Home Chapter 5 Integrated circuits
Integrated circuits

The contemporary robotics theorist Hans Morovec predicts that we will see computer intelligence arise in not too distant future. He researches the density of the human optic nerve, looks at Moore’s law and predicts that machine intelligence will surpass human intelligence by 2030.

Integrated circuits are the result of physics combined with the modern techniques of engineering and manufacturing. This allows solid-state passive components like resistors and capacitors to be integrated with active components like transistors and diodes into micro-packages that allow the integration of many electrical functions on a single device. These integrated circuits can contain as few as two or three transistors to hundreds of transistors to millions of transistors.

Integrated circuits can be created to amplify or respond to variable voltages, and we call these analog or linear integrated circuits. Examples would be amplifiers, timers, oscillators, and voltage regulators.

Digital or logic integrated circuits respond to just two voltage levels. High 5-volts and low 0-volts. They are called digital because they rely on binary math to allow the chips to utilize and count in base two, as apposed to our base ten system of counting.

They include microprocessors, memory chips, and digital clocks. Many integrated circuits combine both analog and digital functions. These are created by the interconnection of transistors, capacitors, and resistors in a micro-size to form a complex electronic system on a sliver of silicon.


Circuit details in creating a microchip


The fabrication process is based on a series of steps called mask layers, which are layered above the silicon and exposed to x-rays. The first process is a layer of silicon dioxide created by exposing the silicon to heat and gases. It grows as rust would grow but more rapidly. After this the silicon wafer is coated with a photoresist, which becomes soluble when exposed to the ultraviolet light used in the process.

The process involves layering or photolithography in which a powerful ultraviolet beam is projected through patterned mask layers. The ultraviolet light allows the exposed areas of the chip to become soft and this is etched away to leave the traces of the microchip that represent the wires and various parts. The different layers of the microchip involve very different masks, each which allows components under each others to link up and be connected in the chip.


Manufacturing Sequence of a chip 


Many have seen the masks as art forms in themselves. In 1990 Cara McCarty did a wonderful exhibit at the Museum of Modern Art in NY called Information Art: Diagramming Microchips in which the curator and museum featured the photo masks used in this process of creating microchips. [10]


Photo mask for a microchip


after deposition and lithographic procedures, the layers are processed to “etch” the patterns that, when precisely aligned and combined with those on successive layers, produce the transistors and connections.


Cut away view of interior of integrated circuits


The types of architectures available in microchips are advancing rapidly with many experimental designs based on trying to understand the biological principles as they may be applied to technological material.

The chip below is an optical sensor artificial eye with foveated vision by Carver Mead the father of VLSI Very Large Scale Integration [11]


Carver Mead photo mask for microchip with Foveated Vision