Stresses in Thin Film Multilayer Interconnect Structures

1992 ◽  
Vol 264 ◽  
Author(s):  
S. M. Bruck ◽  
D. B. Knorr
Keyword(s):  
Thin Film ◽  
Thermal Cycling ◽  
Coefficient Of Thermal Expansion ◽  
Mechanical Test ◽  
Polymer Materials ◽  
Stress Fields ◽  
Processing Temperature ◽  
Multilayer Thin Films ◽  
Individual Layer ◽  
The Difference

AbstractThe difference in coefficient of thermal expansion (CTE) between substrate, polymer, and metal leads to complicated stress fields in multilevel interconnect structures that can potentially compromise reliability. This study uses a materials set representative of the General Electric High Density Interconnect (HDI) multichip module technology to monitor the stress level in the thin film layers of metal and polymer. A Kapton HN® film is bonded to a substrate with heat and pressure using a thin layer of Ultem 1000® thermoplastic as an adhesive. Mechanical test structures consist of single or multilayer thin films fabricated on oxidized silicon or alumina substrates. Layers consist of Ultem, Ultem/Kapton, metal (Ti/Cu/Ti), and Ultem/Kapton/metal. The composite stress due to fabrication and thermal cycling between ambient and 275°C is determined by substrate deflection. The initial stress in the polymer materials is due to the thermal excursion during fabrication. Initial metal stress is intrinsic but becomes extrinsic upon thermal cycling. The composite stress in multilayer structures shows a contribution from each individual layer. The relatively low processing temperature minimizes the magnitude of the stress.

scholarly journals Thermal analysis of metal-ceramic bonding using finite element method

2014 ◽  
Vol 3 (2) ◽  
pp. 216 ◽  
Author(s):  
S. Gopinath ◽  
R Sabarish ◽  
R. Sasidharan
Keyword(s):  
Finite Element ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Bonding Strength ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Processing Temperature ◽  
Element Analysis ◽  
Metal Ceramic ◽  
The Difference

This paper reports a finite element study of effect of bonding strength between metal and ceramic. The bonding strength is evaluated with different processing temperature and holding time. The difference between the coefficients of linear thermal expansion (CTEs) of the metal and ceramic induces thermal stress at the interface. The mismatch thermal stress at the interface region plays an important role in improving bonding strength. Hence, it is essential to evaluate the interface bonding in metal-ceramics joints. The Al/SiC bonding was modeled and analyzed using finite element analysis in ANSYS (v.10). Keywords: Bonding Strength, Coefficient of Thermal Expansion, Thermal Stress, Interface, Al/Sic, FEA.

Recent Progress in Thin Film Multichip Packaging for High Temperature Digital Electronics

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000407-000412
Author(s):  
Kun Fang ◽  
Tami Isaacs-Smith ◽  
R. Wayne Johnson ◽  
Alexey Vert ◽  
Tan Zhang ◽  
...  
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Chemical Vapor ◽  
Digital Circuit ◽  
Film Material ◽  
Active Components ◽  
Process Technology ◽  
Au Stud Bump ◽  
The Difference

A thin film material and process technology is being developed and evaluated for high temperature (300°C) digital multichip modules for use in geothermal well instrumentation. The substrate technology selected is AlN to minimize the difference in the coefficient of thermal expansion between the substrate and the SiC digital die. A thin film/plated Ti/Ti:W/Au metallization is used with a plasma enhanced chemical vapor deposited Si3N4 to create multilayer interconnections. Active components are assembled to the interconnect substrate using Au stud bump thermocompression bonding. The Au stud bump maintains a monometallic interface between the substrate Au pad surface and the Au pads on the SiC die. A digital circuit has been built and successfully tested as an initial demonstration.

Strain Monitoring Near Through Silicon Vias Using Metal Piezoresistive Sensors

2014 ◽  
Author(s):  
Christine Taylor ◽  
Xi Liu ◽  
Suresh K. Sitaraman
Keyword(s):  
Physical Vapor Deposition ◽  
Coefficient Of Thermal Expansion ◽  
Local Stress ◽  
Stress Fields ◽  
Gauge Factor ◽  
Through Silicon Vias ◽  
Sensing Material ◽  
3D Packaging ◽  
The Difference ◽  
Silicon Vias

