LAYOUT DESIGN RULES

1. LAYOUT DESIGN RULES BY Mr. MANU T.M Bellary Engg College,Bellary, karnataka manutmece@yahoo.com

2. Objectives: • Understand the need of design rules in fabrication process. • Different type of design rules and advantages. • Dimensions of different layers and separation in terms of lambda rules. Outcomes: We will understand the different types rules, the dimensions of each layers and advantages of different rules.

3. DESIGN RULES • The physical layout of any ckt to be manufactured using particular process must conform to set of geometric constraints or rules. Which are generally called as layout design rules. • These rules usually specifies the minimum allowable line widths for physical objects on chips, such as metal, poly, diffusion etc.,

4. Why we need design rules • Masks are tooling for manufacturing. • Interface between designer and process engineer. • Manufacturing processes have inherent limitations in accuracy. • Design rules specify geometry of masks which will provide reasonable yields. • Design rules are determined by experience.

5. Types of Design Rules • Scalable Design Rules • Idea: reduce l value for each new process, but keep rules the same • Key advantage: portable layout • Key disadvantage: not everything scales the same • Absolute Design Rules • Based on absolute distances (e.g. 0.75µm) • Tuned to a specific process • Complex, especially for deep submicron • Layouts not portable

6. Design Rule Summary Line size and spacing: • metal1: Minimum width=3l, Minimum Spacing=3l • metal2: Minimum width=3l, Minimum Spacing=4l • poly: Minimum width= 2l, Minimum Spacing=2l • ndiff/pdiff: Minimum width= 3l, Minimum Spacing=3l, minimum ndiff/pdiff seperation=10l • wells: minimum width=10l, min distance form well edge to source/drain=5l • Transistors: • Min width=3l • Min length=2l • Min poly overhang=2l

11. Questions ? Thank you