The Effect of Thermal Shocks on the Stresses in a Sapphire Wafer

Vodenitcharova, T.; Zhang, L.C.; Zarudi, I.; Yin, Y.; Domyo, H.; Ho, Tsz Chung

doi:10.1109/tsm.2006.883591

Cited by 11 publications

(4 citation statements)

References 11 publications

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“…The boundary conditions adopted here are similar to those previously used by the authors [22,23]: the single wafer is considered in thermal equilibrium with the surrounding wafers; the wafer is subjected to radiation on its edges while under high environmental temperature, but subjected to convection on the edges while at low room temperature; the environmental temperature is transferred from the edges through the wafer by heat conduction. Transient heat transfer analysis leads to the same temperature distribution for the anisotropic sapphire wafer, as for the isotropic sapphire wafer [22] because the sapphire thermal properties are not directional dependent, e.g., Figs.…”

Section: Heat Transfermentioning

confidence: 99%

The effect of anisotropy on the deformation and fracture of sapphire wafers subjected to thermal shocks

Vodenitcharova

Zhang

Zarudi

et al. 2007

Journal of Materials Processing Technology

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Section: Heat Transfermentioning

confidence: 99%

The effect of anisotropy on the deformation and fracture of sapphire wafers subjected to thermal shocks

Vodenitcharova

Zhang

Zarudi

et al. 2007

Journal of Materials Processing Technology

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“…The thermal expansion coefficient is linearly related to temperature, as shown in figure 7. It is close to the thermal expansion coefficient of the sapphire wafer described in [28]. To evaluate the stability of the sensor, we recorded the cavity length for 200 min at the room temperature point with a time interval of 1 min, and the measurement results are shown in figure 9.…”

Section: Resultsmentioning

confidence: 64%

An all-sapphire fiber temperature sensor for high-temperature measurement

Cui¹,

Jiang²,

Zhang³

et al. 2022

Meas. Sci. Technol.

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An all-sapphire high-temperature optical fiber sensor with an extrinsic Fabry-Perot interferometer (EFPI) structure is proposed and experimentally demonstrated. The EFPI structure of the sensor is composed of a sapphire ferrule with a sapphire fiber and a polished solid sapphire crystal rod. The first reflection occurs on the left end of the sapphire ferrule, and the second reflection occurs on the right end of the sapphire rod, forming double-beam interference. The interference signal is picked up by the sapphire fiber and transmitted to the white light interferometric demodulator by the multimode fiber. The picked-up signal is demodulated by the Fourier transform and interference algorithms. Experimental results show that the temperature response of the sensor is quadratic, and the sensitivity changes linearly with the temperature range from room temperature to 1500 ℃. The first-order thermal expansion coefficient and the second-order thermal expansion coefficient are 5.4575ⅹ10-6 and 7.3755ⅹ10-9, respectively. The thermal expansion coefficient is linearly related to temperature. Due to all sapphire structure, this sensor solves the problem of thermal expansion coefficient mismatch, which was observed in a previous sensor made of sapphire and ceramic materials. In addition, it improves the high-temperature resistance, so it can be fully qualified for long-term high-temperature measurements above 1000-1500 ℃.

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“…One of the reasons is the rapid temperature variation during heating and/or cooling, which can increase mechanical stresses within the wafer due to the wafer thermal inertia and phase shift which generate a thermal gradient across the entire 6‐inch wafer. [ 25 ] Good crystalline quality h‐BN needs to be grown at high temperature (1280 °C in our case), n‐GaN ≈1100 °C and InGaN ≈700 °C, so for 6‐inch wafers the effect of temperature changes between h‐BN growth and subsequent layer growth are more pronounced. Another reason is the switch of carrier gases, between hydrogen (H 2 ) with high thermal conductivity (482 mW mK −1 at 700 °C [ 26 ] ) and nitrogen (N 2 ) with low thermal conductivity (64 mW mK −1 at 700 °C [ 27 ] ), used for the growth of different layers of GaN‐based LED heterostructures on h‐BN, which causes a sudden change of surface temperature of the wafer and hence a thermal shock.…”

Section: Resultsmentioning

confidence: 99%

Scaling up of Growth, Fabrication, and Device Transfer Process for GaN‐based LEDs on H‐BN Templates to 6‐inch Sapphire Substrates

Vuong

Moudakir

Gujrati

et al. 2023

Adv Materials Technologies

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The growth of hexagonal boron nitride (h‐BN) and van der Waals (vdW) epitaxy of blue multi‐quantum well (MQW) GaN‐based LED heterostructures on 6‐inch sapphire substrates using metal‐organic chemical vapour deposition (MOCVD) is demonstrated. Challenges associated with the growth of large surface h‐BN and the subsequent vdW epitaxy of GaN‐based LED heterostructures are discussed. To overcome these challenges, the spatial uniformity is controlled of the growth temperature, optimizes the slope of temperature variations during the growth and cooling process, and manages the surface temperature during switching of gas flows. With these adaptations, high quality GaN‐based LED heterostructures are grown on h‐BN without any spontaneous delamination. The GaN‐based LED devices are then fabricated on a 6‐inch sapphire wafer, which are lifted off as a membrane and transferred to a flexible copper support. These GaN‐based LED devices emitt bright blue illumination with an electroluminescence peak at 437 nm. This scaling up of growth, lift‐off, and transfer can lead to the commercialization of GaN‐based LEDs on h‐BN template on 6‐inch sapphire substrates, with a process compatible with current modern equipment for the fabrication of LEDs and electronic devices.

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The Effect of Thermal Shocks on the Stresses in a Sapphire Wafer

Cited by 11 publications

References 11 publications

The effect of anisotropy on the deformation and fracture of sapphire wafers subjected to thermal shocks

The effect of anisotropy on the deformation and fracture of sapphire wafers subjected to thermal shocks

An all-sapphire fiber temperature sensor for high-temperature measurement

Scaling up of Growth, Fabrication, and Device Transfer Process for GaN‐based LEDs on H‐BN Templates to 6‐inch Sapphire Substrates

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