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Chapter 3.1

Mask Generation Using CAD Software

(Mask Generation Procedure ­ Labwide) Revision History Contents 1.0 2.0 Introduction CAD Software for Mask Generation 2.1 2.2 2.3 2.4 2.5 3.0 Definitions Graphic Layout Software Conversion Utilities Layout Display Software

Mask Layout Checklist Frequently Asked Questions L-Edit Mask Making Manual External Mask service Mask Making for the ASML300 Wafer Stepper Mask Making for GCAWS2 Mask Making for GCAWS6

Appendix A: Appendix B: Appendix C: Appendix D: Appendix E: Appendix F:

1.0

In tr od uct io n This document reviews the software aspects of mask generation, specifically, the programs and scripts you will need to get your design from layout graphic to mask. For information on operation of the pattern generator and the automatic mask developers, refer to manual entries on the wand. Generating a mask set from a graphics layout is a 4-step process: 1.1 A GDS file, generated with L-edit, Cadence or similar software is submitted. The layer of interest, required magnification value and the topmost structure in the file has to be specified. See https://microlab.berkeley.edu/MNLmembers/computers/tanner.html for information regarding L-edit. 1.2 The next step converts the GDS file to pattern generator specific file ­ a GDS to TAP conversion is performed using the gds2tap script. Steps include: flatten layers and sort flashes (gds2pg, mmask, pgsort2, mm2gds), convert to CIF (gds2cif), convert to TAP (m36gen). 1.3 1.4 Generation of masks on the GCA Mann 3600 Pattern Generator from the TAP and TIX files. Development of mask plates in the APT automatic mask developer.

2.0

CAD Sof twa re f or Mas k Ge ne rat i on

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2 .1

Definitions To avoid confusion, use the following conventions when naming your files: .gds suffix on all GDS format files .cif suffix on all CIF format files .mann suffix on all MANN format files .tap suffix on all TAP/TIX tape data files .tix suffix on all TAP/TIX tape index files The layout must not exceed the usable area of the mask to be made. The following table lists usable ranges for the masks available in the Microlab:

Actual Plate Size English 2.5 inch 3.0 inch 4.0 inch 5.0 inch

Mask Size for the gcapg Metric 60.5 mm 74.0 mm 98.6 mm 125.0 mm

Loss from Borders 2 × 6 mm 2 × 6 mm 2 × 6 mm 2 × 6 mm and corner areas

Usable Range in X-Y 51.5 mm 64.2 mm 89.6 mm 115.0 mm 5.15 × 104 µm 6.42 × 104 µm 8.96 × 104 µm 11.5 × 104 µm

For exposure area on the GCA 10X Reduction Stepper (gcaws6, 5" masks), please refer to lab manual Chapter 4.12 - GCA 8500 Wafer Stepper (6"). To determine mask magnification, refer to the following table: Projection System Quintel Contact Printer (quintel) Canon Mask Aligner (canon) I-Line GCA Wafer Stepper (gcaws6) G-Line GCA Wafer Stepper (gcaws2) ASML DUV Stepper Model 5500/500 (asml300) Reproduction Size 1:1 4:1 10:1 10:1 4:1 Scale Factor 1 4 10 10 4 Layout Size 4" 10 mm × 10 mm 8 mm × 8 mm 10 mm × 10 mm 22 mm * 27.4 mm

Be careful to work within the usable range. Consider whether you will be using a scale factor since this will affect your usable range coordinates. You have the option of centering your layout later during tape, but this will change the coordinates of your alignment marks, which must be specified if you intend to use 5" masks with the GCA 10X Reduction wafer stepper. The pattern generator cannot generate any geometry less than 2 µm on mask level. In case of more complex geometry the minimum features sizes are: 10 µm (diameter) for circles and for angled features the minimum value is 4 µm. Mask polarity is specified using the "invert" command between input and output layer names. Two types of masks are available, which are of opposite polarity. Chrome offers greater accuracy when dealing with line widths down to 2 µm. To decide whether inversion is needed based on the mask polarity you desire, refer to the following figure:

