New generations are emerging in a very competitive semiconductor technology realm, so it is important for engineers, researchers, and technology enthusiasts to be updated on the new Very Large Scale Integration (VLSI) processes in the market. Thus, in this part, the reader will find a clear and all-embracing description of the developments of VLSI processes both in terms of elementary explanation and in matters of the most recent progress within the 2024s. This way, whether you are a professional who needs to adapt to certain changes or a relative beginner, you will have enough information that might come in handy when dealing with a VLSI and its possible future developments.
VLSI is an acronym for very large scale integration and is a sub-discipline in electronic engineering that involves designing many types of interconnecting circuits. These are the ICs made from millions or billions of transistors, and they are used in several electronic products, including mobile phones, computers, and home electronics. The following educational qualifications are required in VLSI: Electronics engineering, Electrical engineering, Computer science, and other related studies to form various positions in the market.
There is a great demand for jobs in VLSI and there are a number of places where one can look for a job in VLSI. For those keen on pursuing a career in VLSI and passionate about electronics, getting into a well-planned VLSI course can open doors to a successful career in the booming VLSI job market. Hence, the VLSI design course is a detailed training program that specifically revolves around designing, implementing, and verifying individual units known as integrated circuits (ICs)/microchips containing hundreds of thousands, millions, or even billions of transistors. VLSI design plays a fundamental role in developing contemporary electronics, including smartphones, computers, and other devices and systems based on integrated circuits.
With VLSI design education being a foundational aspect of the electronics and semiconductor industry, which is growing and evolving quickly, this field provides students access to many career opportunities in the mentioned sector. There is a scarcity of VLSI design engineers due to increasing supply and demand for skilled candidates or VLSI design engineers who have created better and higher-paying job opportunities for VLSI professionals.
VLSI Design Process
Design Specification: VLSI design specifications encompass power consumption, performance, functionality, and chip area, which are crucial in developing integrated circuits. These specifications also include an abstract description of the architecture to be designed for digital devices.
Architectural Design: After establishing the design specifications, the chip’s architecture is crafted based on requirements for functionality, performance, and overall system needs. This design phase details all the chip components’ connections and functions.
RTL Design: Designing electronic circuits with integrated circuits (ICs) involves creating a Register Transfer Level (RTL) design, which provides a high-level description. This RTL description, written in hardware description languages (HDL) such as VHDL or Verilog, serves as the input. It outlines the functionality and behavior of the circuit at a high level.
Functional Verification: Simulation tools are employed to test the behavior and functionality of the integrated circuit under various input scenarios, ensuring it meets specified design requirements. We aim to verify that the ASIC design functions correctly by rigorously checking its behavior against the design’s specifications and functional requirements.
Logic Synthesis: Logic synthesis transforms RTL code into a gate-level netlist using synthesis tools, representing the circuit’s logical architecture with standard cells. Written in HDL (Verilog/VHDL), this netlist details the logic cells and their interconnections. These tools map the HDL-described functionality to a set of standard cells or library elements, optimizing the design’s performance, size, and power consumption during the synthesis process.
Logical Verification: Verification is necessary to ensure the synthesis tool has accurately produced the gate-level netlist. After verification and testing, the gate-level netlist output from logic synthesis is used as input for the physical design.
Physical Design: In this step, the gate-level netlist is converted into a physical layout, representing the IC through planar geometric shapes corresponding to the metal-oxide or semiconductor layers forming the IC’s components. It is common to develop such layouts with tools like Cadence Virtuoso. The physical design process is divided into sub-steps: Partitioning, floor planning, placement, clock tree synthesis, routing, and timing closure are other essentials of chip design.
Here are the steps for Physical Design:
Partitioning: Dividing the system on chip (SoC) into smaller, manageable blocks.
Floorplanning: Placing blocks and I/O ports across the chip area based on design constraints.
Placement: Assigning physical locations to standard cells and components according to the floorplan.
Clock Tree Synthesis: Connecting clocks to all clock pins of sequential circuits using inverters/buffers to balance skew and minimize delay.
Routing: Establishing connections between elements by physically connecting metal traces to macros, standard cells, I/O ports, power, and the clock.
Timing Closure: Ensuring the circuit meets timing requirements for smooth chip operation.
Physical Verification and Sign-off
This stage involves three physical verification steps known as sign-off checks, which ensure the layout functions as intended. The steps for Physical Verification are:
Layout vs. Schematic (LVS): Verifying that the layout matches the schematic to ensure consistent functionalities.
Design Rule Check (DRC): Ensure the design format for the developed layout meets the fabrication guidelines, distance between the tracks, and minimum width policy.
Logic Equivalence Checking (LEC): Formal checking to verify that an RT-level description of a digital circuit is equivalent in function to a gate-level netlist.
Fabrication: The layout output in this case, is a GDS-II file format that semiconductor foundries employ to implement the silicon. As the design guidelines go through physical verification, fabrication is nearly ready for this design, with the “tape-out” term used for the last stage preceding manufacturing. Tape-out is the final stage inherent in the photomask graphic of the circuit, which is forwarded to the foundry company. Fabrication is accomplished through a range of stages, such as wafer growth, epitaxial growth, etching, doping, deposition, and diffusion of materials onto the surface of the wafer, where each stage utilizes a different mask.
Packaging and Testing: Each wafer typically holds hundreds of chips, divided and packaged using the “scribing and cleaving” technique. Chips that fail electrical tests are discarded. Every chip undergoes testing and packaging to ensure it meets all design requirements and functions correctly as intended.
Conclusion
Besides the simple knowledge and understanding of the VLSI design process accompanied by the curriculum of a complex VLSI course, such an opportunity generates fundamental possibilities of gaining a well-established and paid job with a strong-wrought career in the progressive field of electronics industry. This brief devotional guide, if internalized by engineers and technology enthusiasts, will enable those who are carving a path in the engineering world to come up with groundbreaking electronic devices in VLSI aided with modern techniques in this field.