Cross Kelvin Research Articles

Evaluation of Hybrid Bonding Interface Quality by Contact Resistivity Measurement

With the rise of hybrid bonding as a solution for fine pitch 3-D integration, new methods are required to evaluate the bonding quality at a wafer level. Contact resistance is widely used for process control but measurements can be corrupted by the 3-D stack complexity and the misalignment of wafers. In order to measure the specific contact resistivity of dual-damascene interconnects and evaluate the Cu/Cu bonding interface, 3-D cross Kelvin resistors (3-D CKRs) have been specially designed. Electrical characterizations and complementary simulations demonstrate that test structures are functional if the specific contact resistivity is higher than $10^{-{8}}\,\,\Omega \cdot \textsf {cm}^{{2}}$ . Despite bonding defects evidenced by morphological characterization, the specific contact resistivity remained below the measurement limit. The good reconstruction of Cu/Cu interface does not allow contact resistance measurement.

Cross Kelvin force microscopy and conductive atomic force microscopy studies of organic bulk heterojunction blends for local morphology and electrical behavior analysis

Bulk Heterojunction (BHJ) organic photovoltaic devices performances depend on the relative organization and physical properties of the electron-donor and -acceptor materials. In this paper, BHJs of poly(3-hexyl-thiophene) (P3HT) associated with an electron acceptor material, 1-(3-methoxycarbonyl)-propyl-1-phenyl[6,6]C6 (PCBM) or [Ni(4dodpedt)2], are studied in terms of morphology, ordering, and electrical properties. First, comparison between the two BHJs performed by Atomic Force Microscopy (AFM) and Raman characterizations shows that P3HT structuration is improved by blending with [Ni(4dodpedt)2]. Then, the relationship between charges trapping, electrical properties, and film morphology is investigated using conductive AFM and Kelvin Force Microscopy. Measurements in dark condition and under solar cell simulator provide complementary information on electrical phenomena in these organic nanostructures. Finally, time dependent measurement highlights the influence of charges stacking on conduction. Specifically, we demonstrate that charge accumulation initiated by illumination remains valid after switching off the light, and induces the modification in current versus voltage characteristic of P3HT: PCBM blend. Finally, we observe a current increasing which can be attributed to the energy barrier decreasing due to charges trapping in PCBM.

Interfacial Resistive Properties of Nickel Silicide Thin Films to Doped Silicon

Improved means of electrical access to nanotechnology devices and accurate nanoscale characterization of electrical properties of ultrathin layers constituting such electrical contacts is of utmost interest to nanoelectronics researchers. This paper reports on the characterization of interfacial resistive properties of ohmic contacts to doped silicon, incorporating thin films of nickel silicide. Silicon doping was achieved by carefully designed ion implantation of antimony (for n-type) and boron (for p-type). Cross Kelvin resistor test structures were used to extract the specific contact resistivity (SCR) values for the different ohmic contacts fabricated. SCR values, which are quantitative characteristics of interfacial resistive properties, as low as for contacts to antimony-doped silicon and to boron-doped silicon were estimated. These experimental results, representing the lowest such values measured, were based on a rigorous evaluation technique and verified by finite element modeling.

Interfacial Resistive Properties of Multi-layered Silicon-based Ohmic Contacts

AbstractThis article reports on the characterization of two- and three-layer ohmic contacts comprising of titanium disilicide and nickel silicide. Cross Kelvin resistor test structures were used to extract the specific contact resistivity (SCR) values for the different ohmic contacts fabricated. The SCR of aluminum to titanium silicide (Al-TiSi2) ohmic contacts was evaluated to be as low as 6.0 x 10-10 Ωcm2. Three-layer ohmic contacts were created using aluminum and nickel silicide thin films and doped silicon. SCR values as low as 5.0 x 10-9 Ωcm2 to antimony-doped silicon and 3.5 x 10-9 Ωcm2 to boron-doped silicon were evaluated.

Analytical and Finite-Element Modeling of a Cross Kelvin Resistor Test Structure for Low Specific Contact Resistivity

Various test structures have been employed to determine the specific contact resistivity (rho <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> ) of ohmic contacts, and cross Kelvin resistor (CKR) test structures are most suitable for estimating low rho <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> values. The value determined by CKRs includes error due to parasitic resistances that have been difficult to account for when rho <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> is low (< 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> Omega ldr cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). In this paper, an analytical technique for determining the error in measurements from CKR test structures is presented. The analytical model described for circular contacts is based on Bessel function expressions. Using several contacts of different diameter ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> ) with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</i> les 0.4 ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</i> is the width of the CKR arms), the parasitic resistance can be accurately accounted for by extrapolation of experimental data to <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</i> rarr 0. Finite-element modeling and experimental results for metal-to-silicide contacts are used to validate the analytical expressions presented.

Accurate Estimation of Low $( ≪ \hbox{10}^{-8}\ \Omega \cdot \hbox{cm}^{2})$ Values of Specific Contact Resistivity

Advancements in nanotechnology have created the need for efficient means of communication of electrical signals to nanostructures, which can be addressed using low resistance contacts. In order to study and estimate the resistance of such contacts or the resistance posed by the interface(s) in such contacts, accurate test structures and evaluation techniques need to be used. The resistance posed by an interface is quantified using its specific contact resistivity (SCR), and although multiple techniques have been utilized, inaccuracies of such techniques in measuring values of SCR lesser than ( < 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> Omega ldr cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) have been reported. In this letter, an approach for estimating very low values of SCR (lower than the previously limiting ( < 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> Omega ldr cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> )) using a cross Kelvin resistor test structure is demonstrated using aluminum to titanium silicide ohmic contacts, with a minimum estimated SCR value of 6.0 times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> Omega ldr cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