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If you are going to generate a dark field emulsion mask, be sure to place small geometries (such as 2 µm boxes) at the outer corners of the useable range of the layout (see above) to ensure that the field is completely blocked out. If you need a small, single open geometry (dark field), use chrome. If you need a small, single dark geometry (clear field), use emulsion. If emulsion edge resolution is not good enough, other methods have to be considered. If you are making a set of aligning masks for the GCA steppers, make sure that alignment marks are present. Try to place the physical center or your layout on or close to (X, Y) = (0, 0). 2.2 Graphic Layout Software This section describes the graphic editor CAD program, L-Edit available in the Microlab. You may use other utilities (e.g., AutoCAD) if they are able to produce layout files in one of the supported formats (CIF, or GDS). L-Edit is a commercial layout editor licensed from Tanner Research Incorporated. It is a screenoriented editor with simple menus for drawing various shapes on different layers. A windows version of the L-Edit software is currently available on a dedicated PC in the Microlab lobby. LEdit can be used with circuit simulation and analysis modules available from Tanner Research, but the Microlab has not yet purchased licensing for these products. L-Edit supports Tanner's own proprietary file format (TDB) as well as the popular GDS standard. L-Edit supports rotated boxes and polygons. Refer to the following document for further information: L-Edit User Guide from Tanner Research, available in the Microlab lobby.

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2.3

Conversion The gds2tap shell script attempts to guide you through a multi-step file conversion process, from a graphic layout through to the final mask files. gds2tap translates a GDS layout file to the TAP/TIX format used for pattern generation. Users will be prompted for information and stepped through the conversion process. gds2tap does a small amount of error checking as each conversion step is completed. gds2tap may be called with the following arguments: gdsfile Name of the GDS layout file to be converted. layerlist List of GDS layer numbers to be converted, separated with commas or spaces reduction Optical reduction expected: 1x, 4x, 5x, or 10x top_structure Name of the top-most feature to be converted. centered yes if mask be centered at [0,0], otherwise no units Specifies microns or mils as the unit of measurement for this layout Refer to the following documents for further information: UNIX manual page for gds2tap (man gds2tap).

2.4

Utilities This section describes the utilities available to convert files from one CAD format to another. These utilities are called by translation scripts during the translation process. These utilities can be cumbersome to use but they offer processing options and flexibility that may not be available from the translation scripts. 2.4.1 ciftomann ciftomann fractures and translates a CIF file into a MANN file, which is then suitable for mask generation by a pattern generator. Note: ciftomann can now be run on workstation boron2. Fracturing is the process by which large areas are broken into small areas suitable for exposure of photosensitive mask plates by the GCA MANN 3600 Pattern Generator. In addition to the input and output files, ciftomann requires a command file which specifies such information as input layer names, output layer names, scale factor, and layer inversions. ciftomann is invoked by typing: ciftomann -i input_file -o output_file -l log_file -f command_file -p PG3600 -i input_file Specifies the name of the input file, file.cif. -o output_file Specifies the name of the output file, file.mann. -l log_file

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Specifies the name of the log file to which diagnostic and error messages are written, file.err. -f command_file Specifies the name of the command file, file.comm. A command file contains information pertaining to the scale of the mask vs. the layout, layers that are to be translated, how they are to be named, and mask polarity specifications. A typical command file, which, by convention should be names file.comm, looks like this: scale 10 CONT invert CONT METL METI PII PII NII invert NII scale 10 specifies that the layout be magnified by a factor of ten. The scale factors to use are as follows: CONT, METI, PII, and NII are the output layer names. Output layer names must be unique, and should be no longer than 4 characters. Input layer names need not be unique, as shown above. -p pattern_generator specifies for which pattern generator the MANN file is being generated. For the Microlab, the pattern generator available is the GCA MANN 3600. This is designated as PG3600. For further information, consult the manual page for ciftomann, available on-line on all Microlab computers by typing man ciftomann. 2.4.2 cif2gds: Converts a layout from CIF format to GDS format. It is invoked by typing: cif2gds file.cif file.gds where file.cif is the name of the CIF file to be converted and file.gds is the name of the GDS file to be created. For further information, consult the manual page for cif2gds, available on-line on all Microlab computers by typing man cif2gds or visit their website at: http://www.artwork.com/gdsii/cif2gds.htm. The Microlab has a license for cif2gds. 2.4.3 gds2cif: Converts a layout from GDS format to CIF format. It is invoked by typing: gds2cif file.gds file.cif where file.gds is the name of the GDS file to be converted and file.cif is the name of the CIF file to be created. For further information, consult the manual page for gds2cif, available on-line on all Microlab computers by typing man gds2cif. 2.4.4 dxf2gds: Converts a layout from DXF format to GDS format. It is invoked by typing: dxf2gds file.dxf where file.dxf is the name of the DXF file to be converted. 2.4.5 gds2dxf: Converts a layout from GDS format to DXF format. It is invoked by typing: gds2dxf file.gds where file.gds is the name of the GDS file to be converted.

