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prol.5alc - Man Page

define the rules for symbolic to real layout translation

Description

This file describes the rules used by the mbk(1) to rds translator. In the following file, symbolic layout objects are referred as mbk(1) objects, mbk(1) being the internal data structure that supports symbolic representation. On the other hand, rds is a data structure describing mainly rectangles, and is therefore used for real layout representation.

Some syntaxic remarques on the way to write the file follow. The case of identifiers is not significant, so NDIF is equivalent to NdiF. Comments are allowed anywhere in the file, using the sharp (#) as start of comment, and newline as end of comment. A line beginning with a sharp will be ignored, and a line containing a sharp will be read up to the character preeceding it. A newline can be escaped using the backslash ( followed by the newline. If some character, spaces or tabs for example, follow the backslash, chances are that a syntax error will be issued.

First, some important process parameters are needed, the physical grid step, that is the least common multiple of all the technologies values in terms of layout distances, and the λ, computed from a careful observation of the process design rules.
Then, a set of tables is needed, to describe how to translate a symbolic object, belonging to the mbk(1) world, and a set of layout rectangles, in rds.
Each table has a special meaning, and its parametrization exend being not full, some borders are to be evocated. Several type of table exists indeed. Some are needed for object translation, others for post treatment parametrization, others to define cif or gds identifiers regarding rds ones.
Many things seem to be parametrizable, but in fact, mostly, if not only, numbers, names in cif and gds translation tables, and boolean value in post treatement may be changed without problems.

For any table, if some layer is not applicable, it can simply be omitted. The default action is `do nothing', or use a value of 0.0 for all entries.

Layers and Patterns

Since the goal of this file is to allow translation from mbk(1) to rds, the meaning of the layers in both representation shall be known.
Mbk layers

NWELL

minimum width 4 ; N-well.

PWELL

minimum width 4 ; P-well.

NTIE

minimum width 2 ; N diffusion for polarisation.

PTIE

minimum width 2 ; P diffusion for polarisation.

NDIF

minimum width 2 ; N diffusion for transistor.

PDIF

minimum width 2 ; P diffusion for transistor.

NTRANS

minimum width 1 (gate width) ; N transistor.

PTRANS

minimum width 1 (gate width) ; P transistor.

POLY

minimum width 1 ; polysilicon, not transistor gate.

ALU1

minimum width 1 ; first level of metal.

ALU2

minimum width 2 ; second level of metal.

ALU3

minimum width 3 ; third level of metal (unused).

TPOLY

minimum width 1 ; through route for POLY.

TALU1

minimum width 1 ; through route for ALU1.

TALU2

minimum width 2 ; through route for ALU2.

TALU3

minimum width 3 ; through route for ALU3 (unused).

Mbk patterns

CONT_POLY

cut pattern from ALU1 to POLY

CONT_VIA

cut pattern from ALU1 to ALU2

CONT_VIA2

cut pattern from ALU2 to ALU3

CONT_DIF_N

cut pattern from ALU1 to NDIF

CONT_DIF_P

cut pattern from ALU1 to PDIF

CONT_BODY_N

cut pattern from ALU1 to NTIE

CONT_BODY_P

cut pattern from ALU1 to PTIE

C_X_N

corner primitive for L or S shaped N transistor

C_X_P

corner primitive for L or S shaped P transistor

Rds layers

RDS_NWELL

N-well (or N-tub), bulk for P transistors.

RDS_PWELL

P-well (or P-tub), bulk for N transistors.

RDS_NDIF

use for symbolic extractor as equivalent of NDIF.

RDS_PDIF

use for symbolic extractor as equivalent of PDIF.

RDS_NTIE

use for symbolic extractor as equivalent of NTIE.

RDS_PTIE

use for symbolic extractor as equivalent of PTIE.

RDS_POLY

polysillicon run, for cell internal wirering.

RDS_GATE

transistor polysillicon, for gate.

RDS_TPOLY

polysillicon feed through. Indicate to a router that a track is free of polysillicon.

