Microstructure and mechanical strength of snag-based solid liquid inter-diffusion bonds for 3 dimensional integrated circuits

Ladani, Leila; Razmi, Jafar; Bentley, Jordan

doi:10.1016/j.tsf.2010.03.037

Cited by 4 publications

(5 citation statements)

References 28 publications

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“…The pressure was adjusted such that the average thickness remained around 220 lm. 1 The fabrication time for complete transformation to Cu 6 Sn 5 for this configuration was found to be around 45 min at 260°C. 1 In fabrication of 3D ICs, the bond thickness may be reduced to 20 lm and even lower, which is much smaller than the size of the bond in the peeling test configuration.…”

Section: Specimen Fabrication and Mechanical Testingmentioning

confidence: 88%

“…1 The fabrication time for complete transformation to Cu 6 Sn 5 for this configuration was found to be around 45 min at 260°C. 1 In fabrication of 3D ICs, the bond thickness may be reduced to 20 lm and even lower, which is much smaller than the size of the bond in the peeling test configuration. To investigate the size effect and evaluate a real application size specimen, another normal test specimen was fabricated in DCB configuration using a more advanced fabrication technique.…”

Section: Specimen Fabrication and Mechanical Testingmentioning

confidence: 88%

“…New technology based on solid-liquid interdiffusion (SoLID) bonding was recently introduced at the microscale. 1 SoLID bonding, also known as low-temperature transient liquid-phase (LTTLP) bonding 2 or low-temperature (LT) bonding, is preferred over other technologies due to its wide variety of material choices, low temperature, and low cost. The process involves a low temperature melting point (LTM) intermediate material that is deposited on high temperature melting (HTM) substrate.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Strength and Failure Characterization of Sn-Ag-Cu Intermetallic Compound Joints at the Microscale

Ladani

Razmi

2011

Journal of Elec Materi

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Continuous miniaturization of microelectronic devices has led the industry to develop interconnects on the order of a few microns for advanced superhighdensity and three-dimensional integrated circuits (3D ICs). At this scale, interconnects that conventionally consist of solder material will completely transform to intermetallic compounds (IMCs) such as Cu 6 Sn 5 . IMCs are brittle, unlike conventional solder materials that are ductile in nature; therefore, IMCs do not experience large amounts of plasticity or creep before failure. IMCs have not been fully characterized, and their mechanical and thermomechanical reliability is questioned. This study presents experimental efforts to characterize such material. Sn-based microbonds are fabricated in a controlled environment to assure complete transformation of the bonds to Cu 6 Sn 5 IMC. Microstructural analysis including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) is utilized to determine the IMC material composition and degree of copper diffusion into the bond area. Specimens are fabricated with different bond thicknesses and in different configurations for various tests. Normal strength of the bonds is measured utilizing double cantilever beam and peeling tests. Shear tests are conducted to quantify the shear strength of the material. Fourpoint bending tests are conducted to measure the fracture toughness and critical energy release rate. Bonds are fabricated in different sizes, and the size effect is investigated. The shear strength, normal strength, critical energy release rate, and effect of bond size on bond strength are reported.

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Section: Specimen Fabrication and Mechanical Testingmentioning

confidence: 88%

Section: Specimen Fabrication and Mechanical Testingmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Mechanical Strength and Failure Characterization of Sn-Ag-Cu Intermetallic Compound Joints at the Microscale

Ladani

Razmi

2011

Journal of Elec Materi

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“…The significant parameters of concern were the LP, laser speed (LS), spot diameter (SP), and laser travel direction (LT), which were optimized to obtain a finished cut of a single line with the least HAZ. The full Factorial method was applied to the process parameters to achieve optimal conditions [23][24][25]. The optimized parameters were then used to micromachine custom shapes such as squares, triangles, circles and optical shutter.…”

Section: Introductionmentioning

confidence: 99%

Investigation of laser-assisted micromachining of NiTi SMA bimorph based actuators toward developing optical shutters

Gangwar,

Pandiyan,

Iyamperumal Anand

2024

J. Micromech. Microeng.

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This work explores laser-assisted micromachining for the precision cutting of NiTi SMA-based bimorph in a single-pass laser scan. NiTi SMA bimorph was fabricated using the e-beam evaporation technique followed by micromachining using a 1064 nm fiber laser. The influence of laser power, laser speed, spot diameter, and laser travel direction on kerf width and heat-affected zone after micromachining was studied using the design of experiments. The optimized parameter for micromachining was at laser power 5 W with 5 mm/s laser speed and 50 μm spot diameter. Various shapes were cut at the optimized parameter, including an optical shutter of a diameter of 30 mm. A laser speed of 6 mm/s has produced microchannels in the bimorph due to NiTi film removal only. The SEM analysis of the shutter reveals the formation of refined grains at micromachined edges compared to the center of the actuator. Fabricated optical shutter shows negligible optical transmittance in the 450 to 700 nm wavelength range.

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“…Recently, many researchers have investigated the interfacial IMC growth behavior at solid-liquid interface reaction. The effect of the process parameters (such as time, temperature and pressure) on the bonded strength and microstructure of the Sn-3.5Ag/Cu solid-liquid soldering process was investigated (Ladani et al, 2010). It was found that the temperature was the most influential factor on the bonded strength.…”

Section: Introductionmentioning

confidence: 99%

Growth kinetics of IMC at the solid Cu/liquid Sn interface

Zhang

Sun

Liu

2018

SSMT

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Purpose The purpose of this paper is to investigate growth kinetics of interfacial Cu-Sn intermetallic compound (IMC) at the solid Cu/liquid Sn interface. Design/methodology/approach The Sn/Cu solid–liquid interfacial IMCs are fabricated under various soldering temperatures (240°C-270°C) and soldering times (5-240 s) by dipping method. The thickness and morphology of IMC are observed and analyzed by the optical microscope and scanning electron microscope. Findings Holding at 260°C, Cu/Sn solid–liquid interface Cu6Sn5 growth index experience a change from 0.08 to 0.30 within 10-190 s. The growth index is 0.08 in 10-40 s; the growth index is 0.30 in 40-190 s. Cu6Sn5 grain coarsening index is constant within 10-190 s. It is 0.13. The result of the index of Cu6Sn5 grain coarsening is different from predecessors 27 results Cu6Sn5 grain coarsening index for 1/3. This is because Cu6Sn5 grain grows at the expense of its near small grain to reduce the surface Gibbs free energy, and its morphology changes from regular shape to irregular shape. It sets up the mathematical expression about the initial formation time and temperature of Cu3Sn in 240°C-270°C. Originality/value It obtains a mathematical model to express the changes of solid–liquid interface frontier concentration which has an effect on the interfacial Cu6Sn5 layer growth index and the Cu6Sn5 grain coarsening index. Different indexes can be obtained by establishing relevance equations, which can be used to predict the growth of the interface IMC layer. This mathematical model is established to design the solder pads and the sizes of the solder joints.

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Microstructure and mechanical strength of snag-based solid liquid inter-diffusion bonds for 3 dimensional integrated circuits

Cited by 4 publications

References 28 publications

Mechanical Strength and Failure Characterization of Sn-Ag-Cu Intermetallic Compound Joints at the Microscale

Mechanical Strength and Failure Characterization of Sn-Ag-Cu Intermetallic Compound Joints at the Microscale

Investigation of laser-assisted micromachining of NiTi SMA bimorph based actuators toward developing optical shutters

Growth kinetics of IMC at the solid Cu/liquid Sn interface

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