Nondestructive Defect Imaging through Image Intensity Analysis

Author(s):  
J. Demarest ◽  
D. Bearup ◽  
A. Dalton ◽  
L. Hahn ◽  
B. Redder ◽  
...  

Abstract The continually shrinking dimensions of today’s semiconductor technology occasionally allow for novel approaches in imaging defects. It has become desirable to image subsurface voids prior to cross sectioning and some efforts have been made to address this need including the construction of specialized instrumentation [1]. The thickness of the metallization levels at the 65 nm technology node and smaller now allow for the use of the electron beam in a scanning electron microscope (SEM) as a material sensor. At high accelerating voltages (between 20-30 kV) in backscatter imaging mode the numerical gray level values at each pixel location can correlate to the amount of material directly under the electron beam at that location. This is particularly evident when dealing with defined geometries and material sets offering high contrast changes between materials such as those found in semiconductor technology like copper (Cu) metal and conventional dielectric materials. As a result, subsurface voids can be mapped to a reasonable representation prior to cross sectioning and precise pinpointing of the defect location in test structures can occur. This paper discusses this methodology on 65 nm technology with Cu metal lines in a low-k dielectric material for a two level metal test structure. To some extent this work represents a natural extension of a paper presented previously by the author [2].

2005 ◽  
Vol 103-104 ◽  
pp. 357-360
Author(s):  
B.G. Sharma ◽  
Chris Prindle

Interconnect RC delay is the limiting factor for device performance in submicron semiconductor technology. Copper and low-k dielectric materials can reduce this delay and have gained widespread acceptance in the semiconductor industry. The presence of copper interconnects provides unprecedented challenges for via cleaning technology and requires the development of novel process chemistries for improved device capability.


1995 ◽  
Vol 381 ◽  
Author(s):  
Chiu H. Ting ◽  
Thomas E. Seidel

AbstractFor several years the industry has recognized the need of developing low k dielectric material and high conductivity metal for high performance interconnect. Low k dielectric will impact both power and delay favorably, while higher conductivity metal will reduce delay time. In order to be useful, new low k dielectric materials must be carefully characterized for their electrical, chemical, thermal and mechanical properties. In addition, their impact on process integration, fabrication cost and device reliability must also be considered. Since the gestation period for introducing a new material is very long, a set of standard testing methodologies are required to speed up the development process. This review will discuss various material options and the progress of material development and characterization methodologies. Example results will be provided for assessing these parameters.


2006 ◽  
Vol 914 ◽  
Author(s):  
Ryan Scott Smith ◽  
C. J. Uchibori ◽  
P. S. Ho ◽  
T. Nakamura

AbstractVery few porous low-k dielectric materials meet the basic requirements for integration into the back end of the line (BEOL) metallization. According to the International Technology Roadmap for Semiconductors, 2005, candidates for the 45 nm node need a k<2.2 and a minimum adhesion strength of 5 J/m2. Recently, a low-k dielectric material was developed, called nano-clustered silica (NCS). It is a spin-on glass with k<2.3. NCS is constitutively porous, with a micro- and mesopore size of ~2.8 nm. The first reported adhesion strength of this material was 10+ J/m2. We investigated the nature of the adhesive strength of NCS by critical and sub-critical fracture and Fourier Transform IR Spectroscopy (FTIR). The four-point bend technique and a mixed-mode double cantilever beam technique were employed. The sub-critical crack growth studies were performed in humid environments and ambient temperatures. Different post-treatments were used on NCS to achieve different molecular structure, as measured with FTIR. A correlation between molecular structure and critical adhesion energy was found. Atomistic parameters were calculated from the sub-critical crack growth data. A dependency of fracture behavior on post-treatment and, therefore, structure was observed.


2002 ◽  
Vol 716 ◽  
Author(s):  
Jeffrey A. Lee ◽  
Jeffrey T. Wetzel ◽  
Caroline Merrill ◽  
Paul S. Ho

AbstractThe present paper discusses the four-point bending technique employed at The University of Texas at Austin (UT Austin) to characterize adhesion strength of ultra low-k dielectric materials to CVD barrier layers. Adhesion energy between an ultra low-k dielectric material and a barrier layer was measured as a function of porosity (2.0 < k < 2.3). It was found that the fracture energy decreases with the dielectric constant, which correlates with mechanical properties such as Young's modulus and hardness. Adhesion measurement data was also obtained for different lowk / barrier layer interfaces. The independence of interfacial fracture energy on the type of interface suggests that cohesive failure occurs in the low-k material layer and not at the interface. In addition, the very low fracture energies (G < 3 J/2) confirm the weak mechanical properties of such highly porous materials. Experimental results are illustrated with analysis of failure surfaces using Auger Electron Spectroscopy and Scanning Electron Microscopy.


Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 849 ◽  
Author(s):  
Peng Xu ◽  
Zhongliang Pan ◽  
Zhenhua Tang

The ultra-low-k dielectric material replacing the conventional SiO2 dielectric medium in coupled multilayer graphene nanoribbon (MLGNR) interconnects is presented. An equivalent distributed transmission line model of coupled MLGNR interconnects is established to derive the analytical expressions of crosstalk delay, transfer gain, and noise output for 7.5 nm technology node at global level, which take the in-phase and out-of-phase crosstalk into account. The results show that by replacing the SiO2 dielectric mediums with the nanoglass, the maximum reduction of delay time and peak noise voltage are 25.202 ns and 0.102 V for an interconnect length of 3000 µm, respectively. It is demonstrated that the ultra-low-k dielectric materials can significantly reduce delay time and crosstalk noise and increase transfer gain compared with the conventional SiO2 dielectric medium. Moreover, it is found that the coupled MLGNR interconnect under out-of-phase mode has a larger crosstalk delay and a lesser transfer gain than that under in-phase mode, and the peak noise voltage increases with the increase of the coupled MLGNR interconnect length. The results presented in this paper would be useful to aid in the enhancement of performance of on-chip interconnects and provide guidelines for signal characteristic analysis of MLGNR interconnects.


2006 ◽  
Vol 914 ◽  
Author(s):  
Seung-Hyun Rhee ◽  
Conal E. Murray ◽  
Paul R. Besser

AbstractThe measurement and control of the stress state in BEOL interconnects are important to ensure structural integrity and long term reliability of integrated circuits. Thermal stress in interconnects is determined by the thermal-mechanical properties of Cu lines, substrate, and dielectric materials. The effect of BEOL stacks on thermal stress characteristics of Cu lines were investigated using X-ray diffraction stress measurements. The stress characteristics of M1 and M4 level interconnects in full low-k and low-k/oxide hybrid dielectric stacks were evaluated, and the results indicated reduced substrate confinement and an increased impact of the dielectric material on in-plane stresses in higher level interconnects. The effects of dielectric stack and material properties were examined and the implication in the stresses of multilevel interconnects are discussed.


Author(s):  
Liu Binghai ◽  
Mo Zhiqiang ◽  
Hua Younan ◽  
Teong Jennifer

Abstract Electron beam induced radiation damage presents great challenges for the electron microscopy analysis of low k and ultra low k dielectrics due to their beam sensitive nature. In order to minimize the radiation damage, it is necessary to understand the mechanisms behind the damage. This work presents detailed studies regarding the mechanisms behind the effects of probe currents, accelerating voltage and anticharging coating layers on the radiation damage to low/ultralow K dielectrics. The results indicate that the probe current shows a stronger dependence on the size of the condenser lens aperture than the accelerating voltage. Therefore, in terms of the probe current, the condenser lens aperture plays a decisive role in affecting the radiation damage process. In order to minimize the radiation damage, SEM imaging should be conducted with not only a low accelerating voltage but also a small condenser lens aperture to reduce probe current. Based on simulation results, the effects of a coating layer and accelerating voltage are related to the interaction volume and the penetration depth of the electron beam. Pt coating can act as not only an anti-charging layer, but also an effective barrier layer for reducing electron flux that interacts with the low/ultra-low dielectrics.


2007 ◽  
Vol 990 ◽  
Author(s):  
Toh-Ming Lu ◽  
Y. Ou ◽  
P.-I. Wang

ABSTRACTIt is known that the interface between a refractory metal barrier and a dielectric material is stable against thermal treatment at a conventional IC interconnect processing temperature. However, the interface may not be stable against thermal and electrical stress called the bias temperature stress (BTS) at moderate conditions of 150 °C and 0.5 MV/cm. Massive refractory metal ions are seen to drift into low K dielectric materials that contain a mixture of organic and inorganic elements. It is argued that the oxidation of the metal at the interface creates unstable metal ions that are ready to drift into the dielectric film under an electric filed during the BTS test. Dielectric or dielectric capping materials that do not contain oxygen can prevent metal oxidation and are desirable to create a stable metal and dielectric interface.


2010 ◽  
Vol 1249 ◽  
Author(s):  
Alshakim Nelson ◽  
Jitendra S Rathore ◽  
Blake Davis ◽  
Phillip Brock ◽  
Ratnam Sooriyakumaran ◽  
...  

AbstractThe future resolution requirements for the semiconductor industry demand advanced lithographic techniques, such as immersion and extreme ultraviolet (EUV) technologies, which will increase the cost of microelectronics manufacturing. Currently, low-k dielectric materials, which are used as insulating layers between the copper wiring, are indirectly patterned using a set of sacrificial layers and etch processes. The sacrificial layers include a photoresist polymer that must first be imaged prior to transferring the pattern to the underlying layers, including the dielectric layer. In order to reduce the number of processing steps required for semiconductor manufacturing, we have developed a novel photo-patternable low-k dielectric material that (1) eliminates the need for sacrificial layers and (2) reduces the number of wafer processing steps. Silsesquioxane copolymers that undergo acid-catalyzed crosslinking when exposed to 193nm wavelength were synthesized. In addition to the direct photo-patternability, the patterned structures are suitable as a dielectric material with a dielectric constant as low as 2.4, and an appreciable elastic modulus (E > 4.0 GPa). These photo-patternable low-k materials represent a ‘greener' approach to semiconductor manufacturing which has the ability to reduce cost, waste materials, and energy consumption.


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