The world in a p-inch of sand

Today we talk about something we all use but hardly understand how it works.

We all have seen sandy beaches and riversides. This sand is more than 97% Silica which is nothing but Silicon Dioxide (SiO2) commonly also referred to as Quartz. Interestingly, silicon does not exist in pure form in nature because it forms a very stable oxide and rests in peace. Silicon is a semi-conductor which means it's conductivity is less than metals and more than non-metals. When doped with elements like Boron or Arsenic, Silicon's conductivity can be controlled accurately to use it for electronic devices.

Silicon Ingot

Purifying silicon is a very difficult process because it's so stable. It is heated at close to 2000 degree Celsius with Carbon to produce Carbon Monoxide (CO) and Silicon (Si). But this only produces 99% pure Silicon. A seeding process is then used to purify it to 9-nines i.e. 99.9999999%.

9-nines means that only one atom in 1 billion atoms in this photograph is an impurity of iron or some other element.

Silicon Wafers

Once we have 9-nine level purified silicon in the form of an ingot, we slice and polish them into discs which are less than 1 mm thick. These are called Silicon wafers.

The world as our generation sees it is sketched on one inch piece of this silicon wafer with a pen with a tip only 4 nanometer in size. And this is called IC / Integrated Circuit / Chip / Microprocessor. It sits inside every electronic device around us including the phone or computer on which you are reading this, the servers which beam information to the sky, the satellites which reflect the beam back to your device, the televisions we watch and the watches we wear. In case you didn't realise 4 nanometer is the size of 0.0001 times a human hair.

A complex array of super-specialised lenses and super-accurate lasers are used to make this light pen which etches billions of transistors (think of transistors as nano-sized on-off switches) on this wafer to do trillions of calculations per second. And once etched this is how it looks.

Under a scanning tunnelling microscope, this how the writing on the wafer looks like.

As an example - an Intel i7 microprocessor in laptops has more than 3 billion transistors etched on a half inch of Silicon with 8 nanometer etching (pen tip).

The process of etching such nano transistors on the wafer is called Lithography.

Only two companies in the world have the advanced capability of such minute nanometer level lithography - TSMC & ASML. These companies are the backbone of the whole electronic industry today. And buying their technology is not as easy as paying money and buying the machine - it requires approvals and agreements with all major countries in the world because this technology is a more powerful tool than nuclear bombs today in world politics.

Careers of Future : MEMS

Similar amazing technology is also being used in making micro machines and sensors on silicon wafers using Lithography. It is called MEMS - Micro Electro Mechanical Systems. This is also called "Lab on Chip" or SoC or "System on Chip" because a small chip can now carry all sensors, processors, converters, timers on an inch of silicon made of a pinch of sand.

Micro locks with gears. These can secure hard disks and devices in future like passwords secure software information.

DNA injection machine for cells. These machines can hold a cell and inject modified DNA to make new medicines and vaccines for the future.

Accelerometers for small devices like phones & watches. They are the reason your phone knows orientation of your phone and auto-rotates your screen for easy viewing.

If this fascinates you as a student, remember you could be the one designing these micro and maybe even nano machines of the future which make the world faster, smarter and more connected. Before you leave, think and tell us which micro machine would you want to make?

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