Inside look: RFID and other tags
Let the skyfall
When it crumbles,
We will stand tall
And face it all ...
It has been quite a long time since the last article from the beloved (at least I really hope so) series of “Inside Look” series has been published for more than six months. It’s not that there wasn’t something to write or tell about, we just got over things that will become the subject of one of my next articles on Habré (I hope that they will not be sent to junk, since it will not be devoted to IT topics). In the meantime, there’s a free minute, let’s figure out what RFID (Radio-frequency identification) is — simpler labels will join them — or how one small step in technology has drastically changed the lives of millions and even billions of people around the world.
I would like to make a reservation right away.
Before starting work on this article, I really hoped that from microphotographs, and especially from optics, information found on the Internet, and some knowledge from past publications, I could determine where and what elements of the chip are located. At least at the “household” level: they say, this is the memory, this is the power circuit, and here the information is processed. Indeed, it would seem that RFID is the simplest device, the simplest “computer” that you can think of ...
However, life has made its own corrections and everything I managed to find: the general scheme of the device for a new generation of tags , photos of how, for example, it should look memory - I don’t even know why I didn’t pay attention to itin an article about RAM (maybe there will still be an opportunity to improve ?!), and scandals-intrigues-exposures of A5 processors from chipworks .
By tradition, we start with some introductory part.
The history of radio-frequency recognition technology - perhaps that is what all conceivable and inconceivable RFID (radio-frequency identification) variants can be called - goes back to the 1940s, when in the USSR, Europe and the USA actively developed all kinds of electronic equipment .
At that time, any product that worked on electricity was still a curiosity, so the scientists didn’t have a plowed field: wherever you stick, like in the Black Earth region, a shovel stalk - a tree will grow. Judge for yourself: Maxwell proposed his laws only half a century ago ( in 1884 ). And theories based on these equations began to appear after 2-3 decades (between 1900 and 1914), including the theory of radio waves(from their discovery to signal modulation models, etc.). Plus, the preparation and conduct of World War II left their mark on this area.
As a result, by the end of the 40s, “friend or foe” recognition systems were developed, which were slightly larger than those described in this article , but worked essentially on the same principle as modern RFID tags.
The first demonstration close to modern RFID was held in 1973 at the Los Alamos Research Laboratory, and one of the first patents for this kind of identification system was obtained a decade later, in 1983. More detailed RFID history can be found on the Wiki and some other sites ( 1 and 2 ).
Articlein English I like more, from it you can draw a lot of useful information on use, cost of production, standards, etc. etc.
In principle, any RFID tag consists of two main components - an antenna and a microchip. An antenna is needed to pick up the electromagnetic waves of the transmitter (or reader), convert them:
a) into a signal,
b) into electricity to power the chip itself, i.e. performing certain operations, and
c) transmitting a response signal.
This is the case with passive tags. Typically, such tags are relatively “simple” to manufacture and are used mainly in identification cards when the distance between the tag and the transmitter is minimal. The simplest example, which will be discussed in detail below, is a metro map that is used every day, it’s even scary to think, several million people are in Moscow alone.
A beautiful picture illustrating the distribution of the electromagnetic field in the antennas of the reader and the card itself ( Source )
Active tags due to the built-in battery have a significantly larger working radius, dimensions, more complex “stuffing” (you can supplement the tag with a thermometer, hygrometer, and even a whole GPS positioning chip ) and the corresponding price.
Labels can be classified in different ways: by operating frequency (LF - low-frequency ~ 130KHz, HF - high-frequency ~ 14MHz and UHF - ultra-high-frequency ~ 900MHz), by the type of memory inside the label (read only, write once and write repeatedly). By the way, so beloved by all manufacturers and promoted by NFC, it belongs to the HF band, which has a number of well-known problems.
Perhaps this is where we will end with the RFID theory, especially since it seems a little boring to me, and who is interested in the most piquant details from the life of RFID tags - welcome! )
Unfortunately, the cost of RFID tags is quite high compared to other types of identification, therefore, for example, we still buy food and other “popular” goods using barcodes (or bar codes), sometimes QR codes, and protection anti-theft tags (or EAS - electronic article surveillance ) provide the
most common three types (all photos are taken from the Wiki ):
- electromagnetic systems (usually used when selling books, they are glued somewhere between the pages at the spine)
- acoustic systems
- radio frequency systems (usually they, or their analogs in plastic with a latch supply clothes and bottles of elite alcohol, for example)
Ahead of us there are many wonderful discoveries, sometimes completely unexpected and of course hard geek porn in HD !
