RF technologies. Besides RF MEMS technology, III-V compound semiconductor (GaAs, GaN, InP, InSb), ferrite, ferroelectric, silicon-based semiconductor (RF CMOS, SiC and SiGe), and vacuum tube technology are available to the RF designer. Each of the RF technologies offers a distinct trade-off between cost, frequency, gain, large-scale integration, lifetime, linearity, noise figure, packaging, power handling, power consumption, reliability, ruggedness, size, supply voltage, switching time and weight.
MEMS micro electro mechanical systems is an advanced field of engineering which has many scientific applications.
This PPT summarizes about mems, the materials used in mems, materials used in mems, their uses, pros and cons, advantages disadvantages etc..
Micromachined Electro-Mechanical Systems, also called microfabricated Systems, have evoked great interest in the scientific and engineering communities. This is primarily due to several substantive advantages that MEMS offer: orders of magnitude smaller size, better performance than other solutions, possibilities for batch fabrication and cost-effective integration with electronics, virtually zero dc power consumption and potentially large reduction in power consumption, etc.
This Seminar would give an introduction to these exciting developments and the technology and design approaches for the realization of these integrated systems. It would be followed with an introduction to the design of microsensors, such as the pressure sensor and the accelerometer, which began the MEMS revolution.
A systematic approach is developed to select manufacturing Process Chains for the generic elements of a MEMS device. A database of MEMS Process Chains and their attendant process attributes is developed from the existing literature, and used to construct Process Attribute charts. The performance requirements of MEMS beams and trenches are translated into the same set of Process Attributes. This allows for a screening of the Process Chains to obtain a list of candidate manufacturing methods.
I begin with a quick introduction to MEMS technology, micron scale and show that silicon is eminently suited for micromechanical devices and therefore the possibility of integrating MEMS with VLSI electronics. Smart cell phones and wireless enabled devices are poised to become commercial engines for the next generation of MEMS, since MEMS provide not only better functionality with smaller chip area, but also alternative transceiver architectures for improved functionality, performance and reliability.
The application domains cover microsensors and actuators for physical quantities, of which MEMS for automobile & consumer electronics forms a large segment; microfabricated subsystems for communications and computer systems.
MEMS micro electro mechanical systems is an advanced field of engineering which has many scientific applications.
This PPT summarizes about mems, the materials used in mems, materials used in mems, their uses, pros and cons, advantages disadvantages etc..
Micromachined Electro-Mechanical Systems, also called microfabricated Systems, have evoked great interest in the scientific and engineering communities. This is primarily due to several substantive advantages that MEMS offer: orders of magnitude smaller size, better performance than other solutions, possibilities for batch fabrication and cost-effective integration with electronics, virtually zero dc power consumption and potentially large reduction in power consumption, etc.
This Seminar would give an introduction to these exciting developments and the technology and design approaches for the realization of these integrated systems. It would be followed with an introduction to the design of microsensors, such as the pressure sensor and the accelerometer, which began the MEMS revolution.
A systematic approach is developed to select manufacturing Process Chains for the generic elements of a MEMS device. A database of MEMS Process Chains and their attendant process attributes is developed from the existing literature, and used to construct Process Attribute charts. The performance requirements of MEMS beams and trenches are translated into the same set of Process Attributes. This allows for a screening of the Process Chains to obtain a list of candidate manufacturing methods.
I begin with a quick introduction to MEMS technology, micron scale and show that silicon is eminently suited for micromechanical devices and therefore the possibility of integrating MEMS with VLSI electronics. Smart cell phones and wireless enabled devices are poised to become commercial engines for the next generation of MEMS, since MEMS provide not only better functionality with smaller chip area, but also alternative transceiver architectures for improved functionality, performance and reliability.
The application domains cover microsensors and actuators for physical quantities, of which MEMS for automobile & consumer electronics forms a large segment; microfabricated subsystems for communications and computer systems.
In this presentation almost complete data are available like synthesis techniques,properties, functionalisations and Applications, etc. This is very useful for Students who studied about Silicides.
