Heating Plate for CVD Apparatus Used in
Manufacturing TFT LCDs

Liquid crystal display (LCD) based on the thin film transistor (TFT) technology is expanding rapidly focusing on
personal computers and TV sets. In particular, the expansion of the use in TV sets is going to accelerate drasticallythe size increase of TFT LCDs.
In an effort to supply a heating plate (see Figure 1) to be
used in chemical vapor deposition (CVD) apparatuses inmanufacturing TFT LCDs, Furukawa Electric has developed a proprietary technology of aluminum plate welding,thereby promoting development and practical applicationof such heating plates as are applicable to manufacturing
large-sized displays.

Enlarged cross section
Glass substrate
Process chamber

Heating plate

Figure 11.

STRUCTURE

Figure 2 shows the basic structure of Furukawa's heatingplate. Two aluminum alloy plates are bonded together by
hot forging, with heating wires such as sheathed heaters
sandwiched in between, to obtain an integral heatingplate, in which forge welding process is employed toachieve metal-to-metal bonding.
In the forge welding process as shown in Figure 3, theportions to be welded that are formed in advance into a
protrusion-groove (or protrusion-protrusion) shape undergo a rapid and concentrated deformation instantaneously,
so that metal-to-metal bonding is enhanced to attain ahigh level of bonding strength ensuring simultaneously ahigh degree of sealing against high vacuum.
The forge welding process offers a number of advantages such that the process permits partial bonding of any
desired portions by preparing the protrusion-groove (orprotrusion-protrusion) shape mentioned above; in caseairtightness is required, a high degree of sealing againsthigh vacuum is achieved by making the protrusion-groove(or protrusion-protrusion) portions into annular in shape;
and the process requires only a small amount of forging
force due to the force concentration onto the protrusiongroove (or protrusion-protrusion) portions, making theprocess capable of coping with large-sized products.
Features of Furukawa's heating plate fabricated using
the above mentioned forge welding are described below.

Schematics of CVD apparatus and cross section ofheating plate.

Aluminum alloy plate

Material (upper) to be forge welded

Protrusion-groove portions
for welding

Figure 2

Through hole

Structure of heating plate.

①②
Protrusion-groove
Load onportions
protrusion-groove
before welding
portions

Figure 3

Sheathed heater➂
Loadconcentration➃Forge welding
finished

Details of forge welding process.

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2.

FEATURES

1) Stabilized performance is maintained even whenused in a high vacuum.
Heating plates of high cleanliness with stabilized performance when used in a high vacuum can be supplied, since the products are fabricated by forge welding, a proprietary technology of Furukawa Electric,
where aluminum alloy plates are metal-to-metal bonded with heaters sandwiched in between. The airtightness is confirmed to be 10-10 Pa.m3/sec or less byhelium leak test.
2) Large-sized heater plates are available.
Product sizes can be freely selected up to a heater
plate of about 2 m square.
3) Excellent in uniformity of temperature distribution.
Because the heating plate is forge welded in a hightemperature and high-pressure condition, the aluminum alloy plate and the heating wire come into
close contact with each other, thereby ensuring efficient heat conduction. Thus, a heating plate that isexcellent in uniformity of temperature distribution canbe obtained.
4) Surface deformation can be minimized.
Because the heating plate is forge welded in a hightemperature and high-pressure condition using a
metal mold of sufficient surface flatness, a satisfactorysurface flatness after welding is assured. This results
in a minimal residual stress thanks to avoiding the sizing process. Furthermore, the heating plate is forge
welded in a high-temperature equivalent to the ambient temperature of an actual process, so that strain
during the use is also reduced.
5) Hollow passages are possible to be provided.
It is possible to leave the grooves prepared forheaters unfilled without embedding heaters, so thataluminum panels provided with hollow passages forliquids or gases can be manufactured.
6) Aluminum alloys can be freely selected for welding.
Aluminum alloys such as 1050, 3003, 5052 and 6061
that are generally used in semiconductor manufacturing equipment can be forge welded.

3.

4.

IN CONCLUSION

Furukawa's heating plate is based on a simplified bonding
method of forge welding, which also permits meeting theneeds of size increase.
In addition to such a function of heating with built-inheaters, it is possible to provide hollow passages for liquids or gases within the aluminum alloy plates ensuring ahigh degree of sealing. Using this technology, therefore,
we are ready to meet various customer requirements interms of size and application including heating plates,
cooling plates and gas diffusion plates.
Please note that several patents have been filed byFurukawa Electric.
For more information, please contact:
Manufacturing Department, Casting & Forging
Division, Aluminum GroupTEL: +81-285-24-0747
FAX: +81-285-22-2884

MANUFACTURING TRACK RECORDS

1) Size
250 mm square~1200 mm square; circular panels
included
2) Material
1050, 5052 and 6061 aluminum alloys3) Applications
Heating plate for CVD apparatus
Cooling plate for semiconductor manufacturing equipment
Gas diffusion plate for semiconductor manufacturingequipment

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Furukawa Review, No. 222002