New challenges to the modelling and electrical characterisation of ohmic contacts for ULSI devices

Continuing developments in semiconductor process and materials technology have enabled significant reductions to be achieved in the contact resistance R c of devices. This reduction is commonly assessed in terms of the specific contact resistance (SCR) parameter ρ c (Ω cm 2) of the metal–semiconductor interface. Such a reduction in SCR is essential, for as device dimensions decrease, then so also must ρ c and the corresponding contact resistance in order not to compromise the down-scaled ULSI device performance. Thus the ability to accurately model contacts and measure ρ c is essential to ohmic contact development. The cross kelvin resistor (CKR) test structure is commonly used to experimentally measure the Kelvin resistance of an ohmic contact and obtain the specific contact resistance ρ c. The error correction curves generated from computer modelling of the CKR test structure are used to compensate for the semiconductor parasitic resistance, thus giving the SCR value. In this paper the increased difficulty in measuring lower ρ c values, due to trends in technology, is discussed. The challenges presented by the presence of two interfaces in silicided contacts (metal-silicide–silicon) is also discussed. Experimental values of the SCR of an aluminium–titanium silicide interface is determined using multiple CKR test structures.

Novel method to determine contact resistivity and sheet resistance under the contact

A method to determine specific contact resistance and sheet resistivity under the contact using two L-type cross Kelvin resistors is presented. In the model analysed in the present paper, the sheet resistivity under the contact was different from the resistance of the layer outside the contact. This difference is caused by metallurgical reactions taking place during the heat treatment of the metallized wafer.

Modelling the Influence of the Silicon Doping Profile on a Silicide Well Ohmic Contact

AbstractLow values of contact resistance Rc(Ω) and specific contact resistance, ρc(Ωcm2) are essential for ohmic contacts to devices with ULSI dimensions. The incorporation of silicides into contact structures has made a substantial contribution towards this goal. However the modelling and characterisation of these more complex silicide contact structures still requires considerable development. The variation of doping density in the vertical direction will cause a strong local variation in silicon resistivity with depth as well as a pronounced variation in the silicon-silicide barrier layer as a function of depth.In this paper we use a three dimensional (3-D) finite element analysis of sub-micron silicide contacts to illustrate the influence on Rc of the silicon doping profile in the sourcedrain contact regions. In addition, the influence of the doping profile on the current density distribution at the silicon-silicide interface is presented. A comparison of results is made between a uniform doping profile and two ion-implanted profiles. In order to improve the model's accuracy, the often neglected contribution of the metal-silicide barrier (ρca) to Rc is taken into account. Experimental measurements using a Cross Kelvin Resistor (CKR) test structure, have been used to determine ρca (∼3–5 × 10−9Ω.cm2 ) of the aluminium-TiSi2 interface.

Kelvin Test Structure Modeling of Metal-Silicide-Silicon Contacts

ABSTRACTLow resistance ohmic contacts for silicon devices commonly incorporate silicide materials as part of the contact. The electrical characterisation of ohmic contacts requires the use of various test structures such as the Cross Kelvin Resistor in order to determine the specific contact resistance ρc. This paper describes the results of using a three-dimensional finite element model of a Kelvin Resistor test structure in order to determine the influence of the electrical and geometrical parameters of a silicide-well on the magnitude of ρc. The same model of the test structure is further used to model the current density in the contact region. The results indicate that the presence of a silicide-well leads to reduced values of both ρc and the current density.

Electrical characterization of the TiN/Ti/n/sup +/Si (and p/sup +/Si) interfaces by means of a circular resistor test structure

A circular geometry based test structure for contact resistance measurements is introduced, together with a compact analytical model for contact resistivity extraction. The circular resistor structure is intended to be used for VLSI contacts that tend to a rounded shape due to lithographic effects. An application to the TiN/Ti/n/sup +/Si and TiN/Ti/p/sup +/Si interfaces is presented. Good agreement is found with standard models for contact resistivity extraction that rely on cross Kelvin resistor test structures. >

The “SMART” way to define and sustain success

National Productivity ReviewVolume 8, Issue 1 p. 23-33 Article The “SMART” way to define and sustain success Kelvin F. Cross, Kelvin F. Cross Kelvin Cross is a consultant with the consulting firm of Gray Judson &Howard of Cambridge, Massachusetts, and the author of Manufacturing Planning: Key to Improving Industrial Productivity (Marcel Dekker, Inc.).Search for more papers by this authorRichard L. Lynch, Richard L. Lynch Richard Lynch is a senior finance manager at Wang Laboratories in Lowell, Massachusetts, where he is currently the program manager for the new performance measurement system.Search for more papers by this author Kelvin F. Cross, Kelvin F. Cross Kelvin Cross is a consultant with the consulting firm of Gray Judson &Howard of Cambridge, Massachusetts, and the author of Manufacturing Planning: Key to Improving Industrial Productivity (Marcel Dekker, Inc.).Search for more papers by this authorRichard L. Lynch, Richard L. Lynch Richard Lynch is a senior finance manager at Wang Laboratories in Lowell, Massachusetts, where he is currently the program manager for the new performance measurement system.Search for more papers by this author First published: Winter 1988 https://doi.org/10.1002/npr.4040080105Citations: 182 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume8, Issue1Winter 1988Pages 23-33 RelatedInformation

The effect of sheet resistance modifications underneath the contact on the extraction of the contact resistivity: application to the cross Kelvin resistor

The influence of sheet-resistance modifications underneath the contact on the extraction of the contact resistivity is investigated. A generalized scaling theory has been applied to the modeling of the cross Kelvin resistor. It is shown that the errors associated with the contact sheet resistance modification could become appreciable in low-resistance metallizations of interest in VLSI.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>