Monday, June 4, 2012

What is a Silicon Chip?

            The microchip or silicon chip has completely changed the electronic world by providing a new direction to it. It has led to the invention of electronic calculators, personal computers, digital watches, microwave oven, etc.

Peltier Effect Thermoelectric Device

            Silicon chips are tiny crystal of silicon, which contain large number of electronic components. Silicon is the most abundant element found on the earth’s crust. But silicon is not found in a free state in nature.

            The size of a chip is smaller than our fingertips. In 1 square centimeter chip, one million electronic components can be inserted. They have very small electrical circuits, called microcircuits. These are used in transistor radios, digital watches, calculators, and computers. They can be used in miniature electronic devices, as the chips are very small.

            But how is silicon chips made? Silicon chips are made form a single crystal of silicon. Thin wafers of about 0.5 millimeter thick are sliced from a single crystal. One side of each wafer is first polished and then oxidized in a furnace. The disc is covered with a layer of photo resist material and then exposed to ultraviolet light through the clear sections of a mask. A light sensitive coating is applied and the solvent dissolves the exposed areas. Unexposed areas are not affected, so a pattern identical to the mask remains. The exposed areas are etched in hydrofluoric acid. Another solvent removes the resistance.

            Next, the wafer is exposed to chemicals in a furnace, which penetrate the silicon through the oxide gap to make transistors. The process is repeated several times. The wafer is coated with aluminum and a final layer is metals connect the components together. After careful inspection, chips are selected and released for use.

            Today microchips are being used in electronic sewing machines, washing machines, word processors, and so on.