Robert L. Hance

Application of IR variable angle spectroscopic ellipsometry to the determination of free carrier concentration depth profiles

Abstract Free carrier concentration profiles were determined by Fourier Transform Infrared (FTIR) variable angle spectroscopic ellipsometry. The technique exploits carrier absorption in the mid-infrared spectral range and combines the sensitivity of ellipsometry with a simple Drude free carrier absorption model to determine the carrier profile. In this study, the carrier profiles were modeled as graded multilayers that were constrained to a specific functional form (e.g. Gaussian, complementary error function) when appropriate. Carrier profiles from boron and arsenic ion-implanted that had been subjected to furnace or Rapid Thermal Annealing (RTA) annealed silicon wafers were compared to Spreading Resistance Probe and Secondary Ion Mass Spectrometry profiles. p−p+doped epitaxial silicon samples (before and after annealing) were also measured and the results were compared to theory.

Investigation of hydrogen induced changes in SrBi2Ta2O9 ferroelectric films

The effect of hydrogen on strontium bismuth tantalate (SrBi2Ta2O9; SBT) ferroelectric capacitors is investigated. Using several analytical techniques such as x-ray diffraction, electron diffraction, Auger electron, scanning and transmission electron microscopies, the structural and compositional changes in the ferroelectric film are studied as a function of annealing gas and temperature. The mechanism for hydrogen induced damage to the capacitor is identified. Measurements show that the hydrogen induces both structural and compositional changes in the ferroelectric film. Hydrogen reacts with the bismuth oxide to form bismuth and the reduced bismuth diffuses out of the SBT film causing the electrodes to peel.

Iridium film growth with indium tris-acetylacetonate: oxygen and substrate effects

Oxygen and substrate effects on iridium film growth have been investigated by metallorganic chemical vapor deposition (MOCVD), insitu X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Iridium trisacetylacetonate, Ir(CH3COCHCOCH3)3, was used as the Ir precursor. High purity CVD Ir films were obtained when this precursor was codosed with oxygen. Without oxygen, the Ir film contains noticeable carbon. The presence of oxygen not only removes carbon, but also prevents carbon incorporation from other reactive gas components, such as acetone. Oxygen also controls the film deposition rate and has a significant impact on the film morphology. Substrate effects on the initial growth rate are evidenced by the fact that the growth rate on a titanium-carbonitride (TiCN) surface is significantly higher than that on an SiO2 surface. Selective deposition in the presence of oxygen was also observed: compared to SiO2 and Ta2O5 substrates, no deposition (or very slow deposition) was observed on sapphire at 400°C. The topography of films grown on the various substrates was compared using AFM. Ir was roughest when deposited on SiO2 using a low oxygen flow rate. This is because the initial growth of Ir films on SiO2 follows a three-dimensional growth mode on isolated islands,

Fluorine diffusion on a polysilicon grain boundary network in relation to boron penetration from P/sup +/ gates

The combined effect of boron penetration and fluorine transport from P/sup +/ polycrystalline gates on flat-band voltage is studied. The SIMS concentration depth profiles elucidate the effect of annealing temperature on the fluorine transport, which in turn affects the boron penetration induced change in flat-band voltage. The fluorine diffusion in the poly gate is dominated by grain boundary diffusion. The identification of this mechanism is supported by SIMS profiles and a simulation based on a new methodology of network diffusion.<<ETX>>

Evaluation of precursors for chemical vapor deposition of ruthenium

Abstract Several commercially available organometallic precursors have been evaluated for metallorganic chemical vapor deposition (MOCVD) of pure ruthenium films. Of these, only a dimer, [RuC5H5(CO)2]2, proved suitable for CVD. On patterned Si3N4 and flat barium strontium titanate (BST), pure, conductive, conformal ruthenium films were grown from this dimer when oxygen was used as a reaction gas. Without oxygen, significant amounts of carbon were incorporated into the film. Oxygen and substrate temperature effects on ruthenium CVD film growth were investigated by resistivity measurements, in situ X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Growth conditions and possible mechanisms are discussed.