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2.4.6

gds2pg: Converts a CAD layout from GDS format to an intermediate format of fractured shapes for pattern generation. This is the first step of a two-step process to create pattern generator data. The second step (mmask) converts the fractured data into the exact command syntax required for the pattern generator. gds2pg is usually invoked by typing: gds2pg file.gds feature_size layer_list = file.gds is the name of the GDS file to be converted. feature_size is the size (in GDS units) of the smallest expected gap or line width in the layout. layer_list is list of layer numbers to be converted, separated by commas without spaces. = indicates that the topmost structure in the file should be converted. Converted structures are written into output files named structNN.INT, where struct is the name of the structure being converted and NN indicates the layer number of these shapes. The .INT suffix indicates that the file contains data in INTermediate PG format. Conversion results are summarized in a log file input_file.log. This file may contain useful information about errors that occurred during conversion. For further information, consult the manual page for gds2pg, available on-line on all Microlab computers by typing man gds2pg.

2.4.7

mmask mmask converts a CAD layout from intermediate PG format (.INT file) to an ASCII representation of a GCA Mann 3600 command file (Davis-Wilder Mann format, a .DWM file). mmask is invoked by typing: mmask -u:microns -s:1 -p file.INT -u:microns indicates that units of the mask are microns, not mils. -s:1 indicates that data should be converted at a scale of 1:1, i.e. no scaling. -p indicates that mmask should run without user pauses. file.INT is the name of the intermediate data file to be converted. Converted intermediate data from file.INT will be stored in file.DWM. A DWM file must be sorted with pgsort2 and converted to TAP/TIX format with m36gen before it can be downloaded to the pattern generator. For further information, consult the manual page for mmask, available on-line on all Microlab computers by typing man mmask.

2.4.8

pgsort This program will sort the MANN file in such a way as to minimize the stage movement on the pattern generator. It must be run on every mann file before making a tap/tix file. It is invoked by typing: pgsort file.mann file.mann.s where the s indicates that this is the sorted version of file.mann. After sorting, file.mann.s is ready for conversion to TAP/TIX format with m36gen. For further information, consult the manual page for pgsort, available on-line on all Microlab computers by typing man pgsort.

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2.4.9

pgsort2 This program is an alternate version of pgsort above, licensed from Artwork Conversion Software. The name pgsort2 is used to distinguish Artwork's version from the Microlab version. pgsort2 will sort and optimize the flashes in a Davis-Wilder Mann file (.DWM format). This script is used to reduce the number of movements and rotations required during pattern generation. pgsort2 is invoked by typing: pgsort2 -uM -t3600 file.DWM -uM indicates units of the mask are in microns. -t3600 indicates this data is for a Mann 3600 pattern generator. file.DWM is the name of the Davis-Wilder Mann file to be optimized. Optimized data from file.DWM will be stored in file.SOR. This file is also in Davis-Wilder Mann format; the .SOR suffix is used to indicate that this data has already been sorted. The sorted file must be converted to TAP/TIX format with m36gen before it can be transferred to the pattern generator. For further information, consult the manual page for pgsort2, available on-line on all Microlab computers by typing man pgsort2.

2.4.10 m36gen m36gen takes a .mann file and generates two files suitable for use on the GCA MANN 3600 Pattern Generator. m36gen is invoked by typing: m36gen [-c x y] [-t] [-n] -T newfile file.mann.s -c x y Center the masks about the point (x , y), where x and y are integers. Units for GCA MANN 3600 Pattern Generator are 0.1 µm. -c 0 0 will center the mask around the origin, coordinates (0, 0). Be aware that if you use this option to center your layout, the coordinates of your alignment marks will change! -t dx dy Translate the masks by dx in the x direction, dy in the y direction. dx and dy are integers with units of 0.1 µm for GCA MANN 3600 Pattern Generator. -n name The label on each mask will be of the form name layer_name. If not specified, the name defaults to your login name, in capital letters. For example, m36gen -c 0 0 -n CMOS2 -T cmos2 cmos2.mann generates a tape, whose masks are centered at the origin, and labeled CMOS2 layer name. m36gen -t 500 500 -T cmos2 cmos2.mann when executed, will cause the masks to be generated to be translated by 50 microns, in both x and y directions, from its present position. For further information, consult the manual page for m36gen, available on-line on all computers which support CAD tools by typing man m36gen.

