IEC TR 62258-3:2005

TECHNICAL IEC
REPORT TR 62258-3
First edition
2005-06
Semiconductor die products –
Part 3:
Recommendations for good practice
in handling, packing and storage

Reference number
IEC/TR 62258-3:2005(E)
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TECHNICAL IEC
REPORT TR 62258-3
First edition
2005-06
Semiconductor die products –
Part 3:
Recommendations for good practice
in handling, packing and storage

 IEC 2005  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale X

International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue

– 2 – TR 62258-3  IEC:2005(E)

CONTENTS
FOREWORD.4

INTRODUCTION.6

1 Scope and object.7

2 Normative references .7

3 Terms and definitions .8

4 Handling – Good practice .8
4.1 General .8
4.2 Working environmental controls.8
4.3 General handling precautions.8
4.4 Cleanroom good practice.8
5 Process handling issues .12
5.1 Wafer sawing .12
5.2 Die sorting.13
6 Die and wafer transport and storage media .16
6.1 Wafer carriers and cassettes .16
6.2 In-process carriers and transport systems .17
6.3 Packing for shipment of unsawn wafers.17
6.4 Packing for shipment of sawn wafers.18
6.5 Packing for shipment of single wafers .21
6.6 Packing for shipment of die using trays .21
6.7 Packing for shipment of die using tape-and-reel .25
6.8 Secondary packing for shipment.27
7 Storage good practice .28
7.1 Die and wafer storage .28
7.2 Short-term storage environment and conditions.28
7.3 Storage time limitations .28
7.4 Sawn wafer on wafer frame or ring .29
7.5 Die products in the production area .29
7.6 Die in tape-and-reel.29
7.7 Dry-packed die products.29

8 Traceability good practice.29
8.1 General .29
8.2 Wafer traceability .29
8.3 Die products traceability.29
8.4 Wafer and die back side marking.30
9 Guidelines for long-term storage (die banking) of bare die and wafers.30
9.1 General .30
9.2 Preparing for storage.30
9.3 Damage to die products during long-term storage .31
9.4 Long-term storage environment .31
9.5 Recommended inert atmosphere purity .32
9.6 Chemical contamination .32
9.7 Electrical effects.33

TR 62258-3  IEC:2005(E) – 3 –

9.8 Protection from radiation.33

9.9 Periodic qualification of stored die products .33

10 Good practice for automated handling during assembly .34

10.1 Removal of die from shipping media.34

10.2 Equipment out of service .34

Annex A (informative) Planning checklist .35

Annex B (informative) Material specifications.41

Bibliography .44

Figure 1 – Bevel cut for bare die and flip-chip products.12
Figure 2 – Die eject needle .15
Figure 3 – Wafer jar structure.18
Figure 4 – Film frame.19
Figure 5 – Grip ring.20
Figure 6 – Single waffle pack .22
Figure 7 – Stacked waffle packs.23
Figure 8 – Vacuum-release trays.24
Figure 9 – Corner relief in the cavity of a chip tray.25
Figure 10 – Tape-and-reel packing structure .27
Figure 11 – Packaging material for shipment .27

Table 1 – Example die eject marks.15
Table A.1 – Planning checklist .35

– 4 – TR 62258-3  IEC:2005(E)

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
SEMICONDUCTOR DIE PRODUCTS –
Part 3: Recommendations for good practice

in handling, packing and storage

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62258-3, which is a technical report, has been prepared by IEC technical committee 47:
Semiconductor devices.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
47/1794/DTR 47/1806/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

TR 62258-3  IEC:2005(E) – 5 –

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

IEC 62258, as currently conceived, consists of the following parts, under the general title

Semiconductor die products
Part 1: Requirements for procurement and use

Part 2: Exchange data formats

Part 3: Recommendations for good practice in handling, packing and storage

Part 4: Questionnaire for die users and suppliers

Part 5: Requirements for information concerning electrical simulations

Part 6: Requirements for information concerning thermal simulations
Further parts may be added as required.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

———————
At the time of writing, IEC 62258-3 is the only part in existence. Other parts are under consideration.

