1、Section 1. Different Import and Export Formats Available on IE3D. The most popular layout formats in the electronic industry are the GDSII (Calma Stream) format, DXF (AutoCad) format, GERBER format and ACIS format. IE3D has been able to import and export files in GDSII format and CIF (CalTech Interm
2、ediate Form) format directly. Recently, we have implemented the ADIX Format Converter. It can perform bi-directional IE3DGDSIIDXFGERBERACIS conversion. On the File-Export command, we have the following options: (1) DXF; (2) GDS; (3) 3D Text (Zeland); (4) ACIS; (5) GERBER; (6) CIF; (7) FIDELITY. The
3、3D Text is a format created by Zeland Software, Inc. Basically, it allows you to write a structure as a script file. The 3D Text format is discussed in Appendix O. The FIDELITY format is for export only. Basically, you can export a geometry in MGRID into the FIDELITY format for our FIDELITY simulato
4、r. It allows you to define thickness to polygons for 3D objects. Only horizontal polygons (z-directed), x- and y-directed polygons can be exported. Polygons of other orientation will be omitted. Exported FIDELITY structures normally need clean up on FIDELITY because a simulation can be done. More au
5、tomated exporting will be available in the future. In the last one-year, we have implemented the Automatic Geometry to IE3D Flow (or AGIF). AGIF can do 3 jobs: (1) Convert GDSII layout into IE3D models directly. After the conversion, the IE3D geometry can be a full-3D model containing vias, wire bon
6、ds, solder balls, and ports and ready for simulation. Users can create one template for one MMIC or RFIC process. The template can be used for all different GDSII files of the same process to do batch IE3D simulations directly from GDSII files. (2) Perform IE3D simulation on a cell or selected part
7、of a cell from Cadence Virtuoso Custom IC Design Platform. Cadence Virtuoso is the most popular RFIC design layout tool. AGIF can simplify EM simulations of RFIC significantly. In the automatic conversion, AGIF can clean the structure for high efficiency IE3D EM simulations without losing accuracy.
8、For example, pin-vias are parts of many semiconductor processes. Simulating the pin-vias exactly is prohibiting because of the large number of pin vias can kill the simulation easily. AGIF can allow the users to merge pin vias into large vias without changing the electrical properties of the structu
9、re. The process is done automatically with specifications from users. There are many other advanced editing capabilities of IE3D fully automated into AGIF for streamlined IE3D simulations from GDSII and Cadence Virtuoso. (3) Create IE3D models directly from Cadence Allegro Interconnect Design Platfo
10、rm and Cadence APD. Cadence Allegro is a PCB tool and APD is a packaging tool. AGIF allows users to define selected nets as critical nets, reference nets and coupled nets. Then, it can automatically build the IE3D model for the critical nets including the reference nets. The created model can be rea
11、dy for simulation. There is a separate documentation on AGIF. In this menu, we may give a simple example of using AGIF for automated IE3D simulation. In the last couple years, we have also implemented the EMSocket together with Applied Wave Research, Inc. EMSocket basically allows users to create la
12、youts from Microwave Office of AWR, perform IE3D full-wave EM simulations seamless from MWO. The advantages of IE3D and MWO are combined together to make it convenient for designers. EMSocket is available automatically to IE3D and MWO users free of charge. In the next section, we will show the impor
13、ting of a GDSII file. We will use a simple MIM capacitor as an example. The procedure for importing a DXF file is similar except you may need to scale the imported structure after importing because a DXF file may not carry absolute dimensional information.Section 2. Importing an MIM Capacitor in GDS
14、II Format.The shape of the MIM capacitor is shown in Figure 6.1. The bottom plate is on a 100-micron GaAs substrate. The dielectric between the two plates is of thickness 0.2 microns and dielectric constant 6.7. The dimensions of the top plate are 100 microns by 100 microns. The air bridge is at 102
15、-micron level. The GDSII file is in .ie3dsamplesmimcap.gds.Step 1 Run MGRID. Select File-Import command. MGRID will prompt you the Import Options dialog. Select GDSII for Import Format. Many of the options are grayed out because they are for the DXF conversion. For DXF import, you may have to select
