Конструирование и технология электронно-вычислительной аппаратуры (1065432), страница 2

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Preliminary exercises

1. Прочитайте и переведите следующие слова:

Total, local, portion, vertical, factor, starting, material, per meter, temperature, limit, maximum, critical, structure, parallel

1. Определите, к каким частям речи относятся следующие слова, переведите их:

Impurity, selective, layer, lateral, performed, stage, conducting, concentration, solubility,infinitely, chosen, available, succession, limited, definite, diffused, conductivity

1. Образуйте от следующих глаголов существительные и дайте их перевод:

To introduce, To produce, to differ, to distribute, to penetrate, to protect, to relate, to dope, to concentrate, to determine, to limit, to define

1. Переведите следующие определительные блоки существительных:

Silicon oxide film, thin diffused layer, waver bulk, wafer plane, diffusion layer thickness, starting n-type slice, three-layer structure, preceding impurity concentration, chosen impurity, maximum critical solubility

v. Прочитайте текст А и ответьте на вопросы:

1) Какие существуют типы и виды диффузий?

2) Назовите источники диффузантов

Diffusion methods

1. The introduction of impurities into the starting material (a wafer or epitaxial layer) by diffusion at high temperatures is still the basic method of doping of semiconductors aimed at creating diode and transistor structures. Diffusion can be total, or overall, and selective or local. In the first case, diffusion occurs over the entire surface of the slice, through the windows in the mask such as the silicon oxide film.

2. Overall diffusion produces a thin diffused layer on the wafer surface that differs from the epitaxial layer by the inhomogeneous distribution of an impurity in depth.

3. In local diffusion, the impurity penetrates not only into the wafer bulk at right angles to the wafer plane but also spreads over parallel to the wafer plane that is, under the mask.

As a result of this lateral diffusion, the pn junction portion that extends outward becomes protected by the oxide. The relation between the depths of lateral and “vertical” diffusions depends on a number of factors, including the diffusion layer thickness L. The lateral diffusion depth is generally equal to 0.7 L.

1. Diffusion can be performed once and repeatedly. For example, in the first stage of diffusion, it is possible to dope the starting n-type slice with an acceptor impurity to produce a p layer and then, in the second stage, to drive a donor impurity into the p layer to a smaller depth and thus from a three-layer structure. So diffusion can be the double and triple type.

2. In conducting multiple diffusion, one must see that the concentration of every new impurity being introduced exceeds the preceding impurity concentration, otherwise the type of conductivity will remain the same and, hence, the p junction will not be formed. On the other hand, the impurity concentration in silicon or any other starting material cannot be infinitely large: it has an upper limit determined by the parameter called the solid solubility of an impurity. The solid solubility reaches its maximum, , and then starts to fall off.

3. In the last stage of multiple diffusion, therefore, the chosen impurity must have a maximum critical stability. Since the range of available impurity materials is limited, it is not possible to carry out more than three diffusions in succession.

4. The dopants such as boron, phosphorus, and others introduced by diffusion are called diffusants whose sources are chemical compounds. These can be liquids, solids and gases.

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Words to be learned:

1. To occur -происходить

2. To spread over -распространяться

3. To determine -определять

4. To distribute- распространять

5. To reach -

6. Служебные слова:

Otherwise –в противном случае

Hence-следовательно

On the one hand-с одной стороны

On the other hand- с другой стороны

Since-так как, с тех пор, как

Therefore-поэтому

That is - то есть

Such as - такой как

However – однако

VI Переведите следующие словосочетания на английский язык:

Общая диффузия, локальная диффузия, боковая диффузия, неоднородная диффузия, распределение примеси, под маску, через окна в маске, участок p-n прохода; глубина диффузного слоя, получить p-n слой, проводить многократную диффузию, превышать концентрацию предыдущей примеси, исходный материал, предельная растворимость примеси, максимальная предельная растворимость примеси, обеспечение более трех последовательных диффузий.

VII. Найдите в тексте словосочетания, противоположные по значению данным и переведите их:

total diffusion, homogeneous distribution, the introduction of purities, at low temperatures, indefinite portion, a thick layer once, triple type, to remain the same, above the mask, the lower limit, to fall off, the last stage, liquids.

VIII. Закончите предложения, ориентируясь на текст и переведите их.

1) Diffusion occurs only in the definite portions of the slice though the windows in the mask such as

2) Diffusion impurity penetrates not only into the wafer bulk at right angles to the wafer plane but also spreads over…

3) It is possible to dope the staring n-type slice with an acceptor impurity to produce a …

4) The concentration of every new impurity exceeds the preceding impurity concentration, otherwise

5) The impurity concentration in silicon has an upper limit determined by…

6) At a certain temperature, the solubility reaches its maximum and then …

IX. Переведите речевые отрезки. Обратите внимание на перевод сказуемого, первым компонентом которого является личная форма глагола “to be”:

1) The impurity is penetrating to; 2) the impurity is able to penetrate to; 3) the impurity is supposed to penetrate to; 4) the impurity is to penetrate to; 5) the impurity is introduced; 6) this impurity is presently in wide-spread use; 7) this impurity is being applied to; 8) the impurity is to be applied to

X. Переведите речевые отрезки. Обратите внимание на перевод сказуемого, первым компонентом которого является личная форма глагола “to have”:

1) the junction ahs a form of, the junction ha formed; 3) the junction has been formed; 4) the junction has been supposed to form; 5) the junction has to be formed; 6) we have to study the properties of; 7) the properties have been studied.

