clex20.in : Simulating Micro-Loading Effects using Advanced Etching
Requires: CLEVER
Micro-loading etching effects describe the phenomenon whereby the effective material etch rate depends on the hole size of the pattern masking layer.
This can be simulated using the advanced etching module in Victory Process. Once the structure is created, it is loaded into Clever to simulate back end parasitics.
The etch machine characteristics are described by the Fux, Topography and EtchDepoProperties statements. Once the etch machine has been described, the wafer is loaded into this virtual etch machine and is etched for 4 minutes. The created trench structures are then filled with aluminum.
For ease of observation of the micro-loading effects, a 2D cut line of the 3D structure is created and plotted, where it can be clearly seen that the depth of each trench is dependent on the width of the trench.
To load and run this example, select the Load button in DeckBuild > Examples. This will copy the input file and any support files to your current working directory. Select the Run button in DeckBuild to execute the example.
Input Deck
go victoryprocess
Init material=silicon depth=1 layout=clex20.lay gasheight=5 \
resolution=0.05 meshdepth=1
####################
# Create variables #
####################
set sigma=40
set iso=0
set metal1_thick=0.565
###########################
# The process description #
###########################
Deposit MAX material=PMD thickness=1.5
Deposit MAX material=nitride thickness=$metal1_thick
Etch DRY material=nitride thickness=$metal1_thick mask=metal reverse
####################################
# Describe Etch Machine Properties #
####################################
Flux name=clever_flux \
pri_c_function="vonmises" \
pridep=theta \
pripar=$sigma
Topography name=cleveretchmodel flux=clever_flux reaction=fluxdependent
EtchDepoProperties name=clever_rates \
material=silicon rate=0.38 \
material=PMD rate=0.38
#####################################################################
# Put Wafer into Etch Machine Described Above and Run for 4 Minutes #
#####################################################################
Etch model=cleveretchmodel materialproperties=clever_rates time=4
###################################
# Fill Etched Holes with Aluminum #
###################################
deposit material=aluminum thickness=-$metal1_thick max
electrodes mask=metal material=aluminum
save name=clex20_0
#########################
# Create Structure Mesh #
#########################
go victorymesh
load in=clex20_0
remesh delaunay
refine max.size=0.25 regions="Si3N4"
refine max.size=0.5 regions="aluminum"
refine regions="aluminum,pmd" interface.regions="pmd" other.interface.regions="aluminum" grading="quadratic" max.interface.size=0.2
save out=clex20_3D.str
############################################################
# Now Extract Capacitance Network of the Three Metal Lines #
############################################################
go clever
init structure="clex20_3D.str"
material silicon permittivity=11.8
material nitride permittivity=8
material material("PMD") permittivity=4
Interconnect Capacitance AdaptC=0.01
Save Spice="clex20.net"
##############################################
# Make a Cut Line to View a 2D Cross Section #
##############################################
Cut line=(1, 7, 6.75, 7)
save structure="clex20_2D.str"
tonyplot clex20_2D.str -set clex20.set