Transmission line method (TLM) structures are often employed to extract contact resistivity between a metal and a doped semiconductor region. In this article we treat the situation where the doped region is junction-isolated from the substrate. The junction isolation may be leaky resulting in erroneous parameter extraction. The effect of junction leakage is treated both theoretically and through exemplary wafer-level CTLM measurement results on photovoltaic cells (solar cells) and epi-wafer samples. This paper describes how reliable contact resistivity values can be obtained using the transmission line method on junction isolated structures.

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 discussed.

The high-aspect ratio capability of SU-8 photoresist led to the successful use of this epoxy based material in a diversity of microfabricated devices as a construction material as well as for micromolding purposes. Throughout the literature it was noticed that the thermal mismatch of SU-8 and the substrate material silicon generates high film stress in the spin-coated SU-8 causing crack formation in the microstructures. Using baking parameters this crack formation can be minimized but will remain a critical aspect of design. In this study the process was first optimised on non-patterned wafers. Secondly, we transferred this optimised process to a pre-patterned wafer containing deep silicon etch pits to account for a specific application in micromolding. We discuss the behaviour of film stress, number of cracks and crack length. The number of cracks as well as the length of cracks in concave corner designs can be significantly decreased, while round holes resulted even in crack-free microstructures. In the case of pre-patterned wafers no cracks appear around the features, however we observed unsatisfied development within the resist features caused by insufficient solidification in the deep etch pits during Soft Bake. Increased Soft Bake time can overcome these problems but will require more systematic investigations.

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.

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 T. 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.

W and W1-xNx , where x= 15- 22 at%, thin films were grown using the ALD (Atomic Layer Deposition) principle. Growth rate of W films is about 4- 5 monolayers/ cycle at 300- 350 oC. Growth rate of W1-xNx is 0.5 monolayer/cycle at 325- 350 oC. Standard Deviation (STDV) of thickness is about 2% for 20nm layers. Specific resistivity is 180 mW cm for W and as low as 220-340 mWcm for W1-xNx 20nm films. 4- point probe sheet resistivity test is applied to Cu/ Barrier/ SiO2 stacks with ramping temperature. No changes of normalized resistance reflecting Cu-Barrier interaction was measured after 500 oC annealing cycle

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 250°C. Thermodynamical calculations for the WF6:NF3:SiH4:Ar system at different ratios of gas components were made. Simultaneously an experimental study was performed at different deposition conditions. At 385°C, crystalline layers, and at 250°C, amorphous layers with smooth surfaces were obtained under several conditions. The resistivity of W–Si–N layers deposited at 385°C decreases from 3000 μΩ cm to 550 μΩ cm as the W/N ratio increases from 1.3 to 10.2.

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=0.90-0.92