Creation of Silicon Chips

D'yara L.Williams
South Carolina State University
CS 304 - Introduction to Computer Organizatikns & Architecture
Dr. Y. Kim
Feburary 25, 2015 Did you know that microprocessors today have more than 30 layers of complex circuits compared to the 5 layered circuit discovered in 1971? Silicon chips are also known as a monolithic integrated circuits, die, or processors. They’re miniature electronic brains that are everywhere in the electronic world, which processes data in the form of electrical currents traveling along a circuit. The natural semi-conductor of integrated chips is manufactured using sand. Beach sand contains a high percentage of the principal ingredient, silica or silicon dioxide, the most abundant element on earth besides oxygen. The process of making silicon chips is called fabrication. A wafer is a thin silicon disk sliced from a cylindrical ingot that is used as the principal ingredient for building integrated circuits. The creation of silicon chips is processed by ensuring product specifications, architectural specifications, creating a logic design, compose a physical representation and finalizations. However, engineers experience a problem with desiring to make electronic devices simpler but more powerful.
Although the first computers came about before its invention, the silicon microprocessor is the advancement that made the modern computer era explode. The ability to create a microelectric chip out of silicon dioxide was what triggered computers best advancements in energy efficiency and performance. The first microprocessor was the Intel 4004 which was not very powerful, and it could only add and subtract at four for bits at a time. Microprocessors are often classified by the number of transistors and other electronic components contained. According to Moore's Law, Gordon Moore predicted that the number of transistors on a piece of silicon wafer will double every year. Ten year later he updated his prediction and as the number of transistors went up the cost per transistor went down.
To begin with, before a chip is made engineers are to ensure the accuracy of the specifications by creating a design or blueprint. The starting material for a silicon chip is sand which has a high percentage of silica. This can be transformed into a semi conductor which has an excellent conductor or insulator of electricity with minor amount of impurities added. The element silicon dioxide is purified to less than one alien Atom per billion. The Czochralski process ensures removal of the crystal lattice cylinder, called an ingot. This silicon ingot has a diameter of 300 millimetres and weighs about 100 kilograms. The end is then cut into individual silicon discs called wafers with each about one millimeter thick. The wafers are polished to a flawless, mirror smooth surface. This way first then undergo a process known as photo lithography which in Prince a specific pattern on a wafer. It starts by applying a light sensitive, its resistant material called photoresist onto the wafer surface. The photoresist is hardened and parts of it are exposed to the ultra light, making it suitable. The light passes through a mess similar to a stencil like pattern for each layer of the chip which is being use during the fabrication process and then through the lands to shrink and print patterns on each layer of every chip of the wafer. A chemical process removes the soul of a photoresist, leaving a pattern photoresist image is determined by what was on the mast. Ions are embedded beneath the surface of the wafer and regions covered by photoresist. This alters the conductive properties of the silicon in selected locations. After the ion implantation, the photoresist is removed resulting in certain regions being doped with an atom which appear green in image. Although hundreds of chips are usually built on a single wafer. The next step focuses on the smaller pieces of the chips which is known as the transistor. Apply a hard mask material using photolithography to create a fin for a tri gate transistor. The removal of selected portions of materials to define patternerd layers on chips known as etching takes place when defected silicon has been successfully removed , leaving behind a fin with a layer of hard mask on top. After the hard mask is chemically removed it leaves behind a tall, but yet thin silicon fin that contains the channel of transistors. The channel of transistors isnthe region under the gate of a transistor where current flows when the transistor is in "on" state.
Photoresist is applied to portions of the transistor, and a thin silicon dioxide layer is created by inserting the wafer in an oxygen-flled tube-furnace. This layer becomes a temporary gate dielectric. Using photolithography, a temporary layer of polycrystalline silicon is created. This becomes a temporary gate electrode. In another oxidation step, a silicon dioxide layer is created over the entire wafer to insulate the transistor from other elements. The temporary gate electrode and gate dielectric are etched away in preparation for forming the fnal gate. This procedure is called gate-last. Multiple layers of high-k dielectric material are applied to the wafer surface using a method called atomic layer deposition. This material is etched away in some areas, such as the silicon dioxide layer. A metal gate electrode is formed over the wafer and removed from regions other than the gate electrode. The combination of this and the high-k dielectric material improves performance and reduces leakage.Three holes are etched into the insulation layer above the transistor. The holes are flled with copper or another material that creates metal connections to other transistors. The wafers are put into a copper sulphate solution. Copper ions are deposited onto the transistor using a process called electroplating. Copper ions settle as a thin layer of copper on the transistor surface. The excess material is polished off, revealing a specifc pattern of copper. Like a multi-level highway, metal layers interconnect the transistors in a chip. The design of the chip determines how the connections are made. Although chips look flat, they can have more than 30 layers of this complex circuitry. After wafer processing is complete, each chip on a wafer is tested for its functionality. The wafer is cut into pieces called die. Based on the responses received in the wafer sort test, die are selected for packaging. The substrate, the die, and a heat spreader are put together to form a completed processor. The green substrate creates the electrical and mechanical connections so that the processor can interact with the system. The silver-colored heat spreader is a thermal interface that helps dissipate heat. A completed processor, such as the 3rd generation Intel Core processor, is one of the most complex manufactured products on Earth. Processors undergo fnal testing for functionality, performance, and power. Based on fnal test results, processors with the same capabilities are grouped into transporting trays.Intel® processors, such as the 3rd generation Intel Core processor shown here, are sent to system manufacturers in trays, or they are boxed for retail stores.
Being able to make electronic components out of a single piece of silicon like transistors, and then connecting them lead the way for integrated circuits. In order to gain full beneficial of technology computer experience must be secured. The way a chip works is a result of how a chip’s gates and transistors are designed, and the use of the chip. In conclusion, for decades Intel’s continuity of research and development relies on new processes that allows technology to deliver more high performance, and energy efficient technologies.

References: http://www.nobelprize.org/educational/physics/integrated_circuit/history/ http://www.intel.com/content/www/us/en/history/museum-making-silicon.html