RDS_CONT

hole in the isolating layer between polysillicon or active area and first metal level.

RDS_ALU1

first metal level run.

RDS_TALU1

first metal level feed through. Indicates to a router that a track is free of first metal level.

RDS_VIA1

hole in the isolating layer between first metal level and second metal level.

RDS_ALU2

second metal level run.

RDS_TALU2

second metal level feed through. Indicate to a router that a track is free of second metal level.

RDS_VIA2

hole in the isolating layer between second metal level and third metal level.

RDS_ALU3

third metal level run.

RDS_TALU3

third metal level feed through. Indicate to a router that a track is free of third metal level.

RDS_ALU4

fourth metal. (Used only for GaAs designs.)

RDS_VIA3

hole in the isolating layer between third metal level and fourth metal level. (Used only for GaAs designs.)

RDS_ACTIV

active area dropped in N or P implant to build transistors.

RDS_NIMP

implant area, (sometime known as N select), for N transistors.

RDS_PIMP

implant area, (sometime known as P select), for P transistors.

RDS_CPAS

passivation, used in pads.

RDS_USER0

user defined purpose layer. (May be used for DRC logical operations.)

RDS_USER1

user defined purpose layer. (May be used for DRC logical operations.)

RDS_USER2

user defined purpose layer. (May be used for DRC logical operations.)

RDS_REF

virtual layer for the representation of symbolic references

RDS_ABOX

virtual layer needed to indicate the abutment box of a model.

RDS_DEFAULT

default layer, shall never appear anywhere.

File Description

The following lines describe the file, entry by entry, specifying what is expected.

Physical grid

DEFINE PHYSICAL_GRID  .5
This statement defines the minimum grid spacing enforced by the foundry.

Lambda

DEFINE LAMBDA  1
This defines the value of the λ in μ. This value, like any other one in the rest of the file must be a multiple of the PHYSICAL_GRID.

Segment translation table

TABLE MBK_TO_RDS_SEGMENT
This table contains all the information needed to translate a symbolic segment of a given layer onto one, two or three real rectangles of specified layers. An example of this table is given below, with values needed for a technology where one λ is equal to 1.05 and the design grid is set to 0.15 μ.

TABLE MBK_TO_RDS_SEGMENT

  NWELL    RDS_NWELL   VW  3.15  6.30  0.0  ALL
  NDIF     RDS_ACTIV   VW  0.60 -0.90  0.0  ALL \
           RDS_NIMP    VW  2.10  2.10  0.0  ALL
  PDIF     RDS_ACTIV   VW  0.60 -0.90  0.0  ALL \
           RDS_PIMP    VW  2.10  2.10  0.0  ALL
  NTIE     RDS_ACTIV   VW  0.60 -0.90  0.0  ALL \
           RDS_NIMP    VW  1.20  0.30  0.0  ALL
  PTIE     RDS_ACTIV   VW  0.60 -0.90  0.0  ALL \
           RDS_PIMP    VW  1.20  0.30  0.0  ALL
  NTRANS   RDS_GATE    VW  0.00  0.15  0.0  ALL \
           RDS_ACTIV   VW -1.50  4.35  0.0  ALL \
           RDS_NIMP    VW  0.00  7.35  0.0  ALL
  PTRANS   RDS_GATE    VW  0.00  0.15  0.0  ALL \
           RDS_ACTIV   VW -1.50  4.35  0.0  ALL \
           RDS_PIMP    VW  0.00  7.35  0.0  ALL
  POLY     RDS_POLY    VW  0.60  0.15  0.0  ALL
  ALU1     RDS_ALU1    VW  0.90  0.75  0.0  ALL
  ALU2     RDS_ALU2    VW  0.90 -0.30  0.0  ALL
  TPOLY    RDS_TPOLY   VW  0.60  0.15  0.0  ALL
  TALU1    RDS_TALU1   VW  0.90  0.75  0.0  ALL
  TALU2    RDS_TALU2   VW  0.90 -0.30  0.0  ALL

END

The first column is the mbk(1) layer name to be translated, then there one or more groups of 6 columns each. For each physical rectangle, there are 3 parameters :
- rds layer name
- One of VW, LCW, RCW that indicates the `type' of segment to be generated
- physical length extension: DLR
- physical width oversize: DWR
- offset from symbolic axis: OFFSET
- tools for which the generated rectangle is applicable: ALL, DRC (for the symbolic design rule checker, see druc(1)), EXT (for the symbolic extractor, see lynx(1)) These parameters are meant regarding the symbolic segment.

