User 20190913 Monday 20th May 2019
Is there a means to filter selection, such as "ignore instances" or select only a particular layer's shapes?
Is there a means, as in Cadence, to constrain the selectable region of a layout instance (there, a rectangle placed on instance/dwg layer becomes the only "grabbable" extent of a larger layout cell, if present; otherwise, select region defaults to actual extents). Very handy when you have a lot of stuff on top of each other.
Jürgen LayoutEditorFull Monday 20th May 2019
You can lock a layer. Then no more shape from this layer can be selected. Also in the fine select menu there are options to only select shapes or instances. Also invisible layer are ignored by the selection with the mouse. These and some other select option should do anything you need to be able to always select the correct element. If you ever have a situation where anything can no be selected, please let me know, we will review that and improved the LayoutEditor in a way that it can be select.
User 20190913 Thursday 6th June 2019
Maybe I can better describe the function, which I used a lot in Cadence, but is missing from Silvaco and perhaps most tools but is a real nicety.
"Instance" is a built-in drawing layer (independent of PDK, like a few others like "text" and "highlight".
A peculiar feature of the schematic and layout tools is that if an "instance" rectangle is present in a symbol or a layout, the selectable region of that object "collapses" to the instance-feature extents. In symbols this is "cute but not necessary". But consider the layout case.
Suppose I want the I/O ring and its bussing and the scribe line to be a layout object (I do this all the time, don't like a mess of top level small instances and polygons for stuff that will not change as I proceed with the core layout). Now when I am doing core layout, from the top level (as when I route to pads or between top level cells) the "IO_Ring_Scribe" object's extents overlap anything else in the chip and I have only roll-the-dice odds of selecting what I wanted, and equal odds of selecting the IO_Ring_Scribe instead.Yeah, I 'could' use the select-by-name list for instances. Yeah, I -could- toggle and retoggle instance selectability when I want to grab and move a polygon or path.. But I have found it so much better to make the IO_Ring_Scribe only have a 10x10um "handle" at the lower left corner of the chip, so it only gets grabbed if I go right there.
You mention it's possible to "lock layers". Is it possible to "lock instances" - selectively - such that some can be +put to bed" but visible (like, so I can see pin targets but be sure when I click on nearby routing or cell objects, I get what I was pointing at and not "something behind it"?) Making things invisible to prevent selection also makes them invisible as things to route to or things to avoid.
Maybe I need to change my work-style and always work in "edit in place" more, where -everything- is under a cell at the top level and no "0x" data is sitting loose? Make the top level hookup a cell as well? And propagate this style at every level? Hmmm....
This lack also bugs me about Silvaco Expert, I have chips where I've gone for days in top level hookup only to discover that I moved the pad ring somewhere along the way and half my work is messed up just enough to wreck LVS / DRC.
Do you feel me?