Low Stressed In-situ Boron doped Poly SiGe Layers for High-Q Resonators

Polycrystalline silicon-germanium (Poly SixGe1-x) can be used as one of the microstructural materials for MEMS due to its superior mechanical properties [1,2], high quality factor [3] and low thermal budget requirements based on the Ge contents [4] (<450 oC) for post processing on top of CMOS chip. This work deals with the characterization of in-situ boron doped poly SiGe layers LPCVD deposited at 430 oC with a mixture of 0.2% diborane (B2H6) in Argon on 110 nm SiO2. The concerned properties like sheet resistance and residual stress in the deposited layers are investigated at diborane mixture flow of 50 sccm and 100 sccm. It is observed that the deposition rate is decreased with the increase of B2H6 mixture flow. Whereas, the resistivity of these deposited layers decrease linearly with the increase of B2H6 mixture flow. The stress in the deposited layers shows a trend from low tensile to low compressive with the increase of diborane mixture flow. The properties of the layers deposited at 50 sccm of diborane mixture flow shows good results in terms of resistivity, deposition rate, cross load thickness uniformity and residual stress and therefore qualify them to use as structural layers for the realization of disk resonator

Electrical characterization of hot-wire assisted atomic layer deposited Tungsten films

In this work, we applied conventional Van der Pauw and circular transmission line method (CTLM) test structures to determine the sheet and contact resistance of ultra-thin (1-10 nm) tungsten films grown by Hot Wire assisted Atomic Layer Deposition, as well as their temperature coefficient of resistance (TCR). We finally explored the field effect (FE) in these layers

Low-Stress Highly-Conductive In-Situ Boron Doped Ge_0.7Si_0.3 Films by LPCVD

This paper reports on low pressure chemical vapor deposited in-situ boron doped polycrystalline germanium-silicon layers with 70% germanium content. The effect of diborane partial pressure on the properties of the GeSi alloy is investigated. The obtained high boron concentration results in resistivity values less than 1 m_-cm. The layers deposited at low partial pressures of B2H6 exhibit very low stress down to –3MPa.With increasing B2H6 partial pressure first the stress changes from tensile to compressive, followed by a phase transition from polycrystalline to amorphous. The highly doped, low stress poly-Ge0.7Si0.3 layers deposited at 430◦C are further applied in high-Q microelectromechanical resonators envisaged for above-IC integration with CMOS

Electrical properties of plasma-deposited silicon oxide clarified by chemical modeling

Our study is focused on Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon dioxide films at low temperatures (< 150 oC) using Inductively Coupled (IC) High-Density (HD) plasma source. We recently fabricated Thin Film Transistors (TFTs) with high-quality ICPECVD gate oxides, which exhibited a competitive performance. For better understanding of the influence of deposition parameters on both the deposition kinetics and oxide quality, we have modeled the Ar-SiH4-N2O plasma system with 173 chemical reactions. We simulated concentrations of 43 reactive species (such as e.g. SiHx radicals and SiHx + (x=0-3) ions, polysilanes, SiO, SiN, SiH3O, SiH2O, HSiO, etc., as well as atomic hydrogen, nitrogen and oxygen) in plasma. We further used our simulations to qualitatively explain (in terms of concentrations of the reactive species) the influence of SiH4/N2O gas-flow ratio and total gas pressure on film electrical properties and deposition rate

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

Effects of Oxygen, Nitrogen and Fluorine on the Crystallinity of Tungsten by Hot-Wire Assisted ALD

A heated tungsten filament (wire) is well known to generate atomic hydrogen (at-H) by catalytically cracking molecular hydrogen (H2) upon contact. This mechanism is employed in our work on hot-wire (HW) assisted atomic layer deposition (HWALD), a novel energy-enhancement technique. HWALD has been successfully utilized to deposit tungsten (W) films using alternating pulses of WF6 and at-H. Depending on the conditions, either low-resistivity α- or higher-resistivity β-crystalline phases of W can be obtained. This work aims to clarify (i) which factors are decisive for the formed crystal phase and (ii) the role of the residual gases in the film growth mechanism. In this light, the effects of adding impurities (N2O, O2, NH3 and H2O) were investigated. Oxidizing species have a retarding effect on W growth but the process can be re-initiated after stopping their supply. In contrast, nitridizing species have a permanent inhibition effect. Further, the effects of WF6 overdose were studied. The surplus of WF6 appeared to be crucial for the process: in many cases this led to the formation of β-phase W instead of the α-phase, with a memory effect lasting for several deposition runs. Extra fluorine-containing species were thus identified as the likely cause of β-phase formation

Deposition of thin layers containing Ga, C and N by sequential pulses of Trimethylgallium and Ammonia

Gallium nitride (GaN) is a semiconductor with broad applications in the (opto-)electronic industry. State-of-the-art fabrication of GaN demands a nanometer-level control over layer thickness, which can be achieved with atomic layer deposition (ALD). Introducing carbon (C) into GaN layers, similar to introducing C into BN [1] or as a dopant in GaN [2], can facilitate control over material properties such as the band-gap and resistivity, respectively. In this work, we report on our results obtained from thermal deposition of layers, containing varying concentration of gallium (Ga), carbon (C) and nitrogen (N), from trimethylgallium (TMG) and ammonia (NH3) precursors. The precursors were sequentially introduced in a pulsed mode, i.e., without mixing them

Langmuir-probe characterization of an inductively-coupled remote plasma system intended for CVD and ALD

We measured electron density and electron energy distribution function (EEDS) vertically through our reactor for a range of process conditions and for various gases. The EEDF of Ar plasma in the reactor could largely be described by the Maxwell-Boltzmann distribution function, but it also contained a fraction (~10-3) of electrons which were much faster (20-40 eV). At low pressures (6.8-11 µbar), the tail of fast electrons shifted to higher energies (Emax ~50 eV) as we measured more towards the chuck. This tail of fast electrons could be shifted to lower energies (Emax ~30 eV) when we increased pressure to 120 µbar or applied an external magnetic field of 9.5 µT. Addition of small amounts of N2 (1-10%) or N2O (5%) to Ar plasma lowered the total density of slow electrons (approx. by a factor two) but did not change the shape of the fast-electron tail of the EEDF. The ionization degree of Ar-plasma increased from 2.5 104 to 5 104 when an external magnetic field of 9.5 µT was applied