Rules
• Sub-minimum lithography• risky, but often successful, especially in planar areas
• Breaching nitride (substrate contacts and opens)• Stack anchor1 and poly1-poly2-via• don’t include poly1• include poly2 for electrical contact to substrate, or
remove to expose bare substrate
• Double-thick poly• continuous sheet of poly1 enclosed in poly1-poly2-via• poly2 structures on top
ksjp
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MEMS Design & Fab
MCNC/MUMPS access
• Cost is $3,500 per submission• 1cm2 die area per submission• 15 identical dice returned (~$2/mm2)
• Files are submitted by anonymous ftp
• Dicing, bonding, HF release are all available for additional cost
• Parameterized and static design cells are free online (CaMEL)
• Design services are available for additional cost
ksjp
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MEMS Design & Fab
MCNC/MUMPS process specs
Film Thickness (Å) Residual Stress (MPa) Resistance (ohms/sq)
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
Nitride 5600 6000 6400 20 60 100 N/A
Poly0 4600 5000 5400 0 -10 -20 20 30 40
Oxide1 19000 20000 21000 N/A N/A
Poly1 19500 20000 20500 0 -10 -20 5 10 15
Oxide2 7100 7500 7900 N/A N/A
Poly2 14250 15000 15750 0 -10 -20 10 20 30
Metal 4800 5200 5600 0 20 40 0.05 0.06 0.07
Polys are compressive, nitride and metal (Cr/Au) are tensile.
ksjp
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MEMS Design & Fab
MCNC/LIGAMUMPS
ksjp
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MEMS Design & Fab
MCNC/LIGAMUMPS Design Rules
A, W, L must be greater than or equal to 20.0 microns.Photoresist aspect ratio, L/W, must be less than or equal to 10.
