Antenna effect solution

1 Definition of antenna effect

Ion etching and ion implantation processes generate free charges , Conductors such as metal wires or polysilicon in the chip , It's like an antenna , Collect free charge , The longer the antenna, the more charge is collected , When there is enough charge, it will discharge , Possible breakdown of gate oxide , Disable the circuit . This phenomenon is called antenna effect （PAE,process antenna effect）.

commonly Psub and Nwell It is necessary to connect the power supply to the ground , If the wire is connected with Psub or Nwell There is a path between （ insert antenna cell Or connect to the source / Leaky end , Because the on voltage is lower than Gate Breakdown voltage ）, Then the charge passes Psub and Nwell Release will have no effect .

Usually , We use it “ Antenna ratio ”（“antenna ratio”） To measure the antenna effect of a chip Probability of response .“ Antenna ratio ” Is defined as ： Constitute the so-called “ The antenna ” The conductor of （ Usually metal ） The area of is related to The ratio of the area of the connected gate oxide .

2 resolvent

The methods to solve the antenna effect can be divided into jumper method （ Up jumper and down jumper ） And plug-in diode （antenna cell）.

2.1 Jumper method （ Up jumper ）

As shown in Figure 1, the circuit , Blue metal is metal1, Pink is metal2, The chip production process is layer by layer up , First Gate,(source/drain) Source leakage , then metal1,metal2. So in metal2 Before it was made, it was connected Gate Of metal1 Too long produces antenna effect .

chart 1 

Using the upward jumper method to solve this problem only needs to be in Gate End jumper to metal2 that will do , Pictured 2. Is producing metal1 Connect when Gate Of metal1 It is very short and will not cause antenna effect problems , produce metal2 The charge is released from the drain .

chart 2

2.2 Jumper method （ Downward jumper ）

Suppose the graph 3 in , Connect Gate Terminal metal1 Too long produces antenna effect , At this time, select the upward jumper method , Jump to the metal3（ Pictured 4） To solve the problem （ Because jump to only metal2 Or because it is connected to Gate The long metal wire of leads to antenna effect )

chart 3

chart 4

At this time, you can also use the downward jumper method , Put the leaky end metal3 Jump to the metal2, Pictured 5.

chart 5

In conclusion , Using the upward jumper method ,source/drain Pick up Mn layer , that Gate You need to answer Mn even to the extent that Mn+1 layer . If the downward jumper method is used ,Gate Pick up Mn layer , Then the source and drain terminals need to be connected Mn even to the extent that Mn-1 layer .

2.3 Plug in the diode

Diodes can be inserted on the metal layer that produces the antenna effect , The charge is released by the diode . Pictured 3 Shown .

chart 3

3 Apply command

3.1 ICC2 Order to repair the antenna effect

## detail route Automatic jumper and plug antenna cell Set up 
set_app_options -name route.detail.insert_diode_during_routing -value true
set_app_options -name route.diode_libcell_names -value XXX
set_app_options -name route.detail_antenna -value true
set_app_options -name route.detail.hop_layers_to_fix_antenna -value true

create_diodes -options {$port_name $block/instance_name\
 $diode_name $num_of_diodes $max_routing_layer $max_routing_distance}

among max_routing_distance refer to diode pin distance antenna violation pin The maximum distance . Note here that if you specify antenna The type tool still prompts that no available antena cell type , Probably antenna cell Of “is_diode_cell” The attribute is false, The fundamental way to solve this problem is to modify lef In file CLASS Change the type to ：

CLASS CORE ANTENNACELL ;

3.2 Innovus Order to repair the antenna effect

## detail route Automatic jumper and plug antenna Set up 
setNanoRouteMode -drouteFixAntenna true \
-route antenna cell name XXX \
-routeInsertAntennaDiode true

##  Manually insert antenna cell Methods 
attachDiode -diodeCell XX  -pin $pin_name $instance_name -loc {xx xx}