semi合集-English.pdf - 第989页

SEMI E129-1103 © SEMI 2003 27 measurements it is important to use an antenna with a flat frequency response since frequency correction that is comm on in the freque ncy domain is not po ssible for time domai n measuremen…

100%1 / 7923
SEMI E129-1103 © SEMI 2003 26
R3-2.6 The following categories of EMI are
recommended for consideration in setting limits:
• Continuous radiated emission
• Continuous conducted emission
• Transient radiated emission
• Transient conducted emission
• EMI levels on the ground and on the power lines
It is anticipated that FCC and CE regulations would be
considered as one of the factors in setting the limits, but
surveys of the actual environment in the factory will
also need to be considered.
R3-3 EMI Effect on Equipment
R3-3.1 There are three main ways EMI can affect
equipment:
R3-3.1.1 Destruction — The signals created by EMI in
the circuit exceed the breakdown threshold of
components, which leads to their destruction. This is
especially relevant to conducted EMI.
R3-3.1.2 Malfunction — EMI injects pseudo-legitimate
signals into the circuit, which leads to that circuit’s
malfunction. Such malfunction may range from
complete lockup to unwanted operation of the tool.
This is frequently misdiagnosed as software errors.
Often, this type of malfunction involves several tools
connected together.
R3-3.1.3 False Sensor Readings — Signals induced by
EMI add to the signals coming from sensors and leads
equipment to misread sensor data.
R3-4 EMI Measurements
R3-4.1 Measuring EMI can be a very effective tool in
ESD management in the cleanroom, as EMI is a
signature that ESD events are occurring. The following
are some of the parameters and test methods that are
recommended to be checked during such audits.
R3-4.2 Radiated EMI Levels Near Equipment — Both
continuous and transient (peak) should be measured and
identified.
R3-4.3 Conducted EMI on Cables — Both continuous
and transient (peak). Due to practical considerations,
an acceptable method will have to be devised to
measure conducted EMI on hard-to-reach cables.
R3-4.4 Electromagnetic emissions generated by ESD
events have unique properties. These include:
• Very short rise time – as short as hundreds of
picoseconds,
• Very short duration – from a few nanoseconds to
several hundred nanoseconds,
• Very broad frequency range (up to several GHz),
and
• Often high magnitude.
There are several types of equipment available to detect
and measure electromagnetic fields from ESD events.
R3-4.5 AM Radio
R3-4.5.1 Since electromagnetic fields from ESD events
are manifested as short bursts of energy, they may be
detected by a conventional AM radio tuned to a
frequency free of radio stations. The radio produces
“clicks” when it detects ESD events. The AM radio has
difficulties picking up weak and very rapid discharges,
and in industrial environments it is likely to pick up
noise from normal equipment operation.
R3-4.6 EMI Locators
R3-4.6.1 Several types of EMI Locators are available,
including portable handheld types and larger
instruments. The simplest type provides both a visual
and audible indication of the transient EMI from an
ESD event. Although it can discriminate between two
sensitivity levels for EMI, it gives no information
regarding the magnitude of the ESD event that
produced the EMI. Their frequency response is also
limited to approximately 150 MHz and they may miss
the faster EMI signals.
R3-4.6.2 A second type of EMI Locator is a general-
purpose electromagnetic field strength meter with a
bandwidth (up to 2 GHz) to measure EMI from ESD
events. It has a directional antenna to help identify
sources of emission, and provides outputs for emission
levels and the counting of ESD events, including time
stamping. This can be very useful in correlating ESD
events with equipment malfunctions. Some units will
also provide discrimination of multiple ESD events and
provide output signals directly to a computer or factory
management system.
R3-4.7 High-Speed Storage Oscilloscopes
R3-4.7.1 An oscilloscope equipped with proper
antennae provides the most comprehensive information
about waveform and magnitude of EMI caused by ESD
events. The minimum requirements for an oscilloscope
used for this purpose are a 500-MHz bandwidth and a
5-gigasamples/s sampling rate. Instruments with lesser
performance specifications would either miss or
misinterpret EMI parameters.
R3-4.7.2 The use of a high-speed oscilloscope should
be accompanied by the use of a proper antenna for
receiving the electromagnetic fields. For time domain
SEMI E129-1103 © SEMI 2003 27
measurements it is important to use an antenna with a
flat frequency response since frequency correction that
is common in the frequency domain is not possible for
time domain measurements. Another important note is
that a typical oscilloscope captures only one event (i.e.,
first or last one, depending on trigger setting), missing
multiple events that are common.
