EEC 116 - Special Nanometer-Scale Rules


1. Polysilicon width (MOSFET channel length)

Polysilicon width may be only 2 λ unless stated otherwise, or as necessary with polysilicon contacts and vias.

2. Polysilicon 100 λ length limit

Polysilicon wires may not be longer than 100 λ beyond the point where a metal wire (coming from the driver) transitions to a polysilicon wire. The rule must be satisfied for the path from the source driver to every destination in the metal/poly network.

                                      100λ max
                            |<--------------------------->|
     
                                        (poly)
                            X*****************************<Destination
                            |
      Driver>---------------X**********X------------------<Destination
                   (metal)      (poly)       (metal)    
                              

3. nwells and pwells

Draw nwells around all PMOS transistors and pwells around all NMOS transistors and connect them to Gnd or Vdd as appropriate.

Place at least one nwell/psubstrate contact for every 3 squares of nwell/pwell.

4. Polysilicon, Deep Sub-micron

  1. Polysilicon may be oriented in only one direction for the entire chip.

  2. Polysilicon spacing may be only
        a) 8 λ, or
        b) greater than 16 λ
    unless stated otherwise.

  3. All polysilicon that is used for a functional circuit must have other polysilicon at a distance of 8 λ the entire length of both of its long edges. This implies the need for "dummy" poly in some cases. See Fig. 1.

  4. Exceptions:



Figure 1. Example polysilicon structures which satisfy traditional MOSIS rules (top row), and functionally identical ones which satisfy the new "nanometer scale" rules (bottom row).




Todo list:

Updates:
2010/11/22         Posted
2010/11/23         Added nwell/pwell rules
2010/11/24, 0400   Corrected rule 3.4 to 16 lambda, not 12 lambda
2013/10/14         Added detail to ascii figure for polysilicon rule
2013/11/21         Added examples of exceptions to rule #2 in Figure 1,
                   and minor tweaks to polysilicon ascii figure
2014/10/23         Moved poly width to rule #2, plus other reorganization
2014/11/04         Fixed typo: 4.4 should have been 4.3