Six Steps of Integrated Circuit Designing

Published:2011/4/18 2:31:00 Author:LiuQiaoyan From:SeekIC

The design process of integrated circuit is so complex that it takes many years of study and practical experience to understand it. The build up of a digital integrated circuit, for example, can be divided into six different stages according to problems discovered at each level: design of system, logic, circuit, layout, fabrication and testing. These steps are not actually sequential and to get things work right, interactions are needed.

Design of system: This step has close relationship to the main operations and specifications of the chip. At this stage, issues like chip area, functionality, speed, cost, and other design factors are examined during the specifications setting. Before system design and specifications setting, always keep in mind to understand the process technology. For instance, a designer may want to have a chip that can work at the voltage of 3V, but available process technology can only support 6V voltage. On this occasion, the designers has to adjust these specifications to satisfy the available tools. Usually, the welding position of chip is determined by the process technology. Like IBM 0.13um, AMI 0.5um and TSMC 0.35um. To the process, designs based on different process technologies are unique and accordingly soldering foundries are supportive. During this period, what is certainty are the main sections and its output and input characteristics of the process. The contents of the blocks are not illustrated in detail.

Design of logic: The input and output characteristics specified in the previous stage are implemented at this one. To realize the design, logic gates with interconnecting wires are used.

Design of circuit: This stage refers to transfer the logic networks into electronic circuitries by transistors whose combinations are generally used to realize different logic functions. This design is tested by using computer aided design (CAD) tools and comparisons are made between the specifications and the results. The speed, power dissipation, and performance of the final chip will for sure in this stage, and so does the size of the chip due to the number of transistors determine the area of the chip. Skilled designers optimize design variables like transistor sizes, numbers, and circuit architecture and reduce delay, power consumption, and latency among others. The length and width of the transistors must follow the rules of the process technology.

Design of layout: At this stage, the circuit finished in the last stage will transfer to silicon description through geometrical patterns with the help of CAD tools. This process goes on with obeying rules that specifies the space between transistors, wire, wire contacts, and so on. Otherwise the chip will become malfunction after fabrication. Designers must make sure the layout represent the circuit accurately and correctly. A vital step in layout design is extraction, which refers to extract the circuit schematic out of the layout drawing.

Fabrication: This process is very complex as it involves many stages of oxidation, etching, photolithography, etc. Fabrication translates the layout into silicon or other material that is used. As a result, pins for external connections to circuit boards are produced.

Testing: This is the final stage of the chip development. This process was done by using some electronic equipments like probes, oscilloscopes. The related integrated circuit is ITR8307.

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