16、 Length Unit. You also need to define Circular Min Radius (Rmin) and the Segment (Smin), Circular Max Radius (Rmax) and the Segment (Smax). The parameters are for converting circular structures to polygons which are the only objects accepted by IE3D. When we encounter a circular shape with radius R,
17、 we will convert it into a polygon with S-number of segment. The S is calculated based upon the formulas in Table 6.1. It is basically a linear interpolation based upon R, Rmin, Rmax, Smin and Smax. We should choose the Rmin, Rmax, Smin and Smax values wisely. For some applications, the circular sha
18、pes can be electrically large, we should choose Smin and Smax as 12, 16, 24, 36 or even 64. For some applications, the circular shapes are normally for vias and they are electrically very small. We can choose Smin and Smax as 4, 6 or 8. Normally, 6 is a good number. Choosing too big a number will ca
19、use IE3D create too many unknowns and the simulation time will increase substantially while the accuracy is not improved.(a) Original structure with two plates (b) Z-direction magnified by a factor of 30Figure 6.1 The shape of the MIM capacitor to be built from importing.Table 6.1 The formula for Se
20、gments (S) based upon Radius (R).R RangeS FormulaR RminS = SminRmin R S = SmaxStep 2 For GDSII structure, circular shapes are already converted into polygon shapes. We do not need to worry about it. Please select OK to continue. MGRID will prompt you for the GDSII file. Select file .ie3dsamplesmimca
21、p.gds. Select OK continue. MGRID will import the structure from the file. It comes up with the Import Data Options dialog (see Figure 6.2). It will list all the structures detected in the file. There might be multiple structures in a GDSII file. You can select which structure you want to import. For
22、 this particular GDSII file, there is only one structure: mimcap and it is checked. All the layers detected in the structure are shown in the list box at the right. There are many parameters you need to enter. The first group of parameters you need to enter the Basic Parameters for the structure. Th
23、ey contain the substrates and the metallic strip types and the meshing parameters etc. The second group of parameters you need to enter are the layer information. A GDSII file contains only the layer information and the (X, Y) coordinates. It does not contain the Z-coordinates. We need to map the la
24、yers to Z-coordinates. It is also possible a GDSII file use polygons to define the shapes of vias. However, they do not contain the third dimensional information about how the vias are connecting the layers. Figure 6.2 The Import Data Options dialog before the template file .ie3dsamplesmimcap.ctp is
25、 loaded.We need to define all the above data in the Basic Parameters dialog from the button, the layer information dialog at the right and the Automatic Via list box at the lower right corner of Figure 6.2. Certainly, we can define some temporary data first. After we import the geometry into MGRID,
26、we can change the layer z-coordinates, redefine the Basic Parameters, and build the vias using the polygon shapes using the Adv Edit-Build Holes and Vias from Selected Polygons command. It can be a tedious process. Fortunately, we have implemented the Import Template File (.ctp) to ease the process.
27、Step 3 We have already created the Import Template File: .ie3dsamplesmimcap.ctp file for you. Please select Load button. Select the .ie3dsamplesmimcap.ctp file. MGRID will load the .ctp file and use the information in the .ctp file to define the Basic Parameters and the Layer Information dialog (see
28、 Figure 6.3). All the layers are placed at the supposed z-coordinates they should be on. The Basic Parameters are also defined. If you choose the Basic Parameters button, it will show you the GaAs substrate configuration. In case you have to manually enter the import option parameters, after you def
29、ine all the data, you can select the Save button to save the defined data into an Import Template File (.ctp). You can use the .ctp file for future importing of similar structures without going through the same procedure. In fact, we are doing so using the mimcap.ctp file here now.Figure 6.3 The imp
30、ort Data Options dialog after the template file is loaded.Step 4 Please un-check the Merge Polygons option. If you check it, it will try to merge the imported polygons if they are connected. For this case, we would like not to do so. Select OK to continue. MGRID will import the structure with all the Basic Param
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