With 3D system packaging, more chips will be stacked on top of each other and connected by through silicon vias (TSVs). TSVs enable not only miniaturization, but also high bandwidth, lower power consumption, heterogeneous integration and minimal interconnect latency. Due to the difference in the coefficient of thermal expansion (CTE) of various materials in 3D packaging systems, high thermomechanical stresses develop. Stress measurements near these TSVs and bump pads are important to help understand the evolution of die stresses associated with the packaging process. Depending on the package, the pitch of vias/bumps ranges from a few microns to a few tens of microns. Unlike currently-used piezoresistive doped Si sensors that require high-temperature processing, metal-based sensors use low-temperature standard cleanroom processes such as UV lithography and physical vapor deposition. In this paper, nichrome metallic sensors have been fabricated using standard cleanroom processes, and the gauge factor of the sensing material has been determined through tensile and compressive loadings. In parallel to the experiments, finite-element simulations have been carried out to assess the influence of sensors on local stress fields, and it is found that although the influence is minimal for micro-scale sensors, it is essential to account for such change in stress fields.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

Surface Microstructure Evolution Upon Silicidation of Ni(Pt) and the Different Responses to Metal Etch

2013 ◽  
Author(s):  
Wentao Qin ◽  
Dorai Iyer ◽  
Jim Morgan ◽  
Carroll Casteel ◽  
Robert Watkins ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxide Film ◽  
Microstructure Evolution ◽  
Depth Profiling ◽  
Surface Microstructure ◽  
The Difference ◽  
Surface Microstructures ◽  
Pt Films

Abstract Ni(5 at.%Pt ) films were silicided at a temperature below 400 °C and at 550 °C. The two silicidation temperatures had produced different responses to the subsequent metal etch. Catastrophic removal of the silicide was seen with the low silicidation temperature, while the desired etch selectivity was achieved with the high silicidation temperature. The surface microstructures developed were characterized with TEM and Auger depth profiling. The data correlate with both silicidation temperatures and ultimately the difference in the response to the metal etch. With the high silicidation temperature, there existed a thin Si-oxide film that was close to the surface and embedded with particles which contain metals. This thin film is expected to contribute significantly to the desired etch selectivity. The formation of this layer is interpreted thermodynamically.

scholarly journals Reliability Evaluation of Fan-Out Type 3D Packaging-On-Packaging

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 295
Author(s):  
Pao-Hsiung Wang ◽  
Yu-Wei Huang ◽  
Kuo-Ning Chiang
Keyword(s):  
Finite Element ◽  
Thermal Cycling ◽  
Glass Substrate ◽  
High Speed ◽  
Coefficient Of Thermal Expansion ◽  
Three Dimensional ◽  
Design Parameters ◽  
Time To Failure ◽  
Wafer Level ◽  
Fine Pitch

The development of fan-out packaging technology for fine-pitch and high-pin-count applications is a hot topic in semiconductor research. To reduce the package footprint and improve system performance, many applications have adopted packaging-on-packaging (PoP) architecture. Given its inherent characteristics, glass is a good material for high-speed transmission applications. Therefore, this study proposes a fan-out wafer-level packaging (FO-WLP) with glass substrate-type PoP. The reliability life of the proposed FO-WLP was evaluated under thermal cycling conditions through finite element simulations and empirical calculations. Considering the simulation processing time and consistency with the experimentally obtained mean time to failure (MTTF) of the packaging, both two- and three-dimensional finite element models were developed with appropriate mechanical theories, and were verified to have similar MTTFs. Next, the FO-WLP structure was optimized by simulating various design parameters. The coefficient of thermal expansion of the glass substrate exerted the strongest effect on the reliability life under thermal cycling loading. In addition, the upper and lower pad thicknesses and the buffer layer thickness significantly affected the reliability life of both the FO-WLP and the FO-WLP-type PoP.

The Characteristics of Multilayer Thin Films Deposited with Metal Thin Films (Ag, Al, Cu)

2010 ◽  
Vol 97-101 ◽  
pp. 1768-1771 ◽  
Author(s):  
Dong Hun Kim ◽  
Riichi Murakami ◽  
Yun Hae Kim ◽  
Kyung Man Moon ◽  
Seung Jung An ◽  
...  
Keyword(s):  
Thin Films ◽  
Metal Particles ◽  
Zno Thin Films ◽  
Multilayer Thin Films ◽  
Electrical And Optical Properties ◽  
Metal Thin Films ◽  
Continuous Structure ◽  
Glass Substrates ◽  
The Difference ◽  
Sputtering System

In order to study the characteristics of multilayer thin films with a ZnO/ metal/ ZnO structure the manufacture of the thin films was performed by a dc (direct current) magnetron sputtering system on slide glass substrates. The ZnO thin films were manufactured with the thicknesses of 30 nm and 50 nm. Three kinds of metals (Ag, Al and Cu) were deposited with the thicknesses of 4 nm, 8 nm, 12 nm and 16 nm. The electrical and optical properties of the manufactured thin films were then observed. As a result, the multilayer thin films with an Ag layer represented the most excellent electrical conductivity. This is due to the difference in the fundamental electrical properties of each of the metals. The structures of the metal particles deposited on the ZnO thin films were observed by an SEM (scanning electron microscope). The thin films exhibited a continuous structure with regular spaces between the metal particles. This resulted in an increase of transmittance. This is considered by the decrease of scattering and of light absorption on thin films with a continuous structure.

