TSMC 0.18um dummy insertion only covers partial area

[RuihW]

Hi everyone,

I'm having troubles with the dummy insertion in Calibre. The insertion only filled some area no matter how big the fill window I set to. For example, the generated dummy only fits the rectangular region if the origin of the dummy is set to (0,0). Calibre's DRC is set to hierarchy mode. If it's set to use flat mode, then the dummy would be placed on the left edge. But still, it only covers less than 5% of the entire chip. What did I miss here?

 

[ThisIsNotSam]

dummy fill utility is configured not to interact with some layers. if it sees SRAM/ROM or other special zones, it ignores the area and fills around it. Is there something special or something missing that is common to the unfilled area?

 

[RuihW]

dummy fill utility is configured not to interact with some layers. if it sees SRAM/ROM or other special zones, it ignores the area and fills around it. Is there something special or something missing that is common to the unfilled area?

I don't think so. The DMEXCL and POBLK areas are shown below. My biggest confusion is that sometimes the utility filled the area in red circle in flat mode, but it never fill any other area. There's lots of open space above the red circle and the utility just ignored it.

 

[ThisIsNotSam]

and just to be clear, you are still getting density violations after the dummy utility does its thing?

 

[RuihW]

Yes. They only increased the density by 0.5%. I feel like I can do a better job than that by manually filling the empty area.

 

[ThisIsNotSam]

Using the default window size, see if there is a seeting related to "filling small spaces". I know it exists for TSMC65 and 16. If you turn it on, it tends to generate better filling by instantiating a lot of small pieces instead of large pieces of fill.