If someone thought a little theory, welcome to this English site .
The practical part
So, what tags did you manage to find in the world around us:
Left column from top to bottom: Moscow metro map, Aeroexpress train pass, plastic card to enter the building, RFID tag presented by Perekrestok at the RusNanoForum-2011 exhibition. Right column from top to bottom: radio-frequency EAS-tag, acousto-magnetic EAS-tag, bonus ticket for Moscow public transport with a magnetic strip, RFN card of a visitor to RusNanoForum even contains two tags.
The first card of the Moscow metro is announced - let's get started.
In the first circle. Moscow metro ticket
First, we soak the card in plain water to remove paper layers that hide the very heart of this “tag”.
The stripped card of the Moscow metro
Now let's take a closer look at it with a small zoom into the optical microscope:
Microphotographs of the card chip for passage into the Moscow metro The
chip is fixed quite thoroughly and I want to note that all 4 “legs” are connected to the antenna - this will be useful to us later for comparison with another RFID tag. Having folded the plastic base in half at the place where the chip is located, and slightly swaying from side to side, it is easily released. As a result, we have a needle-sized chip:
Optical microphotographs of the chip immediately after separation from the antenna
Well, let's play with focus:
Changing the focus position from the lower layer to the upper
In his article on the "opening" of chips, a colleague BarsMonster used hot acid to burn any organic matter on the surface of the chips. I was with them a little more affectionate and boiled in acetone (with a reflux condenser, of course).
NB! I strongly do not advise repeating all these sado-masochistic actions at home. In BarsMonster is a "testing ground", I - a fume hood in the lab.
Voila, the surface is cleaned, the last layer of metallization was not damaged, and the same polymer “peel” lies next to it: A
cleaned chip and a polymer base that holds the chip firmly on a plastic card
Now let's try etching. The space between the contacts and the metallization layers should be separated by a dielectric, for example, amorphous silicon dioxide. Therefore, for etching we take hydrofluoric acid or HF. We will prepare a not very concentrated solution and proceed.
After holding it for 1 minute in this solution with an armed electron microscope, it is difficult to notice any significant changes:
Microphotographs of the chip etching in HF after 1 minute
By the way, this is a very revealing photo. The charging effect is well manifested on it, and by this contrast (charging / not charging), it is easy to distinguish individual particles of the microcircuit from each other.
Increase the time by another 2 minutes. Since it is desirable to mix the solution slightly during etching so that the etching is more or less uniform, the heaviest parts “fly off” first:
Micrograph of the platform for attaching to the antenna torn from the chip
Let's take a look at a different angle
And here is the place where the pads are attached. In some places, the pins were torn out, and in some places they remained untouched:
About the sizes. The thickness of the metal deposition in the chip can be from 20-30 nm to 100-150 nm, while the distance between the metallization layers, judging by the photographs presented above, is about 950 nm. It turns out that very thin and strained (this is due to the conditions for applying these conductors) the “films” of metals are supported by massive “barrels”, therefore, when acid corrodes the supporting base - silicon dioxide, the films try to relieve tension, and massive contacts between the metallization layers “Fall” into the vacant space under them. It is the size of the elements and some limitations of the experiments that do not accurately etch the dielectric and see the 3D network of conductors between the individual elements of the chip.
Sometimes science turns a little into art, for example, in this way:
We can withstand a couple of minutes in hydrofluoric acid (a total of 5 minutes). The landscape begins to change dramatically - more and more parts are leaving their places. Anarchy sets in:
General view of the chip after a total of 5 minutes of etching
In addition to everything else, we stand the chip in acid, which means we want it or not, but the metal will interact with the acid, gradually dissolving. As shown in an article about camera matrices using EDX analysis, manufacturers are extremely reluctant to shell out gold and use cheaper aluminum. It would seem that an oxide film should form on the surface of such a metal, however, due to the production technology, almost pure aluminum is inside the chip.
After another 2 minutes of aging in acid, another feature of the etching process begins to appear - uniformity. Gradually, layer by layer, it is removed equally over the entire surface, which means that the places where two metallization layers are in contact are etched in the same way as the rest of the surface. As a result, we have “bagels” around the contacts:
“Bagels” around the contacts between the metallization layers.
