Photography – Fluid-treating apparatus – Heating – cooling – or temperature detecting
Reexamination Certificate
2003-03-20
2004-11-09
Rutledge, D. (Department: 2851)
Photography
Fluid-treating apparatus
Heating, cooling, or temperature detecting
C396S611000, C355S030000, C414S935000, C414S940000
Reexamination Certificate
active
06814507
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a substrate treating apparatus for performing a series of treatments of substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, and substrates for optical disks (hereinafter called simply substrates).
(2) Description of the Related Art
Conventionally, such a substrate treating apparatus is used, for example, in a photolithographic process for forming photoresist film on substrates, exposing the substrates having the photoresist film formed thereon, and developing the exposed substrates.
This apparatus will be described with reference to a plan view shown in FIG.
1
. This substrate treating apparatus includes an indexer
103
having a cassette table
101
for receiving a plurality of cassettes C each containing a plurality of (e.g. 25) wafers W to be treated, or wafers W having been treated in treating units
104
described hereinafter, and a transport mechanism
108
a
movable horizontally along the cassettes C for transporting the wafers W between the cassettes C and treating units
104
. The apparatus further includes, besides the treating units
104
, a main substrate transport path
105
along which the wafers W are transported from one treating unit
104
to another, and an interface
106
for transferring the wafers W between the treating units
104
and an external treating apparatus
107
.
The external treating apparatus
107
is an apparatus separate from the substrate treating apparatus, and is detachably attached to the interface
106
of the substrate treating apparatus. Where the substrate treating apparatus is designed for resist application and development as noted above, the external treating apparatus
107
is an exposing apparatus for exposing the wafers W.
The substrate treating apparatus further includes a main transport mechanism
108
b
movable along the main substrate transport path
105
, and a transport mechanism
108
c
movable along a transport path of the interface
106
. In addition, a table
109
a
is disposed at a connection between the indexer
103
and main substrate transport path
105
, and a table
109
b
at a connection between the main substrate transport path
105
and interface
106
.
The above substrate treating apparatus performs substrate treatment through the following procedure. The transport mechanism
108
a
takes one wafer W out of a cassette C containing wafers W to be treated, and transports this wafer W to the table
109
a
to pass the wafer W to the main transport mechanism
108
b.
The main transport mechanism
108
b,
after receiving the wafer W placed on the table
109
a,
transports the wafer W into each treating unit
104
for a predetermined treatment (e.g. resist application) in the treating unit
104
. Upon completion of each predetermined treatment, the main transport mechanism
108
b
takes the wafer W out of the treating unit
104
, and transports the wafer W into another treating unit
104
for a next treatment (e.g. heat treatment).
The plurality of treating units
104
include those for performing heat treatment (hereinafter called “heat-treating units” as appropriate). Some heat-treating units
104
perform, for example, heat treatment after resist application for heat-treating the wafers with photoresist film formed thereon, and other heat-treating units
104
perform heat treatment after exposure for heat-treating the wafers having undergone an exposing process to be described hereinafter. Each heat-treating unit
104
has a hot plate for heating wafers W and a cool plate for cooling the wafers W having been heated, the two plates being arranged one above the other, and a local transport mechanism separate from and independent of the main transport mechanism
108
b
for transporting the wafers W between the hot plate and cool plate.
The local transport mechanism is provided for each heat-treating unit separately from the main transport mechanism
108
b
for the following reasons. For the two types of heat treatment after resist application and after exposure noted above, the time taken after a fixed time of heating by the hot plate until the cooling treatment by the cool plate is extremely important from the processing point of view. Variations in that time (i.e. cooling starting time after the heating treatment) would cause variations in film thickness after the resist application or variations in line-width uniformity after the development. If, for example, the main transport mechanism
108
b
transported the wafer W also between the hot plate and cool plate in each heat-treating unit, it would be difficult to cool, immediately after heating, all of the wafers successively loaded for treatment, because of the time taken in transport to other treating units
104
and the time taken in treatment in other treating units
104
. This would result in a so-called overbaking or variations in the cooling starting time after the heating treatment. Thus, the independent local transport mechanism is provided separately from the main transport mechanism
108
b
to ensure a fixed cooling starting time after the heating treatment.
Further, if the same main transport mechanism were used to transfer wafers to and from the hot plate, the main transport mechanism would become heated and inadvertently apply heat to the wafers. This would affect treatment in other treating units
104
such as resist application and development. The independent local transport mechanism is provided to avoid such an inconvenience also.
After the series of pre-exposure treatment is completed, the main transport mechanism
108
b
transports the wafer W treated in the treating units
104
to the table
109
b,
and deposits the wafer on the table
109
b
to pass the wafer W to the transport mechanism
108
c.
The transport mechanism
108
c
receives the wafer W placed on the table
109
b
and transports the wafer W to the external treating apparatus
107
. The transport mechanism
108
c
loads the wafer W into the external treating apparatus
107
and, after a predetermined treatment (e.g. exposure), takes the wafer W out of the external treating apparatus
107
to transport it to the table
109
b.
Subsequently, the main transport mechanism
108
b
transports the wafer W to the treating units
104
where a series of post-exposure heating and cooling treatment and development is performed. The wafer W having gone through all the treatment is loaded by the transport mechanism
108
a
into a predetermined cassette C. The cassette C is transported away from the cassette table
101
to complete a series of substrate treatment.
The conventional apparatus having such a construction has the following drawback.
The conventional substrate treating apparatus has the local transport mechanism in each heat-treating unit for transporting the wafer W between the hot plate and cool plate to secure a fixed cooling starting time after heating treatment as noted above. In this way, an effort is made for improvement in substrate treating precision. However, variations still occur in substrate treating precision; substrates cannot be treated with high precision.
SUMMARY OF THE INVENTION
This invention has been having regard to the state of the art noted above, and its object is to provide a substrate treating apparatus for treating substrates with high precision.
To solve the problem noted above, Inventor has made intensive research and attained the following findings. In the conventional substrate treating apparatus, the local transport mechanism of the heat-treating unit is provided for transporting wafers W between the hot plate and cool plate. The local transport mechanism accesses the hot plate or cool plate in time of wafer transport, and stands by outside the hot plate and cool plate at other times. That is, the local transport mechanism of the heat-treating unit has a standby position set outside the hot plate and cool plate, and stands by in the environment outside the heat-treating unit after transporting a wafer to
Dainippon Screen Mfg. Co,. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Rutledge D.
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