Experimental validation of electromigration by low frequency noise measurement for advanced copper interconnects application

The measurement of low frequency noise can be considered as an important part in optimization of sensor noise-signal ratio. But sometimes, the intrinsic low frequency noise is affected by contact noise, which can be generated by geometrical defect of thin film. Thus, the measured noise level could not reveal material properties. We report different low frequency noise measurement methods in a general geometry sample of thin film. A detailed analysis of noise measurement has been described by relative equations. Finally, a discussion has been investigated in systematic measurements of low frequency noise at room temperature in La <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.7</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.3</sub> MnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LSMO) thin films and noise measurements are presented by noise spectral densities as function of frequency.

In advanced technology node, the complexity of process, materials selection and limitation of tools' capability, becomes very challenging with respect to meet tight reliability targets. In our fabrication of low-k based BEOL integration scheme, we have demonstrated that by proper inline process characterization, feedback and control at critical process modules, a robust Time Dependent Dielectric Breakdown (TDDB) and Electromigration (EM) performance can be achieved. In this paper, we proposed a working model with inline process parameters characterization, reliability performance evaluation, root causes identification and solutions, to establish a relationship between inline process parameters and BEOL TDDB, EM performance. Our data shows that, to pass TDDB E-model (field driven), Mx final critical dimension (FCD) must be within very tight control of less than FCD target + 0.5nm, and greater than FCD target − 2nm. On the other hand, to pass TDDB SQRT E-model, FCD target − 2nm FCD target − 2nm is needed. Through this working model, we are able to justify and identify the critical process modules and to determine the process window to achieve robust BEOL TDDB and EM performance.

Almost all low noise voltage preamplifier suitable for application in the field of Low Frequency Noise Measurements (either commercially available or proposed in the literature) are single ended input amplifiers. This means that one end of the measuring port of the Device Under Test (DUT) must be connected to common ground. This may be a severe limitation in many interesting measurement configurations, such as the case in which Kelvin connections to the DUT must be employed. In this paper we propose a simple design of a fully differential input ultra low noise amplifier with noise performances, in term of equivalent input voltage noise, comparable to those of the best single ended input amplifiers for low frequency noise measurements reported in the literature. Indeed, the amplifier we propose is characterized by a voltage gain of 80 dB, in the bandwidth from a few tens of mHz up to a few kHz, and by an equivalent input voltage noise as low as 14 nV/√Hz (100 mHz), 2 nV/√Hz (1 Hz), 1.2 nV/√Hz (10 Hz) and 1 nV/√Hz (1 kHz). Such an amplifier can also be employed as a single ended input amplifier by simply shorting to ground one of the two differential input ports.

Defect spectroscopy using 1/ fγ noise of gate leakage current in ultrathin oxide MOSFETs

In this work we show the results of low frequency noise measurements (LFNMs) in staggered bottom gate top contact organic thin film transistors (OTFTs) made with dinaphtho-[2,3-b: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2^{\prime} $ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3^{\prime} $ </tex-math></inline-formula> -f]thieno[3,2-b]thiophene (DNTT) as semiconductor layer and CYTOP <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text {TM}}$ </tex-math></inline-formula> as dielectric layer. The measured 1/f noise follows a correlated number-mobility fluctuation mechanism with an extracted trap density <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ &lt; {10}^{{10}}$ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{-{2}}}$ </tex-math></inline-formula> eV <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> , the lower value ever reported for OTFTs and comparable to c-Si devices. On the other hand, the extracted Coulomb scattering parameter is in the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{7}}$ </tex-math></inline-formula> Vs/C, in line with previous measurements on organic transistors. In particular we found similar results from device batches with technological differences and a much lower noise from reference devices with SiO2 dielectric, suggesting that the low noise and extracted trap density can be mainly attributed to the quality of the DNTT/Cytop <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text {TM}}$ </tex-math></inline-formula> interface.

Identification of the physical signatures of CDM induced latent defects into a DC–DC converter using low frequency noise measurements

This paper will compare the reliability results of first-generation Carbon-doped low k dielectric film with a second-generation Carbon-doped film, developed to have a high mechanical strength (HMS) and improved toughness. The first-generation low k film possessed acceptable unit process results, but was found to have marginal electromigration (EM) performance due to cohesive failures that resulted in Cu extrusion at the anode end of lines. By replacing the first-generation film with the HMS film, EM test median time to fail was increased by a factor of more than two. This improvement was found to be due to increased film fracture toughness.

