Making the Circuit
Now that we have a silicon wafer we have to put the circuit on the wafer. The circuit is tiny and use very precise methods to put the advance circuits on the chip.
First the wafer is heated the silicon reacts with the oxygen to make silicon dioxide layer. Then a layer photoresist and is spun in vacuum and then dried the spinning is done so the layer is even. The wafer is then exposed to ultraviolet light through a photographic mask. The mask is used to block the light to make the circuit on the silicon this step is repeated for each chip on the wafer. Different masks are use to build up different layers. The wafer is the developed in a alkaline solution then area exposed the ultraviolet light on the photoresist is washed away. Hydrofluoric acid is used to dissolve the silicon oxide where the photoresist was washed away.
Now that the circuit is put on it is time to add the transistor to the processor it is called MOSFET.
There are two types of MOSFET P-channel made of p type materials and n-channel made n type material.
First they must create a P type and n type areas on the circuit.
The wafer has a beam of boron ions they implant themselves into the silicon in the gaps in the photoresist called p wells which will be use in the n channel MOSFET. A different photoresist pattern is now applied to make n well for p channel. Yet anther photoresist beam is use to create the n type region in the p well this will act as the source and drain of the n channel. Next a layer of silicon germanium doped with boron is applied.
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