U.S. patent number RE40,052 [Application Number 10/420,917] was granted by the patent office on 2008-02-12 for heat treatment apparatus.
This patent grant is currently assigned to Tokyo Electron Limited. Invention is credited to Nobuyuki Sata, Eiichi Shirakawa.
United States Patent |
RE40,052 |
Shirakawa , et al. |
February 12, 2008 |
Heat treatment apparatus
Abstract
A heat treatment table is divided into two or more regions, a
heater is disposed for each region. On a predetermined portion of
the heat treatment table, a plurality of sensors are disposed
separately each other. A relation between temperatures of the
respective portions on the heat treatment table and temperatures
detected by the sensors is grasped in advance, thereby enables to
surmise a temperature of the respective portion of the heat
treatment table from the temperature detected by the sensors. In
the case of an wafer being actually treated by placing on the heat
treatment table, the temperatures detected by the sensors are
observed, from these detected temperatures, the temperatures of the
respective portions on the heat treatment table, that is,
temperatures affecting the wafer, are surmised.
Inventors: |
Shirakawa; Eiichi (Kumamoto,
JP), Sata; Nobuyuki (Kumamoto, JP) |
Assignee: |
Tokyo Electron Limited (Tokyo,
JP)
|
Family
ID: |
27276169 |
Appl.
No.: |
10/420,917 |
Filed: |
April 23, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09226606 |
Jan 7, 1999 |
06222161 |
Apr 24, 2001 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Jan 12, 1998 [JP] |
|
|
10-004222 |
Jan 19, 1998 [JP] |
|
|
10-007920 |
Jan 19, 1998 [JP] |
|
|
10-007921 |
|
Current U.S.
Class: |
219/390; 392/416;
118/725 |
Current CPC
Class: |
H01L
21/67109 (20130101); H01L 21/67248 (20130101) |
Current International
Class: |
F27B
5/14 (20060101) |
Field of
Search: |
;219/390,405,411
;392/416,418 ;118/724,725,50.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Paik; Sang Y.
Attorney, Agent or Firm: Rader, Fishman & Grauer
PLLC
Claims
What is claimed is:
1. A heat treatment apparatus, which comprises: a heat treatment
table thereon a substrate to be treated is disposed.Iadd., the heat
treatment table being concentrically divided into a plurality of
regions.Iaddend.; .[.two or more.]. .Iadd.a plurality .Iaddend.of
heaters .[.heating each regions obtained by dividing the heat
treatment table into two or more.]. .Iadd.concentrically disposed
in respective regions of the heat treatment table.Iaddend.; .[.at
least one sensor.]. .Iadd.a plurality of sensors for
.Iaddend.detecting .Iadd.a .Iaddend.temperature of .[.the.].
.Iadd.a .Iaddend.predetermined portion of the heat treatment
table.Iadd., the plurality of sensors comprising a first group of
sensors disposed in a horizontal direction of the heat treatment
table and a second group of sensors disposed in a vertical
direction of the heat treatment table.Iaddend.; .[.a.]. means for
surmising .[.the.]. .Iadd.a .Iaddend.temperature of each
.[.portions.]. .Iadd.region .Iaddend.of the heat treatment table
based on the .[.detected temperature.]. .Iadd.temperatures detected
by the first and second group of sensors.Iaddend.; and .[.a.].
means for controlling output of .[.the.]. each .[.heaters.].
.Iadd.heater .Iaddend.based on the .[.detected.]. .Iadd.surmised
.Iaddend.temperature .Iadd.of each region .Iaddend.so that the
temperature of the entire heat treatment table is uniform.[.;
wherein each of the heaters disposed on the heat treatment table
are disposed concentric, and sensors are disposed in a thickness
direction.]. .
2. The heat treatment apparatus as set forth in claim 1.Iadd.,
wherein.Iaddend.: .[.wherein.]. the .Iadd.surmising .Iaddend.means
.[.for surmising the temperature is.]. .Iadd.comprises .Iaddend.an
arithmetic unit which is connected to the .[.sensor.].