The application of 1/f noise measurements to speed up electromigration (EM) testing and provide a better understanding of the underlying mechanisms of electromigration in advanced microelectronics interconnects is investigated. It is shown that 1/f noise measurements can be used for early EM damage detection during EM stress, before any changes in the resistance of the sample are observable. Also, the temperature dependence of the low frequency noise is used to calculate activation energies, which are then demonstrated to be similar to values found for electromigration using standard EM tests. Furthermore, the 1/f noise technique is used to assess and compare the EM properties of various advanced integration schemes and different materials. The 1/f noise measurements provide new evidence for the importance of grain boundary diffusion as a dominant EM failure mechanism in highly scaled interconnects.

The influence of the SiN cap-layer deposition process including different pre-clean treatments on the electromigration (EM) and stressvoiding (SV) behavior of copper dual damascene metallizations has been studied. A remarkable trade-off between the EM and SV performance was revealed depending primarily on the pre-treatment before cap-layer deposition rather than the deposition process itself. On the one hand, an pre-treatment yields improved Cu/SiN-interface properties with higher electromigration failure times and activation energies (1.22-1.26 eV). However, these pre-cleans were found to provoke stressvoiding failures because of the recovery of crystal defects induced in the bulk copper during the plasma treatment. The degree of microstructural damage and hence the SV susceptibility were found to increase with the preclean intensity. In contrast, no SV risk is related to less aggressive pre-clean treatments since they influence only the copper surface. The crystal structure of the bulk remains unaffected and hence, in the absence of any crystal recovery, no vacancies are generated. However, these pre-cleans result in significantly lower EM performance with smaller failure times and activation energies (1.03-1.06 eV). The results illustrate the need to adjust the SiN cap-layer process parameters with respect to both EM and SV performance to meet the overall reliability requirements for these wear-out mechanisms at the same time.

The development of fiber optic interferometric sensor systems has created new demands for single mode semiconductor diode lasers with low output noise power. Recently, several single longitudinal and transverse mode GaAlAs laser diodes have become available. Several experimenters have reported the deleterious effects of optical feedback resulting from fiber optic coupling on the laser's mode structure and high frequency noise spectrum.1-3 Our interest for interferometric sensors is in the low frequency noise, up to a few kilohertz. We report here the first such low frequency noise measurements in fiber coupled and uncoupled single mode diode lasers. Additionally, we also show that the use of index matching fluid can be used to greatly reduce optical feedback and its associated low frequency noise, upon coupling into an optical fiber.

In this study, we demonstrate the capability to detect microscopic stable displacement nature created by proton irradiations with a method based on the discrimination of the three major low frequency noise sources generally observed in semiconductor devices. Low frequency noise measurements are carried out in silicon in-situ phosphorus doped polycrystalline silicon serpentine resistance used as test vehicle. We observe that for the pristine sample, the voltage noise power density can be explained only considering 1/f and thermal noise contribution on the total noise, while for irradiated sample generation recombination noise prevails. Preliminary results on low frequency noise spectroscopy, used as a diagnostic tool in order to identify stable traps created by protons irradiations are presented.

Low frequency noise in short-channel MOSFET's degraded by Fowler-Nordheim and Hot-Carrier Injection

A comparative study of depth profiling of interface states using charge pumping and low frequency noise measurement in SiO 2/HfO 2 gate stack nMOSFETs

Influence of gate leakage current on AlGaN/GaN HEMTs evidenced by low frequency noise and pulsed electrical measurements

The qualification of a technology needs rigorous and numerous stress experiments to attest of a high level of reliability. Low frequency noise measurements are known as an effective characterization method for the evaluation of device reliability. This technique is usually applied on the drain current spectral density, but it is now largely accepted that the gate access is a major reliability indicator. Moreover, devices featuring slight differences in their drain current noise can be subjected to strong differences on their gate leakage currents, and as a consequence on the current low frequency noise (LFN). In the present work, LFN measurements are investigated on the gate and drain currents of two sets of AlGaN/GaN high electron mobility transistors (HEMTs) with high and low gate leakage currents. It is demonstrated that devices featuring weak differences on their drain current can be subjected to strong differences on their gate leakage signatures: moreover, it is found that the high leakage current can generate numerous traps under the gated zone of the transistor, leading to a change of the intrinsic tuning voltage and by consequence of the number of carriers, thus explaining the reduction on the drain current. The transistors show a difference of 3 to 4 decades on their gate current noise and a negligible shift of 20% on their drain current noise. The large variations on the gate LFN signatures between the two sets of devices, and the induced charges for the leaky devices can probably be related with large differences on the expected lifetimes for the devices under test.