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Title
TOF-SIMS investigations of metal impurities in silicon / Lukas Widder
AuthorWidder, Lukas
CensorHutter, Herbert
Published2008
Description86 Bl. : Ill., graph. Darst.
Institutional NoteWien, Techn. Univ., Dipl.-Arb., 2008
Annotation
Zsfassung in dt. Sprache
LanguageEnglish
Document typeThesis (Diplom)
Keywords (DE)TOF-SIMS / Gettering / Diffusion / Kupfer / Natrium / Silizium
Keywords (EN)TOF-SIMS / Gettering / Diffusion / Copper / Sodium / Silicon
Keywords (GND)Massenspektrometrie / Getterung / Diffusion / Kupfer / Natrium / Silicium
URNurn:nbn:at:at-ubtuw:1-23563 Persistent Identifier (URN)
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 The work is publicly available
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TOF-SIMS investigations of metal impurities in silicon [1.63 mb]
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Abstract (German)

In dieser Arbeit wurde Diffusion von Kupfer und Natrium in Silizium untersucht. zuerst wurden Gettering Effekte in Silizium Wafern untersucht. Durch Ionenimplantation und thermische Behandlung werden bestimmte Defekt in Silizium generiert. An diesen Fehlstellen werden diffundierende Kupferatome gesammelt. Dieses Verfahren wird benutzt um in Halbleiterbauteilen aktive Regionen frei von Verunreinigungen zu halten.

Diese Messungen wurden durchgeführt um die Vergleichbarkeit des neuen TOF-SIMS Gerätes mit vorhergehenden Messungen zu überprüfen. Es wurden n-type und Bor-gedoptes Silizium untersucht, in das Sauerstoff, Phosphor oder Silizium Atome implantiert wurden.

Der zweite Teil beschäftigt sich mit der Oberflächendiffusion von Natrium in Silizium. In dieser Arbeit werden einleitende Versuche zu Diffusion von Natriumverunreinigungen in Silizium durchgeführt.

Alle Messungen wurden auf dem TOF-SIMS-Gerät der Arbeitsgruppe Prof.

Herbert Hutter durchgeführt.

Abstract (English)

In this work focus is on copper and sodium impurities in silicon. First, gettering effects in the silicon wafer bulk are investigated. Through ion implantation and annealing processes certain defects are produced in well controllable depths. Copper atoms diffusing through the wafer bulk gather at these lattice defect sites. This proximity gettering procedure is used to keep active device regions free of impurities. Recent investigations of this problem have been done on the previous SIMS (secondary ion mass spectrometry) instrument, so comparability to the use of the new TOF-SIMS instrument was examined.

Two different types of silicon, n-type silicon and highly boron doped silicon, respectively, are used to investigate copper gettering behaviour of oxygen, phosphorus, and silicon ion implanted wafer structures. As a second subject of investigation surface diffusion of sodium into silicon was examined. Sodium is another impurity detrimental to semiconductor devices. It is almost ubiquitous and hardly controllable.

During device manufacturing processes sodium consistently contaminates the silicon surface. In this paper, some preliminary studies of sodium diffusion after sodium containing molecules were applied onto the silicon wafer surface were conducted. Samples were annealed at various temperatures to investigate sodium diffusion barriers and behaviour.

All our measurements were carried out using the fairly new ION-TOF5 instrument. Semiconductor industries work with highly pure silicon material, therefore already low concentrations of impurities can deteriorate the properties and characteristics of semiconductor devices.

SIMS is an excellent analytic method to determine trace elements and impurities in metals and semiconductors due to its very low detection limits and the ability to measure depth profiles.

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