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Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Modern manufacturing is being revolutionized by the use of optics, which can both improve current manufacturing capabilities and enable new ones.
Light can be used to process or probe materials remotely, even through windows isolating harsh or vacuum environments.
With no surface contact, there is no contamination of the process by the probe beam and no wear of tool edges. Scanning provides action over large areas. Light can be used to induce photochemistry, for example, in photolithography to produce submicron features in thin films of photoresist or in rapid prototyping where liquid polymers are solidified by lasers to form a three-dimensional piece from a computer-aided design database. Light can cast images, making it possible to inspect a part or use the image to guide the working tool to the correct area of the work-piece.
Images of the surface topology can be compared to the topology of the ''perfect" image captured in a database or the topology of an identical piece to ensure consistent component fabrication. For these many reasons, optics has reached into every aspect of manufacturing and promises to increase in use with improvements in speed, control, precision, and accuracy.
Numerous optical techniques are used throughout industry and are critical to the manufacture of such diverse and basic products as semiconductor chips, roads and tunnels, and chemicals.
Optical techniques, grouped by function, fall into two broad classes:. Performing manufacturing: Light interacts directly with the finished or intermediate product to change its physical properties, as in the case of photolithography or materials processing.
Controlling manufacturing: Optics is used to provide information about a manufacturing process, as in the chemical industry's use of optical sensors for in-line process control, or to inspect a manufactured. Some applications may be relatively familiar, such as the use of high-power lasers for cutting, drilling, or welding steel. Others are less familiar, such as the use of optical sensors to monitor chemical processes in real-time or the use of lasers for alignment and control in the construction industry.
Some of the challenges that these applications face are unique to a particular industry, but others, such as the need for trained optics technicians or the importance of making equipment robust and reliable, are universal. Table 5. Each has a critical dependence on one or more optical manufacturing techniques. Because of the diversity of U. It endeavors instead to cover a representative sample, including those applications.
Value of shipments billions of dollars a. NOTE: Critical means that a technique is used pervasively and cannot be replaced by alternative nonoptical techniques without major negative economic impact to the entire industry. Major means that a technique is used pervasively and adds significant economic value to the entire industry. Significant means that a technique is used for specialized niche applications within an industry and adds significant economic value to those niche sectors. Emerging means that a technique is being put to increasing use in an industry and has the potential to be of at least significant importance.
An illustrative selection of other applications with significant potential for growth is also given. This chapter is organized in five sections.
Two explore the use of light to perform manufacturing and the use of optics to control manufacturing, respectively.
Industry-by-industry examples follow to highlight the interplay between the various applications of optics to perform manufacturing in each industry. Prospects for increasing the use of optics in manufacturing are discussed in the next section. Findings, conclusions, and recommendations are gathered in the last section. Because of the many unique properties of light and the manner in which light interacts with matter, optics offers a rich variety of application options for manufacturing processes.
The imaging properties of light and its ability to induce photochemical reactions allow highly complex mask patterns to be transferred to photoresist in the optical lithography process. Tightly focused laser beams can deliver thermal energy to the workpiece for cutting, welding, or drilling with a precision and accuracy unmatched by any other technique; they can also induce localized photochemical reactions to generate solid three-dimensional prototype parts.
Additional advantages are the ability to deliver this energy at a distance in a noncontact manner through windows and in various atmospheres. Some of light's diverse range of utility is illustrated in the following applications.
Photolithography plays an essential enabling role in integrated circuit processing. Photolithography requires both an optical system—the step-and-repeat camera stepper that is the workhorse of the integrated circuit IC industry—and an optical material—the light-sensitive photoresist used to transfer the desired pattern to the silicon substrate or thin film of interest Figure 5.
As the demand for faster processing speeds continues, increasing pressure will be put on photolithographic processes to produce smaller feature dimensions, requiring new photolithographic tools, new materials, shorter wavelength light sources, and other more advanced optical system designs. The mask, which defines which areas of the film to be patterned will be exposed to light;. Advances in the resolution and depth of focus of photolithography systems drive increases in the speed and performance of computers and computer-controlled systems.
The photoresist, which changes solubility when exposed to light and transfers the pattern on the mask to the film or layer below the photoresist.
Effective combination of these three elements, with appropriate integrated circuit design, has resulted in tremendous decreases in the minimum size of features and increases in the number of elements on a chip, allowing for increased speed and number of computational operations.
Today, devices with several million transistor cells are commercially available and are fabricated with minimum features of 0. Indeed, the decrease follows an almost perfectly exponential trend known as Moore's law.
The steady decrease in integrated circuit linewidths or feature size has largely been fueled by improvements in the resolution of optical lithography. This improved resolution, in turn, has been enabled by the use of shorter and shorter wavelengths for the exposure tools.
