Microfabrication is the collective term for the technologies used to fabricate components on a micrometer-sized scale. NASAs Glenn Research Center cleanroom. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ...

Origins

Microfabrication technologies originate from the microelectronics industry, and the devices are usually made on silicon wafers even though glass, plastics and many other substrate are in use. Microfabricated devices include integrated circuits (“microchips”), microsensors (e.g. air bag sensors), inkjet nozzles, flat panel displays, laser diodes, and hundreds of others. Micromachining, semiconductor processing, microelectronic fabrication, semiconductor fabrication, MEMS fabrication and integrated circuit technology are terms used instead of microfabrication, but microfabrication is the broad general term. Microelectronics is a subfield of electronics. ... It has been suggested that Silicons ranking be merged into this article or section. ... Glass can be made transparent and flat, or into other shapes and colors as shown in this sphere from the Verrerie of Brehat in Brittany. ... The term plastics covers a range of synthetic or semi-synthetic organic condensation or polymerization products that can be molded or extruded into objects or films or fibers. ... It has been suggested that Wafer prober be merged into this article or section. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... Ink jet printers are the most common type of computer printer; and industry and commerce also use them extensively for special-purpose applications. ... Flat panel displays encompass a growing number of technologies enabling video displays that are lighter and much thinner than traditional television and video displays using cathode ray tubes, usually less than 10 cm (4 inches) thick. ... Experiment with a laser (likely an argon type) (US Military) In physics, a laser is a device that emits light through a specific mechanism for which the term laser is an acronym: light amplification by stimulated emission of radiation. ... Types of diodes A diode functions as the electronic version of a one-way valve. ... NASAs Glenn Research Center cleanroom. ... A mite next to a gear set produced using MEMS. Courtesy Sandia National Laboratories, SUMMiTTM Technologies, www. ...

Traditional machining techniques such as electro-discharge machining, spark erosion machining, and laser drilling have been scaled from the millimeter size range to micrometer range, but they do not share the main idea of microelectronics-originated microfabrication: replication and parallel fabrication of hundreds or millions of identical structures. This parallelism is present in various imprint, casting and molding techniques which have successfully been applied in the microregime. For example, injection moulding of compact discs involves fabrication of micrometer-sized spots on the disc. A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... In the publishing industry, an imprint is a brand name under which a work is published. ... Casting may be used to create artistic sculptures Casting is a manufacturing process by which a molten material such as metal or plastic is introduced into a mold, allowed to solidify within the mold, and then ejected or broken out to make a fabricated part. ... Molding (US) or moulding (UK) can be: moulding or molding, a decorative feature used in interior design and architecture molding or moulding, a process used in manufacturing This is a disambiguation page — a navigational aid which lists pages that might otherwise share the same title. ... Injection moulding is a manufacturing technique for making parts from thermoplastic material in production. ...

Microfabrication processes

Microfabrication is actually a collection of technologies which are utilized in making microdevices. Some of them have very old origins, not connected to manufacturing, like lithography or etching. Polishing was borrowed from optics manufacturing, and many of the vacuum techniques come from 19th century physics research. Electroplating is also a 19th century technique adapted to produce micrometre scale structures, as are various stamping and embossing techniques.

To fabricate a microdevice, many processes must be performed, one after the other, many times repeatedly. In memory chip fabrication some 30 lithography steps, 10 oxidation steps, 20 etching steps, 10 doping steps, and many others are performed.

Typical microfabrication processes include:

• Photolithography
• Etching (microfabrication), such as RIE (Reactive-ion etching) or DRIE (Deep reactive-ion etching)
• Thin film deposition, such as sputtering, chemical vapor deposition (CVD), evaporative deposition, or epitaxy
• Thermal oxidation
• Doping by either thermal diffusion or ion implantation
• Wire bonding
• Chemical-mechanical planarization (CMP)
• Wafer cleaning, also known as "surface preparation" (see below)

The complexity of microfabrication processes can be described by their mask count. This is the number of different pattern layers that constitute the final device. Modern microprocessors are made with 30 masks while a few masks suffice for a microfluidic device or a laser diode. Microfabrication resembles multiple exposure photography, with many patterns aligned to each other to create the final structure. Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a photomask (also called reticle) to the surface of a substrate. ... Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. ... Reactive ion etching (RIE) is a technology using plasma to etch material deposited on wafers. ... DRIE or deep reactive ion etching is a dry etching technique used for creating high aspect ratio structures in micro fabrication. ... Thin-film deposition is any technique for depositing a thin film of material onto a substrate or onto previously deposited layers. ... Sputter deposition is a method of depositing thin films by sputtering a block of source material onto a substrate. Sputtered atoms ejected into the gas phase are not in their thermodynamic equilibrium state, and tend to deposit on all surfaces in the vacuum chamber. ... DC plasma (violet) enhances the growth of carbon nanotubes in this laboratory-scale PECVD apparatus. ... Evaporation is a common method of thin film deposition. ... Epitaxy is the growth of crystals of one material on the crystal face of another (heteroepitaxy) or the same (homoepitaxy) material, such that the two materials have a defined relative structural orientation. ... In microfabrication, thermal oxidation is a way to produce a thin layer of oxide (usually silicon dioxide) on the surface of a wafer (semiconductor). ... In semiconductor production, doping refers to the process of intentionally introducing impurities into an extremely pure (also referred to as intrinsic) semiconductor in order to change its electrical properties. ... Schematic drawing of the effects of diffusion through a semipermeable membrane. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... Wire bonding is a method of making interconnections between a microchip and the outside world as part of semiconductor device fabrication. ... Chemical-mechanical planarization or Chemical-mechanical polishing, commonly abbreviated CMP, is a technique used in semiconductor fabrication for planarizing the top surface of an in-process semiconductor wafer or other substrate. ... A pattern is a form, template, or model (or, more abstractly, a set of rules) which can be used to make or to generate things or parts of a thing, especially if the things that are generated have enough in common for the underlying pattern to be inferred or discerned... A packaged laser diode with penny for scale. ... A four hour long exposure on a Nikon D2h camera is made possible using multiple shorter exposures (using the C.E.M.E.N.T. algorithm). ...