– 6 – TR 62258-3  IEC:2005(E)

INTRODUCTION
Organizations that helped prepare this technical report included the ESPRIT GOOD-DIE

project, DPC, and JEITA.
TR 62258-3  IEC:2005(E) – 7 –

SEMICONDUCTOR DIE PRODUCTS –
Part 3: Recommendations for good practice

in handling, packing and storage

1 Scope and object
This technical report has been developed to facilitate the production, supply and use of
semiconductor die products, including:
– wafers,
– singulated bare die,
– die and wafers with attached connection structures, and
– minimally or partially encapsulated die and wafers.
This report contains suggested good practice for the handling, packing and storage of die
products.
Success in manufacture of electronic assemblies containing die products is enhanced by
attention to handling, storage and environmental conditions. This report provides guidelines
taken from industry experience and is especially useful to those integrating die products into
assemblies for the first time. It is also intended as an aid to setting up and auditing facilities
that handle or use bare die products, from wafer fabrication to final assembly.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references the lasted edition
of the referenced document (including any amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary
IEC 60286-3, Packaging of components for automatic handling – Part 3: Packaging of surface
mount components on continuous tapes
IEC 61340-5-1:1998, Electrostatics – Part 5-1: Protection of electronic devices from

electrostatic phenomena – General requirements
IEC 61340-5-2:1999, Electrostatics – Part 5-2: Protection of electronic devices from
electrostatic phenomena – User guide
IEC 62258-1, Semiconductor die products – Part 1: Requirements for procurement and use
ISO 14644-1, Cleanrooms and associated controlled environments – Part 1: Classification of
air cleanliness
———————
Under consideration.
– 8 – TR 62258-3  IEC:2005(E)

3 Terms and definitions
For the purposes of this document, relevant terms which are defined in IEC 60050, together

with additional terms and acronyms as given is IEC 62258-1, shall apply.

4 Handling – Good practice
4.1 General
Contact with the exposed active surface of die products should be avoided. When contact is
absolutely necessary, only properly designed tools and materials should be used.
The working environment, including tools, materials and containers for handling and transport
of die products should provide for ESD protection (refer to IEC 61340-5-1 and IEC 61340-5-
2).
It should also be realised that die products are sensitive to certain chemicals.
4.2 Working environmental controls
The following are the typical recommended working environmental conditions for most
semiconductor technologies. Characterisation of the particular technology used should be
conducted to determine any specific environmental needs. This working environment should
not be used for storage of semiconductor die.
a) Temperature: 17 °C – 28 °C
+20
b) Humidity 40 % nominal %
−10
c) Particle count: ISO 14644-1, Class 8 or better
4.3 General handling precautions
The selection of appropriate tools is critical to successful handling of bare die and wafers.
There is a range of specialized tools available for correct handling of die and wafers. If any
tooling or equipment is found to damage die products, its use should be suspended
immediately.
Die products should never be allowed to come into contact with each other, or to be stacked
on top of each other without the use of suitable separators.

Die products should never be placed with the active side touching a hard surface. The die
surface may also be damaged if it touches a soft surface that has embedded hard particles,
such as silicon debris.
When handling wafers it is recommended that physical contact should be made only with the
outer periphery and/or the back side of the wafer.
4.4 Cleanroom good practice
Containers of bare die or wafers should only be opened in a work area with a controlled
environment, known as a cleanroom. This applies to any process that exposes the die or
wafer surface to the environment, for example quality checks, die sorting or assembly of
products containing bare die.
Personnel working in these areas need to be adequately trained to ensure that die products
are not physically damaged nor contaminated when handled in the cleanroom.

TR 62258-3  IEC:2005(E) – 9 –

4.4.1 General
ESD damage may be reduced through the use of grounded workstations, conductive wrist

straps and/or shoe straps, conductive material totes, staticide chemicals, conductive floor

waxes, tiles, mats, ionizers, conductive packing foams, and shielded bags. These items can

also improve the efficiency of the environmental controls employed.

Bare die or wafers in process should remain in a clean environment at all times. If wafers are

to be transported between cleanrooms, a suitable wafer carrier should be used and the
container should remain closed during transportation. The container should be externally

cleaned on re-entering the cleanroom.