Effect of Film Thickness on Fatigue Strength of TiAl Alloy Coated with TiAlN Film at Elevated Temperature

2005 ◽  
Vol 297-300 ◽  
pp. 1446-1451 ◽  
Author(s):  
Takeshi Kasuya ◽  
Hideto Suzuki
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Thick Film ◽  
Physical Vapor Deposition ◽  
Tial Alloy ◽  
Testing Machine ◽  
Intermetallic Alloy ◽  
Fracture Control ◽  
The Difference

The fatigue strength of TiAl intermetallic alloy coated with TiAlN film was studied in vacuum at 1073K using a SEM-servo testing machine. In addition, three kinds of TiAlN films were given by physical vapor deposition (1, 3, and 10μ m). The fatigue strength of 3μ m was highest. Also, the fatigue strength of 1μ m was lowest. From this result, existence of optimum film thickness was suggested because the difference of fatigue strength arose in each film thickness. The justification for existence of optimum film thickness is competition of 45-degree crack and 90-degree crack. The 45-degree crack is phenomenon seen in the thin film (1μ m), and is caused by plastic deformation of TiAl substrate. The 45-degree crack is the factor of the fatigue strength fall by the side of thin film. In contrast, the 90-degree crack is phenomenon in the thick film (10μ m), and is caused as result of reaction against load to film. The 90-degree crack is the factor of the fatigue strength fall by the side of thick film. In conclusion, the optimum film thickness can perform meso fracture control, and improves fatigue strength.

Analysis of Long-Term and Thermal Cycling Tests for a Commercial Solid Oxide Fuel Cell

2017 ◽  
Vol 14 (4) ◽  
Author(s):  
Dustin Lee ◽  
Jing-Kai Lin ◽  
Chun-Huang Tsai ◽  
Szu-Han Wu ◽  
Yung-Neng Cheng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Coefficient Of Thermal Expansion ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Flow Rates ◽  
Degradation Rates ◽  
Two Stages

The effects of isothermally long-term and thermal cycling tests on the performance of an ASC type commercial solid oxide fuel cell (SOFC) have been investigated. For the long-term test, the cells were tested over 5000 h in two stages, the first 3000 h and the followed 2000 h, under the different flow rates of hydrogen and air. Regarding the thermal cycling test, 60 cycles in total were also divided into two sections, the temperature ranges of 700 °C to 250 °C and 700 °C to 50 °C were applied for the every single cycle of first 30 cycles and the later 30 cycles, respectively. The results of long-term test show that the average degradation rates for the cell in the first 3000 h and the followed 2000 h under different flow rates of fuel and air are 1.16 and 2.64%/kh, respectively. However, there is only a degradation of 6.6% in voltage for the cell after 60 thermal cycling tests. In addition, it is found that many pores formed in the anode of the cell which caused by the agglomeration of Ni after long-term test. In contrast, the vertical cracks penetrating through the cathode of the cell and the in-plane cracks between the cathode and barrier layer of the cell formed due to the coefficient of thermal expansion (CTE) mismatch after 60 thermal cycling tests.

Measurements of Residual Stress in the Layers of Thin Film Micro-Gas Sensors

2000 ◽  
Vol 657 ◽  
Author(s):  
Youngman Kim ◽  
Sung-Ho Choo
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Micro Gas Sensor ◽  
Thin Film Layer ◽  
Film Layer ◽  
The Difference ◽  
Stress States

ABSTRACTThe mechanical properties of thin film materials are known to be different from those of bulk materials, which are generally overlooked in practice. The difference in mechanical properties can be misleading in the estimation of residual stress states in micro-gas sensors with multi-layer structures during manufacturing and in service.In this study the residual stress of each film layer in a micro-gas sensor was measured according to the five difference sets of film stacking structure used for the sensor. The Pt thin film layer was found to have the highest tensile residual stress, which may affect the reliability of the micro-gas sensor. For the Pt layer the changes in residual stress were measured as a function of processing variables and thermal cycling.

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