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2.5

Layout Display Software This section describes software that may be used to inspect a layout on screen or on paper. Visual inspection may be useful to track down problems in a layout or converted file. 2.5.1 pgcam pgcam may be used to display a PG file on an X Windows graphics terminal. pgcam supports common PG data formats (including Mann 3600 and INTermediate files) and provides menu options for browsing and simple editing of fractured layout structures. pgcam is useful for inspection and manual fix-up of fractured layout files. For further information, consult the manuals from Artwork Conversion Software, available in the Microlab lobby. 2.5.2 pgview pgview is helper program for pgcam above. pgview speeds up the inspection process by automatically creating a job file for pgcam. The command pgview file1.tap file2.tap will create a job file containing the two named TAP files and then invoke the pgcam viewer. For further information, consult the online manual page for pgview. 2.5.3 cifplot cifplot may be used to convert a CIF file into HPGL-2 with Raster Transfer Language extensions which is suitable for plotting on the color wide HP Designjet T1100 plotter in the lobby of the Microlab. If you have never run cifplot before, it is recommended that you run cifplothp first. cifplothp will set up a ~/.cadrc file for you, and it will run cifplot -H for you. The -H flag to cifplot creates the HPGL file. By default, cifplothp will create a ~/.cadrc file which will use /cad/share/CIF/msucolors as the Colormap file. One may modify their ~/.cadrc file to refer to their own Colormap file. On the west wall of the lobby, is a chart, which specifies what color is referenced by which number. In general, cifplot -H will create a file suitable for the plotter. At the present time, cifplot creates files that use TIFF compression (which the HP plotter understands). The color plotter is known as plotter. One may queue a HPGL file created by cifplot with the following command: lp -dplotter filename Or starting from the cif file one may directly convert the file and plot it with the following command: cifplot -H cif-filename | lp ­dplotter Reminder: cifplot is a very CPU intensive program. Please, do not run cifplot directly on Silicon2; run it on workstation boron2. Normally, cifplot returns with the expected size of the plot, and the user is then prompted for a decision whether or not to continue the plot. One may also re-scale the plot.

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***COLOR CIFPLOT v2.0*** Scale: 1 micron is 0.009464 inches (240x) The plot will be 3.27 feet Do you want a plot? y Proceed with the plot. n Abort the plot. r Rotate plot. s New scale factor. (y,n,r,s): y 3.0 Ma s k La you t C he ck l is t Here is a final checklist you should go through before attempting to generate masks: 3.1 Polarity and the Pattern Generator Polarities specified correctly? Dark field emulsion? Geometries needed in corners to force pg to fill field. Small, single open geometry (dark field)? Use chrome - do not invert layer in ciftomann to generate an emulsion mask. Small, single dark geometry (clear field)? Use emulsion - do not invert layer in ciftomann to generate a chrome mask. If emulsion edge resolution is not good enough, send the job out. 3.2 Alignment Marks More than one mask? Alignment marks needed. Offset Coordinates for GCA alignment marks? 3.3 Scale Are scale factor used correct (10, 4, 1)? All geometries larger than or equal to 2 µm (the min value is 10 µm for circles and 4 µm for angled features) on all edges on mask level? Inverting? Will there be filled "spaces" smaller than 2 µm? 3.4 Centering Is the layout centered properly? i.e., is the physical center or your layout on (x, y) = (0, 0)? -c option used with m36gen? Alignment mark offsets will change!

