The thing I want it a notice
Is that the gap of the N-well? not controled by the circuit designers parasitic resistance.
So if I look at the layout viewlet's view a simple little layout of a N-well
this is my width and then this is my length of my N-well..if I..this is my layout viewmy plane view...
sometime people use that(?) plane view...where...
If look at thisI have control over the W and L. The designer controls W and L.
The process engineer that ....making a CMOS processcontrols the gap of the N-well.
So now I go down here in my cross section across this point here
...in this area this thickness is controled by process engineers.
So there is an issue I'm trying to measure the resistance from here to here
I can eject ..... to set a resistance and I can eject W and L but I have no control over thickness.
That lead you to term we'll talk about right now sheet resistance
Dose evetybody follow that ?
OK. So now if I look at any resistivity any material like it associate with a resistance OK? .....
I'm gonna take this ...now I'm not concider what's going on with the p-substrate.
Why ?
Well N-well .... p-substrate are isolated by reverce biased diode.
So I'm gonna only concentrate on a resistance in a current flow through this N-well
'cause(?)... ideally ...since whit this reverse biased diode no current flow down in the substrate.
I should put that on here......
Ideally substrate current equals zero. and all discuss how to do that again at the point....
I don't want you worrying about how I connected the N-well ....how I connected the p-substrate ...
I only want you focusing on there is a resister here and somehow it's gonna be useful...OK ?
Hi ! So I go back
No process engineer set this thickness t
if I'm a engineer set the width and length
oh where do we set that with .....?
Yeah Layout program......yeah Lasi.
woops.....So I go back ....I ....
I need some of useful term so I can look back on a date sheet or something like that...
I'm gonna go through ..OK...if I .take any material here....
and I sketch that material I can write between the two .....
this is a length ah...distance here...is the width...this distance here is the thickness.....
I can write the material's resistance
add this resistivity .... and units of that are ........ohm centimeter...that's material parameter....
divided by the thickness....times L over W.
and....you might say how do you remember that equation ?
I don't !
How do I think of ....how do I come up with it ?
I think what's happening physically....I know that the material...
I know that resistivity here is constant to any material
I don't know what the units of but I think in my head what that equation was
by how physically what's happening. I won't use it to think about this tube.
If I think about this If I make the thickness bigger I have more
cross-sectional area to conduct current right?
I make the pipe big to get more water through the pipe.
That's gonna make the resistivity go down so I know the thickness that I drew here
If I make it thicker the resistance got a go down so I know that's gotta be a denominator.
If I make the pipe wider I also increase a cross sectional view so that's gonna couse the
resistance go down.
So the longer the piece of material that I try to conduct the current through the more resistance I have
and so that I remember the equationand I look at this Michel...
L and W cancell.
This have to have all of you have to have units have ohm
and when I devide by distance I know this unit has ohm・distance and ohm・cm is a common way
to write resistivity of the material. Question ?
All right... so you go OK I remember that whenever you learn the material ..eat in your 245..or whatever...
OK remember that but that's not too useful. I have to design circuit I'm not a material first(?)
I'm not a process engineer. Need something useful out of this.
I can't remember anything complicated....So what we are gonna do ?
We are gonna play... and make L and W ......equal. So let's say L equals W and I of course from third grade
L equals W what do you call that shape ? Year square...to know that all that you know going on is so useful...
So we get a square...If that's the case
I can state the resistance of a square simply rou over t
now think about that for a moment. So I make it the device wider and longer at the same time
but your effect cancell and I end up getting a constant resistance.
OK I increase the diameter of this pipe or the size of this pipe in this direction .....the water is flowing through.
then I increase the length of the pipe and it compensete for it's sheet resistance constant.
So Key point is this is drawn five by five or fifty by fifty....I get the same sheet resistance
cause it's the square from one side to the other.
Now the issue here is how I conduct the current
now that the current assumed uniform from one side to the next. So any questions on that ?
Wow If L equals W I got the rau over t ...rau is the material constant I don't have to control
over that that is set up by a process
t is the thickness that I have that process that set by process engeeners...So I end up getting
this is a constant.
and it's called the sheet resistance with units of ohm.....because rau distance over distance ohm.....
or more collectry ohms par square.Square is really not a unit because...
L equals W so one square so it cancelled I mean realistically ohm's stepped on square to step by
what that resistance is.
All right do some examples....now I wanna make it real
so I go to the mosis web site and I try to find typical sheet resistances....so in N-well process
get your layout of N-well process....
and determine a resistance.
Are their any questions before we do that ?.....
OK ! Let's go over here to ... web site.........and tipe mosis.org....woops!
And I gonna go take a look I haven't any here and while .....
and I gonna look at what is mosis IC fabrication ...ah...
Sorry ? Oh!! sorry...Here we go! Ahm...I see different processes
this mosis go to work I see just on processes I'm gonna pick this one process
AMI Simiconductor which is located where...?..Yeah....
And ah I'm gonna click on it ..and the .processes we're gonna alternatelly
used ...have Micron one we're gonna find out CMOS scale.....
So am I click on AMI simiconductor 0.5 process.....
and in it a little term ....
I can go down here and
click on it later...........なんだかんだ見ていって、結局シートレジスタンスが
見つからなかったのでまた今度ということになった・・・・
（例として、２kΩ／□だとか紹介していた・・・）・・・省略 します( -~- ;)
anyway so going back over here.....
well do it for this process or soon the N-well sheet resistance is 2k par square...
Now in this process ...it's a 0.5 micron process........0.5 micrometer....0.5 micron.
The lamda is a scale factor that were used 0.3 micron. we don't need to worry about that ...this point.
I just point it out.....we are talking about this point more in the future.
