Chip Manufacturing - How are Microchips made? | Infineon

All boats start with a very simple raw material, sand, sand is mainly

made

up of silicon dioxide or silica. Silicon is the second most abundant element in the Earth's crust, but it is only found as a compound with oxygen. Complex chemical and physical processes are required. To ensure that silicon crystals meet the high production standards applied to

chip

s to convert silica sand into silicon, the sand is combined with carbon and heated to an extremely high temperature to remove oxygen, other steps to create the finished product, viz. an extremely pure monocrystalline silicon ingot called a torus with only one impurity atom for every 10 million silicon atoms.

Silicon tori are manufactured in a variety of different diameters, the most common sizes being 150, 200 and 300 millimeters. Wafers with large diameters offer more space for

chip

s. Extremely thin wafers are then cut from the Bulls silicon using a special cutting technique. These wafers are the basic building blocks for subsequent chip production. Silicon is a semiconductor, meaning it can conduct electricity and also act as an insulator. Its atomic structure looks like this in each silicon. The atom has four outer electrons. There are no free cargo carriers. As a result, pure monocrystalline silicon is non-conductive at room temperature to allow it to become conductive.

Small amounts of specific atoms are added as impurities to the wafer. These impurity atoms must have a number. of external electrons which is one more or one less than that of silicon silicon is in the fourteenth group of the periodic table of elements, this means that elements of the thirteenth or fifteenth group must be used in this process known as doped boron and The atoms Phosphorus are the most suitable elements in these groups. They are very close to silicon on the periodic table and therefore have very similar properties. Phosphorus has five outer electrons when inserted into the silicon crystal lattice.

The fifth electron of phosphorus can move freely, which means that the phosphorus crystal of silicon is conductive, in contrast, boron atoms only have three outer electrons when introduced into the silicon lattice one electron of silicon has nothing to What joins this creates electron holes. The holes move through the crystal as positively charged particles forming the material P. Conductive transistors are built on top of the P and N conductive layers that exist on a doped wafer. Transistors are the smallest control units on

microchips

. Their job is to control electrical voltages and currents and they are by far the most important components of electronic circuits.

The chip contains conductive P and n layers

made

of silicon crystals. They also have an additional layer of silicon oxide that acts as an insulator. A layer of electrically conductive polysilicon is applied on top. Each transistor has three terminals, the middle one is attached to the gate. which is electrically conductive polysilicon, if an electrical charge is applied to only the two external terminals, electricity cannot flow since the transistor is blocked, this changes; However, if an additional charge is applied to the middle terminal, the P-shell electrons are attracted to the middle. terminal and accumulate in the area between the silicon crystal and the insulating gate.

A channel is then formed under the door between the islands of n conductive material. Electrons can now flow through this channel. The electrical circuit is closed in this way. The transistor can be switched again. and forward between current and Nabal and disabled between 0 and 1 on and off, but how are these layers created on a wafer? The process for making chips from a wafer begins with the layout and design phase. The highly complex chips are made up of billions of integrated elements and connected transistors that allow sophisticated circuits, such as microcontrollers and cryptographic chips, to be built on a semiconductor surface measuring just a few square millimeters.

The large number of components requires an in-depth design process, which involves defining the chip functions that simulate its technical and physical characteristics. properties that test its functionality and resolve the individual connections of the transistors. Special design tools are used to draw up the blueprints for integrated circuits and develop a three-dimensional sandwich layer architecture. This plan is transferred to photographic masks that provide geometric images of the circuits. They are used as imaging templates during the subsequent chip

manufacturing

process to ensure that the microscopic structures of a chip are reproduced smoothly. They must be manufactured in a dust-free environment with stable levels of temperature and humidity;

In other words, they must be manufactured in a clean room environment. A clean room is a room in which no more than one dust particle larger than 0.5 micrometers in size is allowed in approximately 10 liters of air. This is even cleaner than the air in an operating room, so the ventilation, filtration and supply systems of a clean room have to be extremely sophisticated: several million cubic meters of air and hundreds of volume regulators circulate every hour. air maintain a constant air flow. Employees in these production areas must adhere to an extremely strict dress code. They are not allowed to smoke before work or wear makeup.

