INTEGRATED CIRCUITS

Many advertisements for electronic equipment refer to integrated circuits or solid-state technology. You know the meaning of the term solid-state, but what is an INTEGRATED CIRCUIT? The accepted Navy definition for an integrated circuit is that it consists of elements inseparably associated and formed on or within a single SUBSTRATE (mounting surface). In other words, the circuit components and all interconnections are formed as a unit. You will be concerned with three types of integrated circuits: MONOLITHIC, FILM, and HYBRID.

MONOLITHIC INTEGRATED CIRCUITS are those that are formed completely within a semiconductor substrate. These integrated circuits are commonly referred to as SILICON CHIPS.

FILM INTEGRATED CIRCUITS are broken down into two categories, THIN FILM and THICK FILM. Film components are made of either conductive or nonconductive material that is deposited in desired patterns on a ceramic or glass substrate. Film can only be used as passive circuit components, such as resistors and capacitors. Transistors and/or diodes are added to the substrate to complete the circuit. Differences in thin and thick film will be discussed later in this topic.

HYBRID INTEGRATED CIRCUITS combine two or more integrated circuit types or combine one or more integrated circuit types and DISCRETE (separate) components. Figure 1-5 is an example of a hybrid integrated circuit consisting of silicon chips and film circuitry. The two small squares are chips and the irregularly shaped gray areas are film components.

Figure 1-5. - Hybrid integrated circuit.

STATE-OF-THE-ART MICROELECTRONICS.

Microelectronic technology today includes thin film, thick film, hybrid, and integrated circuits and combinations of these. Such circuits are applied in DIGITAL, SWITCHING, and LINEAR (analog) circuits. Because of the current trend of producing a number of circuits on a single chip, you may look for further increases in the packaging density of electronic circuits. At the same time you may expect a reduction in the size, weight, and number of connections in individual systems. Improvements in reliability and system capability are also to be expected.

Thus, even as existing capabilities are being improved, new areas of microelectronic use are being explored. To predict where all this use of technology will lead is impossible. However, as the demand for increasingly effective electronic systems continues, improvements will continue to be made in state-of-the-art microelectronics to meet the demands.

LARGE-SCALE INTEGRATION (lsi) and VERY LARGE-SCALE INTEGRATION

(vlsi) are the results of improvements in microelectronics production technology. Figure 1-6 is representative of lsi. As shown in the figure, the entire SUBSTRATE WAFER (slice of semiconductor or insulator material) is used instead of one that has been separated into individual circuits. In lsi and vlsi, a variety of circuits can be implanted on a wafer resulting in further size and weight reduction. ICs in modern computers, such as home computers, may contain the entire memory and processing circuits on a single substrate.

Figure 1-6. - Large-scale integration device (lsi).

Large-scale integration is generally applied to integrated circuits consisting of from 1,000 to 2,000 logic gates or from 1,000 to 64,000 bits of memory. A logic gate, as you should recall from NEETS, Module 13, Introduction to Number Systems, Boolean Algebra, and Logic Circuits , is an electronic switching network consisting of combinations of transistors, diodes, and resistors. Very large-scale integration is used in integrated circuits containing over 2,000 logic gates or greater than 64,000 bits of memory.

Q.12 Define integrated circuit.
Q.13 What are the three major types of integrated circuits?
Q.14 How do monolithic ICs differ from film ICs?
Q.15 What is a hybrid IC?
Q.16 How many logic gates could be contained in lsi?