Silicon Carbide in Microsystem Technology — Thin Film Versus Bulk MaterialMariana Amorim Fraga
Mariana Amorim Fraga, Matteo Bosi and Marco Negri (2015). Silicon Carbide in Microsystem Technology — Thin Film Versus Bulk Material, Advanced Silicon Carbide Devices and Processing, Dr. Stephen Saddow (Ed.), InTech, DOI: 10.5772/60970. Available from: https://www.intechopen.com/books/advanced-silicon-carbide-devices-and-processing/silicon-carbide-in-microsystem-technology-thin-film-versus-bulk-material
Compare alloys with microcrystalline grains and nanocrystalline grai.pdfinfoeyecare
Compare alloys with microcrystalline grains and nanocrystalline grains in 800 words
Solution
Alloy
Nanocrystalline
Microcrystalline
1. An alloy is a mixture of metals or a mixture of a metal and another element. Alloys are
defined by metallic bonding character.[1] An alloy may be a solid solution of metal elements (a
single phase) or a mixture of metallic phases (two or more solutions). Intermetallic compounds
are alloys with a defined stoichiometry and crystal structure. Zintl phases are also sometimes
considered alloys depending on bond types (see also: Van Arkel-Ketelaar triangle for
information on classifying bonding in binary compounds).
2. Alloys are used in a wide variety of applications. In some cases, a combination of metals
may reduce the overall cost of the material while preserving important properties. In other cases,
the combination of metals imparts synergistic properties to the constituent metal elements such
as corrosion resistance or mechanical strength. Examples of alloys are steel, solder, brass,
pewter, duralumin, phosphor bronze and amalgams.
3. The alloy constituents are usually measured by mass. Alloys are usually classified as
substitutional or interstitial alloys, depending on the atomic arrangement that forms the alloy.
They can be further classified as homogeneous (consisting of a single phase), or heterogeneous
(consisting of two or more phases) or intermetallic.
4. The components of various alloys contain metallic and non-metallic elements. There are a
large number of possible combination of different metals and each has its own specific set of
properties. The Uses for alloys are limitless depending on the materials involved and the
complexity of the alloy. The alloys are used extensively in fields that involve but are not limited
to; aircrafts, military, commercial, industrial, medical, residential and manufacturing
applications. Alloys like Aluminium, Copper, Nickel, Stainless steel, Titanium all have different
uses in various applications.
1. Nanocrystalline silicon (nc-Si), sometimes also known as microcrystalline silicon (c-Si),
is a form of porous silicon.[1] It is an allotropic form of silicon with paracrystalline structure—is
similar to amorphous silicon (a-Si), in that it has an amorphous phase. Where they differ,
however, is that nc-Si has small grains of crystalline silicon within the amorphous phase. This is
in contrast to polycrystalline silicon (poly-Si) which consists solely of crystalline silicon grains,
separated by grain boundaries. The difference comes solely from the grain size of the crystalline
grains. Most materials with grains in the micrometer range are actually fine-grained polysilicon,
so nanocrystalline silicon is a better term. The term Nanocrystalline silicon refers to a range of
materials around the transition region from amorphous to microcrystalline phase in the silicon
thin film. The crystalline volume fraction (as measured from Raman spectroscopy) is another
criterion to describ.
Silicones are a group of organosilicon polymers which are also known as siloxanes. Organosilicon compounds are those in which organic group is attached to silicon. preparations properties, types and applications of silicones.
references for study of silicones.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
for beginners, providing thorough training in areas such as SEO, digital communication marketing, and PPC training in Noida. After finishing the program, students receive the certifications recognised by top different universitie, setting a strong foundation for a successful career in digital marketing.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
Delivering Micro-Credentials in Technical and Vocational Education and TrainingAG2 Design
Explore how micro-credentials are transforming Technical and Vocational Education and Training (TVET) with this comprehensive slide deck. Discover what micro-credentials are, their importance in TVET, the advantages they offer, and the insights from industry experts. Additionally, learn about the top software applications available for creating and managing micro-credentials. This presentation also includes valuable resources and a discussion on the future of these specialised certifications.