Jewelry production areas in the clean room can only be accessed through a special airlock. The chips are built on a base wafer cut from a pool of silicon, depending on their size. Several dozen or several thousand chips can be manufactured on a wafer. First, the surface of the wafer is oxidized. in a high temperature oven operating at approximately 1000 degrees Celsius to create a non-conductive layer, then a photoresist material is evenly distributed over this non-conductive layer using centrifugal force. This coating process creates a light-sensitive layer through which the wafer is exposed to light. The photographic mask in special exposure machines known as steppers during this process roller-coaster-sized areas of the chip template known as straight khals are used to transfer the complex geometric patterns of the circuit design to the silicon wafer, it is revealed. the exposed area of ​​the chip pattern.

The oxide layer below the unexposed part remains as it is protecting the oxide layer. After this, the exposed oxide layer is removed in the areas that have been developed using wet or plasma etching with special plasma etching gases that They bond to the substrate to be removed. In the reaction chamber, this allows the microscopic layers in the windows that were exposed and developed in the previous step to be removed. Once the photoresist residue has been removed and the wafer has been cleaned, the wafer undergoes further oxidation. Electrically conductive polysilicon is deposited on this insulating layer. then the photoresist is applied again and the wafer is exposed to light through the mask, the exposed photoresist is removed again now the polysilicon and the thin oxide layer are removed, these two layers only remain intact in the center under the photoresist , the next step is the doping process in which impurity atoms are introduced into the exposed silicon and an ion implanter is used to shoot impurity atoms into the silicon.

This changes the conductivity of the exposed silicon by fractions of a micrometer after the photoresist residue has been removed. Another layer of oxide is applied to the wafer. Another cycle of applying photoresist exposure through the mask and removing contact holes is etched to provide access to the conductive layers, allowing contacts and interconnects to be integrated into the wafer. This is done by depositing metal alloys onto the wafer in sputtering machines, again the photoresist. and masks are applied the unexposed strips remain as they are after the etching process providing a point of contact with the underlying layers to give the insulation layer over the interconnects the smooth finish it requires a chemical mechanical process is used to polish the excess material with micrometer precision These individual steps can be repeated several times in the

manufacturing

process until the integrated circuit is complete, depending on the size and type of chip, the wafer will now contain from several dozen to thousands of chips.

Individual chips are usually searched off the wafer. They are not aligned with each other on the wafer because small parts of the wafer chip off during the sawing process. A certain amount of space known as a scribe line is always left between the individual chips. Test structures are also integrated into the space between the individual chips. chips and are used to take measurements immediately after production, these technological structures are destroyed during the sawing process, the size of the resulting chips usually varies between a square millimeter and a few square centimeters, the final manufacturing stage is assembly Here, the individual chips are placed in a package and terminals are attached.

The result is a finished semiconductor device that can be mounted on circuit boards using different types of terminals. More than a thousand connection contacts can be made. Below are some examples of already packaged semiconductor components. Special larger packages are used for the intended power semiconductors. For applications such as trains, electric cars, solar panels and wind turbines, these power semiconductors are designed to switch electrical currents up to several hundred amperes and voltages reaching into the thousands. Switching at this level generates high temperatures and this heat must be dissipated by cooling. Integrated areas in the packages Here you can see some fully packaged power semiconductors, cutting-edge technologies used to perform testing at every step of the manufacturing process to ensure the highest levels of quality in chip performance.

Researchers and developers use scanning electron microscopes to repeatedly check chips at different points in the production process, if we compare today's microelectronics to human hair we can see how small these devices are, the equipment used to check components and analyze defects is Just as precise, these high levels of precision and quality are essential at every stage of the workflow from silicon torus production to clean room fabrication and quality control to deliver these small building blocks that have a such a big impact on our lives today and in the future, after all, the demand for innovative life-making semiconductor solutions is increasing. easier, safer and more ecological for a technology that achieves more, consumes less and is available to everyone.

Microelectronics is the key to a better future. part of your life, part of tomorrow. Infineon