Another clear evidence of this is “knocked out” whole contact groups:
We uproot the contact groups ... The
solvent penetrates into these holes, as we recall, slightly dissolves the metal and etches it the space along the individual metallization layers is something like this: A
micrograph of an etched chip showing two separate dielectrics with a cavity in between
From a different angle, so that there is no doubt, these are really two different layers of silicon dioxide, and beneath, between, above and around them are metallization layers
Another funny discovery is three conclusions, which, most likely, when testing chips on a plate after finishing production cycle for rejection:
Three “test” outputs from the chip
Since after an exhibition at the Festival of Science 2012 in the building of the Fundamental Library of Moscow State University, it draws on art, I cannot deny myself the pleasure of sharing a nanotetris with you:
Let's play tetris?
And we will deal a decisive blow to this chip, placing it in the etching solution for another 7 minutes (total, 14 minutes from the beginning of the experiment, which lasted almost the whole day of work;)). Only the first layer of metallization remained on the surface, after it drains, sources and gates already begin:
In all the mess you can find order - why isn’t your last photo a new emblem for Habr?
The first, the main metallization layer, behind which there are only transistors ...
Well, look in retrospect on what path we took in the etching of the chip:
General microphotographs illustrating the etching process
Ah, yes, I promised geek porno in HD format. Thank you for this BarsMonster and its telephoto microscope:
Clickable Image - HD
Now a little intrigue.
Rumor has it that Mikron designs and manufactures chips for the Moscow metro on its own using similar Mifare technology (at least mounts to the antenna differ - legs of a different shape). On August 22, BarsMonster,
The ticket considered above was apparently made (or just mounted on an antenna?) At the Mikron enterprise (Zelenograd) - see the links below - using the technology known in RFID circles from NXP, which 3 huge letters actually hint at the year of release of the technology (or maybe the year of production) on the upper layer of the metallization of the chip. If we assume that 2009 refers to the year the technology was launched, and the abbreviation CUL1V2 is deciphered as Circuit ULtralite 1 Version 2 (this assumption is also confirmed by this news ), then on the NXP website you can find a detailed description of these chips (last two lines in the list )
By the way, in last year, an excursion to the Mikron plant was organized for participants in the Internet Nanotechnology Olympiad ( photoand video reports), therefore, to say that the equipment is idle there doesn’t make sense, but I would question the statement of “uncle in a white coat” that they produce tags according to 70 nm standards ...
According to statistics compiled by BarsMonster after analyzing 109 ticket chips metro (a fairly representative sample), according to the normal distribution, the chances of finding an “unusual” ticket are ~ 109 ^ 1/2 or about 10%, but they melt away with every ticket opened ...
On the English-language Wiki website there is a lovely article on Mifare, which does not contain a complete but quite extensive with ISOC where and what types of data labels are used.
In the second circle. Aeroexpress Ticket
Next in turn is a ticket that many people use when traveling to other cities of our vast country or abroad through the air gates of Moscow, Sochi or Vladivostok (in my opinion, there are Aeroexpress trains in these three cities only).
Since the chip is practically no different from Mifare, which is used in the Moscow metro, we will start with hardcore:
Focus on the first metallization layer (Clickable image - HD)
Focus on the last metallization layer (Clickable image - HD)
A close look has already noticed the main difference between the two Mifare chips - labeled Philips2001. In fact, back in 1998, Philips bought the American manufacturer of microelectronics - Mikron (not to be confused with our Zelenograd Micron). And in 2006, Philips buddedNXP company.
It is also easy to notice the mark CLU1V1C, which, based on the above, means Circuit ULtralite 1 Version 1C. That is, this label is the predecessor of Mifare, used by the Moscow metro, and, therefore, is compatible with it in terms of basic parameters. However, as in the previous case, 2001 is an indication of the year of development and implementation of the technology or the year of production. It is strange that Aeroexpress uses outdated tags ...
In the third circle. A plastic card
Once, I decided to show my articles and photos to one of my acquaintances on Habrahabr. Then he asked if she had any unnecessary card for the next article about RFID. By that time, she had just moved to study at the EPFL and presented me with a card that allowed me to enter one of the buildings of Moscow State University. The card, respectively, is without any marking, and I’m not even sure that at least something is written on it, except for the usually key to enter the building.
The card is completely plastic, so immediately put it in acetone for literally a couple of tens of minutes:
Take acetone baths
Inside, everything is pretty standard - the antenna and the chip, however, it turned out to be on a small piece of PCB. Unfortunately, without any identification marks - a typical Chinese noname. The only thing you can find out about this chip and card is that they are manufactured / belong to some TK41 standard. Such cards are full on sales such as ali-baba and dealextreme.
