Luc Geenen

New low-stress PECVD poly-SiGe Layers for MEMS

Thick poly-SiGe layers, deposited by plasma-enhanced chemical vapor deposition (PECVD), are very promising structural layers for use in microaccelerometers, microgyroscopes or for thin-film encapsulation, especially for applications where the thermal budget is limited. In this work it is shown for the first time that these layers are an attractive alternative to low-pressure CVD (LPCVD) poly-Si or poly-SiGe because of their high growth rate (100-200 nm/min) and low deposition temperature (520/spl deg/C-590/spl deg/C). The combination of both of these features is impossible to achieve with either LPCVD SiGe (2-30 nm/min growth rate) or LPCVD poly-Si (annealing temperature higher than 900/spl deg/C to achieve structural layer having low tensile stress). Additional advantages are that no nucleation layer is needed (deposition directly on SiO/sub 2/ is possible) and that the as-deposited layers are polycrystalline. No stress or dopant activation anneal of the structural layer is needed since in situ phosphorus doping gives an as-deposited tensile stress down to 20 MPa, and a resistivity of 10 m/spl Omega/-cm to 30 m/spl Omega/-cm. With in situ boron doping, resistivities down to 0.6 m/spl Omega/-cm are possible. The use of these films as an encapsulation layer above an accelerometer is shown.

Modulation of the Ni FUSI workfunction by Yb doping: from midgap to n-type band-edge

The key result in this work is the experimental demonstration that adding Yb to Ni FUSI allows for tuning the work function (WF) from midgap (NiSi ~4.72 eV) to n-type band-edge (~4.22 eV) on thin SiON, maintaining same EOT. In addition, we did not observe any interface adhesion issues found in other reports when WF is modulated by dopants such as As or Sb. We also show that reliability is similar to Ni FUSI. This is a promising technique for nFET gate electrode formation and enables dual gate CMOS technologies for 45 nm and beyond in a manufacturable way

Analysis of selectively grown epitaxial Si1-xGex by spectroscopic ellipsometry and comparison with other established techniques

The increased interest in epitaxial Si 1-x Ge x /Si heterostructures for device applications requires very good control of layer thickness and composition. Unfortunately, most of the well-developed characterization methods, such as Rutherford backscattering spectroscopy (RBS), secondary ion mass spectroscopy, and photoluminescence measurements are unsuitable as production measurement tools. On the other hand, spectroscopic ellipsometry (SE) allows a fast, in-line, and nondestructive analysis, including wafer mapping capabilities. This paper demonstrates the suitability of SE for the determination of both Ge content and layer thickness of epitaxial Si 1-x Ge x for Ge contents between 1 and 35%. By describing the optical dispersion by means of the harmonic oscillator model, we obtained a clear correlation between the Ge content and E n (1), the resonant energy of the first oscillator, and n max , the peak value of the real part of the refractive index. The small spot (30 × 30 μm) size allows one to characterize Si 1-x Ge x layers selectively grown in an isolation structure. The small window size prevents RBS measurements. SE allowed the fine tuning of a selective epitaxial growth process with regard to growth rate, Ge incorporation, and wafer uniformity.

Selective Epitaxy of Si/SiGe to improve pMOS devices by recessed Source/Drain and/or Buried SiGe Channels

SiGe R. Loo, P. Verheyen, R. Rooyackers, C. Walczyk*, F.E. Leys, D. Shamiryan, P.P. Absil, T. Delande, A. Moussa, J.W. Weijtmans, R. Wise, V. Machkaoutsan, C. Arena, J. McCormack, S. Passefort, H. Sorada, A. Inoue, B.C. Lee, S. Hyun, S. Jakschik, and M. Caymax 1 IMEC, Kapeldreef 75, 3001 Leuven (Belgium), *also Universitat Siegen, Holderlinstrasse 35, 7068 Siegen (Germany), Texas Instruments Inc., 13560 North Central Expressway, Dallas (USA), ASM-Belgium, Kapeldreef 75, 3001 Leuven (Belgium), ASM-America, 3440 East University Drive, Phoenix, (USA), KLA-Tencor Corp. 160 Rio Robles, San Jose (USA), Matsushita assignee at IMEC, Samsung assignee at IMEC, Infineon assignee at IMEC

Depth profiling of B through silicide on silicon structures, using secondary ion‐mass spectrometry and resonant postionization mass spectrometry

This article presents a comparison of Cameca IMS 4f secondary ion‐mass spectrometry (SIMS) measurements and resonant postionization mass spectrometry (RIMS) measurements of boron depth profiles in silicide/silicon samples (mainly CoSi2/Si). The emphasis of the comparison was on the shape of the profiles obtained with both techniques. For the SIMS data, we used a quantification procedure including a correction for sensitivity differences in both matrices. The RIMS sensitivity in CoSi2, TiSi2, and Si was explicitly compared using special test samples and shown to be identical to within 15%. Finally, we present preliminary results of the application of SIMS and RIMS to a number of CoSi2/Si samples with an unknown B profile. After application of the correction procedures, both techniques appear to produce nearly identical profile shapes in case of polycrystalline CoSi2 samples. For epitaxially grown crystalline CoSi2, however, differences sometimes remain, depending on the temperature of the second silicidati...