How Do Chips Affect Our Lives?

2021 is the season of (Integrated circuit) chip shortages. Car prices went straight up due to their shortage; international shipping lead time rose and making the shortage even worse. The Graphics Processing Unit (GPU), Solid-State Drive (SSD) the market is still overheating from Crypto mining. These shortages are not only affecting these "bigger picture" items but also things like gaming consoles like the PS5 and your household washer and dryer.

Chips are a set of electronic circuits on a small flat piece of semiconductor material, usually made of silicon. We can divide chips by their functions: memory chips, microprocessors, Commodity ICs (like the one in your TV remote), GPUs, etc.

An Example Of Chips: CPU

A microprocessor (CPU) is the electronic circuitry that executes instructions to a computer program. It is normally comprised of a control unit, a storage unit, and a computing unit. Its core is composed of various logic gate circuits, such as an AND gate, OR gate, NOT gates, etc... No matter what information is input from the outside world when it comes into the CPU, there is 0 or 1. The logic gate only recognizes the voltage level. For example, a sample diode 'AND gate' combines two signals so that the output is on if both signals are present. Here, '1' means high voltage, and '0' means low voltage. Since diodes only allow current to pass through from a certain direction, users can only get a result '1' if both passes are '1's.

Chip Manufacturers And The Machines Behind Them

So, how does one make a chip? The first step is heating up sand with carbon and reducing it into a pure silicon wafer. Since pure silicon doesn't have free charge carriers, the second step is adding elements to make it conductive in certain directions. Adding elements with 3 Valence electrons (like boron) to one side makes P conductive and adding some elements with 5 Valence electrons (like arsenic or phosphorus) makes it N conductive and using layers to form different PN junctions. Modern chips can have up to 100 layers, which all need to align on top of each other with nanometer precision. The size of the features printed on the chip varies depending on the layer, which means that different types of lithography systems are used for different layers.

Steppers play an important role in lithography systems. The term "stepper" is short for a step-and-repeat camera. Steppers are an essential part of this complex process, called photolithography, that creates millions of microscopic circuit elements on the surface of chips of silicon. They are normally expensive and only a few top companies actually own the technology to build it.

Lithography systems directly determine the process (in nm) of the chips, so they basically affect how powerful the chip could be. However, chip manufacturing relies on teamwork, and lithography systems are not the only player here.

Furnaces are involved in the IC industry more than one would think.

Oxidizing: Using a high-temperature furnace to oxidize the silicon wafer to make a non-conductive layer of glass. Results in the chip getting uniformly coated with a thick, light-sensitive liquid called photoresist. To do this usually requires a temperature of 900C-100C.

Die Attached: This process is where a target slice of semiconductor is picked from the waffle and mounted on a substrate or a die bond table. Typically, die bonding technologies include eutectic bonding, epoxy bonding, and solder attach. It usually requires a 200C-500C temperature.

Surface Mount: Reflow soldering of surface mount electronic components to printed circuit boards (PCBs) is typically done in a belt furnace as well and usually requires a 150C-250C temperature.