An Investigation of Residual Stress Effects due to the Anodic Bonding of Glass and Silicon in MEMS Fabrication

2006 ◽  
Vol 5-6 ◽  
pp. 501-508 ◽  
Author(s):  
I. Sadaba ◽  
Colin H.J. Fox ◽  
Stewart McWilliam
Keyword(s):  
Residual Stress ◽  
Anodic Bonding ◽  
Fe Model ◽  
Moderate Pressure ◽  
Mems Devices ◽  
Wafer Level ◽  
Micro Electro Mechanical Systems ◽  
Ion Migration ◽  
Compositional Gradients ◽  
Rate Sensor

Anodic bonding is widely-used in the fabrication of Micro-Electro-Mechanical Systems (MEMS) devices to join silicon and glass components. The process involves the application of temperature, moderate pressure and an electric field. This paper investigates residual stresses arising during anodic bonding, focusing on the resulting induced distortions. Components of a MEMS silicon rate sensor, in which a silicon wafer is anodically bonded to Pyrex™ glass, were used as the vehicle for the investigation. Distortions generated by the anodic bonding process when using two different electrode configurations (point and planar) were measured using a surface optical profiler. These showed a particular pattern across the wafers for both configurations. An efficient FEM study was carried out to model the qualitative effect of the following residual stress sources; thermal stress, glass shrinkage due to structural relaxation and compositional gradients due to ion migration. Importantly, the FE model takes account the actual multi-device wafer-level configuration, as opposed to a single device. The results demonstrate that compositional gradients can make a significant contribution to the observed pattern of distortions.

Wafer Level Micropackaging of MEMS Devices Using Thin Film Anodic Bonding

2002 ◽  
Vol 729 ◽  
Author(s):  
Lauren E. S. Rohwer ◽  
Andrew D. Oliver ◽  
Melissa V. Collins
Keyword(s):  
Shear Strength ◽  
Test Sample ◽  
Anodic Bonding ◽  
Mems Devices ◽  
Wafer Level ◽  
Thermal Actuators ◽  
Wafer Level Packaging ◽  
Hermetic Seal ◽  
Leak Testing ◽  
Before And After

AbstractA wafer level packaging technique that involves anodic bonding of Pyrex wafers to released surface micromachined wafers is demonstrated. Besides providing a hermetic seal, this technique allows full wafer release, provides protection during die separation, and offers the possibility of integration with optoelectronic devices. Anodic bonding was performed under applied voltages up to 1000 V, and temperatures ranging from 280 to 400°C under vacuum (10-4Torr). The quality of the bonded interfaces was evaluated using shear strength testing and leak testing. The shear strength of Pyrex-to-polysilicon and aluminum bonds was ∼10-15 MPa. The functionality of surface micromachined polysilicon devices was tested before and after anodic bonding. 100% of thermal actuators, 94% of torsional ratcheting actuators, and 70% of microengines functioned after bonding. The 70% yield was calculated from a test sample of 25 devices.

Effects of Packaging Induced Stress on MEMS Devices and Its Improvements

2006 ◽  
Vol 326-328 ◽  
pp. 529-532
Author(s):  
Sung Hoon Choa ◽  
Moon Chul Lee ◽  
Yong Chul Cho
Keyword(s):  
Silicon On Insulator ◽  
Anodic Bonding ◽  
Mems Devices ◽  
Wafer Level ◽  
Process Technology ◽  
Molding Compound ◽  
Mems Packaging ◽  
Induced Stress ◽  
Induced Structure ◽  
Glass Process

In MEMS, packaging induced stress or stress induced structure deformation becomes increasing concerns since it directly affects the performance of the device. The conventional MEMS SOI (silicon-on-insulator) gyroscope, packaged using the anodic bonding at the wafer level and EMC (epoxy molding compound) molding, has a deformation of MEMS structure caused by thermal expansion mismatch. Therefore we propose a packaged SiOG (Silicon On Glass) process technology and more robust spring design.

