VLSI Design Flow: RTL to JDS - Lecture 1 Notes

Introduction

Welcome to the course on VLSI Design Flow (RTL to JDS).
This lecture covers:
- Historical perspective of integrated circuits
- Structure of integrated circuits
- Terminologies related to IC fabrication
- Differences and relationship between designing and fabrication

Charles Babbage is considered the father of computers.
Notable quote: "The sources of excellence in work produced by machinery depend on a principle..."
Principle of copying is fundamental to manufacturing excellence.
Relevant to both the Industrial Revolution and the current Digital Revolution, which relies on integrated circuits (ICs).

An electronic circuit consists of active (transistors, diodes) and passive components (resistors, capacitors).
Traditional systems utilized discrete components, which became costly and error-prone as complexity increased.
Integrated Circuit: A monolithic silicon chip that combines multiple components on a single crystal of silicon, minimizing costs and maximizing efficiency.
IC Technology: Developed in the 1960s, enabling the integration of more components with advancements in silicon properties and fabrication techniques (photolithography).

Key technique for fabricating integrated circuits, enabling mass reproduction of complex circuits.
Moore's Law: Prediction made by Gordon Moore in the 1960s stating that the number of components in an IC would double approximately every two years, a trend observed until now.
Advancements in technology have led to smaller transistor sizes (e.g., from 90nm down to 5nm) resulting in increased speed, energy efficiency, and reduced cost per transistor.

Integrated circuits consist of multiple layers:
- Base layers for diffusion and devices (PMOS, NMOS)
- Metal layers for interconnects (10+ layers in advanced ICs)
Why Layers?: Layers allow for complex routing of connections without short-circuits by enabling vertical connections, thus solving planar connection issues.

Silicon Wafer: Thin slice of silicon that serves as a substrate for ICs, typically 300mm in diameter.
Silicon Ingot: A large cylindrical single crystal of silicon used to create wafers.
Die: A small piece of silicon containing a complete integrated circuit, created from a silicon wafer.
Yield: The percentage of defect-free dies from a wafer.
Packaging: The process of encapsulating dies into protective packages for protection and usability.

Designing: Involves determining circuit parameters and layout for desired functionality.
Fabrication: Actual creation of the IC based on the design layout, without altering parameters.
Semiconductor Foundries: Facilities for IC fabrication, requiring significant capital investment and controlled environments.
Business Models:
- Fabulous Design Companies: Focus on design, outsource fabrication.
- Merchant Foundries: Specialize in fabrication for various design companies.
- Integrated Device Manufacturers: Conduct both design and fabrication.

Integrated circuit fabrication relies heavily on photolithography for mass production.
Understanding both designing and fabrication processes is crucial for successful IC development.
Upcoming lectures will explore more concepts related to integrated circuits.