ESE 570 FABRICATION OF CMOS INTEGRATED CIRCUITS
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 2
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 3
Crystal Puller with rotation mechanism
Crystal Seed
Quartz Crucible Heat
Shield
Molten Polysilicon
Ingot Wafer
Water Jacket
Heating Element
Image from Quirk & Serda
Single-Crystal Silicon
● 2010: 300 mm (12 in.) diameter wafers● 2016: 450 mm (18 in.) - goal
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 4
The ROI of 450mm wafers however is compelling. A 450mm fab with equal wafer capacity to a 300mm fab can produce 2x the amount of die. A rough calculation of die cost: a 14nm die from a 450mm wafer will cost 23% less than the same die from a 300mm wafer.
Silicon Wafer Manufacturing
Si Ingots
Si Wafers300 mm(12 in.)
450 mm (18 in.)
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 5
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 6
mask (e.g. metal)
UV light illumination
field area is actually opaque
lens
unexposed die
exposed dieSi wafer coated with photoresist
wafer scan direction
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 7
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 8
PHOTOLITHOGRAPHY
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 9
CMOS Processing Technology
time = 60 stime = 0 s
Boron atoms deposited on
surface
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 10
CMOS Processing TechnologyION IMPLANTATION
N keV
DepthDepth (µm)
0 0.5 1.0 1.5
B in Si Dose: 1015 cm-2
Con
cent
ratio
n (c
m-3) 1*1020
0.5*1020
0
50 keV
200 keV100 keV
400 keV
Boron (B)
Advantages of Ion Implantation Precise control of dose and depth profile. Low temperature process (can use photoresist as mask)
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 11
Acceptors
Metalloids
Chemical Periodic Table
American Chemical Society (ACS)
Donors
Boronatom
Freehole
Phosphorus atom
Freeelectron
Electrons shared by neighbor atoms
5
Doping of Semiconductors
85At
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 12
(d)
Si3N
4
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 13
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 14
Wdrawnn+ n+
p substrate (bulk)
n+ n+G
S D
polygate
S D
gateoxide
Leffective
metal 1
Ldrawn
field oxide
Physical Structure Layout Representation
Schematic Representation
Ldrawn
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 15
nMOS Transistor from a 3D Perspective
GateOxide
FieldOxide
FieldOxide
P-TypeSource/Drain
Regions
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 16
nMOS Transistor
nMOS Transistor
metalroute
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 17
To eliminate the opportunity to create parasitic transistors: 1. “p+ Channel Stop Implant” is introduced in areas where there are to be absent nMOS transistors.2. Increase the the field oxide in areas to be absent nMOS transistors.
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 18
Grow field oxide. Create contact window, deposit & pattern metal film.
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 19
p+ channel stop implant
channel stop
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 20
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 21
Substrate contact
VDD
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 22
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 23
C. Bipolar Transistors
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 24
High-K Dielectric Metal gate MOSFET
MOSFET TECHNOLOGY INNOVATIONSiO
2 Dielectric Poly gate MOSFET
High-K 3D Tri-Gate MOSFET (Intel)
22 nm
High-K Dielectric
=HfO2
Dielectric constant = 25
Dielectric constant = 3.9
Source
Drain
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 25
Contacts and Vias in CMOS Fabrication
Enhanced Feature
1
2
1
2
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 26
Poly-silicide or Silicide = metallurgical combination polysilicon and a refractory metal
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 27
L
W
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 28
p = substrate p = substrate
p+ p+
Field oxide Capacitor oxide
metal
High-k capacitor oxide
Planar Capacitor(metal-p+)
“Trench” Capacitor(metal-p+)
MORE CMOS CAPACITORS
p+
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 29
Metal 1 & Metal 2
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 30
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 31
PHYSICAL LAYER: Design Rules are a set of process-specific geometric rules for preparing layout artwork to enable the layout to be manufacturable, i.e. preserve all of the circuit structures and feature geometries intended by the chip designers.
PURPOSE: Realize fabricated chips that are die area efficient and manufacturable by balancing the conflicting objectives to minimize die area and maximize yield.
DESIGN RULE WAIVER: Explicit permission granted by the fabrication organization to the design organization to violate certain design rules or to allow certain design rule errors on a given design (IP or chip).
. Permits first-order scaling and tend to be more conservative than 'micron' rules.
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 32
To be able to tolerate some level of natural fabrication variations, such as
1. Mask misalignment
2. Dust
3. Process parameters (e.g., lateral diffusion)
4. Rough 3D surfaces
WHY HAVE DESIGN RULES?
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 33
Basic CMOS Process Design Rule Set
8"A3 =
A – N-WELL RULES
B – ACTIVE RULES
C – POLY RULES
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 34
2"
2"
7"
H – METAL 2 RULES
J – METAL 3RULES
I – VIA2 RULES
G – VIA RULES
E – CONTACT RULES
F – METAL 1 RULES
1"
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 35
Potential Consequences of Design Rule Violations
Intended Transistor
Intended Unrelated Poly & DiffusionIntended Unrelated Poly & Diffusion
Catastrophic Error – Unintended misalignment cause Source-Drain short circuit
Catastrophic Error – Unintended overlap cause fabrication of a parasitic Transistor
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 36
Potential Consequences of Design Rule Violations
Intended Contact Alignment
Error – Unintended misalignment cause poor contact
Mask misalignmentBoth Metal 1 & Diffusion
Both Metal 1 & Diffusion
M1 contact to n-diffusionM1 contact to p-diffusion -> Contact MaskM1 contact to poly
Mn contact to Mn-1 for n = 2, 3,.. -> Via Mask
Contact and Via Masks
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 37
http://www.seas.upenn.edu/%7Eese570/manual_16.htm
http://www.seas.upenn.edu/%7Eese570/manual_17.htm
D. Extract parasitic resistances and statistical extraction in later versions of Cadence.
Kenneth R. Laker, University of Pennsylvania, updated 22Jan15 38
poly_not_fet_to all-diff minimum spacing = 0.14 um
EXAMPLE Design Rule Checker Message