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Appendix A

Frequently Asked Questions

1. Do I need to overlap my boxes if I want to make sure that the pattern generator won't leave spaces between them? This should never be required, the pattern generator is normally maintained so that adjacent boxes leave no space or line between them. Furthermore, if you use ciftomann any overlap is deleted before the mask is made anyway. 2. What are the minimum and maximum box sizes which the pattern generator can create? The minimum box size is 2 µm; maximum is 950 µm. These result in a minimum feature size of 0.2 µm when using the GCA wafer steppers (10X reduction) on wafer level. The maximum aperture size of the PG is limited by exposure considerations (preventing lines or spaces from occurring between adjacent boxes), there is no limit to the maximum size of a box. The resolution of a box on the PG is 0.1 µm (e.g. 0.01 µm with the GCA steppers). The maximum position for the center of a box on the PG is ± 57.5 mm from the center of the plate. Note that only features within ± 50.0 mm will print on your wafer, the extra area is typically used for fiducials and labels. 3. Is it true that I should not have designs near the border of my layout? No, you may place your designs anywhere in the exposed area of your wafer. Realize that the GCAWS does not expose the entire 10 mm field of the die, it chops off the corners. 4. Do I need an alignment mark on every layer of my layout? You only need an alignment mark on the first layer of your wafer, you may then align every later layer to this mark. It is generally prudent to include a mark on every layer so you have the option of aligning to any previous masking step, but this is not necessary. 5. Is the pattern generator software sophisticated enough to always correctly invert the data for clear field chrome masks? Not always. There is an option of making an emulsion master and then copying to chrome/ If your features are smaller than 5um, emulsion is not the answer either. The PG is not the best tool for making 1:1 contact masks but it is more than adequate for making the 10X masks for the stepper. If you need better masks for the contact printer, Marilyn has made a copy of the information on outside mask making services. In general, Manhattan-only geometry can invert the mask without difficulty using ciftomann. If you use rotated boxes you cannot invert your mask. 6. What is the easiest way to convert a layout file into the format necessary for the pattern generator? If you are using L-Edit or Cadence to create GDS files, use gds2tap to guide you through the conversion process. gds2tap will prompt you for necessary information and generally assumes you need help understanding what is going on. 7. What does 'Manhattan geometry' mean? Manhattan geometry means all lines are at right angles to each other, you can't have a box turned 45 degrees, for example. 8. What are the minimum sizes for non 'Manhattan geometry'? The minimum features size for non-Manhattan geometry is 10 µm (diameter) in case of circles and 4 µm is applied for angled features.

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9. How does the alignment happen using the GCA steppers? First you align the mask to the GCA column using the fiducials on the mask. Next you align the wafer to the machine using the joysticks and your entered key offset. The mask itself is never directly aligned with the wafer, the marks you align to on the monitor are generated by the computer, not your mask. 10. How do I transfer my mask files to the GCA pattern generator? Mask files may be transferred to the GCA PG via network file sharing from your home directory on argon. For more information, see the procedures described in lab manual Chapter 3.3 - GCA 3600F Pattern Generator.

Appendix B

L-Edit Mask Making Manual

The purpose of this document is to give helpful hints on using L-Edit to generate mask layout patterns and successfully convert the layouts using the Microlab's conversion utilities. Advantages of this layout software Easy to use - This is a straightforward layout editor, which is easy to learn and is recommended for labmembers with little mask making experience. Any angle features - L-Edit allows for any angle lines and polygons, arcs, circles, pie slices and with the new user programmable interface (UPI) can create a wide variety of additional features such as spirals and lettering. Quick turnaround - Because the program is easy to use, it speeds up the mask making procedure significantly. Masks that used to take a week to design and layout now take a day. Advanced features - L-Edit has many advanced features such as process modeling which allows you to visualize the processing steps of the individual layers. L-Edit is a user-friendly layout editor. The program allows you to create multi-layered mask patterns using wires, boxes, circles or arcs of any angle or orientation. The program is straightforward but there are a few beginner points that will make it easier to get started. There is a comprehensive manual for the program, which is located above the computers in the Microlab lobby. Technology File and Settings The program will initially open into a preset technology file that defines the layers, wire widths for the individual layers, internal units, grid spacing etc. You may use these default settings or create one specifically for your masks. Some of the settings defined in the technology file will be important when you try to convert the mask and it is best to get these issues straight before you begin. Internal Units - This defines the precision to which the computer stores your features. This should be set to at least 10 times smaller then your smallest feature size. Problems with conversion will occur if you make a wire that is the same width as the internal units. The computer defines a wire by centering it across the selected coordinates and then would try to place the wire as half an internal unit on either side of the selected coordinate. A good value for the internal units for a contact mask is .1 or .01 microns. So 10 or 100 internal units per micron. Also, make sure you define your spacing in units of microns. Wire Widths - You can define the default width of a wire for each layer in the layer settings. Individual wires widths may then be edited using ctrl-E or by the edit pull down menu when the wire is selected.