Iridium precursor pyrolysis and oxidation reactions and direct liquid injection chemical vapor deposition of iridium films

Abstract Pyrolysis and oxidation reactions of the iridium precursor, (methylcyclopentadienyl)(1,5-cyclooctadiene)iridium (I), were studied to identify the role of O 2 in chemical vapor deposition film growth. A toluene solution of (methylcyclopentadienyl)(1,5-cyclooctadiene)iridium (I) was used in a direct liquid injection chemical vapor deposition process with O 2 to deposit iridium films on SiO 2 and TiN(111) substrates. The precursor decomposition studies revealed O 2 decreases the reaction temperature of (methylcyclopentadienyl)(1,5-cyclooctadiene)iridium (I) from near 760 K to temperatures below 465 K. Oxidation of the precursor ligands acts to prevent greater than 99% of the carbon from incorporating into the deposited film, making the growth surface more reactive. The precursor and oxygen react to form CO, CO 2 and H 2 O. Pure iridium films were deposited on SiO 2 and TiN(111) substrates at temperatures between 550 and 625 K. Under identical conditions, the film nucleation and coalescence rates are nearly 2 times higher on the TiN(111) substrate with 0.22 torr O 2 . The ratio of (111) to (200) X-ray diffraction intensities resembled Ir powder for films deposited on SiO 2 , the same ratio was more than 9 times larger than that of Ir powder for Ir films produced on TiN(111). Decreasing the oxygen partial pressure from 0.66 to 0.22 torr resulted in a 75% reduction in the film growth rate and a 40% reduction in film roughness. Conformal (step coverage approaching unity) iridium films were produced at 550 K in aspect ratio 1–0.25 μm vias in SiO 2 and in aspect ratio 2.5–0.35 μm vias in TiN(111).

Effects of precursors and substrate materials on microstructure, dielectric properties, and step coverage of (Ba, Sr)TiO3 films grown by metalorganic chemical vapor deposition

(Ba, Sr)TiO3 (BST) thin films have been grown on planar Ir/Si and Pt/Si substrates and on three-dimensional (3D) Ir electrodes by metalorganic chemical vapor deposition using two kinds of β-diketonate-based BST precursors. Film growth was studied as a function of film thickness, composition, and substrate temperature. Growth rate was monitored by in situ spectroscopic ellipsometry. The BST films were characterized ex situ by a variety of techniques including x-ray photoelectron spectroscopy, Auger electron microscopy, atomic force microscopy, transmission and scanning electron microscopy, x-ray diffraction, and impedance analyzer. The results reveal that the two sets of BST precursors, albeit slightly different, show quite different reactivities that strongly affect the step coverage on the 3D structure. However, different reactivities have no apparent effect on the microstructure, surface morphology, and dielectric properties of the stoichiometric BST films. These properties strongly depend on the film c...

Al/W/TiN/sub x//TiSi/sub y//Si barrier technology for 1.0- mu m contacts

A reliable contact diffusion barrier has been successfully formed by sintering in nitrogen a physically sputtered W/Ti bilayer. After a 650 degrees C furnace anneal, a TiN/sub x//TiSi/sub y/ layer on contact with the silicon substrate was formed beneath the overlying W. No reaction between N/sub 2/ and W was observed. Arsenic implanted in the silicon substrate tended to retard the silicidation of titanium. Substantial redistribution of both B and As across the silicide layer was also observed during the contact sintering process. The 1.0- mu contacts fabricated with the Al/W/TiN/sub x//TiSi/sub y//Si barrier technology exhibited low and tightly distributed contact resistivities (less than 10/sup -6/ Omega -cm/sup 2/). No excessive leakage of the shallow junctions was observed even after thermally stressing the sample at 400 degrees C for 8 h.<<ETX>>

Effects of Tisi x /Tin x /Al Contact Metallization Process on the Shallow Junction Related Properties

An extremely reliable TiSi x /TiN x diffusion barrier was formed by the rapid thermal annealing of a thin Ti layer which was sputtered into the contacts before Al metallization. The effects of this barrier metal process on the material properties of heavily implanted n + and p + regions were studied. The TiN x -to-TiSi x thickness ratio is determined by the dominant reaction at the sintering temperature. Arsenic implanted in the substrate tends to substantially retard the silicidation of Ti. Substantial redistribution of both B and As across the silicide layer was observed during rapid thermal annealing. Film stress was found to be greatly affected by the annealing temperature. Contact resistance, contact electromigration and thermal stability of the structure were also investigated.

An accelerated sodium resistance test for IC passivation films

A low level IC burn-in failure mechanism caused by post-passivation sodium contamination has been observed. An accelerated stress test has been developed based on SIMS, SEM and TEM analysis. The results have been compared to burn-in data. Four types of passivation films and two types of assembly processes were used to demonstrate the effectiveness of this test.