Ceramic Via Wafer-Level Packaging for MEMS

2005 ◽  
Author(s):  
John M. Heck ◽  
Leonel R. Arana ◽  
Bill Read ◽  
Thomas S. Dory
Keyword(s):  
Mems Devices ◽  
Wafer Level ◽  
Micro Electro Mechanical Systems ◽  
Mems Switches ◽  
Mems Packaging ◽  
Wafer Level Packaging ◽  
Novel Approach ◽  
Electrical Interconnection ◽  
Tin Silver Copper ◽  
Board Level

We will present a novel approach to wafer level packaging for micro-electro-mechanical systems. Like most common MEMS packaging methods today, our approach utilizes a wafer bonding process between a cap wafer and a MEMS device wafer. However, unlike the common methods that use a silicon or glass cap wafer, our approach uses a ceramic wafer with built-in metal-filled vias, that has the same size and shape as a standard 150 mm silicon wafer. This ceramic via wafer packaging method is much less complex than existing methods, since it provides hermetic encapsulation and electrical interconnection of the MEMS devices, as well as a solderable interface on the outside of the package for board-level interconnection. We have demonstrated successful ceramic via wafer-level packaging of MEMS switches using eutectic gold-tin solder as well as tin-silver-copper solder combined with gold thermo-compression bonding. In this paper, we will present the ceramic via MEMS package architecture and discuss the associated bonding and assembly processes.

Wafer Bonding Processes for the Manufacture of Microsystems

2008 ◽  
Author(s):  
Tony Rogers ◽  
Nick Aitken
Keyword(s):  
Bond Strength ◽  
Wafer Bonding ◽  
High Efficiency ◽  
Glass Frit ◽  
Acoustic Microscopy ◽  
Anodic Bonding ◽  
High Yield ◽  
Mems Devices ◽  
Wafer Level ◽  
Wafer Level Packaging

Wafer bonding is a widely used step in the manufacture of Microsystems, and serves several purposes: • Structural component of the MEMS device. • First level packaging. • Encapsulation of vacuum or controlled gas. In addition the technology is becoming more widely used in IC fabrication for wafer level packaging (WLP) and 3D integration. It is also widely used for the fabrication of micro fluidic structures and in the manufacture of high efficiency LED’s. Depending on the application, temperature constraints, material compatibility etc. different wafer bonding processes are available, each with their own benefits and drawbacks. This paper describes various wafer bonding processes that are applicable, not only to silicon, but other materials such as glass and quartz that are commonly used in MEMS devices. The process of selecting the most appropriate bonding process for the particular application is presented along with examples of anodic, glass frit, eutectic, direct, adhesive and thermo-compression bonding. The examples include appropriate metrology for bond strength and quality. The paper also addresses the benefits of being able to treat the wafer surfaces in-situ prior to bonding in order to improve yield and bond strength, and also discusses equipment requirements for achieving high yield wafer bonding, along with high precision alignment accuracy, good force and temperature uniformity, high wafer throughput, etc. Some common problems that can affect yield are identified and discussed. These include local temperature variations, that can occur with anodic bonding, and how to eliminate them; how to cope with materials of different thermal expansion coefficient; how best to deal with out-gassing and achieve vacuum encapsulation; and procedures for multi-stacking wafers of differing thicknesses. The presentation includes infra-red and scanning acoustic microscopy images of various bond types, plus some examples of what can go wrong if the correct manufacturing protocol is not maintained.

Laser Bonding and Modeling for Wafer-Level and Chip-Scale Packaging of Micro-Electro-Mechanical Systems

2002 ◽  
Author(s):  
Yi Tao ◽  
Ajay P. Malshe ◽  
W. D. Brown
Keyword(s):  
Low Temperature ◽  
Continuous Wave ◽  
Bonding Temperature ◽  
Mems Devices ◽  
Wafer Level ◽  
Micro Electro Mechanical Systems ◽  
Silicon Chips ◽  
Laser Bonding ◽  
Sealing Ring ◽  
Carbon Dioxide Co2

