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SEMI E78-1102 © SEMI 1998, 2002 8 JESD22-C101A — Field-Indu ced Charged-Device Model Test Met hod for Electrostat ic Discharge Withstand Thr esholds of Microelectronic C omponents 16.2 Other Docume nts EN 50082 — Generic…

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SEMI E78-1102 © SEMI 1998, 2002 7
additional information to select an appropriate
sensitivity level to reduce ESD-related equipment
interruptions.
12.4.2 Compliance with the desired Sensitivity Level
may be demonstrated using the Faraday Cup method
described in Sections 6.4 and 7.3.
12.4.3 Measurements should be made on products,
carriers, and materials in the equipment input/exit ports
after significant amounts of product have been handled
under normal manufacturing conditions. Measurements
should be made of products and their carriers after they
have undergone normal processing in the equipment
under test. Typically, five measurements of products
and/or carriers should be sufficient to demonstrate
compliance with the selected Sensitivity Level.
12.5 Equipment used in semiconductor manufacturing
should meet the following levels shown in Table 1 for
protection from problems caused by static charge.
Table 1 Recommended Sensitivity Levels
Electrostatic
Discharge
(Nanocoulombs)
Particle
Attraction
(Volts/cm)
Equipment
Malfunction
(Nanocoulombs)
Level 4 100 4000 1200
Level 3 50 400 600
Level 2 10 200 300
Level 1 1 100 150
12.5.1 Sensitivity Level 4 compliance means that
products, reticles, and carriers can leave the equipment
with up to the recommended amounts of static charge
or electrostatic field measured on them according to the
test method used. This level essentially states that the
equipment is used in a process that has no significant
problems handling charged product, nor are there issues
associated with contamination or ESD damage.
12.5.2 At levels 1, 2, or 3 a decision should be made as
to what is the most serious static charge problem. The
Sensitivity Level and test methods are chosen
accordingly. The lower the level of static charge
allowed, the more static control measures the
equipment manufacturer may need to install.
12.5.3 Level 1 may be used primarily by manufacturers
of specialized components such as: gallium arsenide
semiconductors or magneto-resistive (MR) disk drive
read heads; those experiencing significant losses due to
contamination; or those using specialized equipment
with low immunity to ESD or EMI.
12.6 The levels listed in Table 1 have been determined
as the result of analysis of working conditions, or
experiments done in operating semiconductor facilities.
Justifications for these levels are found in Appendix 1.
The actual levels to be used for any piece of production
equipment may be decided by agreement between the
user and manufacturer of the equipment.
12.7 Other levels may be appropriate under specific
equipment conditions and for specific devices.
13 Calculations
13.1 A series of five measurements should be made.
The average of the five measurements should not
exceed the recommended level.
14 Reporting Results
14.1 Data records should contain the following
information:
• Description of equipment under test including
model and serial numbers.
• Description of the equipment operating conditions
and environment.
• Measurement equipment and last calibration date.
• Description of objects measured and measurement
locations.
• Humidity and temperature at measurement location
when measurements were made.
• Results of measurements.
• Personnel making the measurements.
• Any other relevant comments.
15 Precision and Accuracy
15.1 Accuracy of Test Methods — The test methods
referenced in this document do not guarantee precise
measurements of static charge levels. Similarly,
maximum static charge levels recommended in this
document are not stated as precise requirements.
Accuracy of approximately ± 20% is acceptable in all
measuring instrumentation. At low static charge levels
or for more accurate measurements, alternative
instrumentation and test methods may need to be used.
16 Related Documents
16.1 EIA/JEDEC Standards
EIA/JESD22-A114 — Electrostatic Discharge (ESD)
Sensitivity Testing Human Body Model (HBM)
EIA/JESD22-A115 — Electrostatic Discharge (ESD)
Sensitivity Testing Machine Model (MM)
SEMI E78-1102 © SEMI 1998, 2002 8
JESD22-C101A — Field-Induced Charged-Device
Model Test Method for Electrostatic Discharge
Withstand Thresholds of Microelectronic Components
16.2 Other Documents
EN 50082 — Generic Immunity Standard for CE
Compliance, CENELEC European Union
BS EN 61000-6-2 — Electromagnetic compatibility
(EMC) - Generic standards - Immunity for industrial
environments - British Standards Institution (BSI).
