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SEMI E129-1103 © SEMI 2003 16 Euzent, B.L., Maloney, T.J., Donner II, J.C., “Reducing Field Failure Rate with Improved EOS/ESD Design”, Proceedings of the EOS/ESD Sym posium, Las Vegas, NV (1991) , pp. 59-64. Pierce, D.G…
SEMI E129-1103 © SEMI 2003 15
of roughly 10:1 between the two models, other
companies have seen anywhere from 5–20:1 differences
in passing voltages between the two models. There is
also no established voltage correlation between CDM
damage and HBM or MM ESD events. In equipment,
ESD damage events will be related to the MM or CDM
types of ESD. Users will need to determine the type of
ESD hazard to their devices and choose the test method
accordingly.
R1-2 ESD Laboratory Simulation Testing
R1-2.1 Description of Test Methods — Test procedures
discussed here for ESD simulation conform to those
established by the ESD STM5.1, ANSI ESD STM5.2,
ANSI ESD STM5.3.1 and MIL-STD 883 Method
3015.7. Details are to be found in these standards.
Devices are qualified at a level corresponding to the
highest ESD stress they are able to withstand.
R1-2.2 Simulation Test Results — In general all units
must be data-logged both pre- and post-stress test. Any
leakage current equal to or greater than a specific
amount (company dependent—typically 10 µA or less)
is “flagged” as a failure, and any current shift greater
than about 200 nA is marked on the record.
R1-2.3 HBM Stress Testing — A resistance-
capacitance (R-C) network is used to simulate the ESD
event. In an HBM ESD Simulator, a high voltage is
used to charge the capacitor (100 pF) which discharges
through the resistor (1500 Ω) into the device under test.
The present standard test method requires a minimum
of 2 discharges (i.e., 1 positive and 1 negative) per
voltage level.
R1-2.4 MM Stress Testing — An R-C network is also
used in the MM ESD Simulator for ESD testing. High
voltage charges the capacitor (200 pF) which
discharges through the short wire (~0 Ω) into the device
under test. The present standard requires a minimum of
6 discharges (i.e., 3 positive and 3 negative).
R1-2.5 CDM Stress Testing — The package and lead
frame of the device are charged by direct charging or
field induction.
R1-2.5.1 For the Direct Charging Method, direct
contact is made to one of the device leads connected to
the substrate or bulk material of the device. The device
is then discharged via a 1-ohm resistor to ground.
R1-2.5.2 For the Field Induced Method, the device is
placed on a metallic charging plate with the device
packaging material touching the plate. Applying a
voltage to the charging plate raises the potential of the
device. The induced voltage on the device is
discharged to ground through a 1-ohm resistor that
contacts each device lead. The present standard
requires a minimum of 6 discharges (i.e., 3 positive and
3 negative) from each device lead.
R1-3 References
R1-3.1 ESD Association Standards and Advisories
ANSI ESD STM5.2 — Electrostatic Discharge
Sensitivity Testing
– Machine Model
ANSI ESD STM5.3.1 — Charged Device Model
(CDM) – Component Level
ESD ADV11.2 — Triboelectric Charge Accumulation
Testing
ESD S6.1 — Grounding - Recommended Practices
ESD STM5.1 — Electrostatic Discharge Sensitivity
Testing – Human Body Model
ESD TR11-01 — Electrostatic Guidelines and
Considerations for Cleanrooms and Clean
Manufacturing
R1-3.2 JEDEC Documents
JESD22-A114 — Electrostatic Discharge (ESD)
Sensitivity Testing Human Body Model (HBM)
JESD22-C101 — Field-Induced Charged-Device
Model Test Methods for Electrostatic Discharge
Withstand Thresholds of Microelectronic Components
JESD625 — Requirements for Handling Electrostatic-
Discharge-Sensitive (ESDS) Devices
R1-3.3 Other Documents
ANSI IEEE STD 142 — IEEE Recommended Practice
for Grounding of Industrial and Commercial Power
Systems
ANSI/NFPA 70 — National Electrical Code
MIL-STD 883 — Test Method Standard Microcircuits
(Method 3015.7
– Electrostatic Discharge Sensitivity
Classification), Defense Supply Center Columbus, P.O.
Box 3990, Columbus, OH 43216-5000, USA
(
www.dscc.dla.mil)
Avery, L.R., “ESD Protection Structures to Survive the
Charged Device Model (CDM)”, Proceedings of the
EOS/ESD Symposium, Orlando, FL (1987), pp. 186-
191.
Avery, L.R., “Charged Device Model Testing: Trying
to Duplicate Reality”, Proceedings of the EOS/ESD
Symposium, Orlando, FL (1987), pp. 88-92.
Cook, C., Daniel, S., “Characterization and Failure
Analysis of Advanced CMOS Sub-Micron ESD
Protection Structures”, Proceedings of the EOS/ESD
Symposium, Dallas, TX (1992), pp. 149-157.