Deep ultraviolet UV lithography using nm wavelength light is just coming into production use for chips with minimum dimensions as small as 0. A lithography roadmap prepared by SEMATECH projects the minimum feature sizes desired in the future and the technologies that must be developed to achieve them. The workhorse of photolithography is the step-and-repeat camera. Four competing demands on lens performance are 1 increasing resolution, 2 increasing depth of focus, 3 increasing field size, and 4 decreasing aberrations.
Maximum resolution and depth of field are determined primarily by the wavelength of the imaging light and the numerical aperture of the projection lens, with changes that increase resolution and result in decreasing depth of field. The trade-off of resolution with depth of field. Industry anticipates a transition to an exposure wavelength of nm by a change in the excimer laser light source from KrF to ArF. Generations of exposure tools have relied on high-quality fused-silica refractive lenses.
Due to issues of compaction and color center formation with fused silica, which are not adequately understood, the nm exposure tools will likely use, for the first time, some reflective elements as well as CaF refractive elements.
The lack of materials that are adequately transparent at nm or nm is a barrier to further reduction in wavelength, necessitating all-reflective exposure tools for use at these wavelengths. All reflective optical systems with high numerical aperture 0. This situation speaks to the issue of the manufacture of optics covered in Chapter 6. Step-and-scan systems offer another alternative to the step-and-repeat equipment common today.
Because of the difficulty of making bigger lenses, an alternate approach is to combine modest-sized lenses with scanning systems to increase the field size. By synchronously scanning the mask and the wafer through an illuminated area corresponding to the corrected field of the lens, it is possible to achieve patterning over large areas.
The synchronization between the mask and the wafer stages must be kept well under nm, which is not easy. However, for megabit DRAM chips and beyond, step-and-scan technology will likely prove more cost-effective than step-and-repeat because of the smaller optical system employed.
In the past 10 years the transition from 1x to 4x and 5x optical systems has provided a technology respite to the mask-making industry, but the recent emphasis on optical proximity correction combined with the relentless trend toward smaller geometries and more complex structures has accelerated mask making requirements. The mask-making industry generates insufficient revenue to cover the cost of developing new generations of mask-making tools.
Given the current direction, mask making will almost certainly be a major impediment in only a few years, although there are some initiatives under way aimed at alleviating this.
Mask alignment is also a critical issue. Subsequent masks must be precisely aligned with patterns on the silicon wafer with a precision far beyond that of the minimum feature dimensions. New metrology will be required for next-generation systems. One interesting possibility is the conversion to maskless systems that have a large micromirror array or similar device in the lens focal.
In this case the mask pattern is simply a data file stored on an array of hard disks or other high-speed data storage device, which feeds pattern data to the mirror array.
The flexibility of an electronic mask would be unprecedented and could correct for small imperfections in the imaging system. The pattern on the photomask is transferred to the silicon wafer by means of a light-sensitive polymer that is spun uniformly onto the wafer surface. Exposure to UV light changes the solubility of the polymer such that the exposed positive photoresist or unexposed negative photoresist regions can be removed in a solvent after exposure.
Optimum materials exhibit high photosensitivity and uniform absorption of the UV light for uniform solubility and contrast. The key to developing an effective photoresist is to develop a material with excellent etching resistance combined with good imaging characteristics. This combination presents a significant challenge and is the focus of several research efforts today.
Present conventional photoresists are not appropriate for use with the nonconventional lithographic technologies that will be necessary for sub The most notable deficiencies of the conventional novalac-quinonediazide resist are the exposure sensitivity and absorption properties of the materials. New photolithographic tools in general have low-brightness sources, and high-sensitivity resists are highly desirable. For nm lithography, these challenges were accommodated by application of chemically amplified resist technology, which greatly enhances photosensitivity.
However, hydroxystyrene polymers, which form the basis for this technology, are effectively opaque at nm. Thus, new polymer materials are required for nm single-layer resists that possess high optical transparency at the exposure wavelength, combined with good etching resistance and functionality that will effect a change in solubility of the exposed regions.
No matter what technology becomes dominant when today's photolithography capabilities have reached their limits, new optical materials and processes will be required, necessitating enormous investments in research and process development. The introduction of new resist materials and processes will also require a considerable lead time to bring them to the performance level currently realized by conventional materials, as has been the case with new photolithography techniques.
For example, the printing of 0. The next big decrease in resolution, which is expected to be in production in , is the production of 0. What are the alternatives for future advances in photolithography? There are currently several possibilities:. Wavefront Engineering. Because integrated circuit design uses a limited set of objects with limited dimensions, the limitations of classical imaging can be overcome by appropriate design of a mask feature, use of phase-shift masks, or modifying the illumination to change the amplitude and phase of the optical wavefront.