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Grid and Snap - This feature is very useful when generating masks by eye. It is often helpful to change this to parallel the feature size that you are working with. Getting Around Panning and Zooming is easily done by using the right hand number pad or arrow keys for panning and the + and - for zoom. You can pan and zoom while you are drawing objects or window selecting which makes it easy to freehand draw features such as long thin lines. Manhattan, 45-degree angles, any angle features The buttons on the left that designate a wire, box or circle can be clicked multiple times to switch between strictly Manhattan geometry (90 degree angle features), features at 45 degree angles and any angles. Cells and instances You may use many different cells that can contain part or all of the final mask feature. It is often useful to create a cell that contains a feature that is repeated many times in your final layout (top most cell). You can then call (instance) this cell multiple times or instance an array of cells onto your top most cell. If you decide to change one feature in a cell that is repeated, the change will be copied into all the instances of that cell. It is important to remember the name of your top most cell for the conversion. The conversion program can take a guess of what your top most cell will be by using the default (=) but it sometimes picks the wrong cell. If your conversion is producing the wrong pattern, make sure you are converting the correct cell. You may also wish to create a unique name for your top most cell because this will be used as part of the final name of your converted files.

Things To Keep In Mind About The Conversion Program

Drawing acute angles The conversion program has difficulties converting acute angles. It will often take a simple acute angle and break it into a dozen or so rectangles. If an acute angle is necessary, it can be easily and quickly created by manually breaking the angle into small rectangles. Remember that the smallest feature that the pattern generator can flash is a 2-micron square so do not make anything that will appear on the mask as smaller than 2 microns. This method is illustrated below.

Also, if you are generating angles that protrude out of a feature, it is often more efficient to define the angle as a rotated box vs. a triangle or part of a polygon. This method helps avoid acute angles in your patterns and is shown below.

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Both methods will simplify conversion and yield a much lower flash count. Gaps in the Conversion The conversion program will occasionally have gaps when converting random curves. If you have areas with strange features, make sure you view the file using pgcam during the conversion to make sure there are no missing spots. Pgcam has a very useful feature that allows you to place boxes to cover up any gaps. User Programmable Interface The new version of L-Edit is able to utilize C scripts to generate patterns. This capability is very handy for generating complex features such as spirals, ovals or arrays of objects that differ slightly. The UPI can also generate alphanumeric lettering. Getting Ready for the Conversion In order to convert a mask layout, you must save your files in the GDS format. Each layer must have an associated gds number, which you will need for the conversion. This can be changed on either the layers or cif/gds export drop down menus depending on which version you are using. In this same menu, there is an option to define how many rectangles are used to define a circle. Circles are generated with an array of rotated rectangles. The more rectangles you use, the smoother the circle will be. The default is 64 but 20 is sufficient for a well-defined circle and will reduce your flash count. Finally, save your file with the suffix .gds, which can be selected using the Export command. You are now ready for the conversion. Flattening you files eliminate all the cell structures and puts everything onto a single cell. You do not need to flatten you files in order to convert but you may wish to eliminate any unnecessary cells before conversion. Conversion Converting your files is straightforward using the gds2tap conversion script. The conversion programs perform a series of steps and although it is not necessary to understand the details of the conversion program, it may help explain what is occurring with your files. The pattern generator uses a pair of shutters, one for each dimension, which will adjust to define a box or rectangle with a minimum width of 2 microns and a maximum width or a few hundred microns. The shutters can rotate to create angled features and have a minimum rotation angle of 0.5 degrees. The mask is placed on a stage that is translated to expose the entire mask. In order to create the arbitrary features in a mask layout the files must be fractured into a series of boxes and rectangles that the pattern generator can expose. This is the first step in the conversion program. gds2tap allows you to view your files after this step in order to verify that your conversion has performed correctly. Another procedure the conversion program performs is to sort the individual flashes to increase the speed and reduce the wear on the pattern generator (pg).

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The rest of the conversion programs are used to get the information into a form that the pg can understand. Our pg is fairly specialized and accepts files as a modified cif format. Every feature must be defined as a box and the pg will not accept wires or polygons even if they are four sided polygons. The gds2tap script will automatically perform all the functions necessary to make the file pg ready. This conversion can take some time especially for large files. Things to know before you begin the conversion process. Name of the file you wish to convert. gds layer numbers for the layers you wish to convert. Name of the top most cell. Using the default (=) will allow the program to search for the top most cell. Units for the conversion (microns is default). Which lithography system you are using to expose your wafers. Whether you want the mask centered. The script will prompt you for the information at the beginning of the program. To initiate the script, simply type gds2tap. If you have any problems or have other suggestions that would be helpful to the Microlab community please discuss it with the Microlab staff so that it can be incorporated into a continuously improving system. Since we have one site license, the conversion can only be performed by one person at a time. Printing L-Edit does a fairly good job of printing the features, however, the resolution is limited. To obtain a high quality image of your mask layout you can print from pgcam during or after the conversion. Pgcam does an excellent job of printing multilayer layouts with good resolution. It can also print the image to several file types including tiff and eps.

