Every processor must eventually be implemented on an IC. IC technology involves the manner in which we map a digital (gate-level) implementation onto an IC. An IC (Integrated Circuit), often called a “chip,” is a semiconductor device consisting of a set of connected transistors and other devices. A number of different processes exist to build
semiconductors, the most popular of which is CMOS (Complementary Metal Oxide Semiconductor). The IC technologies differ by how customized the IC is for a particular implementation. For lack of a better term, we call these technologies “IC technologies.” IC technology is independent from processor technology; any type of processor can be mapped to any type of IC technology, as illustrated in Figure.
To understand the differences among IC technologies, we must first recognize that semiconductors consist of numerous layers. The bottom layers form the transistors. The middle layers form logic gates. The top layers connect these gates with wires. One way to create these layers is by depositing photo-sensitive chemicals on the chip surface and then shining light through masks to change regions of the chemicals. Thus, the task of building the layers is actually one of designing appropriate masks. A set of masks is often called a layout. The narrowest line that we can create on a chip is called the feature size, which today is well below one micrometer (sub-micron). For each IC technology, all layers must eventually be built to get a working IC; the question is who builds each layer and when.
1 Full-custom/VLSI
In a full-custom IC technology, we optimize all layers for our particular embedded system’s digital implementation. Such optimization includes placing the transistors to minimize interconnection lengths, sizing the transistors to optimize signal transmissions and routing wires among the transistors. Once we complete all the masks, we send the mask specifications to a fabrication.........IC technology - Say Loudly
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