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  1. Layout design formats
  2. Layout editors
  3. Layout template
  4. Layer description

 

Layout design formats

When you want to make a pattern transfer with photolithography, you have to describe or digitize those patterns by geometric shapes, i.e. distinguish the areas where will be passing photons to expose photoresist from the areas where they will be blocked, typically by exposure to UV light. There exist layout design formats to describe such patterns. Some are proprietary, some public, some standard. We recommend that you use dedicated CAD software to generate your designs. Then export the fruits of your work to formats such as:

gds, gdsii, gds2, GDSII (Graphic Database System for Information Interchange, an industry standard), There are many descriptions of gds, such as an anonymous one, or Steven M. Rubin's, or Steve Buchanan's, or in the SPIE Microlithography Handbook . Currently, the format was inherited through acquisitions by Cadence , and there is documentation in their manuals. There are limits which were by convention set to a certain number, such as 199 vertices for a boundary element (199 coordinates for a polygon), but many CAD tools accept higher numbers, sometimes up to the 8191 vertices limit set by the file format. Other problem points are: 32 character limitation for cellnames, 64 (255) layers, 64 (255) datatypes, etc. .

cif, CIF (Caltech Intermediate Format), text based, The Caltech Intermediate Form for LSI Layout Description, [local copy].

Some users generate their layout with scripting, such as Octave/Matlab->CIF, or Octave/Matlab->GDSII, or use a Octave/Matlab toolbox, or python->gdspy->gdsii , etc. . Some users make their design in mechanical world drawing programs such as AutoCAD, Solidworks, Blender, etc., then export to gdsii, or use LinkCAD to convert.

There is no recommendation as to what is right or wrong. However we recommend that you test and validate your toolchain from your tool all the way to the Heidelberg "x-convert" software, as soon as you have drawn a cell with a handfull of polygons, to avoid that you have a great design, that cannot be used due to some syntax error, or a conceptual flaw that requires to redesign everything. Sometimes, a design that cannot be read by the "x-convert" software can be read by a layout tool, and when it is saved under a new name, the reshuffling clears out some incompatibilities.

Proprietary design data, proprietary extensions to standard CAD file formats (tdb, cdba, ...) cannot be used for exporting/transferring layout data for Heidleberg mask generation tools. With many limitations and restrictions, DXF files may be accepted. Find more information on layout format standards in appendices of Computer Aids for VLSI Design.

Layout editors: CAD software

The software listed below (in order of preference) can export valid and standardized data streams for the mask generator.

Software
Description
installation user guide
LinkCAD LinkCAD by Gehriger Engineering, distributor Bay Technology, allows to view, convert and transform layout among many data formats. CMi recommends the use of LinkCAD to transform your layout from your favorite, habitual, special format into “GDSII”, which is the one format which produces the least problems with the Heidelberg Instruments conversion software used for direct write laser MLA150 and VPG200. installation by staff only, license pool.

software available to CMi users

in room BM 1.132

on cmipc27 and cmipc58

not available
L-Edit
L-Edit by Mentor, a Siemens business, (formerly Tanner EDA): a professional CAD application used for integrated circuit mask design. Recommended tool. For CMi users, there are (a limited amount of) licences avaliable. (NB: This is not the Tanner MEMS design flow, but the IC layout tool). self installation following L-Edit Installation manual not available
Klayout
KLayout from klayout.de by Matthias Köfferlein, Germany: fast and accurate viewer. Rudimentary but slick editor. Builds available for windows, linux and mac. Huge potential with ruby scripting. Recommended tool, as it is fast, and free software under GPL2 or later. Install it yourself with the packages and instructions available on their website. not available
Clewin
Clewin by WieWeb (commercial arm PhoeniX Software), Netherlands: a product that has evolved from a simple editor to a powerful mask design tool. Popular tool, often standard within a research group, but proprietary extensions are difficult to handle, especially in downstream tools, read and carefully apply the recommendations in the "how.to.sanitize" user guide.. CMi does not have any license for CleWin. If you decide to purchase, get it directly from WieWeb downloads . Price for CleWin v5 in 2017 is EUR2590 for an entire research group, no user limit. how.to.sanitize.clewin.written.cif.pdf
Glade Glade (Gds, Lef And Def Editor), is a IC layout and schematic editor capable of reading and writing common EDA formats. Available for Windows, Linux and Mac OS X using the Qt gui toolkit. Install it yourself with the packages and instructions available on their website. not available, but read their tutorial/presentation.

LayoutEditor


LayoutEditor by juspertor GmbH, Germany: distinctively versatile tool when editing layouts for IC, MEMS, MCM, PCB, COB, MMIC, LTCC, ... . Builds for windows, linux and macosx. Free version, limited to 500 shapes, Basic version ~EUR50. web download not available
AutoCAD AutoCAD: popular general purpose CAD editor for mechanical drawings. Export of AutoCAD drawings to DXF format is possible with restricted object classes, read before editing: AutoCAD rules . epfl distrilog

or autocad free trial

AutoCAD-to-dxf-to-gdsii tutorial describing the AutoCAD to DXF to GDSII flow
SolidWorks SolidWorks: solid modeling computer-aided design (CAD) and computer-aided engineering (CAE) computer program that runs on Microsoft Windows. SolidWorks is published by Dassault Systèmes. [from Wikipedia]. Export of drawings to DXF then covert to GDSII is possible within limits. Licenses from epfl distrilog are not accessible for use in a laboratory, workshop, Discovery Learning Lab or for a semester-diploma project related to a research project.

