Add tap cell not support add to a specified area. As a wrok around, we can block all other area except the blockage.

The following script is used to create reverse hard blockages.

proc remove_reverse_hard_blockage { } {
  remove_placement_blockage tap_blockage_*
}
 
proc add_reverse_hard_blockage { llx lly rtx rty } {
  set core_bbox [ get_attribute [get_core_area] bbox ]
  set core_llx [ lindex $core_bbox 0 0 ]
  set core_lly [ lindex $core_bbox 0 1 ]
  set core_rtx [ lindex $core_bbox 1 0 ]
  set core_rty [ lindex $core_bbox 1 1 ]
  create_placement_blockage \
    -type hard \
    -name tap_blockage_l  \
    -bbox "$core_llx $core_lly $llx $core_rty"
 
  create_placement_blockage \
    -type hard \
    -name tap_blockage_b  \
    -bbox "$core_llx $core_lly $core_rtx $lly"
 
  create_placement_blockage \
    -type hard \
    -name tap_blockage_r  \
    -bbox "$rtx $core_lly $core_rtx $core_rty"
 
  create_placement_blockage \
    -type hard \
    -name tap_blockage_t  \
    -bbox "$core_llx $rty $core_rtx $core_rty"
}