The processor step by step: how a processor is created

Our daily lives involve the continuous use of electronic devices which contain a processor as their beating heart. Processors are chips made up of millions of transistors. Their primary purpose is to carry out instructions, which are particularly complex.

What materials are used to build processors?

Several materials are required to build a processor, starting with silica, the second most common material in the earth’s crust, present in large quantities in sand. Used as a base for the construction of electronic chips, silicon is a semiconductor which can be rapidly transformed into a conductor or insulator of electricity via the insertion of tiny elements of impurity.

In order to be used for the construction of chips, the silica must undergo a purification process until it contains less than one impure atom per two billion. During this process, the silicon is transformed first into a state of fusion and then into a solid state. In this last state, it forms a cylindrical-shaped crystalline grid, the so-called ingot.

From ingot to wafer

The next step involves the ingot being sliced into many discs (the wafers). Each of these has a diameter of 30mm and a thickness of approximately 1mm. Subsequently, the single wafers are treated and polished to obtain a mirror-like surface.

It is essential to remember that, over time, the size of the wafers has increased. In future, it is expected that this will increase further to a diameter of 450mm. It will then be possible to increase the number of chips that can be produced from a single wafer, thereby optimising the production process (the construction of a wafer can take several days, one reason why Wafer Labs operate 24 hours a day) thereby reducing costs.

The photolithography phase

The next step in the creation of a processor is photolithography, a phase which involves the printing of a specific pattern onto the wafer. The process begins with the application of a photoresist liquid, which is poured onto the wafer while it is rotated, in order to guarantee even distribution.

The liquid is called this due to its sensitivity to certain light frequencies and for its resistance to chemical substances which, in subsequent phases, are used for the removal of sections of the material’s layers. The removal happens when the photoresist on the wafer is bombarded by a strip of ions.

Final phases

What we have just described are the initial phases in the production of a processor. The process continues step by step with the creation of the transistor, etching and the removal of the photoresist. Then there is the phase of dielectric gate creation from silicon dioxide and the temporary electrode gate is also created. After more stages, it is time to check the wafer sections, which is done using a tester to analyse individual chips and detect any defective ones.

Immediately after this, the wafer is cut and the selection of single chips begins; these are identified according to technical and design requirements and sent for the packing phase. Then it is time for assembly, which requires the use of a heat exchanger during the shaping of the finished processor.

The whole process is concluded with a test dedicated specifically to each single processor, which is analysed while taking into account performance, power and functionality. According to the results obtained, all processors with the same capacity are packaged together and sent to the laptop producers. Those destined for mass distribution are stored in special boxes.

Translated by Joanne Beckwith