I really like the explanation . Please dont stop making videos on all the concepts . I have all the support to the channel When the subscriber counts are huge please also plan QA sessions . All the best I am your new subscriber from today .
Thank you for your helpful videos. I love the way you make the video professionally. It helps my work a lots. Although in your list, there are 15 sessions in the series "Various standard cells in ASIC Design", I see 8 sessions in your videos. I hope you could complete the rest of this series (8.Sequential cell, 9.Combinational cell, 11.Clock cell, 12.Level shifter cell, 14. ECO cell, 15. Antena cell). I learn about this field by myself through your videos.
hello sir. am follwowing your all videos.its really helping me alottt..Requesting you to make videos on actual icc2 tool commands. and also make videos on conjection ,routing and cts stages in PD flow.thanku
I couldn't find sessions "# 12 , #13, #14" in your playlist (Level shifter cell , ECO cell , Antenna cell) . ... Did you also record video on that topics ? If yes, can you please share the link ?
Thanks for the video... One small request sir, can u please show us the live example of this cells in tool ..how to place in core area with commands... Thank you
Using FILL1 cells where you can use FILL16/8 is generally not recommended due to several potential issues that can arise: Metal Slotting: When you replace larger filler cells (FILL16/8) with multiple smaller filler cells (FILL1), the design may end up with narrow metal gaps. These gaps can cause slotting in the metal layers, which can degrade the integrity and performance of the interconnects. Metal Dishing: Metal dishing occurs during the Chemical Mechanical Polishing (CMP) process. It happens when the metal surface becomes uneven due to over-polishing. Using many small filler cells instead of fewer larger ones can exacerbate this issue, leading to uneven metal layers. Dielectric Erosion: Similar to metal dishing, dielectric erosion is the excessive removal of dielectric material during the CMP process. An increased number of small cells can create more areas where the dielectric material is unevenly polished away, leading to erosion. In summary, while it might be tempting to use smaller filler cells due to availability or other reasons, it introduces risks related to the integrity and performance of the metal interconnects and the dielectric material in the design. Therefore, it's better to use the appropriately sized filler cells (FILL16/8) as intended to avoid these issues.
I understand the need to filler cells. At the end (all ECOs are done) before tape out, do we replace spare cells by filler cells. If we keep spare cells, they keep draining power even though they are not being used. So, is it good idea to replace spare cells by filler cells or not?
Due to this empty space, there exist discontinuity in n well and p substrate layer, so during manufacturing extra mask are needed in order to pattern such layout. Hence cost of manufacturing increases. So, It is preferred there should not be any discontinuity in n well and p substrate layer.
Not exactly, No extra mask needed. But for better reliability, ease of fabrication process and base DRC mitigation. We prefer continuous well. It also help to even potential distribution across well.
@@amulyaraavi4089 in timing report we might not see the delay..but while extraction with star rc or qrc , extraction tool considers only rc factor of cell irrespective of physical or logical. That's why we see diffrence in extraction results with and without filler cells in design. In that case these 16 1w cells may give more rc value (delay) compared to 1 16w cell. @teamvlsi or @amulya raavi please correct me if I have wrong perspective about the issue
We cant use Filler cells instead of Endcap cells and we cant use Endcap cells instead of Filler cells. Both have their own individual purposes to serve. ENDCAP: It has its POLY and OD designed with respect to the edges and corners. It will be half cut w.r.t left/right/top/bottom. Half empty area wont be having POLY/OD. How does this help? This helps to isolate the domains. ENDCAPs are the boundary cells which isolates your IPs from the block, Block from the CHIP and what it protects? It protects your standard cells sitting at the edges or corners? How it will protect? As there is half empty area, but in another half empty area there will be POLY/OD which will act as extension to the nearby standard cell POLY/OD. During fabrication process, if there is any cutting or any kind of process which can impact the POLY/OD, then it will touch the ENDCAP POLY / OD and it wont impact the standard cells POLY/OD. FILLER: It doesn't have the POLY/OD structure similar to ENDCAP. It won't help you to isolate. Also, hence Filler can't be used instead of ENDCAP. Coming back to reverse, Can ENDCAP be used instead of Filler cells? If they are used instead of Filler Cells, then it will break the continuity of the POLY/OD, and there will be lots of BASE DRC Violations, because the design of ENDCAPs are very specifically w.r.t boundaries (of Chip/Block/IP/Memories/etc.) in terms of LEFT/RIGHT/BOTTOM/TOP/CORNER - All the ENDCAPs will be different in terms of POLY/OD Internal Structure @TeamVLSI Please correct if anything wrong ... Thank You, Tejal
drive strengths are different 16w and 8w ...if we have 16w space we add 16w filler cell ...but we can also add two 8w filler cells ...delay will incerase use of two 8w cells...i think so....but here no physical and functional connection here...
while there will be space in standard cells there discontinuity in power supply and n well so there will be drc violations to follow, in order to follow those drc rules we are using this filler cells to continue the power supply and n well
Take a bow to your hard work these videos are very useful...