.Iadd.sensors; .Iaddend.and.[., based on the detected temperature,
surmises mathematically the temperatures of the each portions of
the heat treatment table;.]. .[.wherein.]. the controlling means
.[.is.]. .Iadd.comprises .Iaddend.a control unit which is connected
to the arithmetic unit.[.and, based on the surmised temperatures of
the each portions, controls the output of the each heaters so that
the temperature of the entire heat treatment table is uniform.].
.
3. A heat treatment apparatus, which comprises: a heat treatment
table thereon a substrate to be treated is disposed.Iadd., the heat
treatment table being concentrically divided into a plurality of
regions.Iaddend.; .[.two or more.]. .Iadd.a plurality .Iaddend.of
heaters .[.heating each regions obtained by dividing the heat
treatment table into two or more regions.]. .Iadd.concentrically
disposed in respective regions of the heat treatment
table.Iaddend.; .[.at least one sensor.]. .Iadd.a plurality of
sensors for .Iaddend.detecting .Iadd.a .Iaddend.temperature of
.[.the.]. .Iadd.a .Iaddend.predetermined portion of the heat
treatment table.Iadd., the plurality of sensors comprising a first
group of sensors disposed in a horizontal direction of the heat
treatment table and a second group of sensors disposed in a
vertical direction of the heat treatment table.Iaddend.; .[.a.].
means for surmising .Iadd.an .Iaddend.amount of heat .Iadd.to be
.Iaddend.supplied to each .[.portions.]. .Iadd.region .Iaddend.of
the substrate to be treated based on the .[.detected temperature.].
.Iadd.temperatures detected by the first and second groups of
sensors.Iaddend.; and .[.a.]. means for controlling output of
.[.the.]. each .[.heaters.]. .Iadd.heater .Iaddend.based on the
surmised amount of heat so that the amount of heat supplied to the
substrate to be treated is uniform.[.; wherein each of the heaters
disposed on the heat treatment table are disposed concentric, and
sensors are disposed in a thickness direction.]. .
4. The heat treatment apparatus as set forth in claim 3.Iadd.,
wherein.Iaddend.: .[.wherein.]. the .Iadd.surmising .Iaddend.means
.[.for surmising the temperature is.]. .Iadd.comprises .Iaddend.an
arithmetic unit which is connected to the .[.sensor and, based on
the detected temperature, surmises mathematically the amount of
heat supplied to the each portions of the substrate to be
treated.]. .Iadd.sensors.Iaddend.; .Iadd.and .Iaddend.
.[.wherein.]. the controlling means .[.is.]. .Iadd.comprises
.Iaddend.a control unit which is connected to the arithmetic
unit.[.and, based on the surmised temperatures of the each
portions, controls the output of the each heaters so that the
amount of heat supplied to the substrate to be treated is
uniform.]. .
5. The heat treatment apparatus as set forth in claim 1, further
.[.comprises.]. .Iadd.comprising.Iaddend.: a cover assembly which
is disposed opposite to the heat treatment table above the heat
treatment table and evacuates a gas heated by the heat treatment
table.Iadd., the cover assembly having a plurality of upper heaters
disposed on a surface opposite to the heat treatment table, the
upper heaters being divided into a plurality of concentric groups
of heaters, each of concentric groups of heaters further comprising
a plurality of independent heaters.Iaddend..[.; wherein, on the
surface opposite to the heat treatment table of the cover assembly,
a plurality of upper heaters are disposed divided concentric.].
.
6. The heat treatment apparatus as set forth in claim 3,
.[.which.]. further .[.comprises.]. .Iadd.comprising.Iaddend.: a
cover assembly which is disposed opposite to the heat treatment
table above the heat treatment table and evacuates a gas heated by
the heat treatment table.Iadd., the cover assembly having a
plurality of upper heaters disposed on a surface opposite to the
heat treatment table, the upper heaters being divided into a
plurality of concentric groups of heaters, each of concentric
groups of heaters further comprising a plurality of independent
heaters.Iaddend..[.; wherein, on the surface opposite to the heat
treatment table of the cover assembly, a plurality of upper heaters
are disposed divided concentric.]. .