Appendix C

External Mask service

External mask making services are used by members to fabricate masks that are beyond the capability of our pattern generator (internal service) or whenever this tool is not available due to maintenance service. Appended is a list of recommended mask making companies along with contact names:

1. Photronics - Contact person for UCB is Carole Martinez Tel: (408) 733 -7500 Main Fax: (408) 980-8680 http://www.photronics.com/ Contact person at Photonics Milpitas, highly recommended by some members: Brian Fraser ([email protected])

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2. Photo-sciences, contact person for UCB is Roger horseman Tel: (408) 748-7673 Fax: (408) 748-7749 http://www.photo-sciences.com/

3.Bench Mark, contact person: John W. Sumner. [email protected] work no. 781-246-3303 x19 http://www.benchmarktech.com/

If you choose a different mask making company, make sure that they are familiar with the type of mask, material and template we use on our steppers defect free masks for our contact aligners. Be sure to verify all externally produced masks with the test jig as described at Chapter 4.19 . Contact process staff if you have any questions or need additional information.

Appendix D

Mask Making for the ASML300 Wafer Stepper (ASML DUV Stepper Model 5500/300)

Purpose This chapter gives guidelines for mask generation from your layout design. R e t ic le Spe c if ic at io ns Nominal edge length: Recommended thickness: Optional thickness: Recommended glass type: Recommended reticle flatness: P at ter n Spe c if ic at io ns The maximum field size is: Wafer Level Diameter Maximum Y Maximum X 31.1 mm 27.4 mm 22.0 mm Reticle Level 124.4 mm 129.6 mm 88.0 mm 6-inch square 0.250 inch 0.150 inch or 0.120 inch Ultra low thermal expansion quartz 1 micron

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Mask Generation Using CAD Software For correct operation, in addition to the device layout image, the reticle must have: Patterns for pre-alignment of the reticle to the reticle table. Reticle alignment marks for aligning the reticle to the wafer. Minimum features size is 0.25 micron. L oc at io n of A S ML Mar k F i l e The file/layout is available in .GDS format on silicon:/mercury4/cad/asml300/ To get started, you will need: 1. Your layout design scaled to what you expect on the wafer. 2. File for the ASML (/mercury4/cad/asml300/) is also wafer scaled. 3. A CAD editor such L-edit or Cadence. How to generate final layout and submit mask request using ledit: a) First open the following link : /home/mercury4/cad/asml300 Here you can find the following files : asml300-1field.gds asml300-4field-mixmatch.gds asml300-4field.gds

Chapter 3.1

Use the "cell" command and one of the asml300 file. Then use the "cell" command followed by "instance" to bring up your design layout. Finally merge the two together. Note: Always open up on of these files then bring up your layout as an instance, so that positions of the pre- and alignment marks do not change.

b) Check coordinates of the pre- and alignment marks on layout to make sure that they are correct at wafer level, as follows: Pattern Reticle alignment mark 1 Reticle alignment mark 2 Border needed for clear field mask only Pre-alignment mark 1 Pre alignment mark 2 Border needed for clear field mask only X size (mm) 0.875 0.875 2.125 0.3668 0.3668 2 Y size (mm) 0.875 0.875 2.125 0.3668 0.3668 2 16.375 -16.375 0 0 X pos (mm) 16.9375 -16.9375 Y pos (mm) 17.375 17.375 Remarks Mark on right top side of the wafer Mark on right top side of the wafer With chrome border Mark on right center side of the wafer Mark on left center side of the wafer With chrome border

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Mask Generation Using CAD Software

Chapter 3.1

c) Save the merged file as .gds and use gds2tap shell script to get the .tap/.tix files. Please use the workstation boron2. CAD jobs (i.e., gds2tap) on Silicon will be killed immediately. usage: gds2tap may be called with the following arguments: gdsfile Name of the GDS layout file to be converted. layerlist List of GDS layer numbers to be converted, separated with commas or spaces reduction Optical reduction expected: 4X top_structure Name of the top-most feature to be converted centered Use no, since you want to keep your settings Warning: Using centering option will individually centered layer and change the coordinates of your alignment marks. units Microns Refer to the following documents for further information: UNIX manual page for gds2tap (man gds2tap) . Note: The standard requirement for the fiducials is the chrome border, so to get a dark filed mask is simple, while generating a clear field mask requires more concerns.

