Sachpazis Costas: Geotechnical Engineering: A student's Perspective Introduction
Stick Diagram and Lambda Based Design Rules
1. Stick Diagram
&
Lambda Based Design Rules
Presented by:
TAHSIN AL MAHI
Student ID: 140934
Year: 4 Term: I
ECE Discipline
Khulna University
Khulna
7/29/2018 ECE KU 1
2. 7/29/2018 ECE KU 2
Presentation Outline
Top Down Hierarchy of System Design in VLSI
What is Stick Diagram
Stick Encodings
A CMOS inverter
Color Codes
Some Rules
What is Lambda Based Design Rule
Design Rules
3. 7/29/2018 ECE KU 3
Top Down Hierarchy of System Design in VLSI
System Specifications
System Design
Subsystem Design
Logic Design
Logic Circuit Electronic Circuit
Stick Diagram
Mask Layout
Fabrication
Chip
4. 7/29/2018 ECE KU 4
What is Stick Diagram?
o Stick diagram is a cartoon of a layout.
o Conveying layer information through the use of a color code or
monochrome encoding.
o Monochrome encodings are black and white lines.
D
S
G G
S
D
a b
Fig: (a) nMOS; (b) Stick Diagram of the nMOS
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Stick Encoding Layer
Diffusion Layer (n-type or p-type)
Polysilicon
Metal
Contact Cut (Diffusion layer with Metal)
Buried Contact (Diffusion layer with polysilicon)
Implant (Channel between drain and source)
Demarcation line (between n and p type)
VIA (Contact between metal 1 and metal 2)
Body to substrate connection
Stick Encodings
6. 7/29/2018 ECE KU 6
A CMOS Inverter
D
S
G
S
D
G
a b
Fig: (a) CMOS inverter; (b) Stick diagram of the CMOS inverter
DDV
outVinV
GND
DDV
GND
inV outV
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Color Codes
Layer Layer Name
Metal 1
Polysilicon
n-type diffusion
p-type diffusion
Demarcation line
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Some Rules
Rule 1: When two or more ‘sticks’ of the same type cross or touch each
other that represents electrical contact.
Fig: Same type of sticks are crossing
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Some Rules…
Rule 2: When two or more ‘sticks’ of different type cross or touch each
other there is no electrical contact. If electrical contact is needed we have to
show the connection explicitly.
Fig: Electrical contact between two different sticks
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Some Rules…
Rule 3: When a poly crosses diffusion it represents a transistor.
Fig: Transistor made out by crossing over diffusion and polysilicon
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Some Rules…
Rule 4: In CMOS a demarcation line is drawn to separate the nMOS and
the pMOS.
Fig: Demarcation line separating nMOS and pMOS
12. 7/29/2018 ECE KU 12
What is Lambda Based Design Rule
o Setting out mask dimensions along a size-independent way.
o Mead and Conway provided these rules.
o (Lambda) is a unit and can be of any value.
o According this rule line widths, separations and extensions are
expressed in terms of .
o Mask layout is designed according to Lambda Based Designed Rule.
o Nowadays, .
nm14
16. 7/29/2018 ECE KU 16
Design Rules…
2 Minimum
Implant for an nMOS
depletion mode
transistor to extend 2y
minimum beyond
channel in all
directions
2 Minimum
minimum
2
2 minimum
2
Fig: Transistor Design Rules (CMOS)
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Design Rules…
minimum3
2
minimum
Fig: Transistor Design Rules (Metal 1 to Polysilicon or to Diffusion)
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Design Rules…
Metal 2
Metal 1
2 minimum separation
(if other spacings allows)
Cut
44 area of overlap with
22 via at center
Fig: Transistor Design Rules (contact from metal 2 to metal 1 and thence to other layers)
19. 7/29/2018 ECE KU 19
Reference
Basic VLSI Design by Douglas A. Pucknell & Kamran Eshraghian
Stick Diagrams, Maharishi Markandeshwar University, Haryana, India