Improving the reliability of eutectic bonding vertical power light-emitting diodes by a Mo buffer layer

Chang, Liann‐Be; Yen, Chia-I; You, Ting-Wei; Jeng, Ming–Jer; Wu, Chun–Te; Hu, Sung-Cheng; Kuo, Yang-Kuao

doi:10.1016/j.tsf.2014.03.029

Cited by 4 publications

(7 citation statements)

References 12 publications

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“…The upper and lower layers are electroplated Cu layers. The middle is an inter-metallic compound (IMC) layer without via, cracks and cracks, which is formed by solid–liquid diffusion growth [ 22 ]. According to energy dispersive spectrometer (EDS) analysis, the ratio of the number of Cu atoms to the number of Sn atoms is about 11:3, and then the composition analysis of the cross sections of different bonding bumps is basically close to the atomic ratio of Cu 3 Sn, so the intermediate layer was determined to be Cu 3 Sn [ 23 ].…”

Section: Resultsmentioning

confidence: 99%

Research of Wafer Level Bonding Process Based on Cu–Sn Eutectic

Tian

Wang

et al. 2020

Micromachines

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In 3D-system packaging technologies, eutectic bonding is the key technology of multilayer chip stacking and vertical interconnection. Optimized from the aspects of the thickness of the electroplated metal layer, the pretreatment of the wafer surface removes the oxide layer, the mutual alignment between the wafers, the temperature of the wafer bonding, the uniformity of pressure and the deviation of the bonding process. Under the pretreatment conditions of plasma treatment and citric acid cleaning, no oxide layer was obtained on the metal surface. Cu/Sn bumps bonded under the condition of 0.135 Mpa, temperature of 280 °C, Sn thickness of 3–4 μm and a Cu-thickness of five micrometers. Bonded push crystal strength ≥18 kg/cm2, the average contact resistance of the bonding interface is about 3.35 mΩ, and the bonding yield is 100%. All performance indicators meet and exceed the industry standards.

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Section: Resultsmentioning

confidence: 99%

Research of Wafer Level Bonding Process Based on Cu–Sn Eutectic

Tian

Wang

et al. 2020

Micromachines

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“…The Cu ion diffusion is responsible for the non-radiative recombination, which leads to the loss of the light output power. 31 Furthermore, this implies that the significant blocking ability of Cu ion diffusion and the output power drop can be effectively improved by employing a Mo buffer layer in the VLED package.…”

Section: Methodsmentioning

confidence: 99%

“…30 It is clear that the CTE value of Mo is similar to that of the LED material (GaN or GaAs), and therefore, Mo can act as a buffer layer between the semiconductor VLED and the Al-based substrate to avoid cracking in long-term operations. 31 Some of these studies provided strong alternatives to conventional buffer layers, particularly for Al or Cu materials, for higher thermal reliability or improved heat dissipation.…”

Section: Introductionmentioning

confidence: 99%

“…In the present study, we propose an approach for improving thermal stability and reducing energy consumption between the GaAs VLED chip/MCPCB substrate interface by adding a Mo buffer layer. 31 The structural, electrical, and optical properties of these VLED packages under different buffer layer conditions were characterized. Thermal shock tests (TST) were also carried out to determine the increase in thermal stability of the VLED package with the Mo/Cu buffer layers.…”

Section: Introductionmentioning

confidence: 99%

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The Improvement of Bonding Metal Layers in a GaAs Vertical Structure Light-Emitting Diode Package

Chang

Jeng

et al. 2020

Journal of Elec Materi

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This paper presents an investigation into the reliability of substrate bonding between metal layers and gallium arsenide vertical-injection light-emitting diodes (GaAs VLEDs). In this study, molybdenum (Mo) acts as a buffer layer between the GaAs VLED and the aluminum-based metal core printed circuit board (MCPCB). The thermal expansion coefficient (CTE) value of GaAs is approximately equal to that of the Mo layer under the substrate. This is beneficial for slowing the decay of the adhesive bond due to temperature cycling from À 40°C to 125°C for 50 cycles. The experimental results show that the use of the Mo buffer layer greatly improved the electrical and optical performance of the LED packages. The average leakage current was reduced from 33.63 mA to 2.37 mA at the reversed voltage of À 3 V and the increase in light output power was 130% at an injection current of 0.7 A. The results also show that a Mo buffer layer can reduce the risk of cracking on bonding wires after the thermal shock test (TST). These results are useful for improving the aging of GaAs VLEDs.

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“…This method provided a convenient method using an IR microscope to evaluate bonding quality without destroying the bonded pairs. Furthermore, the method for improving the reliability of Au/Si eutectic bonding with either an Mo-buffered layer [ 10 ] or localized bonding [ 11 ] was also studied. However, there have been few reports about the influence of contact force and the heating/cooling rate on Au/Si eutectic bonding quality.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers

Shang

Yin

et al. 2017

Micromachines

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Au/Si eutectic bonding is considered to BE a promising technology for creating 3D structures and hermetic packaging in micro-electro-mechanical system (MEMS) devices. However, it suffers from the problems of a non-uniform bonding interface and complex processes for the interconnection of metal wires. This paper presents a novel Au/Si eutectic wafer bonding structure and an implementation method for MEMS accelerometer packaging. The related processing parameters influencing the Au/Si eutectic bonding quality were widely investigated. It was found that a high temperature of 400 °C with a low heating/cooling rate of 5 °C/min is crucial for successful Au/Si eutectic bonding. High contact force is beneficial for bonding uniformity, but the bonding strength and bonding yield decrease when the contact force increases from 3000 to 5000 N due to the metal squeezing out of the interface. The application of TiW as an adhesion layer on a glass substrate, compared with a commonly used Cr or Ti layer, significantly improves the bonding quality. The bonding strength is higher than 50 MPa, and the bonding yield is above 90% for the presented Au/Si eutectic bonding. Furthermore, the wafer-level vacuum packaging of the MEMS accelerometer was achieved based on Au/Si eutectic bonding and anodic bonding with one process. Testing results show a nonlinearity of 0.91% and a sensitivity of 1.06 V/g for the MEMS accelerometer. This Au/Si eutectic bonding process can be applied to the development of reliable, low-temperature, low-cost fabrication and hermetic packaging for MEMS devices.

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Improving the reliability of eutectic bonding vertical power light-emitting diodes by a Mo buffer layer

Cited by 4 publications

References 12 publications

Research of Wafer Level Bonding Process Based on Cu–Sn Eutectic

Research of Wafer Level Bonding Process Based on Cu–Sn Eutectic

The Improvement of Bonding Metal Layers in a GaAs Vertical Structure Light-Emitting Diode Package

Investigation of Au/Si Eutectic Wafer Bonding for MEMS Accelerometers

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