SEMI E129-1103 © SEMI 2003 16
Euzent, B.L., Maloney, T.J., Donner II, J.C., “Reducing
Field Failure Rate with Improved EOS/ESD Design”,
Proceedings of the EOS/ESD Symposium, Las Vegas,
NV (1991), pp. 59-64.
Pierce, D.G., Shiley, W., Mulcahy, B., Wunder, M.,
“Electrical Overstress Testing of a 256K UVEPROM to
Rectangular and Double Exponential Pulses”,
Proceedings of the EOS/ESD Symposium, Anaheim,
CA (1988), pp. 137-146.
Renninger, R.G., Jon, M.C., Lin, D.L., Diep, T.,
Welsher, T.L., “ A Field-Induced Charged-Device
Model Simulator”, Proceedings of the EOS/ESD
Symposium, New Orleans, LA (1989), pp. 59-71.
NOTICE: Unless otherwise indicated, all documents
cited shall be the latest published versions.
R1-4 Acknowledgement
Contributed by Leo G. Henry, Ph.D., email:
leogesd@pacbell.
SEMI E129-1103 © SEMI 2003 17
RELATED INFORMATION 2
STATIC CONTROL METHODS
NOTICE: The material contained in this related information is not an official part of SEMI E129 and is not
intended to modify or supersede the guide in any way. These notes are provided as a source of information to aid in
the application of the guide, and are to be considered reference material. Determination of the suitability of the
material is solely the responsibility of the user. This related information was approved by full letter ballot
procedures on September 3, 2003.
R2-1 Static Charge Control
R2-1.1 It is usually impossible to eliminate static
electricity from work areas, but with proper use of
equipment and remedial procedures, most static
problems can be controlled. Many approaches to
controlling static charge have been tried over the years
and it is clear that there exists no single method for
controlling all static charge problems. However, it has
been shown that a consistently applied process for static
charge control greatly reduces problems associated with
static electricity.
R2-1.2 One overriding issue should not be forgotten in
the choice of static control materials and procedures.
This is the need for compatibility with the cleanliness
requirements of the area in which they are installed. A
variety of static control materials are available, but
some may not be cleanroom compatible due to issues of
particle shedding, outgassing, or their chemical
makeup. Each manufacturing area in the
semiconductor factory should contain only those static
control materials that are appropriate to the cleanliness
requirements of the area. Consult ESD TR11 for
additional information.
R2-2 Charge Generation
R2-2.1 Triboelectric Charging
R2-2.1.1 A fundamental law of nature states that an
electrostatic charge is generated whenever two
dissimilar materials contact and then separate. The
materials themselves, intimacy of contact, speed of
separation and a variety of other factors determine the
amount or level of electrostatic charge that is generated
during any given contact and separation event.
Predicting the level of charge ahead of time is nearly
impossible. Due to this unpredictability, the best that
can be done in a factory setting is to understand that
electrostatic charge generation will always occur.
However, electrostatic charge generation can be
measured and charge mitigation is normally a
possibility. Reducing charge generation requires
modification of surfaces to increase lubricity (i.e.,
reduce friction), increase conductivity (i.e., allows
charges to relax and flow back), and make the surfaces
chemically similar. Normally, more than one of the
above actions is required to provide a low charge-
generating system.
R2-2.1.2 While no intrinsic test method exists for the
determination of triboelectric charge-generation
properties, several practical evaluation techniques that
apply to many factory situations may be found in ESD
ADV 11.2.
R2-2.2 Effect of Humidity on Charge Generation
R2-2.2.1 It is generally understood that at constant
temperature and at increased relative humidity the
normally observed manifestations of static charge
generation, such as static cling and static shocks, are
greatly reduced. This does not mean that static charge
is not present in the environment. Even at 90% RH,
static charge may accumulate at a sufficient level to
cause problems with some processes or cause damage
to sensitive parts. Most factory processes, including
cleanrooms, are run at a humidity level of 30–70%.
Within this range, most of the humidity-dependant low-
charging materials will function within their intended
specifications. At lower humidity, surfaces dry out and
may become a source of charge generation.
R2-2.2.2 Specifying a humidity level for a factory is a
reasonably good idea if kept realistic. However,
maintaining a minimal level of humidity may be very
expensive in some areas of the world during normally
dry winter months. It could be more important and cost
effective to choose materials that provide the required
function for charge generation or dissipation at the
lowest expected humidity. Many parts of the world
experience humidity levels of 10% or less during the
winter months when outside air is brought inside and
then heated to warm interior spaces. In these locations,
which include the northern tier of US states and
Canada, much of northern Asia, as well as northern
Europe, careful attention to material selection is of
major importance to assure adequate dissipative and
low charge-generation performance.
R2-3 Grounding Conductors and Static
Dissipative Materials
R2-3.1 The primary method of controlling static charge
is grounding. If there is a path for the charge to flow to
earth ground, the static charge on facility surfaces,