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SEMI D18-0299 E © SEMI 19 99, 2001 2 4.11 cassette t op domain — volume ( hi gher than z 9 above the top su bstrate) that contains the top of the cassette. 4.12 conveyor rails — featu r es on t h e b ottom of the cassett…

SEMI D18-0299

SPECIFICATION FOR CASSETTES USED FOR HORIZONTAL

TRANSPORT AND STORAGE OF FLAT PANEL DISPLAY

SUBSTRATES

This specification was technically approved by the Flat Panel Display Equipment Committee and is the direct

responsibility of the North American Flat Panel Display Committee. Current edition approved by the North

American Regional Standards Committee on August 15, 1998. Initially available at www.semi.org

September 1998; to be published February 1999.

This document was editorially modified in October 2000 to correct a formatting error. Changes were made

to Figure 5.

1 Purpose

1.1 This standard specifies the cassettes used to

horizontally transport and store glass substrates 0.7

mm-1.1 mm thick (max) in a flat panel display (FPD)

manufacturing facility.

2 Scope

2.1 This standard is intended to set an appropriate

level of specification that places minimal limits on

innovation while ensuring modularity and inter-

changeability at all mechanical interfaces. Most of the

requirements given in this specification are in the form

of algebraic expressions defining maximum or

minimum dimensions referenced from the length and

width of the intended substrate with very few required

surfaces. Only the mechanical interfaces for cassettes

are specified; no materials requirements or micro-

contamination limits are given. However, this standard

has been written so that cassettes of various designs and

materials can be manufactured in conformance with it.

3 Referenced Standards

NOTE: As listed or revised, all documents cited shall be the

latest publications of adopted standards.

3.1 SEMI Standards

SEMI D3 — Quality Area Specification for Flat Panel

Display Substrates

SEMI D5 — Standard Size for Flat Panel Display

Substrates

SEMI D6 — Standard Edge Length and Thickness for

Flat Panel Display Mask Substrates

SEMI D9 —Definitions for Flat Panel Display

Substrates

SEMI D11 — Specification for Flat Panel Display

Glass Substrate Cassettes

SEMI D21 — Terminology for Flat Panel Display

Masks

SEMI E15 — Specification for Tool Load Port

SEMI E44 — Guide for Procurement and Acceptance

of Minienvironments

4 Terminology

4.1 bilateral datum plane — a vertical plane that

equally bisects the substrate and that is perpendicular to

both the horizontal and facial datum planes.

4.2 carrier capacity — the number of substrates that a

carrier holds.

4.3 cassette — (as defined in SEMI E44)

4.4 cassette bottom domain — volume (below z4

above the horizontal datum plane) that contains the

bottom of the cassette.

4.5 cassette bottom opening — an opening through the

cassette bottom domain that provides access to the glass

substrates for external roller drive mechanisms to move

substrates into/from the cassette.

4.6 cassette front — the area between the cassette top

and bottom domains through which substrates pass

during loading and unloading.

4.7 cassette rear — the area between the cassette top

and bottom domains opposite the cassette front.

4.8 cassette rear domains — volumes (from z4 above

the horizontal datum plane to z9 above the top

substrate) that contain rear columns which prevent the

substrates from exiting the cassette rear.

4.9 cassette placement sensing pads — surfaces on the

bottom of the cassette for triggering optical or

mechanical sensors.

4.10 cassette side domains — volumes (from z4 above

the horizontal datum plane to z9 above the top

substrate) that contain the mizo teeth and mizo plates

that support the substrates.

SEMI D18-0299

4.11 cassette top domain — volume (higher than z9

above the top substrate) that contains the top of the

cassette.

4.12 conveyor rails — features on the bottom of the

cassette for supporting the cassette on roller conveyors.

4.13 conveying surface



entire bottom surface of

cassette (z15 above the horizontal datum plane),

excluding the V-rail, V-groove, and float roller zones,

for supporting the cassette on roller conveyors

4.14 facial datum plane — a vertical plane that

equally bisects the substrates when the centers of the

substrates are aligned and that is parallel to the front

side of the carrier (where substrates are removed or

inserted) and is perpendicular to the bilateral datum

plane. On tool load ports, it is also parallel to the load

face plane (as defined in SEMI E15) on the side of the

tool where the carrier is loaded and unloaded.