Clickable Image - HD
In the fourth circle. Crossroads
Next, I want to consider two tags presented at the RosNanoForum 2011 exhibition. The first of them was presented with great pathos, saying that it was almost a panacea for thieves and shoplifting. Anyway, this label will completely transfer stores to self-service. Unfortunately, an effective manager turned out to be a little more than completely incompetent in matters of school physics. And after the offer to check the effectiveness of it and the tag with the help of a strong magnet attached to the tag, I quickly hushed up the subject ...
After a couple of purchases in SmartShop, I had a few tags left. Having cleared one of them of glue and a white protective layer, we see the following:
New label of the Perekrestok chain of stores
We act the same way as Mifare, carefully disconnect it from the polymer base and antenna and put it on the table of the optical microscope:
Optical microphotographs of the label supposed to be used in SmartShop
By a lucky chance (either glue pumped up, or it was planned so), the label was quickly torn off , and its surface was left without any traces of glue. I would like to draw attention to the fact that if Mifare has all 4 contacts attached to the antenna (2 contacts at each end), then here we see that two contacts are connected to two small areas that I do not contact with the antenna.
Let's play a little with focus in different parts of the label:
Change the focus ... The
maximum magnification of the optical microscope
Apparently, the last photo in the upper left shows the EEPROM memory module, since it occupies about a third of the chip surface and has a “regular” structure.
The image is clickable - HD
This label maker intensely hides their origin. Agree, the size of this remark is “P5 Alien” is several times smaller than the inscription “NXP” or “Philips”. It reminds me of light trolling from Samsung, which was noticed by the guys from chipworks after opening the Galaxy S and called “silicon art”:
But back to our mark. Searches on the Internet led to two sites - Wiki and the manufacturer Alien Tech . After wandering around the site of the company, the type of tag is very quickly - Higgs 3 and fullspecification for it .
Higgs 3 belongs to the EPC gen2 standard. More details can always be found here .
In the fifth circle. Tags used in RosNanoForum badges
For dessert, I saved the tags that were used for identification at RosNanoForum in 2011. As you can see from the photo below, the badge is not simple, but has two labels - one in plain sight (narrow at the very bottom), and the second is hidden inside.
Unfortunately, the big tag - the usual Mifare, exactly the same as used in the Moscow metro, but the small one - is slightly different from everything that we saw earlier: The
picture is clickable - HD
This is an RFID tag from NXP, but of a different standard than Mifare and much smaller, and released in 2007. The name read on the right is t5 (S?) L35 (S?) 10V0 (O?) E. But to decrypt it did not work ...
1. Yes, we completely forgot about the magnetic card used to pay for public transport in Moscow - I am correcting:
Light points in the bottom photo may be just particles of magnetic material used to write information to the card.
2. Two words about NFC. In the summer, a rather interesting article was published on the development of NFC in Russia, however, at a frequency of 2.4 MHz.
3. By the way, the RFID store is already open - you can try it ...
PS: The author thanks the BarsMonster user , who, by the way, can also be congratulated on the successful translation of the article into English , which your humble servant has yet to do ... and with them ten - OMG!
PPS:Not so long ago, an article was published on the 3DNews website dedicated to the study of displays of various top-end and not-so-devices. If you still have not decided on the choice of a smartphone, then you are definitely here ...
Firstly , a complete list of published articles on Habré:
Opening the Nvidia 8600M GT chip , a more detailed article is given here: Modern chips - an inside look Inside
view: CD and HDD
Inside view: LED bulbs
Inside view: LED industry in Russia
Inside view: Flash -memory and RAM
Inside view: the world around us
Inside view: LCD and E-Ink displays
Inside view: digital camera arrays
Inside view: Plastic Logic
Inside view: RFID and other marks
Inside view: graduate school in EPFL. Part 1
Inside Look: Graduate School at EPFL. Part 2
Inside view: the world around us - 2
Inside view: the world around us - 3
Inside view: the world around us - 4
Microview: comparison of displays of modern smartphones
. Secondly , in addition to the HabraHabr blog , articles and videos can be read and viewed on Nanometer.ru , YouTube , and Dirty .
Thirdly , if you, dear reader, liked the article or you want to stimulate writing new ones, then proceed according to the following maxim: "pay what you want"
WebMoney (R296920395341 or Z333281944680)
Sometimes it is possible to read briefly, and sometimes not so much about the news of science and technology on my Telegram channel - we are welcome;)