Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Gate direction of mos transistor in layout

Status
Not open for further replies.

John Xu

Member level 3
Joined
Jul 22, 2005
Messages
59
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,938
Hi,
I have a question on the gate direction of mos transistor in layout. We know, in layout, for the matched transistor/device, they are asked to place in the same orientation to keep matching. But for those unneedded transistors, are they needed to place in the same orientation? Place them in different orientation will afect the product yield?


Thanks in advance
 

John Xu

Member level 3
Joined
Jul 22, 2005
Messages
59
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,938
vbhupendra said:
definately it will !
hi,vbhupendra
Thanks for the reply! Would you like to elaborate it a bit more? We passed the design in full case. So for the mos transistor, we confirmed it with typ,ss,ff,sf and fs. It can not guarantee all the corners fall into this range?

thanks
 

vijay.kumarreddy

Member level 4
Joined
Jan 6, 2006
Messages
78
Helped
12
Reputation
24
Reaction score
9
Trophy points
1,288
Location
Bangalore,India
Activity points
2,017
In general practice the matched devices should be placed in the same orientation.If differs the mobility og=f the caarriers changes inturn mobility related to the gain,current....All these quantities will change. u can place other devices which requires no matching in different orientation.
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

Hughes

Advanced Member level 3
Joined
Jun 10, 2003
Messages
717
Helped
113
Reputation
226
Reaction score
25
Trophy points
1,298
Activity points
5,986
John Xu said:
Hi,
I have a question on the gate direction of mos transistor in layout. We know, in layout, for the matched transistor/device, they are asked to place in the same orientation to keep matching. But for those unneedded transistors, are they needed to place in the same orientation? Place them in different orientation will afect the product yield?


Thanks in advance
Devices that don't have matching requirements needn't be in the same direction.
BTW, what are unneeded transistors?
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

eda_freak

Member level 3
Joined
Jun 20, 2005
Messages
62
Helped
12
Reputation
24
Reaction score
2
Trophy points
1,288
Activity points
1,997
If you are talking about horizontal poly and vertical poly then...generally we like to keep safe and matched transisitors are oriented in same direction. topologies of common centroid are followed. but in case you have a very stable process where the foundry guarantees proper construction you can have exceptions that is very rare to my knowledge...but it does happen atleast in digital core of your chip...yeild to size tradeoffs do exist...
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

leeenghan

Advanced Member level 4
Joined
Dec 28, 2004
Messages
118
Helped
16
Reputation
32
Reaction score
8
Trophy points
1,298
Activity points
1,333
Hi,

My opinion is that it will not affect anything. However, take for another case that you have two groups of matching transistors, but the two groups need not be matched. It is still good to put the transistor in both groups in the same orientation because it allow the process engineer to optimise the fabrication process to achieve better yield.

Regards,
Eng Han
www.eda-utilities.com
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

John Xu

Member level 3
Joined
Jul 22, 2005
Messages
59
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,938
[quote="Hughes
Devices that don't have matching requirements needn't be in the same direction.
BTW, what are unneeded transistors?[/quote]

Hi,Hughes,
Sorry for the typo,.The "unneeded transistors"means those unneeded matched transistors.

regards
 

vbhupendra

Full Member level 4
Joined
May 11, 2005
Messages
235
Helped
15
Reputation
30
Reaction score
8
Trophy points
1,298
Location
GOA, INDIA
Activity points
3,219
John Xu said:
vbhupendra said:
definately it will !
hi,vbhupendra
Thanks for the reply! Would you like to elaborate it a bit more? We passed the design in full case. So for the mos transistor, we confirmed it with typ,ss,ff,sf and fs. It can not guarantee all the corners fall into this range?

thanks
I would have thought u r talking of dummy (as unconnected transitors) !!!
 

YESH_23

Member level 4
Joined
Dec 20, 2005
Messages
78
Helped
8
Reputation
16
Reaction score
4
Trophy points
1,288
Location
INDIA
Activity points
1,951
some process doesnt allow orientation of transistors in both directions

but some will allow in all the directions i.e in vertical & horizontal direction
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

bg21359

Member level 3
Joined
Mar 1, 2005
Messages
56
Helped
7
Reputation
12
Reaction score
4
Trophy points
1,288
Activity points
1,802
For deep submicron technology such as 65nm or 45nm, in general only one poly(active) direction is allowed. But for other not so deep submicron technology, it maybe OK for using 2 poly directions to those non-critical circuitry.
 

    John Xu

    points: 2
    Helpful Answer Positive Rating

YESH_23

Member level 4
Joined
Dec 20, 2005
Messages
78
Helped
8
Reputation
16
Reaction score
4
Trophy points
1,288
Location
INDIA
Activity points
1,951
i think that the direction of the poly depend up on the pdk of the fab that we are using....

correct me if i am wrong...
 

shiva4u

Member level 1
Joined
Feb 3, 2006
Messages
33
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Activity points
1,570
Hi,
The basic rule for matching is the orientation, but we may not follow the orientation for the whole chip. But if you follow orientation throughout the chip, the performance of your chip will be better ( It meets what designer wants ), Please refer to the ion implantation effects in razavi (last chapter). And think urself what happens to other transistor functionality if you dont follow orientation.
Thanks & REgards,
Shiva.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top