29-06-2012, 11:49 AM
Silicon in Photonics
Silicon in Photonics.doc (Size: 347.5 KB / Downloads: 33)
Abstract
In the 1970’s a new form of electronic data networking was born in the form of optical communication. Since that time, optical communications has continued to advance. Two keys to this advancement are the increased speed of communications (now at the speed of light) and the increased amount of data that can be transmitted at once (i.e., bandwidth). Just as some of the pioneers of the first computers failed to perceive a need for more than a few of these systems, so have some presumed that the need for more speed and bandwidth for electronic communications must surely have reached its usable limit. But as the latest and near future advancements in computing technology demonstrate, processing speeds in the CPU of most computers are now reaching great numbers (in excess of 3 GHz) and will continue to increase in speeds at comparable rates for the foreseeable future (in accordance with Moore’s Law*). With this steady increase in processing power, it is apparent that the bits and bytes that have to be fed into these new generation speed kings will fall short of the capabilities provided by the copper connections that now exist in motherboards, network interface cards, and potentially any other component the computer has to communicate with to carry out its functions. In the words of Intel’s engineers Mario Paniccia and Sean Koehl “As newer, faster microprocessors roll out, the copper connections that feed those processors within computers and servers will prove inadequate to handle the crushing tides of data.”(Paniccia & Koehl, 2006).
CMOS manufacturing processes:
There is an inexorable trend in the electronics industry to make things smaller, faster (or smarter), and cheaper. This is thanks in a large part to the invention of the microchip, semiconductor chip, or more specifically, the Complimentary Metal Oxide Semiconductor chip. To fully understand the scope of Silicon Photonics requires understanding the processes involved in creating a CMOS chip.
CMOS chips are built on a substrate of Silicon (Si). Silicon is used because of its properties as a natural semiconductor – it can function equally well as a conductor or an insulator of electricity – and it is both inexpensive and abundant (it is made from sand). A wafer of silicon is produced and a layer of Silicon Dioxide ( ) is placed on top of the wafer. This is then followed up with a layer of chemical called a ‘photoresist’, so named because when exposed to a certain wavelength of light the chemical hardens. Using that wavelength, a pattern is laid out in the layer of photoresist; then the photoresist that was not exposed to light is washed away. The surrounding layer of that is not masked by the hardened photoresist can then be etched from the wafer. The hardened photoresist is then taken off and what is left is the electronic component or circuit. In most cases, this process is performed many times over and layer upon layer is built up to form complex components and circuits.
Silicon in Photonics.doc (Size: 347.5 KB / Downloads: 33)
Abstract
In the 1970’s a new form of electronic data networking was born in the form of optical communication. Since that time, optical communications has continued to advance. Two keys to this advancement are the increased speed of communications (now at the speed of light) and the increased amount of data that can be transmitted at once (i.e., bandwidth). Just as some of the pioneers of the first computers failed to perceive a need for more than a few of these systems, so have some presumed that the need for more speed and bandwidth for electronic communications must surely have reached its usable limit. But as the latest and near future advancements in computing technology demonstrate, processing speeds in the CPU of most computers are now reaching great numbers (in excess of 3 GHz) and will continue to increase in speeds at comparable rates for the foreseeable future (in accordance with Moore’s Law*). With this steady increase in processing power, it is apparent that the bits and bytes that have to be fed into these new generation speed kings will fall short of the capabilities provided by the copper connections that now exist in motherboards, network interface cards, and potentially any other component the computer has to communicate with to carry out its functions. In the words of Intel’s engineers Mario Paniccia and Sean Koehl “As newer, faster microprocessors roll out, the copper connections that feed those processors within computers and servers will prove inadequate to handle the crushing tides of data.”(Paniccia & Koehl, 2006).
CMOS manufacturing processes:
There is an inexorable trend in the electronics industry to make things smaller, faster (or smarter), and cheaper. This is thanks in a large part to the invention of the microchip, semiconductor chip, or more specifically, the Complimentary Metal Oxide Semiconductor chip. To fully understand the scope of Silicon Photonics requires understanding the processes involved in creating a CMOS chip.
CMOS chips are built on a substrate of Silicon (Si). Silicon is used because of its properties as a natural semiconductor – it can function equally well as a conductor or an insulator of electricity – and it is both inexpensive and abundant (it is made from sand). A wafer of silicon is produced and a layer of Silicon Dioxide ( ) is placed on top of the wafer. This is then followed up with a layer of chemical called a ‘photoresist’, so named because when exposed to a certain wavelength of light the chemical hardens. Using that wavelength, a pattern is laid out in the layer of photoresist; then the photoresist that was not exposed to light is washed away. The surrounding layer of that is not masked by the hardened photoresist can then be etched from the wafer. The hardened photoresist is then taken off and what is left is the electronic component or circuit. In most cases, this process is performed many times over and layer upon layer is built up to form complex components and circuits.