scholarly journals The Wafer-Level Integration of Single-Crystal LiNbO3 on Silicon via Polyimide Material

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 70
Author(s):  
Xiangyu Yang ◽  
Wenping Geng ◽  
Kaixi Bi ◽  
Linyu Mei ◽  
Yaqing Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Bonding Strength ◽  
Coefficient Of Thermal Expansion ◽  
Micro Electro Mechanical System ◽  
Temperature Tolerance ◽  
Wafer Level ◽  
Mems Sensors ◽  
Oh Groups ◽  
Silicon Based

In situ measurements of sensing signals in space platforms requires that the micro-electro-mechanical system (MEMS) sensors be located directly at the point to be measured and in contact with the subject to be measured. Traditional radiation-tolerant silicon-based MEMS sensors cannot acquire spatial signals directly. Compared to silicon-based structures, LiNbO3 single crystalline has wide application prospects in the aerospace field owing to its excellent corrosion resistance, low-temperature resistance and radiation resistance. In our work, 4-inch LiNbO3 and LiNbO3/Cr/Au wafers are fabricated to silicon substrate by means of a polyimide bonding method, respectively. The low-temperature bonding process (≤100 ℃) is also useful for heterostructure to avoid wafer fragmentation results from a coefficient of thermal expansion (CTE) mismatch. The hydrophilic polyimide surfaces result from the increasing of -OH groups were acquired based on contact angle and X-ray photoelectron spectroscopy characterizations. A tight and defect-free bonding interface was confirmed by scanning electron microscopy. More importantly, benefiting from low-temperature tolerance and radiation-hardened properties of polyimide material, the bonding strength of the heterostructure based on oxygen plasma activation achieved 6.582 MPa and 3.339 MPa corresponding to room temperature and ultra-low temperature (≈ -263.15 °C), which meets the bonding strength requirements of aerospace applications.

Low temperature Si-Si, SiO2-SiO2 covalent bonding structures with thin siloxane layer

2013 ◽  
Vol 2013 (1) ◽  
pp. 000424-000428
Author(s):  
Jeongyub Lee ◽  
Kunmo Chu ◽  
Yongyoung Park ◽  
Wooyoung Yang ◽  
Wenxu Xianyu ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Layer Thickness ◽  
Bonding Strength ◽  
Oxygen Plasma ◽  
Coefficient Of Thermal Expansion ◽  
Bonding Temperature ◽  
Bonding Process ◽  
Oxygen Plasma Treatment ◽  
Adhesion Properties

We present new Si to Si, SiO2 to SiO2 bonding technologies for low temperature applications (<200°C). Direct bonding process between Si (or SiO2) substrates makes high bonding strength without contamination problems. However, high temperature over 1000°C is needed for the reliable Si to Si and SiO2 to SiO2 direct bonding processes. To reduce the bonding temperature, thin siloxane layer and low-powered oxygen plasma treatment was used in this study. We used dimethyl siloxane layer having siloxane chains (-Si-O-)n and methyl ends. Siloxane layer is able to be bonded strongly with Si-based substrates at low temperature (<200°C) when oxygen plasma is treated on it. Polymerized siloxane layer such as PDMS has much higher coefficient of thermal expansion (CTE) of 300ppm/K than Si of 2.6ppm/K. When the bonded structure is cooled or heated, the interfaces is possibly distorted and cracked by the high residual stress between siloxane layer and Si substrate. To solve these problems, we developed new fabrications of reducing the siloxane layer thickness to 3∼4nm, that is the monomer layer levels. Extremely thin thickness of siloxane layer prevented the problems of the CTE differences. The Si to Si bonding structure with siloxane layer showed strong adhesion properties in this study. The bonded body kept reliable bonding force when it was heated to high temperature (∼900°C). The feasible wafer-level bonding process was demonstrated. We investigated the siloxane layer thickness by TEM images. The bonding strength was confirmed by dicing test by 1mm and measured over 20MPa. We also expended this new development to SiO2 to SiO2 bonding structures. Low temperature bonding between non-Si substrates such as GaN was possible with thin siloxane layer when amorphous Si thin film was deposited on these substrates.

Low Temperature Al-Al Thermo-compression Bonding with Sn Oxidation Protect Layer for Wafer-level Hermetic Sealing

2016 ◽  
Vol 136 (6) ◽  
pp. 237-243 ◽  
Author(s):  
Shiro Satoh ◽  
Hideyuki Fukushi ◽  
Masayoshi Esashi ◽  
Shuji Tanaka
Keyword(s):  
Low Temperature ◽  
Wafer Level ◽  
Hermetic Sealing

scholarly journals Impact of high temperatures on aluminoceladonite studied by Mössbauer, Raman, X-ray diffraction and X-ray photoelectron spectroscopy

2021 ◽  
Author(s):  
Mariola Kądziołka-Gaweł ◽  
Maria Czaja ◽  
Mateusz Dulski ◽  
Tomasz Krzykawski ◽  
Magdalena Szubka
Keyword(s):  
Photoelectron Spectroscopy ◽  
Integral Intensity ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
Structural Reorganization ◽  
Oh Groups ◽  
X Ray ◽  
Al Content ◽  
Integral Intensity Ratio ◽  
Higher Temperature

AbstractMössbauer, Raman, X-ray diffraction and X-ray photoelectron spectroscopies were used to examine the effects of temperature on the structure of two aluminoceladonite samples. The process of oxidation of Fe2+ to Fe3+ ions started at about 350 °C for the sample richer in Al and at 300 °C for the sample somewhat lower Al-content. Mössbauer results show that this process may be associated with dehydroxylation or even initiate it. The first stage of dehydroxylation takes place at a temperature > 350 °C when the adjacent OH groups are replaced with a single residual oxygen atom. Up to ~500 °C, Fe ions do not migrate from cis-octahedra to trans-octahedra sites, but the coordination number of polyhedra changes from six to five. This temperature can be treated as the second stage of dehydroxylation. The temperature dependence on the integral intensity ratio between bands centered at ~590 and 705 cm−1 (I590/I705) clearly reflects the temperature at which six-coordinated polyhedra are transformed into five-coordinated polyhedra. X-ray photoelectron spectra obtained in the region of the Si2p, Al2p, Fe2p, K2p and O1s core levels, highlighted a route to identify the position of Si, Al, K and Fe cations in a structure of layered silicates with temperature. All the measurements show that the sample with a higher aluminum content and a lower iron content in octahedral sites starts to undergo a structural reorganization at a relatively higher temperature than the less aluminum-rich sample does. This suggests that iron may perform an important role in the initiation of the dehydroxylation of aluminoceladonites.

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

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