Connectors translation table

TABLE MBK_TO_RDS_CONNECTOR
This table contains all the information needed to translate a symbolic connector of a given layer onto one single real rectangle.
An example of this table is given below, with values needed for a technology where one λ is equal to 1.05 and the design grid is set to 0.15 μ.

TABLE MBK_TO_RDS_CONNECTOR

  POLY     RDS_POLY  0.6   0.15
  ALU1     RDS_ALU1  0.9   0.75
  ALU2     RDS_ALU2  0.9  -0.3

END

One symbolic connector is translated into one physical rectangle using 3 parameters :
- rds layer name
- physical width oversize: DWR
- physical extension on each side of the abutment box: DER


It is discouraged to use active or well layers as connectors while designing.

Vias translation table

TABLE MBK_TO_RDS_VIA
This table contains all the information needed to translate a symbolic via of a given layer onto one to four real rectangles of user specified layers. An example of this table is given below, with values needed for a technology where one λ is equal to 1.05 and the design grid is set to 0.15 μ.

TABLE MBK_TO_RDS_VIA

  CONT_BODY_N RDS_ALU1 3   RDS_CONT  1.5 RDS_ACTIV 3.3 RDS_NIMP 4.5
  CONT_BODY_P RDS_ALU1 3   RDS_CONT  1.5 RDS_ACTIV 3.3 RDS_PIMP 4.5
  CONT_DIF_N  RDS_ALU1 3   RDS_CONT  1.5 RDS_ACTIV 3.3 RDS_NIMP 6.3
  CONT_DIF_P  RDS_ALU1 3   RDS_CONT  1.5 RDS_ACTIV 3.3 RDS_PIMP 6.3
  CONT_POLY   RDS_ALU1 3   RDS_CONT  1.5 RDS_POLY  3
  CONT_VIA    RDS_ALU1 3   RDS_VIA1  1.5 RDS_ALU2  3
  CONT_VIA2
  C_X_N       RDS_GATE 1.2 RDS_ACTIV 5.4 RDS_NIMP  8.4
  C_X_P       RDS_GATE 1.2 RDS_ACTIV 5.4 RDS_PIMP  8.4

END

This table describes how to translate one symbolic via, to 2, 3 or 4 physical rectangles. The table is defined as follow : The first column is the mbk(1) via name to translate, then there are 4 groups of 2 columns each, which correspond to four potential targets rds rectangles of user specified layer. In one group the first column is the rds layer name, the second one is the rds layer width. The rectangle is centered on the contact coordinates, and expands in the four direction of half the given width value.

Denotching values table

TABLE S2R_OVERSIZE_DENOTCH
This table contains the oversize value needed to erase notches. All the rectangles of the same rds layer are oversized by this value and then merged altogether and undersized by the same value. An example of this table is given below.

TABLE S2R_OVERSIZE_DENOTCH

  RDS_NWELL   3.00
  RDS_POLY    0.75
  RDS_GATE    0.75
  RDS_ALU1    0.75
  RDS_ALU2    0.75
  RDS_ACTIV   1.05
  RDS_NIMP    2.55
  RDS_PIMP    2.55

END

For some rds layers, like RDS_NWELL, RDS_NIMP and RDS_PIMP, two rectangles distant from less or equal the minimun spacing design rule must be merged in a single one. In this case, the oversize value is equal to the minimum spacing rule between two edges of the same layer divided by 2.
Some other rds layers, like RDS_ALU1, ..., must not be merged. In this case, the oversize value is equal to the minimum spacing rule between two edges of the same layer divided by 2, minus the physical grid.
Some layers never create notch, such as RDS_VIA1 or RDS_CONT, so the oversize value is null.

