Paths ending with 90 Degree bend less than 1/2 width long problem

Hi,

We recently had a mask tooling problem with paths ending with 90 Degree
bend and the last segment is less than 1/2 width long. During MEBES
fracture from the centerline of the path on the short end segment back
towards the longer edge is getting filled in with data instead of
leaving a notch the width of the path. The extra filled in area was
causing a short to the next polygon. Has anyone else experienced this
problem?

We are now trying to search for instances like this and I don't think
Diva or Assura can find them so we need to write a skill routine to
look for it.

The small rectangle with the X in it below is the extra data being
filled in.
____________________________
|_X_|____
| | |
--------------------------------------------------- |
|
________________________________|

Thanks in Advance,
Tim

 

I assume you're using a path type with zero end extension? I've seen these
types of paths before, when writing a tool that reads GDSII, and I would
think of them as degenerate, invalid paths. What tool is generating these,
and why do you want a path like this? Seems to me like a hack to get
around a spacing design rule if there really is another shape that close
to the end of the path. If the intent is really to have a path with a
notch cut out of the end, isn't it better to just use a polygon? If you
can identify these paths (paths with a segment length less than the
width), then you should be able to convert it into a polygon from within
Cadence and then it should work.

Frank

 

We are currently in the process of writting a skill routine to search
the hierarchy to find these paths and convert them to polygons.

These paths can be made by; the create path command, the stretch
command, the move command, the add wire command & autorouting. Virtuoso
does give a warning when you add a path with the short segment but it
still allows it. These are usually created during an add when you end
the path at a pin. I myself, and I believe most layouters, don't like
to overlap objects on each other but preffer butting them to each
other.

The other layout tools I have used wouldn't allow the creation of a
path like this.

We found this on the layout of a modeling device were the layout person
ran an extremely thick path to the device to cut down on the metal
resistance. It wasa 100um wide path that connected to the pin of the
device so a large short was created in MEBES.

I was surprized that no one else has hit this problem yet.

Thanks,
Tim

 

Tim,

This is a quite well known problem. Calibre detects it as a
Warning during the load of the GDSII.

I wrote this Skill routine some years ago, processing all layouts
in a library.
It has 2 modes. One with a checking without modifying anything, and
the other with the automatic correction with dbConvertPathToPolygon()

Here it is :

/*
Function Name : ktPath2Poly.il
Category : layout
Date : August 13th, 2003
Revision : 1.1
Prerequisites : none
SW Release : 4.4.3, 4.4.6, 5.0.33, 5.1.41
Author : Kholdoun TORKI (CMP, Grenoble, FRANCE)
http://cmp.imag.fr

Synopsis : Procedure to tranform paths to polygons,
where the pathes end segments are less
than the half path width.

Known Problem : Pathes which are touching another structure
in the same layer are indeed processed.
No way to recognize if it is violating or not.
The path is then converted to polygon by default.
*/

procedure(ktPath2Poly()
prog((cvId sLibName sViewName tLibName tViewName)
cvId = geGetEditCellView()
if(cvId != nil then
tLibName = cvId~>cellView~>libName
tViewName = cvId~>cellView~>viewName
else
tLibName = ""
tViewName = ""
sprintf(msg "Cellview is not being viewed at this time.")
)
sLibName = hiCreateStringField(
?name 'sLibName
?prompt "Library Name"
?defValue tLibName
)
sViewName = hiCreateStringField(
?name 'sViewName
?prompt "View Name"
?defValue tViewName
)
sProc = hiCreateBooleanButton(
?name 'sProc
?buttonText "Path to Polygon ?"
)

p2pLayForm = hiCreateForm('p2pLayForm
"Transform Paths to Polygons"
"ktPath2Polygon()"
list(list(sLibName 0:0 350:35 170)
list(sViewName 0:35 350:35 170)
list(sProc 0:70 350:35 170)
)
)
hiDisplayForm(p2pLayForm)
)
)

procedure( ktPath2Polygon( )

prog( ( designLib designView cellName cell cvId shape )

designLib = ddGetObj( p2pLayForm->sLibName->value )
designView = ddGetObj( p2pLayForm->sViewName->value )

if( !designLib then
error( "Can not open %s. Exiting.\n" designLib )
)

rpt = outfile("path2Poly.report")

