Semiconductors have transformed the modern world and made possible a vast range of computer-powered technologies. But exactly how are they made? Here, we’ll take a look.
What is a semiconductor?
A semiconductor put simply, is a material that becomes conductive only under certain conditions. The most popular example, silicon, is used in everything from simple transistors to modern processing units. As time has gone by, semiconductors have gotten more intricate, and the process through which they are manufactured has gotten more sophisticated. Let’s take a look at that process, from start to finish.
Cleaning
Before a silicon wafer can be imprinted with a design, every trace of contamination must be removed. The slightest imperfection will cause a manufacturing fault, and so this is performing using chemical additives.
Film Disposition
The wafer will then be added with a thin layer of metal. This is usually aluminum or silicon oxide. This layer can be bonded either through electrodeposition or through heat.
Post-deposition cleaning
The second round of cleaning usually follows. This is typically performed using fine brushes or through a spray of deionized water.
Resist coating
Another layer is added, this time of a photosensitive chemical called a resist. To prevent pooling, the wafer is spun so that the resist spreads to the edge of the wafer.
Exposure
Ultraviolet radiation is blasted on to the wafer, selectively removing the parts of the resist where the circuit paths need to be.
Development
A special corrosive is applied, which removes the resist and exposes the underlying film.
Etching
The remaining resist acts as a mask for the chemical agent which is then applied. This is typically a strong acid, like hydrochloric acid. This stage is often substituted by a special bombardment of ions. Additives like phosphor and boron are then supplemented.
Activation
Specially controlled light, such as that of a flash lamp or a laser, is applied to the wafer. The activation creates tiny transistors on the surface of the wafer.
Resist stripping
Having done its job, the resist layer can now be stripped away using special chemicals or gases. The semiconductor is now intact and functional.
Assembly
A semiconductor can’t quite be used in a circuit just yet. It first needs to be sliced into individual chips and housed in a package, which will, in turn, be soldered onto a circuit board. The se packages come in a range of shapes and sizes, with the more complicated circuits needing hundreds or even thousands of connective points.
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