1. Design Rule
EMT 251

2. Design Rules
Design rules are a set of geometrical specifications that dictate the design of the layout masks
A design rule set provides numerical values
For minimum dimensions
For minimum line spacings
Design rules must be followed to insure functional structures on the fabricated chip
Design rules change with technological advances (

3. Silicon Foundry A standard
A foundry allows designers to submit designs using a state-of-the-art process
Each foundry state simpler set of design rules called lambda design rules
All widths, spacings, and distances are written in the form
Value =
TSMC (Taiwan Semiconductor Manufacturing Corporation)

4. Design Rules Classification
Minimum width
Minimum spacing

5. 3D Perspective
Polysilicon
Aluminum

6. CMOS Process Layers Layer Polysilicon Metal1 Metal2 Contact To Poly
Contact To Diffusion
Via
Well (p,n)
Active Area (n+,p+)
Color
Representation
Yellow
Green
Red
Blue
Magenta
Black
Select (p+,n+)

7. Layers in 0.35 mm CMOS process

8. Design rules and Layout
Why we use design rules?
Interface between designer and process engineer
Guidelines for constructing process masks
Unit dimension: Minimum line width
scalable design rules: lambda parameter
absolute dimensions (micron rules)

9. Intra-Layer Design Rules

10. Transistor Layout

11. Vias and Contacts

12. Select Layer

13. When a transistor is formed?
Gate is formed where polySi crosses diffusion with thin oxide between these layers.

14. Message from Design Rule Checker
Measure twice, fab once!!

15. Thank You