Ring width

TABLE S2R_BLOC_RING_WIDTH
s2r must merge segments to erase notches even if those segments are in two different hierarchical level blocs, for example, two blocs abuted side to side. So, it must be able to fetch segments inside blocs.  It is not needed to flatten the entire bloc, only a ring is necessary. The ring is computed from the abutment box edges or from  the envelop edges of the overlapping blocs.
An example of this table is given below.

TABLE S2R_BLOC_RING_WIDTH

  RDS_NWELL   6
  RDS_POLY    1.8
  RDS_GATE    1.8
  RDS_ALU1    1.8
  RDS_ALU2    1.8
  RDS_ACTIV   2.4
  RDS_NIMP    1.8
  RDS_PIMP    1.8

END

The normal ring width is the minimum spacing design rule between two segments of the same rds layer.
A zero means that no ring is wanted for that rds layer.

Minimum real layer width design rule

TABLE S2R_MINIMUM_LAYER_WIDTH
This table contains the minimum width of each rds layer. It is used by s2r to avoid creating rectangles below the minimum  required, during the merge operation.

TABLE S2R_MINIMUM_LAYER_WIDTH
  RDS_NWELL   6
  RDS_POLY    1.2
  RDS_GATE    1.2
  RDS_ALU1    1.8
  RDS_ALU2    1.8
  RDS_ACTIV   1.2
  RDS_NIMP    2.7
  RDS_PIMP    2.7

END

A zero can be specified, when it is sure that this layer is  not to be merged, because not treated by s2r.

Post treatment configuration table

TABLE S2R_POST_TREAT
This table indicates to s2r which rds layers must be post-processed. Precicely if a layer is only to be be translated, or translated and then post-processed. Translated means translate and fit from symbolic to real, and postreated that it should also be merged with its neighbours. For example, it's not necessary to merge cut layers such as RDS_CONT. 

TABLE S2R_POST_TREAT

  RDS_NWELL        TREAT NULL
  RDS_PWELL      NOTREAT NULL
  RDS_NDIF       NOTREAT NULL
  RDS_PDIF       NOTREAT NULL
  RDS_NTIE       NOTREAT NULL
  RDS_PTIE       NOTREAT NULL
  RDS_POLY         TREAT NULL
  RDS_GATE         TREAT NULL
  RDS_TPOLY      NOTREAT NULL
  RDS_CONT       NOTREAT NULL
  RDS_ALU1         TREAT NULL
  RDS_TALU1      NOTREAT NULL
  RDS_VIA1       NOTREAT NULL
  RDS_ALU2         TREAT NULL
  RDS_TALU2      NOTREAT NULL
  RDS_VIA2       NOTREAT NULL
  RDS_ALU3       NOTREAT NULL
  RDS_TALU3      NOTREAT NULL
  RDS_ACTIV        TREAT NULL
  RDS_NIMP         TREAT RDS_PIMP
  RDS_PIMP         TREAT RDS_NIMP
  RDS_REF        NOTREAT NULL
  RDS_ABOX       NOTREAT NULL

END

If set to NOTREAT, the first parameter indicates a translation. If set to TREAT, then the layer is translated and then post-treated
To post-process creates problems with the implantation layers. It is possible to have a good symbolic layout (no symbolic design rule errors), and have a resulting layout with DRC violations, created by a poor post-processing. It is due to the fact that these layers do not exist in symbolic, so it is not possible to apply them drc verifications. If two rectangles of these layers are too close (less than a given value), they must be merged. Generally, there is no problem, but when corners are too near it is impossible to merge with the classical algorithm, expand, merge, then shrink.
Rectangles, known as scotches, are created to merge anyway, like this :

