What are the EM model-supported formats and in which order are they honored by Voltus?
1. Text-based EM model
When -process_techgen_em_rules false and -em_models are used together, the tool uses EM rules from the EM-based text file only.
2. ICT-EM file
When -process_techgen_em_rules is set to 'true', the tool uses EM rules are picked in the following priority:
- ICT-EM file provided using -ict_em_models ICTEM.txt
- qrcTechFile provided using -extraction_tech_file qrcTechFile
- qrcTechFile from Tech PGV provided using -power_grid_library
EM Modeling using QRC Technology File
In addition to the set_rail_analysis_config -em_models file command parameter,
you can use the QRC Techfile for EM model specification.
The set_rail_analysis_config -process_techgen_em_rules true parameter
specifies to process the EM models in the ICT section of the qrcTechFile.
Important
The -process_techgen_em_rules and -em_models parameters of the
set_rail_analysis_config command are mutually exclusive. If none of these
parameters are specified, rj analysis will not be performed.
when -process_techgen_em_rules is specified with -extraction_tech_file, the
extraction technology file will be processed.f -process_techgen_em_rules is
specified without -extraction_tech_file, the .cl model will be processed.
set_rail_analysis_mode \
-method static \
-em_models textEM_model.txt \
-process_techgen_em_rules true \
-ict_em_models ICTEM.txt \
-extraction_tech_file qrcTechFile \
-power_grid_library \
{tech.cl cells.cl} \
-em_temperature 125 \
-em_threshold 0.8
1. Text-based EM model
When '-process_techgen_em_rules false' and '-em_models' are used together, the tool uses EM rules from the EM-based text file only.
2. ICT-EM file
When '-process_techgen_em_rules is set to 'true', the tool uses EM rules are picked in the following priority:
1. ICT-EM file provided using -ict_em_models ICTEM.txt
2. qrcTechFile provided using -extraction_tech_file qrcTechFile
3. qrcTechFile from Tech PGV provided using -power_grid_library
Note: When '-process_techgen_em_rules is set to 'false'(default)and the '-em_models' option is also not used, EM analysis will be disabled.
Terminologies used in the calculation.
Current_density_terminology.png
Example:
Current : 6.327329e-03mA. (Tool calculated)
Current density(J): = I/Metal area
= I/(width*thickness)
= 6.327329e-03mA / (0.18um*0.15um)
= 6.327329e-03mA / (0.18e-04cm * 0.15e-04cm)
= 2.343455e+04 (A/cm2)
Max current density (Jmax) from file, = max current density *Jmax_factor
= 8e+05*1
= 8e+05 (A/cm2)
Max current (Ilimit) = Jmax * metal area = 8e+05 (A/cm2) * (0.18um*0.15um)
= 2.16e-01mA
I/Ilimit = 6.327329e-03mA / 2.16e-01mA
= 0.0292932
Note: J/Jmax = I/Ilimit.
Current density(J) / Max current density (Jmax) = 2.343455e+04 (A/cm2)/8e+05 (A/cm2) = 0.0292932
Understanding and validating Power EM report generated using "analyze_rail" command
./era_run_no_scale/vdd_d_25C_avg_1/Reports/vdd_d/vdd_d.rj.avg.rpt
The /Reports//.rj.avg.rpt report captures the related parameters used to check the reliability of metal/via on Power network.
# The current or EM limit at via layer is reported as the value per cut for a via cluster
# EM Reporting Threshold: 0.9
# Total Violations: 223
#
# Report format:
# Short (Blech) Length with N/A indicates a loop in layout, and benefit factor would be 1.0.
# I/Ilimit I(mA) Ilimit(mA) Layer Location ShortLength Width ViaArea Via Fix Width/ Current Benefit J(A/cm^2) Jmax(A/cm^2) ResistorID
# {X1 Y1 X2 Y2} (um) (um) (nm^2) Cuts Via Direction Factor
#
2.97901 5.958016e+00 2.000000e+00 MET4 {6153.6200 890.6800 6153.6200 896.6300} N/A 2 N/A N/A 5.95802 N/A 1.00 2.979008e+05 1.000000e+05 141466
I(mA) :
This current value (4.708982e-02)that flows through the Metal/Via resistor is calculated by the tool.
Ilimit (mA):
This is the current limit(2.992880e-02)whose value is provided by the foundry depending upon its width and thickness.
1. For Metal layers Ilimit calculation:
If the -ict_em_models option is used, refer to the article #20466998.
If the -em_models is used, refer to the article #20467159.
2. For Via layer Ilimit calculation:
If the -ict_em_models option is used, refer to the article #20466988.
If the-em_models option is used, refer to the article #11141402.
Current Direction:
Current Direction is applicable only to via layers where 'D" denotes down, "U" denotes up.