4.15 first substrate end-effector clearance — the

distance (dimension z9) between the top of the cassette

bottom domain and the first nominal substrate seating

plane.

4.16 first nominal substrate height — the distance

(dimension z5) from the horizontal datum plane to the

first nominal substrate seating plane.

4.17 horizontal datum plane — load height as defined

in SEMI E15.

4.18 mizo plate — a plate that contains mizo teeth and

may provide structure to the cassette.

4.19 mizo teeth — elements that support the substrates

in the cassette.

4.20 nominal center line — the intersection of the

facial and bilateral datum planes.

4.21 nominal substrate seating plane — a horizontal

plane that contains the nominal bottom surface of the

substrate as it rests on the mizo teeth.

4.22 optical substrate sensing paths — lines of sight

for optically sensing the positions of the substrates.

4.23 robotic handling flanges — projections on the

cassette for handling of the cassette.

4.24 substrate extraction volume — the open space

for extracting a substrate from the cassette.

4.25 substrate pitch — the distance between adjacent

nominal substrate seating planes.

4.26 substrate set-down volume — the open space for

inserting and setting down a substrate in the cassette.

4.27 substrate pick-up volume — the space that

contains entire bottom of a substrate if the wafer is

pushed to the rear of the cassette.

5 Ordering Information

5.1 Intended Use — This standard is intended to

specify cassettes over a reasonable lifetime of use, not

just those in new condition. The purchaser needs to

specify the time period, the number of cycles and any

special conditions to which the cassettes will be

exposed. It is under these conditions that the cassettes

must remain in compliance with the requirements listed

in Section 6.

5.2 Temperature Ranges — The purchase of the

cassettes needs to specify three sets of temperatures to

which the cassettes might be exposed. An operating

temperature range is the set of environmental

temperatures in which the cassettes will remain in

compliance with the requirements listed in Section 6

(e.g. 23°C ± 5°C). A temporary temperature range is

the set of environmental temperatures to which the

cassettes can be exposed such that when the cassettes

return to the operating temperature range, the cassettes

will be in compliance with the requirements listed in

Section 6 (e.g. 90°C maximum during cleaning of the

cassette). Also, the purchaser needs to specify a range

of temperatures for the substrates that might be inserted

in the cassettes.

5.3 Pitch and Capacity Options — The purchaser

needs to specify the pitch and capacity of the cassettes.

Table 2 provides two options of pitch and capacity.

Additional pitch and capacity options are not yet

defined, but should be specified in the same manner.

5.4 Material — To be agreed upon between supplier

and user. Construction may be of one or more molded

or machines parts.

6 Requirements

6.1 Dimensions — Most of the dimensions of the

cassette are determined with respect to the three

orthogonal datum planes defined in that standard: the

horizontal datum plane, the facial datum plane, and the

bilateral datum plane (see Figure 1).

6.2 Cassette Physical Alignment Interface — The

cassette should be registered to the tool interface by one

of the three following types of registrations (Type A, B

or C). The locations of the registration features have

been chosen such that all three types may coexist on the

same cassette

6.2.1 Cassette Physical Alignment Interface-Type A —

This registration consists of three features (not

specified, but recommended to be inverted V-shaped

SEMI D18-0299

grooves) placed on the bottom of the cassette that mate

with three coupling pins located on the tool interface.

The coupling pins are located by dimensions x14 and

y13 relative to the bilateral and facial datum planes

respectively.

6.2.1.1 Coupling Pin Shapes — The physical

alignment mechanism on the bottom of the wafer

carrier consists of features (not specified in this

standard) that mate with three pins underneath. As

shown in Figure 5 and defined in Table 3, each pin is

radially symmetric about the vertical center axis line

and can be seen as the intersection of a cylinder of

diameter d1 and a sphere of radius r3 (which might

contact a flat plate). An additional rounding radius r5

provides contact with angled mating surfaces, and blend

radii r4 and r6 smooth the resulting edges. The final

roughness height of the over-all surface finish must be

less than or equal to r7. Dimensions r2 and z13 have

zero tolerance because they only give a distance to

another toleranced dimension. (Dimensions in

parenthesis are not part of the requirements in this

standard but are intended to clarify the preparation of

manufacturing instructions.)

