The document provides an overview of flash memory devices, detailing their internal components and how data is stored within. It explains the structure and connectivity of memory cells, highlighting the technological advancements in semiconductor manufacturing. Additionally, the text encourages interest in electronic engineering and offers resources for further exploration of the topic.

1. What is inside a Flash memory
device?
Etienne Nowak
May 2010
with data freely available on the web from Semiconductor Insights Inc.
All done without permission for non-commercial purpose
in a curiosity and educational purpose only

2. Flash memory device
• You all have several Flash memory devices at
less than 1 meter from you.
• They are present in you Flash memory (in USB,
Memory card, SIM Card they are the main
component. In Cell Phone, iPod devices, Set
up Boxes, they are a key components
• However who knows what is inside this black
tiny chips?
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3. Objective
• I hope this will help you to realize the work of
people invested on these things
• One key challenge for explaining what I am
doing is that it is not possible to show it!
• Hope this will solve a bit this gap!
• It’s not a course on flash memory devices.
• There is no explanations it’s just for the eyes.
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4. Introduction
• Here is an example of 2008 state of the art
16Gb NAND device. NAND product from
different manufacturer will looks roughly the
same.
• This will give us a 2GB devices but depending
on the packaging if 8 pieces are stacked
together this could give us a 16GB chip.
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5. iPhone Main PCB
This is a 16GB Flash memory cell
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6. Overview
• Now make a close up on the memory chip itself
• Lets explain how this 20*12mm hold 16Gbit of your data
Inside view
Outside view
2 cm
• Connection from the external to the silicon chip 6

7. The Silicon chip
• This is what is obtained from silicon wafers
7
14mm

8. Closer look Silicon Chip
50um
50um 50um
50um
8
50um 14mm

9. Closer look
Memory array
• 200 um you can’t see it without a
microscope
20um
Zoom
50um
200um
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10. • There is 4 level of
connection from the top Memory Array Cut
to the bottom: Metal 3,
Metal 2, Metal 1, Poly 2
Metal 3
and then the substrate Metal 2
Metal 1
Poly 2
Substrate
Cut and
Zoom x10
Here we are at top level Metal 3
so the rectangle are at Metal 2
Metal 3 Metal 1
Poly 2
Substrate
10um Cut and
Zoom x10
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11. Connection from the array to the
cell
10um 100nm 1um
Metal 3 level Metal 2 level Metal 1 level
First Metal 3 is seen
then it is etched in
order to see Metal2.
Then Metal 2 is etched
in order to see Metal
1. And so on for Poly 2
1um 1um and for the substrate
Poly 2 level Substrate level 11

12. The memory cell (1/4)
The cell is at the
section of Poly 2
level and
Substrate level
1um
1um Here is the
memory cell
Substrate level
This plot is
connection for
Metal 1
These plots are
connection for
Metal 2
You can see the
1um 1um Substrate level
1um
under the Poly2
Poly 2 level level 12
Poly 2 level

13. The memory cell (2/4)
Substrate level
The small points are Here is stored your data
single Silicon atom with 100 electrons!
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14. The memory cell (3/4)
Poly 2 level
1um
The small points are
single Silicon atom Here is stored your data
with 100 electrons!
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15. Memory cell (4/4)
• The data is stored in the
orange zone with electrons
• With 100 electrons it’s a 0
• Without electrons it’s a 1
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Poly 2 level

16. Break
• Now you know where your data are stored.
• But how to access them?
• Don’t forget that we have a 16Gbit cell this
means you have 8 000 000 000 memory cell*
with or without electrons in the chip. This is
more than the number of humans on Earth.
• Let’s see how you connect them and access
them
* In fact in the present chip, it’s a 2 bit per cell device so you have 4 level of electrons
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and 8 000 000 000 cells creating 16 Gbit of data.

17. Connection with
external world
Cut
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18. Connection inside the chip
• Here is
example of
Metal 2 to
Substrate 1um
connection
Substrate level
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19. Row decoder (1/2)
Memory Array
Next slide
Metal 3 level Metal 2 level
Memory Array
Memory Array
Next slide Next slide
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Poly level Metal 1 level

20. Row decoder (2/2)
• This are circuit allowing to select a row in the array
Previous slide
Poly level Metal 2 level
Previous slide Previous slide
Poly level Metal 1 level 20

21. Sense Amplifiers
• This are circuits to know if it’s a 0 or 1 that is
stored
Metal 3 level Metal 2 level
Poly level Metal 1 level 21

22. What means doubling size?
• This means doubling density of the memory cell. Here is
example with different Toshiba cell generation.
• In microelectronics the children are always smaller than
the parents, roughly half the size*.
100 nm
43 nm generation
56 nm generation
70 nm generation
90 nm generation
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* Look at “Moore Law” on the Internet and you will have plenty of information on this fact.

23. That’s the end!
• Hoping you enjoy it and that you will pay
more attention to your memory card the next
time you use it!
• You loved it and you don’t know what to do
then consider electronic engineering and
especially the microelectronic or
semiconductor industry!
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24. Still interested?
• Look on the web about:
– Flash memory
– Semiconductor industry
– Non volatile memory
– IEEE
– CMOS
–…
• You will find plenty of available material
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