Valeriy Sukharev

A model for electromigration-induced degradation mechanisms in dual-inlaid copper interconnects: Effect of interface bonding strength

A physical model and a simulation algorithm are used to predict an electromigration-(EM-) induced void nucleation and growth in dual-inlaid copper interconnect. Incorporation of all important atom migration driving forces into the mass balance equation and its solution together with solution of the coupled electromagnetics, heat transfer, and elasticity problems allows to simulate EM-induced degradation in a variety of dual-inlaid copper interconnect segments characterized by different dominant channels for mass transport. The interface bonding strengths, significantly influencing the interface diffusivity and consequently the mass transport along interfaces, result in completely different degradation and failure pictures for the weak and strengthened copper∕capping layer interfaces. Strengthening of the top interface of inlaid copper interconnect metal line is a promising way to prolong the EM lifetime. The results of the numerical simulation have been proven experimentally by the EM degradation studies ...

Analytical modeling of silicon etch process in high density plasma

Plasma etching of silicon is one of the important etching processes used in modern integrated circuit manufacturing and micro-electro-mechanical systems fabrication. A good understanding of this process leads to better models which are the key to easier and less costly plasma etching process design. The main focus of this paper is on the simulation of the ion reflection from feature sidewalls and the resulting microtrenches. Pure Cl2 plasma was used for experiments because of the simple chemistry. SPEEDIE (Stanford etching and deposition profile simulator) was used in this work. Langmuir adsorption model was used for etching kinetics. Self-consistent calculations were done for fluxes using surface coverage dependent sticking probabilities. For ion reflection, it was assumed that the reflected ions come off with a distribution about the specular reflection angle. This distribution is modeled as cosnθ (θu2002is the deviation from the specular angle) and is important in getting the correct shape for microtrenche...

Effect of interface strength on electromigration-induced inlaid copper interconnect degradation: Experiment and simulation

Abstract Both in situ microscopy experiments at embedded inlaid copper interconnect structures and numerical simulations based on a physical model provide information about electromigration-induced degradation mechanisms in on-chip interconnects. It is shown that the modification of the bonding strength of the weakest interface results in completely changed degradation and failure mechanisms. Transmission electron microscopy (TEM) images of standard Cu/SiNx interfaces are compared with strengthened interfaces, e. g., after applying an additional metal coating or a self-assembled monolayer (SAM) on top of the polished copper lines. The changed degradation mechanisms as observed with the in situ scanning electron microscopy (SEM) experiment and as predicted based on the numerical simulations are explained based on TEM images.

Physically-based simulation of the early and long-term failures in the copper dual damascene interconnect

We have developed a novel physical model and a simulation algorithm capable of predicting electromigration (EM) induced void nucleation and growth in an arbitrary interconnect segment. Incorporation of all important atom migration causes into the mass balance equation and its solution together with solution of the corresponding electromagnetic, heat transfer and electromagnetic, heat transfer and elasticity problems, in a coupled manner, has allowed to discriminate an early failure from a long term one taking place in a via containing copper dual damascene (DD) structure.

A model for electromigration-induced degradation mechanisms in dual-inlaid copper interconnects

Incorporation of all important atom migration driving forces into the mass balance equation and its solution together with solution of the coupled electromagnetics, heat transfer, and elasticity problems allows one to simulate electromigration (EM)-induced degradation in a variety of dual-inlaid Cu interconnect segments characterized by different dominant channels for mass transport. The interface bonding strengths, significantly influencing the interface diffusivity and consequently the mass transport along interfaces, result in completely different degradation and failure pictures for the weak and strengthened Cu/capping layer interfaces. Strengthening of the top interface of the inlaid Cu interconnect metal line is a promising way to prolong the EM lifetime. The results of the numerical simulation have been proven by EM degradation studies on test structures in an in-situ scanning SEM experiment. The correspondence between simulation results and experimental data indicates the applicability of the developed model for the optimization of the physical and electrical design rules.

Electromigration reliability of low capacitance air-gap interconnect structures

The electromigration lifetimes of aluminum lines with low capacitance air-gap structures is evaluated and compared to the case of traditional gapfill passivation. Electromigration lifetime of air-gap interconnect structures is determined to be significantly higher than that of the gapfill case. Failure analysis indicates that the elasticity of the airgap sidewall passivation reduces the line stress incurred during electromigration and increases the time necessary to reach the critical stress for void nucleation. Simulations support the experimental results. Capacitance measurements and simulations show the air-gap structures reduce capacitance by as much as 40%.

Fluctuation Model of Chemical Mechanical Planarization

A novel physically based model of material polishing is developed on the basis of an etch pit nucleation-annihilation approach in dissolution kinetics. A sublinear Prestons equation as well as a pattern-dependent rate of material removal are derived from this model. The calculation results fit well with the available experimental data. Although the model is highly idealized, no adjustable parameters are required.

Physically Based Simulation of Electromigration‐Induced Degradation of Inlaid Copper Interconnects

A novel physical model and a simulation algorithm capable of predicting electromigration (EM) induced void nucleation and growth in an arbitrary interconnect segment have been developed. EM‐induced void nucleation and growth in dual damascene (DD) copper interconnect structures have been predicted with a developed physical model and a simulation algorithm. The incorporation of all important contributions to directed atom migration into the mass balance equation and its solution together with the solution of the corresponding electromagnetics, heat transfer and elasticity problems, in a coupled manner, allows to simulate EM‐induced degradation in dual‐inlaid copper interconnect segments characterized by different dominant channels for EM‐induced mass transport. Model provides a capability for the EM design rules generation/optimization with the physically based simulations. A simulation‐based optimization of interconnect architecture, segment geometry, material properties and some of the process parameters...

Physically-based simulation of electromigration induced failures in copper dual-damascene interconnect

We have developed a novel physical model and a simulation algorithm capable of predicting electromigration (EM) induced void nucleation and growth in an arbitrary interconnect segment. Incorporation of all important atom migration causes into the mass balance equation and its solution together with solution of the corresponding electromagnetics, heat transfer and elasticity problems, in a coupled manner, has provided a capability for the EM design rules generation/optimization with the physically based simulations. As an example, we have demonstrated the model capability to discriminate an early failure from a long term one taking place in a via containing copper dual damascene (DD) structure.

Electromigration simulation in Cu-low-K multilevel interconnect segments

We present a physically based simulation model of electromigration (EM) induced failure development. Transient, 3-D, fully linked multiphysics simulation scheme has been developed on the basis of the proposed model. Simulations have been done on the realistic interconnect structures. Obtained simulation results have been found to fit well to available experimental data regarding the location of void nucleation sites and grow kinetics.