Chapter 7 IC Station

7.1 Creating a cell
7.2 Placement and routing
7.3 Design rule checking (DRC)
7.4 LVS checking

7.1 Creating a cell

Invoke ICStation typing the command

# adk_ic In the session palette click on create, to create a new layout; open option is used to view existing layouts.

Fill the appeared dialog box as follows

cell name : mycounter
library, process: use the corresponding files inside $ADK/technology/ic/ami05
rules : ami05.rules in the above directory

Click with connectivity and EDDM as source type

Using the navigator choose the layout viewpoint inside mycounter.

EDDM Schematic Viewpoit: $MGC_WD/mycounter/layout

Also in logic loading options change logic loading type to "Flat". This is not important in our design, but in large hierarchical designs determining the correct type may be very important.

7.2 Placement and routing

When blank screen is loaded, click on Place & Route in the IC Palettes. This will bring you the Place & Route palette menu.

In the Place & Route menu:

Click Autofp and then just click OK to the appeared dialog box. IC Station automatically places the floorplan shapes. Now, you should see green lines on the screen.

Next thing to do is to place the standard cells (the components used from the AMI library) onto the floorplan. Click StdCel menu item, under Autoplc. Accept the coming dialog box as is.

Now you should see all you standard cells placed, with yellow lines in between. The yellow lines denote the overflows; unconnected nets.

The last step of placement is to place our ports. Click on Ports and then press OK in the dialog box, to let IC Station automatically place them.

When placement is complete, the overflows should be routed; that is, the unconnected nets should be connected using metal connectors. There are two metal layers in IC Station, metal1 and metal2. You can pass from one layer to another using a via.

Let's go back to our job. Click on All under Autorou. Accept the coming dialog box, as we always do. You should see metal paths instead of overflows now.

IC Station tries to route all overflows, but sometimes it fails to route a few. You must find out if there is any. Note that you must search for unrouted overflows even if you don't see any; they may not be visible in large designs. Follow the procedure below.

Open the Setup Select Filter dialog box from Setup>Select Filter and choose only overflow in the select filter.

In the layout window firstly do "unselect all" and then "select all". If "nothing new selected" message appears in the Message Area, there are no overflows left. Otherwise, there are some. Find them and try to route with the OvrFlw command in the place&route palette. If it fails you have to route the overflows manually.

After routing is completed open the Setup Select Filter dialog box again and fill the select filter.

You can also decrease the area and via count of your chip by using Compct and MinVia commands under PR Edit.

The layout is shown below.

7.3 Design rule checking (DRC)

We have technology specific design rules, such as; metal or via widths, spacing between objects, etc. The design rules must be obeyed if you want a working IC. To see if our design passes DRC do the following

Click on ICrules in the IC Palettes menu to go to ICrules palette.

Click Check and then accept the appeared dialog box. DRC results are displayed in the Message Area. "Total Results" shows the number of errors.

Click First under Set Scan To, the type of error is displayed in the Message Area. Use View to zoom to the error location and Next to see the next error. You must correct every error.

Repeat this check until you see "Total Results" is zero.

7.4 LVS Checking

LVS (Layout Versus Schematic) checks the correspondence of the layout to the schematic.

Click ICtrace(M) in the IC Palettes menu. In the ICtrace(M) menu click LVS.

Specify source name as the lvs viewpoint inside mycounter.

Click on the Setup LVS button. In the Setup LVS form do the following changes and click OK.

Ground Names : VSS GND

Recognize Gates : Yes

After the check is completed, use Report >LVS to view the results. If there are no errors you should see a tick and a smiling face in the report file. Fix any errors before going to the next chapter.