+--------+            +--------+           +-----+--+
|////////|            |////////|           |/////|//|
|//+--+//|            |//+--+//|           |//+--|//|
|//|  |//|  gives ->  |//|  |//|     or -> |//|  |//|
|//+--+//|            +-----------+        |//+--|//|
|////////|            |///////////|        |/////|//|
+--------+            +--------+//|        +-----|//|     
    ^    +--------+            |//|-----+        |//+--------+
    |    |////////|            |//|/////|        |///////////|
    o--->|//+--+//|            |//|--+//|        +-----------+
    |    |//|  |//|            |//|  |//|           |//|  |//|
implant  |//+--+//|            |//|--+//|           |//|--+//|
 areas   |////////|            |//|/////|           |//|/////|
         +--------+            +--+-----+           +--+-----+

A N implantation layer should not overlap a P implantation one. We say that P implantations and N implantations are  complementary. A scotch will not be created if it intersects with  any of the rectangles of the complementary layers.
If a record contains in the second field a rds layer different from NULL, it indicates the complementary layer. This implies that if it is a layer that might need scotches the algorithm will try not to intersect with it when creating scotches.

Extraction graph table

TABLE LYNX_GRAPH
This table gives the connexion graph between the rds layers. For each layer, the list of the connectable layers is written. Up to now, the extractor works only on translated symbolic layout.

TABLE LYNX_GRAPH

  RDS_NDIF RDS_CONT RDS_NDIF
  RDS_PDIF RDS_CONT RDS_PDIF
  RDS_NTIE RDS_CONT RDS_NTIE
  RDS_PTIE RDS_CONT RDS_PTIE
  RDS_POLY RDS_CONT RDS_GATE RDS_POLY
  RDS_GATE RDS_POLY RDS_GATE
  RDS_CONT RDS_PDIF RDS_NDIF RDS_POLY RDS_PTIE RDS_NTIE RDS_ALU1 RDS_CONT
  RDS_ALU1 RDS_CONT RDS_VIA1 RDS_ALU1 RDS_REF
  RDS_REF  RDS_CONT RDS_VIA1 RDS_ALU1 RDS_REF
  RDS_VIA1 RDS_ALU1 RDS_ALU2 RDS_VIA1
  RDS_ALU2 RDS_VIA1 RDS_VIA2 RDS_ALU2
  RDS_VIA2 RDS_ALU2 RDS_ALU3 RDS_VIA2
  RDS_ALU3 RDS_VIA2 RDS_ALU3

END
Extraction capacitance table

TABLE LYNX_CAPA
This table gives the capacitance in picofarad per square lambda of each layer. The extractor computes only substrat capacitances. The capacitances associated with gate or drain or sources are not computed. On the other hand the transistor sizes (area, perimeter) are computed. (This is to ensure compatibility with Spice).

TABLE LYNX_CAPA

  RDS_POLY    1.00e-04
  RDS_ALU1    0.50e-04
  RDS_ALU2    0.25e-04
 
END
Cif translation table

TABLE CIF_LAYER
This table gives the equivalence between internal layers and their representation in the cif file format. A table may look like that (for MOSIS layers):

TABLE CIF_LAYER

  RDS_NWELL   CWN
  RDS_PWELL   CWP
  RDS_ACTIV   CAA
  RDS_NIMP    CSN
  RDS_PIMP    CSP
  RDS_POLY    CPG
  RDS_GATE    CPG
  RDS_CONT    CCA
  RDS_ALU1    CMF
  RDS_VIA1    CVA
  RDS_ALU2    CMS

END
Gds translation table

TABLE GDS_LAYER
This table gives the equivalence between internal layers and there representation in the gds file. A table may look like that (for CMP layers):

TABLE GDS_LAYER

  RDS_NWELL    1
  RDS_POLY    11
  RDS_GATE    11
  RDS_CONT    16
  RDS_ALU1    17
  RDS_VIA1    18
  RDS_ALU2    19
  RDS_ACTIV    2
  RDS_NIMP    12
  RDS_PIMP    14
  RDS_CPAS    20

END

See Also

Insights on the symbolic to real translation process are available in the file mapping.ps

Info

October 1, 1997 ASIM/LIP6 RDS FILE FORMATS