; open each cell in the design library
foreach( cell designLib~>cells
cellName = cell~>name


fprintf(rpt " \n Processing paths of cell %s \n" cellName)
printf( " \n Processing paths of cell %s \n" cellName)

cvId = dbOpenCellViewByType( p2pLayForm->sLibName->value cellName
p2pLayForm->sViewName->value "" "a")
if( !cvId then
hiGetAttention()
printf("CellView %s %s %s does not exist !!\n"
p2pLayForm->sLibName->value cellN
ame p2pLayForm->sViewName->value)
else

path22 = nil
d2 = 0.0000
w2 = 0.0000

(foreach p cvId~>shapes

path2 = nil

(if (p~>objType == "path") then
w = p~>width
w2 = (w / 2)
po = p~>points
ppo = p~>nPoints


if( (ppo == 2 ) then
coord1 = car(po)
coord2 = car(cdr(po))

x10 = car(coord1)
x20 = car(coord2)
y10 = car(cdr(coord1))
y20 = car(cdr(coord2))
if( (x10 != x20) && (y10 != y20) then
bext = p~>beginExt
eext = p~>endExt
d2 = ( sqrt((y20-y10)**2 + (x20-x10)**2) + bext + eext)
if( d2 <= w2 then
path2 = t

if( p2pLayForm->sProc->value then
dbConvertPathToPolygon(p)
)

path22 = path2
fprintf(rpt "x10 = %f y10 = %f x20 = %f y20 = %f \n" x10 y10 x20 y20)
printf("x10 = %f y10 = %f x20 = %f y20 = %f \n" x10 y10 x20 y20)
); if d2<w2
); if x10==x20 y10==y20
); if ppo==2

if( (ppo > 2) then

coord1 = car(po)
coord2 = car(cdr(po))

x1 = car(coord1)
x2 = car(coord2)
y1 = car(cdr(coord1))
y2 = car(cdr(coord2))
bext = p~>beginExt
d2 = ( sqrt((y2-y1)**2 + (x2-x1)**2) + bext)

if( d2 <= w2
then path2 = t
path22 = path2
fprintf(rpt "x1 = %f y1 = %f x2 = %f y2 = %f \n" x1 y1 x2 y2)
printf("x1 = %f y1 = %f x2 = %f y2 = %f \n" x1 y1 x2 y2)
); if d2<w2


coord11 = nthelem(ppo-1 po)
coord22 = nthelem(ppo po)

x11 = car(coord11)
x22 = car(coord22)
y11 = car(cdr(coord11))
y22 = car(cdr(coord22))
eext = p~>endExt
d2 = ( sqrt((y22-y11)**2 + (x22-x11)**2) + eext)

if( d2 <= w2 then
path2 = t
path22 = path2
fprintf(rpt "x11 = %f y11 = %f x22 = %f y22 = %f \n" x11 y11
x22 y22)
printf("x11 = %f y11 = %f x22 = %f y22 = %f \n" x11 y11 x22 y22)
); if d2<w2


if( p2pLayForm->sProc->value && path2 == t then
dbConvertPathToPolygon(p)
)

); if ppo>2
); if p path
); foreach p


if( (path22 == t) && p2pLayForm->sProc->value then
dbSave( cvId )
)


dbClose( cvId )

) ; end if
) ; end foreach

fprintf(rpt " \n")


printf(" \n")

close(rpt)

printf("load \"ktPath2Poly.il\" \n")
printf("ktPath2Poly")

) ; end prog
); end procedure p2p


;*************************************************************
;ktpath2Poly()
;FUNCTION
; UI for Path to Polygon
;*************************************************************
procedure( ktPath2PolyPullDown()
let( (ktPath2PolyField)
ktPath2PolyField=hiCreateMenuItem(
?name 'ktPath2PolyField
?itemText "*Path to Polygon"
?callback "ktPath2Poly()"
)

; add "*Path to Polygon" item under Custom Layout Verify menus.
unless( leVerifyMenu->ktPath2PolyField
hiAddMenuItem( leVerifyMenu ktPath2PolyField)
)

)) ; END ktPath2PolyPullDown()
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


Hope it helps.

===================
Kholdoun TORKI
http://cmp.imag.fr
===================

 

Hi Kholdoun,

Thanks for the skill code that should be a great help!

Thanks Again,
Tim

 

Hi Tim,

Note that this code also supports the 45 degres (or all angles)
end segments.

Regards,

===================
Kholdoun TORKI
http://cmp.imag.fr
===================