7. The heat treatment apparatus as set forth in claim 1.Iadd.,
wherein.Iaddend.: .Iadd.the controlling means comprises a memory
element storing a reference table which specifies the temperature
of each region of the heat treatment table through the detected
temperatures of the predetermined portions; and.Iaddend. .Iadd.the
surmising means surmises the temperature of each region of the heat
treatment table based on the reference table stored in the memory
element.Iaddend. .[.wherein thus each heaters disposed to the heat
treatment table are disposed concentric, and sensors are disposed
in one line in a diameter direction of the heat treatment table..].
.
8. The heat treatment apparatus as set forth in claim .[.1.].
.Iadd.7, wherein.Iaddend.: .Iadd.the reference table stored in the
memory element further specifies a power supply to the heaters
based on the surmised temperatures; and the controlling means
controls the output of each heater based on the reference table
stored in the memory element.Iaddend. .[.wherein the each heaters
disposed on the heat treatment table are disposed concentric, and
sensors are disposed in one line in a diameter direction and in a
thickness direction..]. .
9. The heat treatment apparatus as set forth in claim 3.Iadd.,
wherein.Iaddend.: .Iadd.the controlling means comprises a memory
element storing a reference table which specifies the amount of
heat supplied to each region of the substrate through the detected
temperatures of the predetermined portions; and the surmising means
surmises the amount of heat supplied to each region of the
substrate based on the reference table stored in the memory
element.Iaddend. .[.wherein the each heaters disposed to the heat
treatment table are disposed concentric, and sensors are disposed
in one line in a diameter direction..].
10. The heat treatment apparatus as set forth in claim .[.3.].
.Iadd.9, wherein.Iaddend.: .Iadd.the reference table stored in the
memory element further specifies a power supply to the heaters
based on the surmised amount of heat; and the controlling means
controls the output of each heater based on the reference table
stored in the memory element.Iaddend. .[.wherein the each heaters
disposed on the heat treatment table are disposed concentric, and
sensors are disposed in one line in a diameter direction and in a
thickness direction.]. .
11. The heat treatment apparatus .Iadd.as .Iaddend.set forth in
claim 1, further comprising: .[.a first heating means for heating a
lower surface of a substrate to be treated to a predetermined
temperature; and a second heating means for.]. .Iadd.an upper
heater unit .Iaddend.heating an upper surface of the substrate to
be treated at a temperature higher than .[.the first heating
means.]. .Iadd.a temperature of the heaters.Iaddend..
12. The heat treatment apparatus as set forth in claim 11,
.[.which.]. further .[.comprises.]. .Iadd.comprising.Iaddend.:
.[.a.]. means for controlling the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.to a temperature where the
substrate to be treated is exposed to heat treatment at an aimed
temperature.
13. A heat treatment apparatus as set forth in claim 12,
.[.which.]. further .[.comprises.]. .Iadd.comprising.Iaddend.:
.[.a.]. means for detecting .[.the.]. .Iadd.a .Iaddend.temperature
of the substrate to be treated; wherein .[.the controlling means is
a means for controlling the second heating means,.]. .Iadd.the
upper heater unit controlling means controls the upper heater unit
.Iaddend.based on the detected temperature of the substrate to be
treated, so that a temperature of heat treatment of the substrate
to be treated is an aimed temperature.
14. The heat treatment apparatus as set forth in claim 12.Iadd.,
further comprising a cover assembly which is disposed opposite to
the heat treatment table above the heat treatment table and
evacuates a gas heated by the heat treatment table,
wherein.Iaddend.: .[.wherein the first heating means is a heating
plate thereon a substrate to be treated is disposed, and which
comprises further a cover assembly which is disposed opposite to
the heating plate above the heating plate and evacuates a gas
heated by the heating plate;.]. the .[.second heating means is.].
