Showing papers by "Stefan E. Schulz published in 2011"

Method for the production of a substrate having a coating comprising copper, and coated substrate and device prepared by this method

Abstract: A method for producing a substrate with a copper or a copper-containing coating is disclosed. The method comprises a first step wherein a first precursor, a second precursor and a substrate are provided. The first precursor is a copper complex that contains no fluorine and the second precursor is selected from a ruthenium complex, a nickel complex, a palladium complex or mixtures thereof. In the second step, a layer is deposited at least on partial regions of a surface of the substrate by using the first precursor and the second precursor by means of atomic layer deposition (ALD). The molar ratio of the first precursor:second precursor used for the ALD extends from 90:10 to 99.99:0.01. The obtained layer contains copper and at least one of ruthenium, nickel and palladium. Finally, a reduction is performed step in which a reducing agent acts on the substrate obtained after depositing the copper-containing layer.

Influence of copper on the catalytic carbon nanotube growth process

Abstract: For Cu/carbon nanotube(CNT) hybrid interconnect technology the growth of CNTs on a conductive substrate connected to Cu lines is required. CNTs were grown by catalytic chemical vapour deposition and the effect of a Cu layer beneath was investigated. By electron energy loss spectroscopy (EELS) we found the Cu to diffuse into the catalyst. This influences CNT growth. Therefore, incorporation of a sufficient diffusion barrier between the Cu layer and the substrate is required. As diffusion barriers we used Ta and TaN.

Thermal ALD of Cu via reduction of Cu x O films for the advanced metallization in spintronic and ULSI interconnect systems

Abstract: In this work, an approach for copper atomic layer deposition (ALD) via reduction of Cu x O films was investigated regarding applications in ULSI interconnects, like Cu seed layers directly grown on diffusion barriers (e. g. TaN) or possible liner materials (e. g. Ru or Ni) as well as non-ferromagnetic spacer layers between ferromagnetic films in GMR sensor elements, like Ni or Co. The thermal Cu x O ALD process is based on the Cu (I) β-diketonate precursor [(nBu 3 P) 2 Cu(acac)] and a mixture of water vapor and oxygen (“wet O 2 ”) as co-reactant at temperatures between 100 and 130 °C. Highly efficient conversions of the Cu x O to metallic Cu films are realized by a vapor phase treatment with formic acid (HCOOH), especially on Ru substrates. Electrochemical deposition (ECD) experiments on Cu ALD seed / Ru liner stacks in typical interconnect patterns are showing nearly perfectly filling behavior. For improving the HCOOH reduction on arbitrary substrates, a catalytic amount of Ru was successful introduced into the Cu x O films during the ALD with a precursor mixture of the Cu (I) β-diketonate and an organometallic Ru precursor. Furthermore, molecular and atomic hydrogen were studied as promising alternative reducing agents.

Electrical property improvements of ultra low-k ILD using a silylation process feasible for process integration.

Abstract: In this paper the effect of a vapor phase based silylation process on patterned test structures using ULK based ILD's was investigated. It was found that the resistance to capacitance (RC) behavior can be improved. This improvement was found to be scalable, meaning with decreasing metal pitch the RC improvement increases. The silylation process provides in addition a decrease of the leakage current and was found to have adequate defectivity. As the process is feasible for production and the improvement of the electrical properties increases with smaller feature size, it can be assumed that extra costs of the restoration process will be paid out for future technology nodes, if ULK as an ILD is used.

Surface modification of porous low-k material by plasma treatment and its application on reducing the damage from sputtering and CMP process

Abstract: The influence of CH 4 , H 2 , NH 3 and He plasma on the properties of porous low-k material is studied. It is found that the H 2 , He, NH 3 plasma can cause huge carbon depletion in the porous low-k material, and change the low-k surface from hydrophobic to hydrophilic, which will induce moisture uptake into the low-k material during the CMP process, and results in the increase of the k value and leakage current. The CH 4 plasma can make low-k material more resist against moisture uptake and keep the k value and leakage current of low-k films stable.

A Less Damaging Patterning Regime for a Successful Integration of Ultra Low-k Materials in Modern Nanoelectronic Devices

Abstract: This paper describes a three-step process regime for the integration of porous SiCOH based ultra low-k materials in existing copper damascene technologies. During the work with these complex and sensitive materials, it became more and more clear, that a successful patterning depends not only on the etch step but also on the adjustment between the etch and the following cleaning and k-restore processes. The presented process regime starts with a reactive ion etch process for trench patterning followed by a post etch clean to remove etch residues. Finally a k-restore process was performed to repair the damaged regions in the trench sidewalls. In this work it became clear, that the etch chemistry influences not only the results of the etch process ostensibly sidewall damage but also kind and effect of the post etch clean. Each plasma composition results in the necessity of a customized post etch cleaning solution. Finally a k-restore process using Hexamethyldisilazane (HMDS) as restore chemical was demonstrated successfully. Enhanced temperatures and an additional UV-treatment are possibilities to promote the restore effect.