If you wish to use Solidworks for nonprofit research, a workshop, Discovery Learning Lab, a semester or diploma project related to research at EPFL, you must request these licenses from https://solidworks.epfl.ch/

If you use Solidworks for a course which is in the Academic calendar, please contact us at solidworks.admin@groupes.epfl.ch

At this point, we recommend that you contact solidworks@epfl to see if you are allowed to use this tool.

SolidWorks-to-dxf-to-gdsii.
tutorial describing the SolidWorks to DXF to GDSII flow.

 

Layout template for CMi users: starter kit

CMi user library available for download:

Filename
Description
Template_CMi_V6_2.gds Current GDSII template with sets of alignment marks for MA6Gen3 assisted alignment, and spectrometer fiber feedthrough positions for MA6Gen3 SMILE and GSL modes.
Template_CMi_4mmhead_V5_0.gds
General GDS template for contact exposure using optical alignment.
High resolution mode, mask writing with the 4 mm head. Step size for the manufacturing grid is 200 nm.
Template_CMi_10mmhead_V5_0.gds
General GDS template for contact exposure using optical alignment.
Low resolution mode, mask writing with the 10 mm head. Step size for the manufacturing grid is 0.5 um.
Template_CMi_MixMatch_V5_0.gds
General GDS template with alignment marks for e-beam and optical lithography.
High resolution mode, mask writing with the 4 mm head. Step size for the manufacturing grid is 200 nm.

Layout template layer description

Description of layers used in the template files:

GDS #
Layer function
Notes
50
Wafer frame

Layer shows the frame and flat location of a 100 mm Si wafer. This layer is normally removed from the layout.
51
Mask frame

The frame of a standard 5" mask plate used in the contact aligners at CMi. This layer is always removed from the layout.
52
CMi logo

The logo of CMi and mask information for identification of mask plates. This layer is normally kept and updated, and can be removed if necessary.
53
Dicing marks

The matrix of crosses show an example guideline set for dicing the wafer into dies. The layer should be kept only if dicing will occur; the step size can be adjusted to adapt layout.
54
MA6BA6 alignment mark
location area
Demonstration of the area visible with the Karl Suss aligners in the CMi. Alignment marks outside of this area cannot be found with the objectives. This layer should always be removed.
55
EVG150 robot arm
handling area
Demonstration of the area where the robot arm suction cups will be in contact with the backside of the wafer. This layer should always be removed.
56
SB6 contact area

Demonstration of the area where the fixture and the pin is in contact with the wafers during the bonding process. This layer should always be removed.
57
Resolution test
patterns
Test patterns to determine best achievable resolution; can be used during a lithography process, and mask fabrication. These patterns are adapted to the DWL writing modes, and can be replaced or removed if necessary.
58
Top side layer 1
alignment marks
First layer of structures for top side layer-to-layer alignment. Other marks may also be used. These can be removed if there is no need for alignment.
59
Top side layer 2
alignment marks
Second layer of structures for top side layer-to-layer alignment. Depending on process steps and layout, this layer might need to be inverted for better visibility.
60
Top side layer 3
alignment marks
Third layer of structures for top side layer-to-layer alignment. Depending on process steps and layout, this layer might need to be inverted for better visibility.
61
Back side layer 1
alignment marks
First layer of structures for back side layer-to-layer alignment. Other marks may also be used. These can be removed if there is no need for back side alignment.
62
Back side layer 2
alignment marks
Second layer of structures for back side layer-to-layer alignment.
63
DWL alignment marks

Patterns for alignment with the laserwriter. This layer should only be kept for direct write alignment with the DWL200 or inspiration for VPG200.
64
Wafer edge mask see-throughs. Fiber feedthroughs. E-beam alignment marks,
A 2mm wide edge of a 100mm wafer. Allows to peek through the mask by the means of this visual feedback coarsly align the wafer edge with the design. Primary flat scale allows for good alignment with crystal plane. Feedthrough positions for spectrometer fiber used on MA6Gen3 in SMILE and GSL modes. Set of alignment marks to allow both optical and e-beam lithography with alignment in one process flow. Please contact CMi staff for further information.
65
MLA150 BSA areas, vacuum channels.
The MLA150 chuck has four rectangular holes that allow the back side alignment BSA cameras to look at the wafer from the back side. This is where you must place your alignment marks, if you want to do BSA. The traditional two BSA areas are located along the x-axis, here there are two additional ones along y-axis. Tthe traces of the vacuum clamping channels are given as well.
159
inverted TSA layer2
alignment marks of layer 59, inverted, inside a 2mm x 2mm square, so that you see through that opening in the mask the marks on layer 58 on the substrate below
160
inverted TSA layer3
alignment marks of layer 60, inverted, inside a 2mm x 2mm square, so that you see through that opening in the mask the marks on layer 58/59 on the substrate below