6.2.1.2 The three features on the bottom of the cassette

that mate with the coupling pins must provide a lead-in

capability that corrects a cassette misalignment of up to

10 mm (0.4 in.) in any horizontal direction, although 15

mm (0.6 in.) is recommended. The exclusion zones for

the three coupling features on the cassette is shown in

Figure 3 and Table 1 and specified by dimensions x14,

z9 and r1.

6.2.2 Cassette Physical Alignment Interface-Type B —

Consists of three features, a V-rail, float surface, and

facial datum plane V-groove. The V-rail and float

surface are located on the bottom of the cassette and

mate with the two V-rail rollers and one float surface

roller, respectively, mounted on the tool interface. The

facial datum plane V-groove is located about the facial

datum plane through the bottom surface of the cassette

and mates with the facial datum plane lock pin located

on the tool interface shown in Figure 3. The V-rail

roller and the float surface roller are located by

dimensions x15 and x16 relative to the bilateral datum

plane respectively shown in Figure 6. The dimension

relative to the facial datum plane for the V-rail rollers

are not specified but recommended to be located

furthest from and symmetrical about the facial datum

plane as shown in Figure 3 and 6. The float surface

roller revolute axis must lie on the facial datum plane.

6.2.2.1 The V-rail and float surface rollers are defined

in Figure 7 and Table 4. Each roller is radially

symmetric about the revolute axis. The rollers are

circumferentially radiused of dimension r8. The

diameter of the rollers is not specified but the tangential

surface created by dimension r8 must lie on the

horizontal datum plane. The facial datum plane lock pin

radius is equal to r8 and must be positioned into the

facial datum plane V-groove to fully constrain the

cassette to the facial datum plane. The facial datum

plane lock pin is translated out of the facial datum plane

V-groove to allow the cassette to be rolled in and out of

the tool interface. Although only three rollers are

specified it is recommended to increase the total

number of rollers so that the cassette is fully supported

while being loaded and unloaded to the tool interface.

All rollers except for the V-rail and float roller must be

positioned so that the tangent of the r8 dimension lies

below the horizontal datum plane.

6.2.2.2 The three features on the bottom of the cassette

that mate with the rollers and lock pin must provide a

lead-in capability that corrects a cassette misalignment

of up to 10 mm (0.4 in.) in any horizontal direction,

although 15 mm (0.6 in.) is recommended. The V-rail

and facial datum plane V-groove are not specified but

recommended to be inverted V-shaped grooves. The V-

rail is recommended to extend the full length of the

cassette from the cassette front to the cassette rear. The

float surface is not specified but recommended to be a

flat surface extending the full length of the cassette

from the cassette front to the cassette rear. The

exclusion zones for these features are shown in Figure 3

and 6 and specified by dimensions x15, x16 through

x22.

6.2.3 Cassette Physical Alignment Interface-Type C —

to be developed.

6.3 Conveyor Rails — If the cassette is to be used on

roller conveyors, each conveyor rail should extend the

maximum distance from front to back. The exclusion

zones for conveyor rails are shown in Figure 3 and 6

and specified by dimensions x13 and x22 and extends to

the outer boundary of the cassette.

6.4 Conveying SurfaceIf the cassette is to be

transported on roller conveyors that support the entire

bottom of the cassette, the bottom surface excluding the

V-rail, V-groove, and float roller zones is to be used.

The location of this surface with respect to the

horizontal datum plane is specified by dimension z3.

6.5 Substrate Orientation and Numbering — The

substrates must be horizontal when the carrier is placed

on the coupling, and the substrates are numbered in

increasing order from bottom to top (so the bottom

substrate is substrate number 1, the next substrate up is

substrate number 2, etc.)

6.6 Cassette Sides and Rear — Figure 2 shows a top

view of the boundaries of the cassette side domains

(which contain the parts of the cassette higher than z4

above the horizontal datum plane and lower than z9