For more detailed information on delivering micro-credentials in TVET, visit this https://tvettrainer.com/delivering-micro-credentials-in-tvet/
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
2. MATERIALS FOR MEMS AND
MICROSYSTEMS
This chapter will cover the materials used in “silicon-based”
MEMS and microsystems. As such, silicon will be the
principal material to be studied.
Other materials to be dealt with are silicon compounds such
as: SiO2,SiC, Si3N4 and polysilicon.
Also will be covered are electrically conducting of silicon
piezoresistors and piezoelectric crystals for
electromechanical actuations and signal transductions.
An overview of polymers, which are the “rising stars” to be
used as MEMS and microsystems substrate materials, will
be studied too.
3. Silicon – an ideal substrate material for
MEMS
Silicon is a host of materials commonly used in the
semiconductor integrated circuit industry.
Normally deposited as thin films, they include silicon
oxides, silicon nitrides, and silicon carbides, metals such
as aluminum, titanium, tungsten, and copper, and
polymers such as photoresist and polyimide.
It is mechanically stable and it is feasible to be
integrated into electronics on the same substrate (b/c it is
a semiconducting material).
Electronics for signal transduction such as the p or n-
type piezoresistive can be readily integrated with the Si
substrate-ideal for transistors.
4. It has a melting point at 1400oC, which is about
twice higher than that of aluminum. This high
melting point makes silicon dimensionally stable
even at elevated temperature.
Its thermal expansion coefficient is about 8 times
smaller than that of steel, and is more than 10 times
smaller than that of aluminum
5. Single-Crystal Silicon
For silicon to be used as a substrate material in
integrated circuits and MEMS, it has to be in a
pure single-crystal form.
The most commonly used method of producing
single-crystal silicon is the Czochralski (CZ)
method.
The Czochralski method for producing single-
crystal silicon
6.
7. The Czochralski method for producing single-crystal silicon
Equipment: a crucible and a “puller”.
Procedure:
(1) Raw Si (quartzite) + coal, coke, woodchips)
are melted in the crucible.
(2) A “seed” crystal is brought to be in contact
with molten Si to form larger crystal.
(3) The “puller” slowly pulls the molten Si up
to form pure Si “boule” after the
solidification.
(4) The diameters of the “bologna-like” boules
vary from 100 mm (4”) to 300 mm (12”) in
diameters.
Chemical reaction for the process: SiC + SiO2 → Si + CO +
SiO
8.
9. Pure silicon wafers
Pure silicon boules of 300 mm diameter and 30
ft long, can weigh up to 400 Kg.
These boules are sliced into thin disks (wafers)
using
diamond saws.
Standard sizes of wafers are:
100 mm (4”) diameter x 500 μm thick.
150 mm (6”) diameter x 750 μm thick.
200 mm (8”) diameter x 1 mm thick
300 mm (12”) diameter x 750 μm thick
(tentative).
10.
11. Single Silicon Crystal Structure
Single silicon crystals are basically of “face-
cubic-center” (FCC) structure.
The crystal structure of a typical FCC crystal is
shown below:
12. •Single crystal silicon, however has 4 extra atoms in
the interior.
•The situation is like to merge two FCC crystals
together as shown below:
13. •Total no. of atoms in a single silicon crystal =
18.
•The unsymmetrical distribution of atoms within
the crystal make pure
silicon anisotropic in its mechanical properties.
• In general, however, we treat silicon as an
isotropic material.
14.
15. Silicon Compounds
There are 3 principal silicon compounds used in
MEMS and microsystems:
Silicon dioxide (SiO2), Silicon carbide (SiC) and
silicon nitride (Si3N4) – each has distinct
characteristic and unique applications.
16. Silicon dioxide (SiO2):
•It is least expensive material to offer good
thermal and electrical insulation.
•Also used a low-cost material for “masks” in
micro fabrication processes such as etching,
deposition and diffusion.