Is that the gap of the N-well? not controled by the circuit designers parasitic resistance.
So if I look at the layout viewlet's view a simple little layout of a N-well
this is my width and then this is my length of my N-well..if I..this is my layout viewmy plane view...
sometime people use that(?) plane view...where...
If look at thisI have control over the W and L. The designer controls W and L.
The process engineer that ....making a CMOS processcontrols the gap of the N-well.
So now I go down here in my cross section across this point here
...in this area this thickness is controled by process engineers.
So there is an issue I'm trying to measure the resistance from here to here
I can eject ..... to set a resistance and I can eject W and L but I have no control over thickness.
That lead you to term we'll talk about right now sheet resistance
Dose evetybody follow that ?
OK. So now if I look at any resistivity any material like it associate with a resistance OK? .....
I'm gonna take this ...now I'm not concider what's going on with the p-substrate.
Why ?
Well N-well .... p-substrate are isolated by reverce biased diode.
So I'm gonna only concentrate on a resistance in a current flow through this N-well
'cause(?)... ideally ...since whit this reverse biased diode no current flow down in the substrate.
I should put that on here......
Ideally substrate current equals zero. and all discuss how to do that again at the point....
I don't want you worrying about how I connected the N-well ....how I connected the p-substrate ...
I only want you focusing on there is a resister here and somehow it's gonna be useful...OK ?
Hi ! So I go back
No process engineer set this thickness t
if I'm a engineer set the width and length
oh where do we set that with .....?
Yeah Layout program......yeah Lasi.
woops.....So I go back ....I ....
I need some of useful term so I can look back on a date sheet or something like that...
I'm gonna go through ..OK...if I .take any material here....
and I sketch that material I can write between the two .....
this is a length ah...distance here...is the width...this distance here is the thickness.....
I can write the material's resistance
add this resistivity .... and units of that are ........ohm centimeter...that's material parameter....
divided by the thickness....times L over W.
and....you might say how do you remember that equation ?
I don't !
How do I think of ....how do I come up with it ?
I think what's happening physically....I know that the material...
I know that resistivity here is constant to any material
I don't know what the units of but I think in my head what that equation was
by how physically what's happening. I won't use it to think about this tube.
If I think about this If I make the thickness bigger I have more
cross-sectional area to conduct current right?
I make the pipe big to get more water through the pipe.
That's gonna make the resistivity go down so I know the thickness that I drew here
If I make it thicker the resistance got a go down so I know that's gotta be a denominator.
If I make the pipe wider I also increase a cross sectional view so that's gonna couse the
resistance go down.
So the longer the piece of material that I try to conduct the current through the more resistance I have
and so that I remember the equationand I look at this Michel...
L and W cancell.
This have to have all of you have to have units have ohm
and when I devide by distance I know this unit has ohm・distance and ohm・cm is a common way
to write resistivity of the material. Question ?
All right... so you go OK I remember that whenever you learn the material ..eat in your 245..or whatever...
OK remember that but that's not too useful. I have to design circuit I'm not a material first(?)
I'm not a process engineer. Need something useful out of this.
I can't remember anything complicated....So what we are gonna do ?
We are gonna play... and make L and W ......equal. So let's say L equals W and I of course from third grade
L equals W what do you call that shape ? Year square...to know that all that you know going on is so useful...
So we get a square...If that's the case
I can state the resistance of a square simply rou over t
now think about that for a moment. So I make it the device wider and longer at the same time
but your effect cancell and I end up getting a constant resistance.
OK I increase the diameter of this pipe or the size of this pipe in this direction .....the water is flowing through.
then I increase the length of the pipe and it compensete for it's sheet resistance constant.
So Key point is this is drawn five by five or fifty by fifty....I get the same sheet resistance
cause it's the square from one side to the other.
Now the issue here is how I conduct the current
now that the current assumed uniform from one side to the next. So any questions on that ?
Wow If L equals W I got the rau over t ...rau is the material constant I don't have to control
over that that is set up by a process
t is the thickness that I have that process that set by process engeeners...So I end up getting
this is a constant.
and it's called the sheet resistance with units of ohm.....because rau distance over distance ohm.....
or more collectry ohms par square.Square is really not a unit because...
L equals W so one square so it cancelled I mean realistically ohm's stepped on square to step by
what that resistance is.
All right do some examples....now I wanna make it real
so I go to the mosis web site and I try to find typical sheet resistances....so in N-well process
get your layout of N-well process....
and determine a resistance.
Are their any questions before we do that ?.....
OK ! Let's go over here to ... web site.........and tipe mosis.org....woops!
And I gonna go take a look I haven't any here and while .....
and I gonna look at what is mosis IC fabrication ...ah...
Sorry ? Oh!! sorry...Here we go! Ahm...I see different processes
this mosis go to work I see just on processes I'm gonna pick this one process
AMI Simiconductor which is located where...?..Yeah....
And ah I'm gonna click on it ..and the .processes we're gonna alternatelly
used ...have Micron one we're gonna find out CMOS scale.....
So am I click on AMI simiconductor 0.5 process.....
and in it a little term ....
I can go down here and
click on it later...........なんだかんだ見ていって、結局シートレジスタンスが
見つからなかったのでまた今度ということになった・・・・
（例として、２kΩ／□だとか紹介していた・・・）・・・省略 します( -~- ;)
anyway so going back over here.....
well do it for this process or soon the N-well sheet resistance is 2k par square...
Now in this process ...it's a 0.5 micron process........0.5 micrometer....0.5 micron.
The lamda is a scale factor that were used 0.3 micron. we don't need to worry about that ...this point.
I just point it out.....we are talking about this point more in the future.
