Triangular Voltage Sweep Measurements Research Articles

Self-Controlled Constant-Current Temperature Stress for Triangular Voltage Sweep Measurements of Cu

We present a new methodology for the characterization of Cu diffusion barriers, which is based on Triangular Voltage Sweep (TVS) measurements of Cu+ after Constant-Current Temperature Stress (CCTS). We show that CCTS-TVS measurements are effective for identifying defective Cu diffusion barriers. Finally, we discuss about mechanisms of Cu+ drift into dielectrics.

Self-Controlled Constant-Current Temperature Stress for Triangular Voltage Sweep Measurements of Cu

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Comparison of PVD, PECVD & PEALD Ru(-C) films as Cu diffusion barriers by means of bias temperature stress measurements

The diffusion barrier properties of PVD Ru and PECVD / PEALD Ru-C films, deposited by RuEtcp 2 precursor and N 2/H 2 plasma, were compared on the basis of bias temperature stress measurements. An MIS test structure was used to distinguish between thermal diffusion induced by annealing and a Cu field drift due to applied electric fields. BTS-CV, TZDB and TDDB measurements revealed that the barrier performance is significantly better for PEALD and PECVD Ru-C films. This improvement is associated with carbon impurities in the Ru films with a concentration in the order of several percent according to ToF-SIMS and ERDA. The TDDB mean time to failure at 250 °C, +5 MV/cm was 7 s for PVD Ru samples, ≈500 s for PECVD Ru-C, ≈800 s for PEALD Ru-C and >3600 s for PVD TaN. Triangular voltage sweep measurements at 300 °C, 0.1 V/s confirmed the presence of Cu ions inside the SiO 2 for degraded dots, in contrast to the Al reference sample and to PVD TaN, which performed best among all the Cu barriers under test. XRD data suggests that PEALD and PECVD Ru-C films are only weakly crystalline.

Characterization of Plasma Damage in Low-k Films by TVS Measurements

AbstractWe evaluated Triangular Voltage Sweep (TVS) measurements as a technique to characterize plasma damage in low-k films. Blanket wafers with low-k films of different porosity and k value were prepared. Our samples included an SiOC:H material with 7% porosity and k value of 3.0, deposited on 200mm wafers, and two SiOC:H materials with 25% porosity and k value of 2.5, deposited on 300mm wafers. Before deposition, a thin layer of dry thermal oxide (2 – 5 nm) was grown on the n-type wafers to stabilize the silicon interface. After deposition, low-k films were exposed to N2/H2 plasma for different times in order to induce different degree of plasma damage. Untreated low-k films were always included as a reference. For electrical measurements, metal dots were deposited on pieces to fabricate Metal-Insulator-Semiconductor capacitors.TVS measurements were performed at 190°C on the different samples. On samples exposed to N2/H2 plasma, we detected a current peak in the TVS trace, whose magnitude increased with exposure time to plasma. No peaks were detected on untreated films. This indicates that TVS measurements are sensitive to plasma damage. Furthermore, TVS results correlated well with FTIR spectra that showed increasing damage and H2O uptake with increasing exposure time to plasma. We conclude that TVS measurements are suitable for characterizing the degree of plasma damage in low-k films and complement well materials analysis, because with the help of TVS a link to leakage properties can be made. As an application, we used TVS measurements for evaluating restoration of plasma damaged low-k films by long N2-bake at high temperature. Wafer pieces from each sample were baked at 350°C for 4h30min in N2 atmosphere. A few pieces were measured immediately after baking. The remaining pieces were either left exposed to ambient for a few days or dipped in deionized H2O for a few hours to evaluate recovery of hydrophobic properties. The different treatments (N2-bake, exposure to ambient, H2O dipping) were always performed on blanket wafer pieces. Metal dots for electrical measurements were only deposited after the treatment. CV and FTIR measurements were performed before and after treatments to evaluate change in k-value and material structure, respectively. Our data show that long N2-bake at high temperature can partially restore damaged low-k films. The magnitude of the damage-related TVS peak was significantly reduced after heat treatment and remained stable even after H2O dipping. CV measurements performed on baked pieces after 6 days of exposure to ambient showed a reduced k-value. Consistently, FTIR spectra showed a significant reduction of H2O content soon after baking. The materials remained stable over several days and only minor reincorporation of H2O occurred after exposure to ambient or H2O dipping. Therefore, long N2-bake at high temperature can partially restore leakage (TVS), k-value (CV) and hydrophobic properties (FTIR) of damaged low-k films.

Detection of Copper and Water in Low-k Dielectrics by Triangular Voltage Sweep Measurements

AbstractMetal-Insulator-Semiconductor (MIS) planar capacitors were fabricated in order to systematically investigate the effect of Cu and water in Cu/low-k structures by Triangular Voltage Sweep (TVS) measurements. We were able to resolve peculiar features in the TVS traces of Cu and water contaminated samples, which were related to Cu ions and protons, respectively. We demonstrate that these features can be used to distinguish the two ionic species. As these features do not depend on the specific dielectric, we provide a methodology to detect and distinguish Cu and water in porous low-k materials embedded in MIS structures.