R3-4.7.3 Spectrum analyzers common in EMC test and
wireless communication are not practical for detecting
EMI from ESD events due to their unacceptably low
acquisition speed.
R3-4.8 Below is comparison Table R3-1 of EMI/ESD
measurement instruments.
R3-5 EMI and Ground
R3-5.1 An essential component of EMI management is
a consideration of EMI in grounding. High impedance
to ground at high frequencies prevents EMI from being
dissipated. Long ground wires act as receiving
antennae that inject high-frequency signals into tools.
A common ground for several tools, with high
impedance to the rest of the grounding network,
facilitates propagation of EMI from one noisy tool to
another.
R3-6 Related Documents
R3-6.1 SEMI Standards
SEMI E33 — Specification for Semiconductor
Manufacturing Facility Electromagnetic Compatibility
R3-6.2 ANSI Documents
ANSI C63.13 — American National Standard Guide on
the Application and Evaluation of EMI Power-Line
Filters for Commercial Use.
(http://standards.ieee.org/reading/ieee/std_public/descri
ption/emc/C63.13-1991_desc.html)
ANSI C63.16 — American National Standard Guide
for Electrostatic Discharge Test Methodologies and
Criteria for Electronic Equipment.
http://standards.ieee.org/reading/ieee/std_public/descrip
tion/emc/C63.16-1993_desc.html
R3-6.3 EN / IEEE Documents
EN 61000-4-2 / IEC 61000-4-2 — Electromagnetic
compatibility (EMC) – Part 4: Testing and
measurement techniques. Section 2: Electrostatic
discharge immunity test (ESD).
EN 61000-4-3 / IEC 61000-4-3 (ENV 50140 & ENV
50204) — Electromagnetic compatibility (EMC) – Part
4: Testing and measurement techniques, Section 3:
Radiated, radio frequency, electromagnetic field
immunity test
EN 61000-4-4 / IEC 61000-4-4 — Electromagnetic
compatibility (EMC) – Part 4: Testing and
measurement techniques. Section 4: Electrical fast
transient / burst immunity test IEC 61000-4-4-am2 to
Ed. 1:2001
EN 61000-4-5 / IEC 61000-4-5 (ENV 50142) —
Electromagnetic compatibility (EMC) – Part 4: Testing
and measurement techniques. Section 5: Surge
immunity requirements
EN 61000-4-6/ IEC 61000-4-6 (ENV 50141) —
Electromagnetic compatibility (EMC) – Part 4-6:
Testing and measurement techniques - Immunity to
conducted disturbances, induced by radio-frequency
fields
EN 61000-6-2 — Electromagnetic compatibility (EMC)
– Part 6-2: Generic standards—Immunity for industrial
environments.
R3-6.4 IEEE Documents
IEEE 518 — IEEE Guide for the Installation of
Electrical Equipment to Minimize Electrical Noise
Inputs to Controllers from External Sources
(
http://standards.ieee.org/reading/ieee/std_public/descri
ption/emc/518-1982_desc.html)
Table R3-1 EMI/ESD Measuring Instruments
Instrument Ease-of-Use Cost Sensitivity Multiple
Discharges
Event
Magnitude
Event Count
AM Radio Easy $ Low No No No
EMI Locators Easy to Medium $$-$$$$ Medium to High Some High/Low to Full
Range
Some
High-Speed
Storage
Oscilloscope
Difficult $$$$$ High No Full Range Some
SEMI E129-1103 © SEMI 2003 28
R3-7 ACKNOWLEDGEMENT
Contributed by Vladimir Kraz, Credence Technologies,
3601-A Caldwell Drive, Soquel CA 95073,
vladimir@credencetech.com
NOTICE: SEMI makes no warranties or
representations as to the suitability of the standards set
forth herein for any particular application. The
determination of the suitability of the standard is solely
the responsibility of the user. Users are cautioned to
refer to manufacturer's instructions, product labels,
product data sheets, and other relevant literature,
respecting any materials or equipment mentioned
herein. These standards are subject to change without
notice.
By publication of this standard, Semiconductor
Equipment and Materials International (SEMI) takes no
position respecting the validity of any patent rights or
copyrights asserted in connection with any items
mentioned in this standard. Users of this standard are
expressly advised that determination of any such patent
rights or copyrights, and the risk of infringement of
such rights are entirely their own responsibility.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
f
the contents in whole or in part is forbidden without express written
consent of SEMI.