Microchip Fabrication: A Practical Guide to Semiconductor Processing / Edition 6

by Peter Van Zant

Overview

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The most complete, current guide to semiconductor processing

Fully revised to cover the latest advances in the field, Microchip Fabrication, Sixth Edition explains every stage of semiconductor processing, from raw material preparation to testing to packaging and shipping the finished device. This practical resource provides easy-to-understand information on the physics, chemistry, and electronic fundamentals underlying the sophisticated manufacturing materials and processes of modern semiconductors.

State-of-the-art processes and cutting-edge technologies used in the patterning, doping, and layering steps are discussed in this new edition. Filled with detailed illustrations and real-world examples, this is a comprehensive, up-to-date introduction to the technological backbone of the high-tech industry.

COVERAGE INCLUDES:

• The semiconductor industry
• Properties of semiconductor materials and chemicals
• Crystal growth and silicon wafer preparation
• Wafer fabrication and packaging
• Contamination control
• Productivity and process yields
• Oxidation
• The ten-step patterning process—surface preparation to exposure; developing to final inspection
• Next generation lithography
• Doping
• Layer deposition
• Metallization
• Process and device evaluation
• The business of wafer fabrication
• Devices and integrated circuit formation
• Integrated circuits
• Packaging

Product Details

ISBN-13:	9780071821018
Publisher:	McGraw Hill LLC
Publication date:	01/10/2014
Edition description:	New Edition
Pages:	576
Product dimensions:	7.50(w) x 9.40(h) x 1.30(d)

About the Author

Peter Van Zant is an internationally known semiconductor professional with an extensive background in process engineering, training, consulting, and writing. He is the principal of Peter Van Zant Associates, a firm that supplies writing, training, and consulting services to business and industry. Van Zant’s books and training materials are used by chip manufacturers, industry suppliers, colleges, and universities. Peter Van Zant Associates' customers have included Intel, National Semiconductor, Applied Materials, Air Products and Chemicals, SCP Global Inc., and a number of educational institutions.

Read an Excerpt

Chapter 2: Semiconductor Materials and Process Chemicals

Semiconductor Production Materials

Germanium and Silicon

Germanium and silicon are the two elemental semiconductors. The first transistor was made with germanium as were the initial devices of the solid state era. However germanium presents problems in processing and in device performance. Its 937°C melting point limits high temperature processing. More importantly, its lack of a natural occurring oxide leaves the surface prone to electrical leakage.

The development of silicon/silicon dioxide planar processing solved the leakage problem of integrated circuits, flattened the surface profile of the circuits and allowed higher temperature processing due to its 1415°C melting point. Consequently, silicon represents over 90% of the wafers processed world-wide.

Semiconducting Compounds

There are many semiconducting compounds formed from elements listed in columns III and IV and II to VI of the periodic table. Of these compounds, the ones most used in commercial semiconductor devices are gallium arsenide (GaAs) and gallium arsenide-phosphide (GaAsP), indium phosphide (InP), gallium aluminum arsenic (GaAlAs), and indium gallium phosphide (InGaP).1 These compounds have special properties.' Diodes made from GaAs and GaAsP give off visible and laser light when activated with an electrical current. They are the materials used to make the light emitting diodes (LED's) used in electronic panel displays.

An important property of gallium arsenide is its high (electrical) carrier mobility. This property allows a gallium arsenide device to react to high frequency microwaves and effectively switch theminto electrical currents in communications systems faster than silicon devices.

This same property, carrier mobility, is the basis for the excitement over gallium arsenide transistors and I.C.'s. Devices of GaAs operate two to three times faster than comparable silicon devices and find applications in super fast computers and real time control circuits such as airplane controls.

GaAs has a natural resistance to radiation caused leakage. Radiation, such as that found in space, causes holes and electrons to form in semiconductor materials. It gives rise to unwanted currents that can cause the device or circuit to malfunction or cease functioning. Devices that can perform in a radiation environment are known as radiation hardened. GaAs are naturally radiation hardened.

GaAs is also semi-insulating. In an integrated circuit, this property minimizes leakage between adjacent devices, allowing a higher pack ing density, which in turn results in a faster circuit since the holes and electrons travel shorter distances. In silicon circuits, special isolating structures must be built into the surface to control surface leakage. These structures take up valuable space and reduce the density of the circuit.

Despite all of the advantages, GaAs is not expected to replace silicon as the main stream semiconducting material. The reasons reside in the trade-off's between performance and processing difficulty. While GaAs circuits are very fast, the majority of electronic products do not require their level of speed. On the performance side, GaAs, like germanium, does not possess a natural oxide. To compensate layers of dielectrics must be deposited on the GaAs, which leads to longer processing and lower yields. Also, half of the atoms in GaAs are arsenic, a element very dangerous to human beings. Unfortunately the arsenic evaporates from the compound at normal process temperatures, requiring the addition of suppression layers (caps) or pressurized process chambers. These steps lengthen the processing and add to its cost.

Evaporation also occurs during the crystal growing stage resulting in nonuniform crystals and wafers. The nonuniformity produces wafers that are very prone to breakage during fab processing. Also, the production of large diameter GaAs wafers has lagged that of silicon (see Chapter 3).

Despite the problems, gallium arsenide is an important semiconducting material which will continue to increase in use and will probably have a major influence on computer performance of the future.

Silicon Germanium

A competitor to GaAs are silicon/germanium (SiGe) structures. The combination increases transistor speeds to levels allowing ultra fast radios and personal communication devices.' Device/IC structures feature a layer of germanium deposited by ultrahigh vacuum/chemical vapor deposition (UHV/CVD).4 Bipolar transistors are formed in the Ge layer. Unlike the simpler transistors formed in silicon technology, SiGe required transistors with hetrostructures or heterojunctions. These are structures with several layers and specific dopant levels to allow high frequency operations (see Chapter 16).

A comparison of the major semiconducting production materials and silicon dioxide is presented in Fig. 2.14...

Table of Contents

Chapter 1: The Semiconductor Industry. Chapter 2: Semiconductor Materials and Process Chemicals. Chapter 3: Manufacturing Wafers. Chapter 4: Overview of Wafer Fabrication. Chapter 5: Contamincation Control. Chapter 6: Process Yields. Chapter 7: Oxidation. Chapter 8: Basic Patterning - Surface Preparation to Exposure. Chapter 9: Basic Patterning - Developing to Final Inspection. Chapter 10: Advanced Photolithography Processes. Chapter 11: Doping. Chapter 12: Deposition. Chapter 13: Metallization. Chapter 14: Process and Device Evaluation. Chapter 15: The Business of Wafer Fabrication. Chapter 16: Semiconductor Devices and Integrated Circuit Formation. Chapter 17: Integrated Circuit Types. Chapter 18: Packaging. Index.

Editorial Reviews

Using a math-free approach, Van Zant, a semiconductor manufacturing consultant and trainer, explains the stages of the manufacturing process, from the raw materials needed, to packaging and shipping the final product. This time-tested guide also includes discussions of testing, commercial integrated circuit types, the history of the industry, and recent technological advances in semiconductor development, such as copper metallization, damascene patterning, and new cleaning techniques. Annotation c. Book News, Inc., Portland, OR (booknews.com)

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