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Next, a machine called a stepper ( [link] ) is calibrated to project an extremely fine and focused image through a special type ofreticle film in a manner similar to that of a simple slide projector. The light that is transmitted through the reticle isprojected onto the photoresist layer, which reacts to the light and begins to harden. All of the parts of the wafer exposed to thislight harden into a tough crust while the parts in shadow remain soft. This particular step is known by the name ofphotoelectrochemical etching because it achieves an etching effect, resulting in a chip.

An artist’s illustration of a stepper (image from Solid State Electronics).

Hundreds of copies of the chip are etched onto the wafer until the entire surface has been exposed. Once this process is complete, the entirewafer is submerged into an etching bath, which washes away any parts of the photoresist that remain unexposed along with theinsulating chemicals underneath. The hardened areas of the photoresist, however, remain and protect the layers of materialunderneath them. This process of depositing chemicals, coating with a photoresist, exposure to light over a film mask, and etching andwashing away is repeated more than a dozen times. The result is an elaborate, three-dimensional construction of interlocking siliconwires.

This product is then coated with another insulating layer and is plated with a thin layer of metal, usuallyeither aluminum or copper. Yet another photoresist is laid down on top of this metal plating, and after the wafer is exposed in astepper, the process repeats with another layer of metal. After this step has been repeated several more times, a final wash stepis performed, and a finished semiconductor product rolls off the assembly line, at last.

What is a clean room?

A typical semiconductor fabrication facility, or “fab” in industry jargon, looks like a normal two- or three-story officebuilding from the outside, and most of the interior space is devoted to one or more “clean rooms,” in which the semiconductorsare actually made. A clean room is designed with a fanatical attention to detail aimed towards keeping the room immaculate anddust-free ( [link] ).

An industry clean room at AP Tech (photo from Napa Gateway).

Most if not all surfaces inside these clean rooms are composed of stainless steel, and these surfaces aresloped whenever possible or perforated by grating to avoid giving dust a place to settle. The air is filtered through both theceiling and the floor to remove particles that are down to 1/100 the width of a human hair. Lighting is characteristically brightand slightly yellowish to prevent mildew from forming behind equipment or in recessed corners, and even the workers in a cleanroom must be absolutely spotless.

Workers in these rooms must be covered from head to toe in “bunny suits” that completely seal the body in abulky suit, helmet, battery pack, gloves, and boots. Once sealed in these suits, the workers often look more like space explorers in ascience fiction movie than computer chip employees, but in order to even enter the stainless steel locker room to suit up to beginwith, they must first pass through a series of air lock doors, stand under a number of “air showers” that actually blow dust offof clothing, and walk across a sticky floor matting that removes grime from the bottom of shoes.

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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