Extreme Ultraviolet EUV. At wavelengths as short as 14 nm, small numerical aperture reflective systems can provide high-resolution and depth of focus. Hurdles to overcome include EUV-robust and reliable x-ray sources, defect-free EUV masks, aspheric reflective optics, and surface imaging photoresists.
Electron Beam. This approach would, however, require a significant departure from current industry processing; for example, electron beam lithography requires processing under vacuum.
High cost and low throughput continue to limit the use of this technology.
Optics is the branch of physics that studies the behaviour and properties of light , including its interactions with matter and the construction of instruments that use or detect it. Because light is an electromagnetic wave , other forms of electromagnetic radiation such as X-rays , microwaves , and radio waves exhibit similar properties. Most optical phenomena can be accounted for using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics , treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces.
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The core component of any optical device is a lens that changes the direction of rays of light. Positive lenses that resemble parentheses face to face— —cause rays of light to converge to a focus. Negative lenses— —cause rays to diffuse, to spread apart. This comes about because light slows as it passes through a dense but translucent medium, like glass or plastic and, in slowing, a ray will refract or bend.
Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Modern manufacturing is being revolutionized by the use of optics, which can both improve current manufacturing capabilities and enable new ones. Light can be used to process or probe materials remotely, even through windows isolating harsh or vacuum environments.
Он в ловушке. Дэвид Беккер умрет. Халохот поднимался вверх с пистолетом в руке, прижимаясь вплотную к стене на тот случай, если Беккер попытается напасть на него сверху.
Железные подсвечники, установленные на каждой площадке, стали бы хорошим оружием, если бы Беккер решил ими воспользоваться. Но если держать дистанцию, можно заметить его вовремя.
У пистолета куда большая дальность действия, чем у полутораметрового подсвечника. Халохот двигался быстро, но осторожно. Ступени были настолько крутыми, что на них нашли свою смерть множество туристов.
Это вам не Америка - никаких предупреждающих знаков, никаких поручней, никаких табличек с надписями, что страховые компании претензий не принимают.
Activities in the Optical Device Business
У меня неотложное дело! - рявкнул Беккер. Он схватил парня за рукав. - У нее кольцо, которое принадлежит .
- Он покачал головой и возобновил работу. Дэвид Беккер стоял в центре пустого зала и думал, что делать .
Видел ли кто-нибудь из вас фильм Толстый и тонкий о Манхэттенском проекте. Примененные атомные бомбы были неодинаковы. В них использовалось разное топливо - разные элементы. Соши хлопнула в ладоши. - Он прав. Я читала об. В бомбах было разное топливо. В одной урановое, в другой плутониевое. Это два разных элемента.
Зачем же ты убил Чатрукьяна? - бросила. - Я не убивал его! - Крик Хейла перекрыл вой сирены. - Его столкнул вниз Стратмор. Я все это видел, потому что прятался в подсобке. Чатрукьян хотел вызвать службу безопасности, что разрушило бы все планы Стратмора.
Ну и ловок, подумала Сьюзан.
Беккер поморщился. - Предпочитаю вид спорта, в котором я могу выиграть. - Победа любой ценой? - улыбнулась Сьюзан. Защитник Джорджтауна перехватил опасную передачу, и по трибунам пронесся одобрительный гул. Сьюзан наклонилась к Дэвиду и шепнула ему на ухо: - Доктор. Он смотрел на нее с недоумением.
Он поздравил меня с обнаружением черного хода в Попрыгунчике, - продолжал Хейл. - И назвал это победой в борьбе за личные права граждан всего мира. Ты должна признать, Сьюзан, что этот черный ход был придуман для того, чтобы ввести мир в заблуждение и преспокойно читать электронную почту.
Именно здесь вирус мог бы причинить наибольший ущерб, и именно здесь Джабба проводил большую часть времени. Однако в данный момент у него был перерыв и он поглощал пирог с сыром и перцем в круглосуточной столовой АНБ.
Если не преследовать Хейла, черный ход останется секретом. Но Стратмор понимал, что Хейл не станет долго держать язык за зубами. И все же… секрет Цифровой крепости будет служить Хейлу единственной гарантией, и он, быть может, будет вести себя благоразумно. Как бы там ни было, Стратмор знал, что Хейла можно будет всегда ликвидировать в случае необходимости.
Глядя на экран, Фонтейн увидел, как полностью исчезла первая из пяти защитных стен. - Бастион рухнул! - крикнул техник, сидевший в задней части комнаты.