Thanks a lot Venkata.
Its my pleasure.
Keep watching, keep learning and keep supporting us!!!
I really like the explanation .
Please dont stop making videos on all the concepts .
I have all the support to the channel
When the subscriber counts are huge please also plan QA sessions .
All the best
I am your new subscriber from today .
Thank you Vicky!
Your idea seems interesting, Thanks for that. We will think upon it. :)
Thank you for your helpful videos. I love the way you make the video professionally. It helps my work a lots. Although in your list, there are 15 sessions in the series "Various standard cells in ASIC Design", I see 8 sessions in your videos. I hope you could complete the rest of this series (8.Sequential cell, 9.Combinational cell, 11.Clock cell, 12.Level shifter cell, 14. ECO cell, 15. Antena cell). I learn about this field by myself through your videos.
Thanks a lot for your reminder. I will cover all those soon.
@@TeamVLSI I waiting for team VLSI
@@TeamVLSI Request you to please upload the remaining sessions sir. Thanks a lot for your efforts.
Thank you for making these videos, these are really helpful and very informative..
Thanks dear,
Glad it was helpful!
hello sir. am follwowing your all videos.its really helping me alottt..Requesting you to make videos on actual icc2 tool commands. and also make videos on conjection ,routing and cts stages in PD flow.thanku
Noted!
Nicely explained...sir
Thank you @Habiba
Its for well continuation..
any recommended text book for this course?
Thanks for video
Most welcome @Arun
I couldn't find sessions "# 12 , #13, #14" in your playlist (Level shifter cell , ECO cell , Antenna cell) . ... Did you also record video on that topics ? If yes, can you please share the link ?
Hi Raheel,
I missed those, but will upload soon.
Thanks for reminding me.
@@TeamVLSI Sie, waiting for these videos.
If you have added then please share link, I am not able to find those videos.
Thanks for the video... One small request sir, can u please show us the live example of this cells in tool ..how to place in core area with commands... Thank you
Noted
Thank you for this video. Could you please give answer of question 20:19 minute?
Hi Aysa,
Bigger the filler, lesser is variation, so generally tool first try to place big size filler which can fit than then smaller.
Using FILL1 cells where you can use FILL16/8 is generally not recommended due to several potential issues that can arise:
Metal Slotting:
When you replace larger filler cells (FILL16/8) with multiple smaller filler cells (FILL1), the design may end up with narrow metal gaps. These gaps can cause slotting in the metal layers, which can degrade the integrity and performance of the interconnects.
Metal Dishing:
Metal dishing occurs during the Chemical Mechanical Polishing (CMP) process. It happens when the metal surface becomes uneven due to over-polishing. Using many small filler cells instead of fewer larger ones can exacerbate this issue, leading to uneven metal layers.
Dielectric Erosion:
Similar to metal dishing, dielectric erosion is the excessive removal of dielectric material during the CMP process. An increased number of small cells can create more areas where the dielectric material is unevenly polished away, leading to erosion.
In summary, while it might be tempting to use smaller filler cells due to availability or other reasons, it introduces risks related to the integrity and performance of the metal interconnects and the dielectric material in the design. Therefore, it's better to use the appropriately sized filler cells (FILL16/8) as intended to avoid these issues.
I understand the need to filler cells. At the end (all ECOs are done) before tape out, do we replace spare cells by filler cells. If we keep spare cells, they keep draining power even though they are not being used. So, is it good idea to replace spare cells by filler cells or not?
Hi Krishna,
Yes unused spare cells will add some leakage power but this is not adding a significant number in total leakage power number.
Please answer the 2nd question that you have asked?
What is metal fill stage? At 26:00
Hi Raj,
Answer is first we add filler cells (base fill only) on postRoute db and then we do metal fill.