3
MIL-STD 883C — Notice 8 – Method 3015.7 –
Electrostatic Discharge Sensitivity Classification
3 BSI, 389 Chiswick High Road, GB - LONDON W4 4AL
SEMI E78-1102 © SEMI 1998, 2002 9
APPENDIX 1
DETERMINING STATIC SENSITIVITY LEVELS
NOTE: This appendix was approved as an official part of SEMI E78 by full letter ballot procedure. This appendix offers
information related to the Sensitivity Levels contained in Section 12.5.
A1-1 Recommended Levels
A1-1.1 The recommended charge and electrostatic
field levels in this guide are not based on specific
protection thresholds for individual devices or process
tools. Rather, their aim is to classify the types of ESD
events or static levels that are likely to be of concern.
Tool manufacturers and users should determine the type
of events that are of most concern to their products and
process, so as to apply this guide to their needs.
Information on specific device damage thresholds and
tool sensitivities is best determined on an individual
basis.
A1-2 Justification of Guide Recommendations
in Section 12.5 and Table 1
A1-2.1 Recommendations for ESD Damage
A1-2.1.1 Related Information R1-1 discusses test
methods for determining ESD damage thresholds for
semiconductor devices. Devices are qualified according
to the highest ESD stresses they can withstand without
measurable change in their operating parameters. This
section attempts to develop guide recommendations for
minimizing ESD damage based on that discussion.
A1-2.1.2 Industry Device Damage Levels — Each of
the test methods, HBM, MM, and CDM have a set of
qualification levels defined. These are contained below.
HBM Classification Levels
Class Voltage
0 < 250
1A 250–499
1B 500–999
1C 1000–1999
2 2000–3999
3A 4000–7999
3B ≥ 8000
MM Classification Levels
Class Voltage
M1 < 100
M2 100–199
M3 200–399
M4 ≥ 400
CDM Classification Levels
Class Voltage
C1 < 125
C2 125–249
C3 250–499
C4 500–999
C5 1000–1499
C6 1500–1999
C7 ≥ 2000
A1-2.1.3 Charge Levels for ESD Damage — As
discussed in Related Information R1-1.4, ESD
Simulator testing uses different capacitances for each
model. For HBM it is 100 picofarads, for MM it is 200
picofarads, and for CDM it depends on the capacitance
of the actual device being tested. In any case, it is
charge (charge = voltage × capacitance) that damages
the device. It would seem appropriate, therefore, that
the guide recommendations in Table 1 Section 12.5 be
stated in units of charges (e.g. nanocoulombs).
A1-2.1.4 Guide Recommendations — Based on
industry testing reflected in device data sheets, there
appears to be a wide range for ESD immunity in
semiconductor devices. This document deals primarily
with ESD occurring within equipment. HBM type ESD
discharges are the least likely to occur within
equipment. Charged equipment parts contacting devices
(MM) and charged devices contacting machine parts
(CDM) are the most likely causes of ESD damage to
devices in equipment. The following sensitivity levels
are defined with respect to the existing industry MM
and CDM classifications.
A1-2.1.4.1 Level 4 — Devices are essentially
unaffected by any reasonable level of ESD encountered
in equipment. Devices pass testing at levels higher than
MM Class M4 (400 volts × 200 picofarads = 80
nanocoulombs). Equipment should not create or store
charge on itself or on devices in excess of the guide
recommendation. Guide recommendation (table 1 in
Section 12.5) – 100 nanocoulombs.
A1-2.1.4.2 Level 3 — Devices are affected by
moderate levels of static charge in equipment. Devices
pass testing for MM Class M4 (400 V × 200 picofarads
= 80 nanocoulombs) and most of MM Class M3 (over
250 volts × 200 picofarads = 50 nanocoulombs). Guide