It is recommended that die or wafers should not be handled manually. Handling die or wafers
with bare hands should be avoided since this will cause contamination from skin oil, skin
flakes, and a variety of other contaminants from human and other sources. Even when using
gloves, handling may cause contamination by transfer of plasticizer from the glove. However,
it is acceptable to handle wafers with a gloved hand as long as the wafer is held on the edge
and the active surface is not touched at all.
All surfaces coming in contact with die products throughout the process should be clean and,
when practicable, non-metallic. Any hard material in contact with the die products may cause
scratches or chipping. These principles should be observed at all times, since if one die or
wafer becomes contaminated, the contaminants may be transferred to other surfaces, process
equipment and wafers.
Care should be taken to avoid contaminating surfaces used for product handling. Working
surfaces should not be used to hold non-clean items, such as equipment covers, internal
parts or personal belongings. Wiping a surface clean may not adequately remove oils and
residues.
4.4.2 Attire
4.4.2.1 Hats, hoods, nets, masks and shoes
Head and facial hair should be completely enclosed at all times using appropriate hoods or
nets to avoid contamination from skin particles or hair.
It is recommended that masks are worn at all times while in the production area with exposed
wafers or die to prevent contamination by spittle. Masks should cover the mouth, and ideally,
the nose and should be replaced daily or more often if they become contaminated.
Special ESD-safe cleanroom shoes should be worn within the cleanroom. These shoes should

be kept inside the cleanroom or changing area and only be taken outside the area for
cleaning or repair. Alternatively, overshoes may be used which should be discarded
immediately after use in suitable waste containers. Some overshoes are suitable for re-use
after washing, however, they are not intended to be re-used without being cleaned.
4.4.2.2 Smocks and gowns
Special smocks and gowns should be worn within the cleanroom, to cover normal clothing.
They should be selected according to the cleanroom classification and should be made of
material that is both anti-static and lint-free.
4.4.2.3 Gloves
Gloves serve as the final barrier in preventing release of skin flakes, skin oils, and other
hand-carried contaminants. Disposable vinyl gloves that are approved for cleanrooms are
appropriate for general use.
– 10 – TR 62258-3  IEC:2005(E)

Cotton gloves or other gloves that shed lint or powder should not be worn in handling die

products, even under vinyl gloves. Polyester or nylon gloves may be worn under vinyl gloves.

Rubber gloves packed with powder should not to be used.

Gloves should be replaced each time the cleanroom is entered, or more often if they become

contaminated in any way, for example by ink or from touching the face. Gloves that have rips

or tears should be replaced immediately.

When gowning, gloves should always be put on last, after other items. Gloves should be worn

over cuffs on sleeves and should be held at the wrists only at all times.

No contact should be made with face, hair, or other potential sources of contamination by
gloved hands; such contamination can be transferred to other items, including die products,
process equipment and handling equipment.
4.4.2.4 Finger cots
Finger cots are often used instead of gloves. These offer less protection from contamination,
but are more convenient for some operations, for example wafer quality control inspection. It
is recommended that finger cots be worn on all fingers to prevent inadvertent contamination
from an uncovered finger. Finger cots should be kept and used in the cleanroom area and not
kept in the cleanroom gowning area.
Finger cots should not be re-used and should be replaced if torn or damaged. Fresh finger
cots should be used after re-entering the cleanroom.
4.4.3 Conduct
Food and drink should not be taken into the cleanroom.
Hands should be washed before gowning and entering the work area, especially after
handling foods.
Cosmetics should not be worn in the cleanroom as the chemicals they contain could damage
or contaminate die products. Excessive use of creams and lotions should also be avoided
since chemical additives may also damage or contaminate die products.
The following are some of the practices and items that should be prohibited in the controlled
environment:
a) smoking or the use of any tobacco product;

b) acts of personal hygiene or grooming;
c) hair brushes or combs;
d) chewing-gum, sweets or candy;
e) plants or cut flowers;
f) pencils or erasers;
g) paper or card products not designed for cleanroom use.
4.4.4 Tools
The use of automated equipment and vacuum tools is preferred at all times for handling die
and wafers. Any tool used should not generate ESD hazards.
Tools should only be used for their designed purpose in handling die products and should not
be used as screwdrivers, pry bars, letter openers, etc.

TR 62258-3  IEC:2005(E) – 11 –

4.4.4.1 Pick-up tools and collets

A wafer extraction tool should be used to assist in guiding the wafer out of a cassette in order

to avoid scratching or damaging the wafer.

Vacuum wand-tips and die pick-up collets should be cleaned regularly using appropriate

materials such as isopropyl alcohol and polyester cleanroom wipes. Extreme care should be

taken in handling and cleaning die pick-up tools that touch the active surface of the die.