Cleanliness in wafer fabrication

Microfabrication is carried out in cleanrooms, where air has been filtered of particle contamination and temperature, humidity, vibrations and electrical disturbances are under stringent control. Smoke, dust, bacteria and cells are micrometers in size, and their presence will destroy the functionality of a microfabricated device. NASAs Glenn Research Center cleanroom. ... Fig. ... This article or section is not written in the formal tone expected of an encyclopedia article. ... Smoke from a wildfire Smoke is a suspension in air (aerosol) of small particles resulting from incomplete combustion of a fuel. ... After just three years of use, dust has blocked this laptop heat sink, making the computer unusable Dust is a general name for minute solid particles with diameters less than 500 micrometers (otherwise, please see sand or granulates and, more generally, finely divided matter). ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. POOP Cells in culture, stained for keratin (red) and DNA (green). ...

Cleanrooms provide passive cleanliness but the wafers are also actively cleaned before every critical step. RCA-1 clean in ammonia-peroxide solution removes organic contamination and particles; RCA-2 cleaning in hydrogen chloride-peroxide mixture removes metallic impurities. Sulphuric acid-peroxide mixture (a.k.a. Piranha) removes organics. Hydrogen fluoride removes native oxide from silicon surface. These are all wet cleaning steps in solutions. Dry cleaning methods include oxygen and argon plasma treatments to remove unwanted surface layers, or hydrogen bake at elevated temperature to remove native oxide before epitaxy. Pre-gate cleaning is the most critical cleaning step in CMOS fabrication: it ensures that the ca. 2 nm thick oxide of a MOS transistor can be grown in an orderly fashion. Oxidation, and all high temperature steps are very sensitive to contamination, and cleaning steps must precede high temperature steps. Ammonia is a compound with the formula NH3. ... A peroxide is a compound containing an oxygen-oxygen single bond. ... R-phrases , S-phrases , , , , Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ... It has been suggested that Silicons ranking be merged into this article or section. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Epitaxy is the growth of crystals of one material on the crystal face of another (heteroepitaxy) or the same (homoepitaxy) material, such that the two materials have a defined relative structural orientation. ... The most fundamental reactions in chemistry are the redox processes. ...

Surface preparation is just a different viewpoint, all the steps are the same as described above: it is about leaving the wafer surface in a controlled and well known state before you start processing. Wafers are contaminated by previous process steps (e.g. metals bombarded from chamber walls by energetic ions during ion implantation), or they may have gathered polymers from wafer boxes, and this might be different depending on wait time. Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ...

Wafer cleaning and surface preparation work a little bit like the machines in a bowling alley: first they remove all unwanted bits and pieces, and then they reconstruct the desired pattern so that the game can go on. Bowling is the common name for several sports that involve rolling a ball towards a target or to knock down pins. ...

See also

Wikibooks has more about this subject:

Microtechnology

• Semiconductor fabrication
• Integrated circuit
• Microelectronics
• Sensors
• Actuators
• Transducers
• Microfluidics
• 3D microfabrication

Image File history File links Wikibooks-logo-en. ... NASAs Glenn Research Center cleanroom. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... Microelectronics is a subfield of electronics. ... A sensor is a technological device or biological organ that detects, or senses, a signal or physical condition. ... An actuator is the mechanism by which an agent acts upon an environment. ... A transducer is a device that converts one type of energy to another, or responds to a physical parameter. ... Glass microfluidic devices from Syrris and Dolomite Microfluidics deals with the behavior, precise control and manipulation of microliter and nanoliter volumes of fluids. ... This article or section is in need of attention from an expert on the subject. ...

References

• Journal of Microelectromechanical Systems (J.MEMS)
• Sensors and Actuators A: Physical
• Sensors and Actuators B: Chemical
• Journal of Micromechanics and Microengineering (JMM)
• Lab on a Chip
• IEEE Transactions of Electron Devices,
• Journal of Vacuum Science and Technology A: Vacuum, Surfaces, Films
• Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures: Processing, Measurement, and Phenomena

The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ...

Books about microfabrication

• (2004)Geschke, Klank & Telleman, eds.: Microsystem Engineering of Lab-on-a-chip Devices, 1st ed, John Wiley & Sons. ISBN 3-527-30733-8.
• "Introduction to Microfabrication" (2004) by S. Franssila
• "Fundamentals of Microfabrication" (2nd ed, 2002) by M. Madou
• Micromachined Transducers Sourcebook by Gregory Kovacs(1998)
• Brodie & Murray: The Physics of Microfabrication (1982),
• D. Widmann, H. Mader, H. Friedrich: Tehnology of Integrated Circuits (2000),
• J. Plummer, M.Deal, P.Griffin: Silicon VLSI Technology (2000),
• G.S. May & S.S. Sze: Fundamentals of Semiconductor Processing (2003),
• P. van Zant: Microchip Fabrication (2000, 5th ed),
• R.C. Jaeger: Introduction to Microelectronic Fabrication (2001, 2nd ed),
• S. Wolf & R.N. Tauber: Silicon Processing for the VLSI Era, Vol 1: Process technology (1999, 2nd ed),
• S.A. Campbell: The Science and Engineering of Microelectronic Fabrication (2001, 2nd ed)
• T. Hattori: Ultraclean Surface Processing of Silicon Wafers : Secrets of VLSI Manufacturing