Clear field mask making for ASML with the Pattern Generator Some considerations: Dark field mask means: the patterns will be clear (exposed), background area remains chrome (i.e. contact holes) Clear field mask: the data, pattern should be unexposed (chrome) and the background will be clear. The reticle alignment marks must have a dark (chrome) background with an area of at least 8.0 × 8.0 mm2 centered around on each alignment mark. There is no option for utilizing emulsion or iron mask for ASML (chrome only). Generating a clear field chrome mask requires higher flash numbers than the dark filed version of the same layout. Maximum density allowed for the Pattern Generator: 140 thousand flashes. Be aware: Inverting a layer could result some very small features on your design. It will be dropped by the Pattern Generator if smaller than 2 microns on the mask.

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Mask Generation Using CAD Software

Chapter 3.1

Appendix E

Mask Making for GCAWS2

D Fiducials - 3600 Control System Facilities for Making Five Types of Fiducials The gcaws2 uses the D Fiducial only. Fiducials are placed 103 mm (4.12") apart when a 5" plate is used. This fiducial is specified in response to a fiducial question in the job setup.

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Mask Generation Using CAD Software

Chapter 3.1

Appendix F

Mask Making for GCAWS6

Purpose This appendix gives guidelines for GCAWS6 mask generation from your layout design. Ap p lic ab le Do cu me nt Chapter 4.12 - GCAWS6 6" Wafer Stepper R e t ic le Spe c if ic at io ns Nominal edge length: Reticle thickness: Recommended glass type: P at ter n Spe c if ic at io ns The maximum field size is: Wafer Level Maximum Y Maximum X 15.6 mm 15.6 mm Reticle Level 78.0 mm 78.0 mm 5-inch square 0.09 inch Soda lime glass (STD)

The recommended field size is: Wafer Level Maximum Y Maximum X 10.06 mm 10.06 mm Reticle Level 50.3 mm 50.3 mm

For correct operation, in addition to the device layout image, the reticle must have: Reticle alignment marks for aligning the reticle to the reticle table (RMS alignment windows). Global alignment targets for aligning the reticle to the wafer. Optional micro-DFAS alignment targets for finer alignment.

L oc at io n of GC A W S 6 T e mp la t e F i l e The template file for GCAWS6 is available in .GDS or .CIF formats on silicon:/mercury4/cad/gcaws6/ The template contains the following objects: Border for the recommended die size RMS alignment windows (for reticle alignment) Global alignment targets (in the center of the die) Micro DFAS alignment marks (in the corners of the die)

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Mask Generation Using CAD Software

Chapter 3.1

P o s it io ns & L oc at ion s of t he A l ig n me nt Ma r ks X size (mm)

Pattern RMS alignment window #1 (Reticle alignment window #1) RMS alignment window #2 (Reticle alignment window #2) Standard die size*

Y size (mm)

X pos (mm)

Y pos (mm)

Remarks

0.4

0.4

-2.2

11.5

Upper left part of the pattern

0.4

0.4

0.0

-11.5

Lower center part of the pattern

10.06

10.06

0.0

0.0

With chrome border Mark can be moved anywhere within the image field. Positive and negative phase targets may be used. 1, 2 or 4 marks can be used per field in combination with the global alignment target to optimize the alignment. Mark(s) can be placed anywhere within the image field. For the best results, however, the 2 targets should be placed across from each other in the field as close to the X-axis as possible; 4 marks per field should be located in the 4 corners, diagonally across from each other. Both positive and negative phase marks can be used.

Global alignment mark

0.132

0.132

0.0

0.0

Micro-DFAS marks (Fine alignment marks)

0.117

0.107

*Note: The die size can freely be chosen between 0 to 15.6 mm. However, if your die size differs from the standard one, a new job has to be created on the GCAWS6 machine.

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Chapter 3.1 - Mask Generation Using CAD Software
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