Please make videos of Double patterning ,oddcycle violation
Please make a video sir @ team VLSI
Due to this empty space, there exist discontinuity in n well and p substrate layer, so during manufacturing extra mask are needed in order to pattern such layout. Hence cost of manufacturing increases. So, It is preferred there should not be any discontinuity in n well and p substrate layer.
Not exactly, No extra mask needed. But for better reliability, ease of fabrication process and base DRC mitigation. We prefer continuous well. It also help to even potential distribution across well.
Since fabricating a single 16w filler cell reduces fabrication cost comapered to 16 seperate 1W cells.So we use different W cells.
Something else...
@@TeamVLSI ok I ll find it
@@abishekguggari1180 what is the answer for this
It will reduce the run time to insert filler cell for large designs....hope this helps
What is n well, pwell and metal rail minimum spacing violation?
Hi Raj,
You need to refer the DRM of particular tech node to get that answer.
One big cell delay can be less when compared to 16single width cells. Correct me if I'm wrong!
right.
How? filler cells don't have any logic right? Then why cell delay came in to picture?
@@amulyaraavi4089 in timing report we might not see the delay..but while extraction with star rc or qrc , extraction tool considers only rc factor of cell irrespective of physical or logical. That's why we see diffrence in extraction results with and without filler cells in design. In that case these 16 1w cells may give more rc value (delay) compared to 1 16w cell. @teamvlsi or @amulya raavi please correct me if I have wrong perspective about the issue
@@shaikmahammadakram8487 even if RC extraction shows more R/C values, what is the big deal, if they are not connected to core logic.
Command to add filler cells in synopsis tool sir????
It is placed to have nwell continuity, it is good at fab
Both the wells not only n
can i say filler cell a kind of spare cell or vice versa
No, That is not correct.
Please make video on antenna cell
Thanks Neha,
We will try to make it soon.
Hi,
I think wider cells will be used because of IR related issues.
How?
OK.. I found out the answer
But I need explanation in detail
metal slotting, metal dishing, dielectric erosion issues are seen
Please tell, can we use filler cells at the place of endcap and reverse, if yes.. please tell the reason, if not, please tell the reason
still no any reply, @TeamVlsi pls respond
We cant use Filler cells instead of Endcap cells and we cant use Endcap cells instead of Filler cells.
Both have their own individual purposes to serve.
ENDCAP: It has its POLY and OD designed with respect to the edges and corners. It will be half cut w.r.t left/right/top/bottom.
Half empty area wont be having POLY/OD. How does this help? This helps to isolate the domains. ENDCAPs are the boundary cells which isolates your IPs from the block, Block from the CHIP and what it protects? It protects your standard cells sitting at the edges or corners? How it will protect? As there is half empty area, but in another half empty area there will be POLY/OD which will act as extension to the nearby standard cell POLY/OD. During fabrication process, if there is any cutting or any kind of process which can impact the POLY/OD, then it will touch the ENDCAP POLY / OD and it wont impact the standard cells POLY/OD.
FILLER: It doesn't have the POLY/OD structure similar to ENDCAP. It won't help you to isolate.
Also, hence Filler can't be used instead of ENDCAP.
Coming back to reverse, Can ENDCAP be used instead of Filler cells?
If they are used instead of Filler Cells, then it will break the continuity of the POLY/OD, and there will be lots of BASE DRC Violations, because the design of ENDCAPs are very specifically w.r.t boundaries (of Chip/Block/IP/Memories/etc.) in terms of LEFT/RIGHT/BOTTOM/TOP/CORNER - All the ENDCAPs will be different in terms of POLY/OD Internal Structure
@TeamVLSI Please correct if anything wrong ...
Thank You,
Tejal
drive strengths are different 16w and 8w ...if we have 16w space we add 16w filler cell ...but we can also add two 8w filler cells ...delay will incerase use of two 8w cells...i think so....but here no physical and functional connection here...
while there will be space in standard cells there discontinuity in power supply and n well
so there will be drc violations to follow, in order to follow those drc rules we are using this filler cells to continue the power supply and n well
Why we need to do metal fill
There are many reasons for metal fill, uniform etching rate is one of them.
the tool will replace the std cell automatically
connectivity will be lost
right.
Due to empty spaces well discontinuity happens , It will create problem in fabrications....
Guys please correct me if M wrong..
Yes, It will cause DRC Error.