XI. Переведите следующие предложения, обращая внимание на служебные слова:

1. An integrated circuit is a special kind of microelectronics and at our current level of IC development however we must face several problems.

2. Microelectronics I a name for extremely small electronic components and hence for circuit assemblies made by thin-film, thick film or semiconductor techniques.

3. An integrated circuit has been fabricated as an assembly of electronic elements in a single structure, that is it cannot be divided without destroying its electronic function.

4. Integrated electronics will develop further. It will move not only towards more functions per slice, but toward new types of functions.

5. Since the range of materials is limited it is impossible to carry out more than three diffusions in succession.

6. Semiconductors are used in a wide variety of solid-state devices, such as transistors, integrated circuits, diods and so on.

7. Silicon has been the backbone (основа) of the semiconductor industry since the production of commercial transistors.

XII. Ответьте на вопросы по тексту.

1. What is the difference between local and overall diffusion?

2. What does the relation between the lateral and “vertical” diffusion depend on?

3. What types of diffusion do you know?

4. Why should the concentration of every new impurity exceed the preceding impurity concentration?

5. What parameter determines the upper limit of the impurity concentration?

6. What does the solid solubility depend on?

7. Is it possible to carry out more than three diffusions in succession?

8. What are the sources of diffusants?

XIII. Дайте определение следующих терминов:

Overall diffusion; local diffusion; the first stage of diffusion; the second stage of diffusion; multiple diffusion; the solid solubility of an impurity; the diffusant

XIV. Составьте аннотацию к тексту.

XV.Расскажите о методах диффузии.

XVI.Прочитайте текст В за 4-5 мин. И ответьте на следующие вопросы:

1. В каких целях используются однозонные и двухзонные печи?

2. Какие виды истчников диффзанта используются в диффузионных печах?

3. Какую функцию выполняет стекло при использовании жидких источников диффузанта?

The Process of Doping in Diffusion Furnaces

1. As with epitaxial growth and thermal oxidation, the process of doping involves gas-transport reactions carried out in single-zone or double-zone diffusion furnaces.

2. A double –zone furnace consists of two high-temperature zones, one for decomposing the solid source of a diffusant and the other for performing the diffusion proper.

3. Liquid and gaseous sources of a diffusant do not need high temperature for evaporation, and so they allow the use of single-zone furnaces; a diffusant source is forced into the furnace tube in the gaseous state.

4. If liquid sources of a dopant are used, the diffusion is performed in the oxidizing atmosphere by adding oxygen to the carrier gas. Oxygen combines chemically with the surface atoms to form the oxide , which is in essence a glass. At a temperature above 1000° C these glasses are in the liquid state. They coat the silicon surface with a thin film, so that the diffusion takes place, strictly speaking, from the liquid phase. The glass solidifies to produce a sealing (защитный) layer that protects the silicon surface at the spots of diffusion, that is, in the windows of the oxide mask. With the use of solid diffusant surfaces (oxides), the glass layer forms in the process of diffusion the addition of oxygen.

XVI Прочитайте текст С со словарем.

Сравните диффузные методы с методом ионной имплантации.

Какие существуют сходства и различия, преимущества и недостатки того или иного метода.

Ion Implantation

1. This is the method of doping of a slice (or an epitaxial layer) by bombarding it with impurity ions accelerated to an energy enough to enable the ions to penetrate rather deep into slice bulk.

2. Special installations similar to charged-particle accelerators employed in nuclear physics provide for ionization of impurity atoms, ion acceleration, and focusing of the ion beam. The dopants are the same as those used in the diffusion process.

3. Ion implantation, like diffusion, can be overall and local (selective). An important merit of ion implantation is that ions, travelling along the straight line, penetrate only into the slice bulk at right angles to the surface and do not affect the regions under the mask, in other words, the process analogous to lateral diffusion does not exist here.

4. As with diffusion, multiple ion implantation for “driving” one layer into the other is in principle possible. However, it is difficult to compromise between the ion energy, exposure time, and annealing conditions required for multiple ion implantation. For this reason ion implantation enjoys popularity mainly in growing thin single layers.

5. The main advantages of ion implantation are a low temperature needed for the process and its good controllability. The first feature offers the possibility of performing ion implantation at any stage of the technological cycle, thereby dispensing with the additional diffusion of impurities into the layers prepared earlier.

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Terminology

Photolithography –фотлитография

Photoresist -фоторезист

Oxide-окись

Oxidate- окислить

Oxidation- окисление

Характеристики

Список файлов книги