In this work, low temperature selective solder (Pb37/Sn63) bonding of silicon chips or wafers for MEMS applications using a continuous wave (CW) carbon dioxide (CO2) laser at a wavelength of 10.6μm was examined. The low reflectivity, fair transmittance, and high absorptivity of silicon at the 10.6μm wavelength led to selective heating of the silicon and reflow of an electroplated or screen printed intermediate solder layer which produced silicon-solder-silicon joints. Finite element simulations were carried out to optimize the process parameters in order to achieve uniform heating and minimum induced thermal stress. The bonding process was performed on the fixtures in a vacuum chamber at an air pressure of one milliTorr to achieve fluxless soldering and vacuum encapsulation of silicon dies. The bonding temperature at the sealing ring was close to the reflow temperature of the eutectic lead tin solder, 183°C. Pull test results showed that the joint was sufficiently strong and could not be separated before the silicon die broke. Helium leak testing showed that the leak rate of the package was below 10−8 atm · cc/sec under optimized bonding conditions. The results of the Design of Experiment (DOE) method indicated that both laser incident power and scribe velocity significantly influenced bonding results. This novel method is especially suitable for vacuum bonding wafers containing MEMS and other micro devices with low temperature budgets where managing stress distribution is important. Further, sealed encapsulated and released wafers can be diced without damaging the MEMS devices at wafer scale.

Wafer level hermetic sealing of MEMS devices with vertical feedthroughs using anodic bonding

2015 ◽  
Vol 224 ◽  
pp. 169-176 ◽  
Author(s):  
Mustafa Mert Torunbalci ◽  
Said Emre Alper ◽  
Tayfun Akin
Keyword(s):  
Anodic Bonding ◽  
Mems Devices ◽  
Wafer Level ◽  
Hermetic Sealing

Study on bearing stiffness characteristics with residual stress in carburized layer

2020 ◽  
pp. 095440622096079
Author(s):  
Junshuai Liang ◽  
Ning Li ◽  
Jingyu Zhai ◽  
BaoGang Wen ◽  
Qingkai Han ◽  
...  
Keyword(s):  
Residual Stress ◽  
Contact Stiffness ◽  
Roller Bearing ◽  
High Load ◽  
Axial Stiffness ◽  
Fe Model ◽  
Low Load ◽  
Bearing Stiffness ◽  
Carburized Layer ◽  
Stiffness Characteristics

In this study, a layering method of carburized ring is presented. A finite element (FE) model for analyzing bearing stiffness characteristics is established considering the residual stress in the carburized layer. The residual stress in the carburized layer of a double-row conical roller bearing is tested and the influence of the distribution of residual stress in carburized layer on the bearing stiffness is investigated. Results show that the residual stress in the carburized layer increases the contact stiffness of the bearing by 5% in the low-load zone and 3% in the high-load zone. The radial stiffness of the bearing is increased by 5% in the low-load zone and 3% in the high-load zone. The axial stiffness is increased by 6%, and the angular stiffness increased by 4%. The larger the thickness of the carburized layer, the greater the residual compressive stress in the carburized layer, the deeper the position of the maximum residual stresses in the carburized layer will lead to the greater stiffness of the bearing.

An all-silicon process platfom for wafer-level vacuum packaged MEMS devices

2021 ◽  
pp. 1-1
Author(s):  
Mustafa Mert Torunbalci ◽  
Hasan Dogan Gavcar ◽  
Ferhat Yesil ◽  
Said Emre Alper ◽  
Tayfun Akin
Keyword(s):  
Mems Devices ◽  
Wafer Level

scholarly journals Effect of rare earth oxide CeO2 on the anodic bonding performance of PEG-based MEMS encapsulation materials

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402110077
Author(s):  
Chao Du ◽  
Cuirong Liu ◽  
Xu Yin ◽  
Haocheng Zhao
Keyword(s):  
Tensile Strength ◽  
Rare Earth ◽  
Rare Earth Oxide ◽  
Solid Polymer Electrolytes ◽  
Anodic Bonding ◽  
Solid Polymer ◽  
Bonding Layer ◽  
Scanning Calorimetry ◽  
Ion Migration ◽  
Bonding Performance

Herein, we synthesized a new polyethylene glycol (PEG)-based solid polymer electrolyte containing a rare earth oxide, CeO2, using mechanical metallurgy to prepare an encapsulation bonding material for MEMS. The effects of CeO2 content (0–15 wt.%) on the anodic bonding properties of the composites were investigated. Samples were analyzed and characterized by alternating current impedance spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, tensile strength tests, and anodic bonding experiments. CeO2 reduced the crystallinity of the material, promoted ion migration, increased the conductivity, increased the peak current of the bonding process, and increased the tensile strength. The maximum bonding efficiency and optimal bonding layer were obtained at 8 wt% CeO2. This study expands the applications of solid polymer electrolytes as encapsulation bonding materials.

Sign in / Sign up

Export Citation Format

Share Document