•Used as sacrificial material in “surface
micromachining”.
•Above all, it is very easy to produce:
- by dry heating of silicon: Si + O2 → SiO2
- or by oxide silicon in wet steam: Si + 2H2O →
SiO2 + 2H2
17. Silicon carbide (SiC)
Its very high melting point and resistance to chemical reactions make
it ideal candidate material for being masks in micro fabrication
processes.
It has superior dimensional stability.
Silicon nitride (Si3N4)
Produced by chemical reaction:
3SiCl2H2 + 4NH3 → Si3N4 + 6HCL + 6H2
Used as excellent barrier to diffusion to water and ions.
Its ultra strong resistance to oxidation and many etchants make it a
superior material for masks in deep etching.
Also used as high strength electric insulators.
18. Polycrystalline silicon
It is usually called “Polysilicon”.
It is an aggregation of pure silicon crystals with
randomly orientations deposited on the top of
silicon substrates:
19.
20. •These polysilicon usually are highly doped
silicon.
•They are deposited to the substrate surfaces to
produce localized “resistors” and “gates for
transistors”
•Being randomly oriented, polysilicon is even
stronger than single silicon crystals.
21. Silicon Piezoresistors
Piezoresistance = a change in electrical
resistance of solids when
subjected to stress fields. Doped silicon are
piezoresistors (p-type or n-type).
Relationship between change of resistance {ΔR}
and stresses {σ}:
{ΔR} = [π] {σ}
where {ΔR} = { ΔRxx ΔRyy ΔRzz ΔRxy ΔRxz
ΔRyz}T represents the change of resistances in
22. an infinitesimally small cubic piezoresistive crystal
element with corresponding stress components:
{σ} = {σxx σyy σzz σxy σxz σyz}T and [π] =
piezoresistive coefficient matrix.
23. Gallium Arsenide (GaAs)
GaAs is a compound simiconductor with equal
number of Ga and As atoms.
Because it is a compound, it is more difficult to
process.
It is excellent material for monolithic integration
of electronic and photonic devices on a single
substrate.
GaAs is also a good thermal insulator.
Low yield strength (only 1/3 of that of silicon) –
“bad”.
24. A comparison of GaAs and silicon as substrate materials in micromachining:
25. Quartz
Quartz is a compound of SiO2.
The single-unit cell is in shape of tetrahedron:
Quartz crystal is made of up to 6 rings with 6
silicon atoms.
26. Quartz is ideal material for sensors because of
its extreme dimensional
stability.
● It is used as piezoelectric material in many
devices.
● It is also excellent material for microfluics
systems used in biomedical
applications.
● It offers excellent electric insulation in
microsystems.
● A major disadvantage is its hard in machining.
It is usually etched in
HF/NH4F into desired shapes.
33. Polymers
What is polymer?
Polymers include: Plastics, adhesives,
Plexiglass and Lucite.
Principal applications of polymers in MEMS:
Currently in biomedical applications and
adhesive bonding.
New applications involve using polymers as
substrates with electric conductivity made
possible by doping.
34. Molecular structure of polymers:
It is made up of long chains of organic
(hydrocarbon) molecules.
The molecules can be as long as a few
hundred nm.
Characteristics of polymers:
Low melting point; Poor electric
conductivity
Thermoplastics and thermosets are
common industrial products
Thermoplastics are easier to form into
shapes.
Thermosets have higher mechanical
strength even at temperature up to 350oC
35. Polymers as industrial materials
Polymers are popular materials used for many
industrial products for the following advantages:
Light weight
Ease in processing
Low cost of raw materials and processes for producing
polymers
High corrosion resistance
High electrical resistance
High flexibility in structures
High dimensional stability
36. Packaging Materials
Unlike IC packaging in which plastic or ceramic are
extensively used as encapsulate materials for the
delicate IC circuits, MEMS packaging involve a great
variety of materials-varying from plastic and
polymers to stainless steel, as can be seen in a
specially packaged micropressure sensor: