The basic raw material for microchips is sand, primarily made up of silicon dioxide (silica).
Silicon is the second most abundant element in the Earth's crust but is found only as a compound with oxygen.
Conversion of Silica Sand to Silicon
The sand is combined with carbon and heated to a high temperature to remove the oxygen.
Resulting product is pure mono-crystalline silicon ingot (bull) with one impurity atom per 10 million silicon atoms.
Silicon bulls are produced in various diameters; common sizes are 150, 200, and 300 millimeters.
Thin wafers are cut from the silicon bulls for chip production.
Properties of Silicon
Silicon is a semiconductor, capable of conducting electricity and acting as an insulator.
Pure mono-crystalline silicon is non-conductive at room temperature.
Conductivity is achieved by doping with small quantities of specific atoms (boron or phosphorus).
Doping Process
To become conductive, silicon wafers are doped with elements from the 13th or 15th groups of the periodic table (e.g., boron and phosphorus).
Phosphorus-doped silicon (N conductive) has free electrons.
Boron-doped silicon (P conductive) creates holes.
Transistors on Wafers
Transistors control electric voltages and currents, key components in electronic circuits.
Transistors have P and N conductive layers and an insulating silicon oxide layer.
Construction involves three terminals; the middle one is the gate made of electrically conductive polysilicon.
Chip Manufacturing Process
Design Phase: Includes defining chip functions, simulating properties, testing functionality, and developing a 3D architecture of sandwich layers.
Cleanroom Environment: Chips must be fabricated in dust-free, temperature, and humidity-controlled environments.
Oxidation and Layering: Wafers oxidized in high-temperature furnaces to form non-conductive layers, followed by photoresist application, light exposure, and etching.
Doping and Interconnections: Doping through ion implanters changes conductivity; successive kayers application include metal alloys using sputtering machines.
Final Stages of Fabrication
Assembly: Individual chips are cut from the wafer, placed in packages, and terminals are attached.
Packaging: Packaging varies based on application, especially for power semiconductors in high-stress environments like electric vehicles and solar panels.
Quality Control: Scanning electron microscopes and other high-precision equipment ensure the highest quality and chip yields.
Impact and Future of Microelectronics
Microelectronics are crucial for innovations making life easier, safer, and greener.
Demand is rising for semiconductor solutions that achieve more, consume less, and are accessible to everyone.
Key to a better future: Microelectronics are intertwined with daily life and future technological advancements.