Characterisation of Ta-based barrier films on SiLK for Cu-metalisation

Structures with Ta, TaxN1-x, Ta90C10, Ta95Si5 on SiLK were tested using in-situ 4- point probe resistance measurements during annealing up to 400oC. The change in normalized resistance by a factor of up to 2.58 was attributed to oxygen diffusion out of SiLK layer into the barriers. No direct chemical reaction between hydrocarbons from the SiLK and the barriers was observed. The concentration coefficient of resistivity for O in Ta was calculated to be 6.7μΩ*cm/at % for pure Ta and 2.65 μΩ*cm/at % in TaxN1-x with x=0.90-0.9

Atomic layer deposition of W_1.5N barrier films for Cu Metallization

An atomic layer deposition process to grow tungsten nitride films was established at 350 degrees C with a pulse sequence of WF6/NH3/C2H4/SiH4/NH3. The film composition was determined with Rutherford backscattering as W1.5N, being a mixture of WN and W2N phases. The growth rate was similar to 1 x 10(15) W atom/cm(2) per cycle (monolayer of W2N or WN). The films with a thickness of 16 nm showed root-mean-square roughness as low as 0.43-0.76 nm. The resistivity of the films was stable after 50 cycles at a value of 480 mu Omega cm. Results of four-point probe sheet resistance measurements at elevated temperature demonstrated that our films are nonreactive with Cu at least up to 500 degrees C. Results of I-V measurements of p(+)/n diodes before and after heat-treatment in (N-2 + 5% H-2) ambient at 400 degrees C for 30 min confirmed excellent diffusion barrier properties of the films. (c) 2005 The Electrochemical Society. All rights reserved

Diffusion barriers for Cu metallisation in Si integrated circuits:deposition and related thin film properties

In modern integrated circuits with Cu interconnects a diffusion barrier is used between the dielectric and Cu in order to prevent diffusion of Cu through the dielectrics. The choice of such a barrier requires a material exploration and a study of the material reactivity with both Cu and the dielectric used in the back-end processing. This thesis presents results of a study focused on the growth processes of tungsten nitride silicide films by CVD; tungsten nitride and tungsten carbidonitride films by ALD. The suitability of these materials as a diffusion barrier has also been evaluated by testing film properties such as resistivity, RMS-roughness, the reactivity with Cu, blocking properties to Cu diffusion and adhesion. A combination of Cu and the tungsten silicide nitride with a Si to W ratio ≥0.8 has shown Si diffusion out of the barriers into Cu resulting in a large increase of Curesistivity. Thus, these materials failed the criterion of low reactivity with Cu, which has been tested with four-point probe in situ sheet resistance measurements at elevated temperatures. Tungsten nitride and tungsten carbonitride films are shown to have low reactivity with Cu. Moreover, good blocking properties of these films against Cu and Al diffusion have been demonstrated on capacitors and p+/n diodes

Micromolding for ceramic microneedle arrays

The fabrication process of ceramic microneedle arrays (MNAs) is presented. This includes the manufacturing of an SU-8/Si-master, its double replication resulting in a PDMS mold for production by micromolding and ceramic sintering. The robustness of the replicated structures was tested by means of microindentation techniques eliminating shear forces and by manual application of MNAs into silicone rubber. No damages of MNAs were observed using controlled microindentation. After the manual application, however, some microneedles were broken and left in the silicone. The opportunities and the ways to solve underlying problems of the fabrication process will be suggested and discusse

Growth and Properties of LPCVD W-Si-N Barrier Layers

In this work the low-temperature low pressure chemical vapour deposition (LPCVD) of W–Si–N compounds in the WF6–NF3–SiH4–Ar system is presented. Layers were deposited on oxidised Si-wafers at 385 and 25

Barrier properties of ALD1,5N thin films

W1.5N films grown by ALD from WF6, NH3, C2H4 and SiH4 as precursors were tested as Cu diffusion barriers in p+/n diodes and capacitors with SiO2 as a dielectric. I-V and C-V, C-t characteristics were measured before and after anneal. The layers exhibit excellent barrier properties against both Cu and Al interaction with silicon. No changes of current and capacitance attributed to a barrier failure were observed after annealing at 400°C. Samples without the barrier showed a drastic change of the I-V characteristics. The composition of the films was W1.5N as determined with RBS, being a mixture of WN and W2N phases The RMS- roughness was as low as 0.5-0.7 nm for a film with a thickness of 25 nm. © 2005 Materials Research Society

Applying ceramic nanoporous microneedle arrays as a transport interface in egg plants and an ex-vivo human skin model

Nanoporous microneedle arrays from Al2O3 were fabricated via a micromolding process using a PDMS mold generated via a double replication process from a SU-8/Si-master as a template. Hg-porosity measurements showed that the porosity obtained was a function of the temperature used for sintering, resulting in an average pore diameter of 80 nm between 1300 and 1500 °C. Using egg plants it was shown that these nanoporous needles allowed both the delivery of substances, and the extraction of compounds. Subsequently, the delivery of compounds has been evaluated in an ex vivo human skin model using a microneedle array saturated with a labeled monoclonal against a specific marker, DC-SIGN, which is representative for dendritic cells when activated by an antigen. By the latter, it was demonstrated that ceramic nanoporous microneedle arrays are potentially useful for the delivery of vaccine