In-Situ-Messungen der mechanischen Spannungen in gesputterten Metall- und Oxidschichten

This thesis covers the stress evolution in thin sputtered metal and oxide films. To achieve this, a deposition system for reactive direct-current sputtering with integrated in-situ wafer curvature setup has been developed and is presented here. At first, metal films (zinc, zirconium, niobium and titanium) have been deposited and analyzed during growth. By mixing oxygen into the sputter gas, the corresponding oxide films have been obtained. The stress evolution during the growth of the metals depends strongly on the mobility of the deposited material and therefor on its melting point. Zinc with a low melting point exhibits the same stress development which has been observed during growth of evaporated films of high mobility. Due to its high mobility, all defects, which occur due the bombardment by reflected argon during sputtering can anneal. In the case of the low mobility metals, effects of the grain boundaries leading to tensile stress and of the bombardment leading to compressive stress have been observed. The analysis of the stress changes upon change of stoichiometry from metallic to oxidic films reveal that these changes cannot be explained by a single effect only. On the one hand, the target oxidizes, which changes the bombardment of the growing film and on the other hand, the growth of the film is affected directly. Adding small amounts of oxygen into the sputter gas leads to nano-crystalline films by immobilizing the grain boundaries of the growing metallic film. This causes high tensile stresses even if the same metallic film grown at the same deposition conditions just without addition of oxygen contained compressive stresses. The oxygen also influences the sputter target, which oxidizes increasingly upon increasing oxygen flow, until the whole target is covered with an oxide layer. In this growing oxide layer, an increasing number of oxygen ions is created, which is accelerated towards the substrate and causes high compressive stresses. Changes between the different oxides have also been found in the beginning of growth. The amorphous oxides niobium oxide and titanium oxide exhibit tensile stresses in the beginning of growth, while the crystalline oxides zinc oxide and zirconium oxide no tensile stresses can be found. Here, the compressive stresses dominate already in the beginning of the growth process. This behavior has been related to the structure and therefor to the different amount of grain boundaries in the material.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2005

Author dc:creator

• Drese, Robert Jens

Contributors dc:contributor

• Wuttig, Matthias

• info:eu-repo/classification/ddc/530
• Physik
• in-situ
• mechanische Spannungen
• dünne Schichten
• Sputter Deposition
• Wafer-Curvature
• stress
• thin films
• wafer curvature

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-124219%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62691