Wafer vacuum pick-up tools should be used to grasp the back (unpatterned) side of the

wafers only.
The largest pick-up tool compatible with the die size should be used in order to deliver the
maximum vacuum to the surface of the die. For very small die, increasing the bore size of the
pick-up tool may be necessary; most tool suppliers have this capability. Damaged tooling,
irregular edges on the tooling, and so forth can also adversely affect die pick-up, since this
would prevent the tool from making a good seal with the die. A soft tip on the tool is
recommended as this will assist in die pick-up and reduce any damage to the die surface.
At no time should a "hard-faced" tool be used for die removal, unless it is designed for "edge
contact" of the die only. Tools of this type are typically referred to as collets. Heated collets
should not be used to remove die from the membrane due to the temperature limits of PVC.
Note that some die have junctions extending to the edge of the die, especially discrete power
devices, so that any chipping of the edges of these die may cause leakage or shorts.
If any die are dropped in the assembly work area, they should be inspected by microscope for
mechanical damage and contamination prior to returning them to the die bank. It should be
ensured that individually-handled die are correctly oriented in a die carrier before they are
reintroduced to assembly equipment. Any individual die that fall to the floor of a production
line should be scrapped.
4.4.4.2 Tweezers
Manual handling of individual die with tweezers should be prohibited, but it is recognized that
for low-volume use, tweezers may have to be used for operations where conditions do not
permit the use of other types of pick-up tools. Where tweezers are used to handle bare die,
care should be taken not to chip the edge of the die. They should not come in contact with the
active surface since this may create scratches or damage bumps on flip-chip die.
Tweezers for handling wafers are of a special design and should be made of plastic or be
coated with PTFE and have an off-set to limit the distance they extend onto the wafer. These
tweezers should be used to grasp the wafer at the flat of the outside edge and should not be
allowed to extend into its centre. The larger tip should contact only the back side of the wafer.

Tweezers should be cleaned regularly using suitable cleaning materials such as methanol or
isopropyl alcohol and a polyester clean-room wipe. They should remain at the work area at
assigned locations and should not be stored with personal belongings or hung on garments.
Tweezers with a damaged coating should not be used.
4.4.5 Protocol
A protocol should be established in each cleanroom area which shows how personnel and
materials are to move from one class-level environment to another without compromising
each environment, product, carriers, or protective clothing. This protocol should include the
following:
a) physical path to follow for personnel travelling from one area to another;
b) required protective clothing, care, and dressing sequence during gowning or removing;

– 12 – TR 62258-3  IEC:2005(E)

c) approved flow of materials through the area and required protective packaging;

d) restrictions of materials that are allowed in each area;

e) requirements for managing process equipment in the area, including bringing in new

equipment or repairing equipment;

f) maintenance and cleaning of the cleanroom environment.

5 Process handling issues
5.1 Wafer sawing
Wafer sawing is an essential process in the preparation of die products where supplied in
unsawn wafer form. Normally, separation into individual components is carried out by cutting
the wafer using a high-speed, high-precision, diamond-tipped saw blade. The wafer is affixed
to a pressure-sensitive adhesive (PSA) tape mounted to a film frame. Film frames are
manufactured from several materials and come in various sizes to accommodate equipment
needs and wafer sizes.
Silicon wafers are brittle and special attention needs to be given to the sawing operation to
ensure that the individual die are separated without causing damage. For example, particular
consideration should be given to
– saw blade type,
– blade rotation speed,
– feed speed,
– flow rate of rinse and cutting water,
– adhesive film type,
– depth of cut,
– dual blade sawing to fully cut away process control modules/test structures in the saw
lane, and
– back side and front side chipping.
It is recommended that a "bevel" cut be used for bare die and flip-chip products. This is to
help eliminate front, side and back side edge chipping and cracks. The bevel process also
eliminates metal flakes from the die edge caused when a nickel/diamond blade cuts through
the aluminium test grids in the streets. Due to the potential defects caused by cracks and
metal particulate, any deviation from this recommendation can affect the quality of the die.
Figure 1 provides a pictorial view of the bevelled edge for both wire-bonded and flip-chip
processing.
Key
1 Bare die
2 Flip-chip
3 Bevel edge
IEC  712/05
4 Substrate
Figure 1 – Bevel cut for bare die and flip-chip products

TR 62258-3  IEC:2005(E) – 13 –

It is not recommended that a finger or any tool is run under a mounted cut wafer to check the
saw cut. This can cause edge chipping by adjacent die moving against each other.

Other wafer material, such as gallium arsenide (GaAs), composites such as silicon on
sapphire (SoS) or bonded wafers, require special saw processes.

