5 crucial steps in semiconductor manufacturing

Devices such as smartphones, smart watches, gaming consoles etc. are classic examples of how technology has evolved and the power these devices hold comes from the microchips which are small but extremely powerful pieces of technology which are manufactured through a process which is not simple. Here we will explain the 5 crucial steps involved in semiconductor manufacturing:

Deposition: The process starts with a silicon wafer. Wafers are cut from an ingot (bar with 99.99% silicon) and are polished until they are smooth. Thin films of isolating, semiconducting or conducting materials are then deposited on the wafer so that the first layer gets printed on it. This process is called deposition.

Photoresist coating: After the deposition phase, the wafer is covered with either a positive or negative light sensitive coating which is called resist or photoresist. In the positive resist, the areas that are exposed to ultraviolet light change their structure and are made more soluble for deposition and etching. On the contrary, in the negative resist, the areas which are exposed to light become strong because they polymerise, making them difficult to dissolve.

Lithography: This process determines how small the transistors on the chip will be. Here, the chip wafer is inserted into the lithography machine and is exposed to extreme ultraviolet light or deep ultraviolet light which is projected on the wafer through the reticle. When light hits the surface of the resin, a chemical change happens in which the pattern from the reticle is replicated on the layer of the resin. This process is tricky because getting the exact pattern requires precision and refraction, particle interference or chemical and physical defects can hamper the process.

Etching and Ionization: The degraded resin is removed to reveal the desired pattern during the etching stage, where the wafer is baked and developed and some of the resin is washed away to reveal the exact pattern. After etching comes ionisation, during which the wafer is bombarded with positive or negative ions that control the flow of electricity and help create the electronic switches that are transistors.

Packaging: Single wafers or square chips are sliced with a diamond saw, the size of which can vary depending on the type of chip. The chip dye is placed on a substrate and then a head spreader is placed on top of it to close the lid.

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