Mobile Ion Detection in Organosiloxane Polymer Using Triangular Voltage Sweep

The triangular voltage sweep (TVS) technique has been traditionally used for mobile ion detection in gate oxides. In this paper, we present and discuss the results of TVS measurements on plasma enhanced chemical vapor deposited (PECVD) silicon oxide and a low dielectric constant hybrid organosiloxane polymer (HOSP). A variety of gate metals were studied to detect and separate mobile ion effects associated with the metal. For the PECVD oxide, no peak was detected with Al gate metal, whereas a large peak was detected with Cu; allowing us to correlate the observed peak to mobile copper ions. TVS traces revealed no peak for Pt/HOSP capacitors, but peaks were detected with Cu, Ta, and Al capacitors. Thus, the appearance of mobile ion peaks in the TVS traces correlated well with the previously published bias-temperature stressing (BTS) induced instability of these capacitors, where the flatband voltage shifts during BTS were in the order with no shift observed for Pt capacitors. The effects of temperature, voltage sweep rate, and bias hold time were also investigated for Al/HOSP and Cu/HOSP capacitors. Cu peaks were one to two orders of magnitude smaller than Al peaks under all conditions investigated. It was concluded that the peaks originate from the gate metal. © 2002 The Electrochemical Society. All rights reserved.

Electron cyclotron resonance microwave discharge for oxide deposition using tetramethylcyclotetrasiloxane

Results of the dielectric oxide films deposited at 300 °C using tetramethylcyclotetrasiloxane/oxygen chemistry in a reactor with electron cyclotron resonance microwave discharge are presented. We have found that quality oxide is deposited with an O2/tetramethylcyclotetrasiloxane flow-rate ratio of greater than 3. The properties of the deposited films are characterized by prism coupler, infrared spectroscopy, Auger electron spectroscopy, Rutherford backscattering spectrometry, and triangular voltage sweep measurements. The deposition rate using tetramethylcyclotetrasiloxane is found to be about four times higher than tetraethylorthosilicate under similar processing conditions. We have obtained oxide films with superior quality (both material and electrical properties) at a deposition rate of 5000 Å/min. The step coverage of oxide is found to be excellent when rf bias is applied on the substrate during the deposition. We have demonstrated that trenches with aspect ratios ≥1.50 can be filled without voids. Details of reaction chemistries for oxide deposition in the electron cyclotron resonance reactor and the effect of ion bombardment on the oxide profile are discussed.

Electron Cyclotron Resonance Microwave Discharge for Oxide Deposition Using Tetraethoxysilane

In this paper, results of the dielectric oxide films deposited using tetraethoxysilane chemistry in a reactor with electron cyclotron resonance (ECR) microwave discharge are presented. In the reactor, gas is introduced into the plasma chamber and TEOS is introduced into the deposition chamber, which is downstream of the plasma. The properties of the deposited films are characterized by prism coupler, infrared, Auger electron spectroscopy, Rutherford backscattering, and triangular voltage sweep measurements. The quality of the deposited films is found to be critically dependent on the ratio of flow rate to the TEOS flow rate during the deposition. The consumption rate of TEOS in the reaction is high and the deposition rate is found to be proportional to the flow rate of TEOS. By applying additional RF bias on the substrate during deposition, the oxide profile can be modified and the reentrant angle which is normally observed on the shoulder of the profile can be eliminated. We have also observed that ion bombardments during the deposition play important roles in determining the oxide quality. In this study we have demonstrated that the quality of the oxide deposited using a bias ECR reactor is good in terms of both material and electrical properties. In addition, the step coverage is excellent for Al lines with high aspect ratios. The reaction chemistries for oxide deposition in the ECR reactor and the effects from impacts of energized ions during oxide deposition to the film quality and the profile are also discussed.

The mobility of Na+, Li+, and K+ ions in thermally grown SiO2 films

Na+, Li+, and K+ ions have been implanted in thermally grown oxides (Tox =1000 °C) of metal-oxide-silicon structures. The mobilities of the Na+ and Li+ ions have been determined by means of the isothermal transient ionic current method in the temperature range 100–300 °C. The K+ mobility has been obtained by means of triangular voltage sweep measurements in the range 350–450 °C. The results show that the Na+ and the Li+ mobilities are not significantly different. The activation energies of the three measured mobilities are shown to agree with a quantitative model which has been developed by Anderson and Stuart [J. Am. Ceram. Soc. 37, 573 (1954)].

Donor generation in monocrystalline silicon by halogen implantation

Cl +, F + and Ar + ions were implanted in n-type, floating zone, 2 Ωcm, (100)-surface or orientated Si wafers. The implantation doses were 10 14 and 10 15 cm 2, the energy was 25 keV. After the implantation the wafers were annealed and/or oxidized at 1000°C. By performing capacitance-voltage measurements, (e.g. HFCV and Schottky CV) the following effects were observed: • - an increasing n-type doping profile towards the Si-surface. • - increase of the oxide growth rate. The origin of the donorsites is probably a complex formed out of an implantation damage centre and a halogen atom. The increase of the oxide growth rate can be explained by catalytic reactions of the halogen ions, just as was found for oxidation in a HCl/O 2 atmosphere. In the case of the Cl implanted and oxidized samples, part of the chlorine is incorporated in the oxide, as measured with Ruterford Backscattering. However, TVS (triangular voltage sweep) measurements reveal that gettering of mobile Na + ions does not occur in these oxides.