5.1.1 Guidelines for mounting wafers

Experience in the industry points to the importance of selecting the proper film material for

use when mounting wafers. Defect reduction has been observed after wafer dicing when

certain films are used. It is recommended that the film vendor be contacted to determine the

optimum film for the application. Such things as a higher modulus film, higher tack level and
UV films have all shown improved performance in reducing die chipping and fractures.
5.1.2 Use of water
Water is used in the sawing process as a lubricant, coolant and slurry rinse. Only ultra-pure
water should be used to ensure that the die are not damaged by contaminants in the water.
Ultra-pure water commonly produced by deionization is also highly resistive and static
charges may build up during sawing. To reduce this static hazard, it is normal to introduce a
small amount of pure carbon dioxide gas to the water by bubbling. However, excessive CO
may result in the water becoming acidic and corrosive, therefore the addition of CO should
be controlled.
Water additives may be used to improve the cutting process. Any additive used should be
fully assessed to ensure die are not damaged by chemicals contained in the additive.
5.1.3 Washing and drying
Residue from the cutting process may remain on the surface of the wafer. It is normal to rinse
or wash the cut wafer using ultra-pure water.
The process used to dry the wafer after washing should ensure that the surface is clean
and dry.
5.2 Die sorting
Die products may be supplied in wafer form, either pre-sawn on adhesive film or unsawn,
which will require sawing before use. In either case, individual die are removed from the
adhesive film used in the sawing process to incorporate them into the end product.
Different types of equipment are available for this process and care should be taken to match

the equipment to the wafer type and technology. Die especially sensitive to damage are those
with unprotected surfaces such as unpassivated die or very thin or fragile die.
Die removed from the adhesive film may be placed into a die carrier for subsequent assembly.
This process is known as die sorting and provides for segregation of electrically good die from
bad die or separation into different grades of die. Carrier systems for individual die include
chip trays, vacuum release trays and tape-and-reel.
5.2.1 Guidelines for handling frames containing sawn wafers
The wafer to be sorted will be mounted on the film frame after sawing. The frame should be
well positioned on a holding fixture. The fixture should securely hold the frame during any
indexing, loading, unloading or die removal.

– 14 – TR 62258-3  IEC:2005(E)

5.2.2 Vacuum
Best results are obtained under good vacuum conditions at the pick-up tool and beneath the

wafer-film. Manufacturers’ recommendations on vacuum pressures should be followed.

5.2.3 Pick-up tools
See 4.4.4.1.
5.2.4 Die contact and removal
Contact force between the pick-up tool and the die should be minimized so that the die is

properly engaged by the pick-up tool; the rate of ascent should initially be slow. Timing of the
rise of the plunge-up needles and the pick-up tool need to be such that the die remains in
contact with the pick-up tool until complete separation from the film has occurred. Rapid
ascent may cause large die to separate from the tool before the die has separated from the
membrane.
5.2.5 Removal from wafer film
The ‘de facto’ standard adhesive-backed film, used for mounting wafers to be sawn, changes
adhesive strength after the tape is taken off the roll. This is due to the addition of a silicone
spray, which serves as a release liner. Gradually, over a period of a few weeks, this additive
is released to the atmosphere. This causes the adhesion level to increase after sawing by a
factor of five or more and may make the die more difficult to remove during the die sorting
process. To minimize this effect, the die sorting process should take place as soon as
possible after sawing. Other forms of adhesive-backed film, such as UV tape, are available
that do not exhibit this phenomenon.
5.2.6 Needle marks
During the die sorting process, it is common to use a needle or needle bed to remove die from
the adhesive-backed film used at sawing. However, some wafers are not suitable for needle
offload, such as thin or fragile wafers. For small die, the needle should have a small radius tip
and smaller angle A (see Figure 2). The needle should puncture the film to allow the
adhesive-backed film to peel off the die, without causing damage to the back of the die. For
large die, the needle(s) should have a tip with a large radius and larger angle A. These
needles should not puncture the film, but should elevate the die, allowing the film to peel off
without leaving any adhesive residue on the back of the die.
Die have various back side surface finishes, some of which are more susceptible to damage
by a needle than others.
The profile of the tip of the needle is important to ensure that damage does not occur in the
die sorting process, the most important featuring being the radius of the tip as shown in
Figure 2.
TR 62258-3  IEC:2005(E) – 15 –

A°
∅D
L
R
Key:
1 ∅D diameter of needle
2 A angle of needle tip
3 L length of needle
4 R radius of tip
IEC  713/05
Figure 2 – Die eject needle
Examples of marks caused by die eject needles on the back surface of a back-lapped die are
shown in Table 1.
Table 1 – Example die eject marks
Description Normal lighting Dark-field lighting Accept/reject Cause/remedy
Backlapped wafer Accept Correct die eject
– normal surface set-up – no visible
appearance. needle mark or film
adhesive residue
No needle mark or
film adhesive
residue
Excessive needle Reject unless there Heavy needle mark
mark showing is no evidence of caused by too
micro-cracks microcracks much ‘over-travel’
or wrong choice of
needle. Reduce
over-travel or
change needle
Excessive needle Reject Too much over-
mark, scratches travel and incorrect
and micro-cracks machine set-up
resulting in needle
bounce. Adjust
machine set-up, die
eject speed and
needle over-travel
Excessive needle Reject Die eject not
mark with scrape perpendicular to die
and residue surface caused by
incorrect machine
set-up or broken
needle. Check
machine die
eject/replace
needle
– 16 – TR 62258-3  IEC:2005(E)

5.2.7 Unpassivated die and MEMS

Some types of die are unpassivated and require special handling to avoid damage to the top

active surface. Use of a normal vacuum pick-up tip can scratch the active surface. A soft

rubber tip or collet that grips the edge of the die may be used.

MEMS and sensors may have mechanical features in the centre of the active surface that are

susceptible to damage if a normal pick-up tip is used. In this case, a collet that grips the edge

of the die should be used.
MEMS and sensors may also have mechanical features that extend through the die. In this

case, normal die ejection using a needle should not be used as this may damage the
mechanical features on the underside of the die.
6 Die and wafer transport and storage media
Various shipping and storage media are available for transport or storage of die and wafers.
Wafer cassettes may be used for transportation and storage within a single facility. Wafer
shipping carriers and containers may be used when transferring product between facilities.
Shipping and storage boxes may be used to handle sawn wafers on frames (adhesive-backed
film held rigid by a frame). Chip trays, vacuum release trays or reels of adhesive-backed
carrier tape or pocketed tape may be used to transport singulated die.
Exposure to the work-area air should be kept to a minimum. Wafers and die should be kept in
suitable closed wafer storage containers, or reels of die on tape kept in sealed bags.
Containers of die or wafers should not be opened outside the cleanroom since the product
may be contaminated by particles or moisture in the air. Product shipped via air transportation
should be sealed in hermetic bags or containers.
Die and wafer containers should not be touched with ungloved hands, even outside the
cleanroom, since ionic contamination may be transferred from the container to the product
when subsequently opened in the cleanroom.
Die and wafer storage containers and cassettes should be cleaned regularly, especially
whenever visible contamination is present.
Die and wafers should remain in their carriers at all times and should only be removed when
they are in process.
Wherever possible, wafer handling tools should be used to manipulate wafers in cassettes. If
wafers have to be manipulated by hand, only the edge of the wafers should be touched by a

gloved hand. Refer to Clause 5 for information on handling.
6.1 Wafer carriers and cassettes
At various points during their production, semiconductor wafers are transported between
different equipment and facilities, such as:
– raw wafer processing and shipping;
– wafer processing including patterning, metallization and passivation;
– back-end processing including test, thinning and bumping;
– finished wafer shipping and handling.
Any of these stages can take place in facilities remote from each other. It is also common to
have some stages sub-contracted out to another company.

TR 62258-3  IEC:2005(E) – 17 –

It is important to differentiate between transportation or process carriers and shipping carriers

or systems. Wafer breakages easily occur when a carrier intended for transportation of wafers

within a facility is used to ship wafers to a different facility. These carriers are designed to

hold the wafers securely for hand or robotic transportation within a facility, but they are not

designed for packing in a box and sending via a transport company.

Care should be exercised in choosing the best shipping or process carrier. Damage to the

edge of the wafer, in unsawn form, can cause micro-cracks to form which may propagate

through the wafer at a later stage, for example during mounting on film, back-grinding or

sawing. This may lead to the wafer breaking into pieces or shattering when handled.

Wafer cassettes should be handled from the ends, touching only the exterior surfaces. Avoid
picking up a cassette from the top.
If it is necessary to transfer wafers to a different carrier, slide transfer of wafers (cassette to
cassette) should be used whenever possible. Wafers should slide gently. Dump transferring
wafers from cassette to cassette should never take place since this is likely to damage or
contaminate wafers.
6.2 In-process carriers and transport systems
A wafer cassette is the primary form of container used in transporting and storing wafers.
Whenever practical, cassettes of wafers should be handled
...