.Iadd.upper heater unit comprises .Iaddend.at least one heater
disposed on a surface of the cover assembly opposed to the
.[.heating plate.]. .Iadd.heat treatment table.Iaddend.; and the
controlling means comprises .[.a first control unit for maintaining
the heating plate at a predetermined temperature, and a second
control unit.]. .Iadd.the upper heater unit controlling means
.Iaddend.for adjusting the heater to a temperature which is higher
than .[.the heating plate.]. .Iadd.a temperature of the heat
treatment table .Iaddend.and under which the substrate to be
treated is treated at an aimed temperature.
15. The heat treatment apparatus as set forth in claim 12.Iadd.,
further comprising.Iaddend.: .Iadd.a cover assembly which is
disposed opposite to the heat treatment table above the heat
treatment table and evacuates a gas heated by the heat treatment
table; and means for detecting a temperature of the substrate to be
treated, wherein:.Iaddend. .[.wherein the first heating means is a
heating plate thereon a substrate to be treated is disposed, and
which comprises further a cover assembly which is disposed opposite
to the heating plate above the heating plate and evacuates a gas
heated by the heating plate, and a sensor for detecting the
temperature of the substrate to be treated;.]. the .[.second
heating means is.]. .Iadd.upper heater unit comprises .Iaddend.at
least one heater disposed on a surface of the cover assembly
opposed to the .[.heating plate.]. .Iadd.heat treatment
table.Iaddend.; and the controlling means comprises .[.a first
control unit for maintaining the heating plate at a predetermined
temperature, and a second control unit.]. .Iadd.the upper heater
unit controlling means .Iaddend.for adjusting the heater, based on
the detected temperature of the substrate to be treated, to a
temperature which is higher than .[.the heating plate.]. .Iadd.a
temperature of the heat treatment table .Iaddend.and under which
the substrate to be treated is treated at an aimed temperature.
16. The heat treatment apparatus as set forth in claim 14: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is divided into a plurality of
heaters capable of turning on and off an electric power source
independently.
17. The heat treatment apparatus as set forth in claim 14: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is disposed concentric.
18. The heat treatment apparatus as set forth in claim 17: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is divided into two or more parts
along a diameter direction.
19. The heat treatment apparatus as set forth in claim 14: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is a gradation heater of which
heating capacity is continuously inclined from the center of the
cover assembly to the periphery portion.
20. The heat treatment apparatus as set forth in claim 14: wherein
the .[.the heating plate is a thermal surface plate which
maintains.]. .Iadd.heat treatment table is maintained at .Iaddend.a
predetermined temperature by heating medium vapor circulating
inside thereof.
21. The heat treatment apparatus as set forth in claim 14: wherein,
on a lower surface side of the cover assembly, a flat surface
opposite to the .[.heating plate.]. .Iadd.heat treatment table
.Iaddend.is formed.
22. The heat treatment apparatus as set forth in claim .[.8.].
.Iadd.7, wherein.Iaddend.: .[.wherein.]. the .Iadd.surmising
.Iaddend.means .[.for surmising the temperature is.].
.Iadd.comprises .Iaddend.an arithmetic unit which is connected to
the .Iadd.sensors; and .Iaddend..[.sensor and, based on the
detected temperature, surmises mathematically the temperatures of
the each portions of the heat treatment table;.]. .[.wherein.]. the
controlling means .[.is.]. .Iadd.comprises .Iaddend.a control unit
which is connected to the arithmetic unit .[.and, based on the
surmised temperatures of the each portions, controls the output of
the each heaters so that the temperature of the entire heat
treatment table is uniform.]. .
23. The heat treatment apparatus as set forth in claim 8.Iadd.,
wherein.Iaddend.: .Iadd.the surmising means comprises an arithmetic
unit which is connected to the sensors; and the controlling means
comprises a control unit which is connected to the arithmetic
unit.Iaddend. .[.wherein each of the heaters disposed to the heat
treatment table are disposed concentric, and sensors are disposed
in one line in a diameter direction of the heat treatment table.].
.
24. The heat treatment apparatus as set forth in claim .[.10.].
.Iadd.9, wherein.Iaddend.: .[.wherein.]. the .Iadd.surmising
.Iaddend.means .[.for surmising the temperature is.].
.Iadd.comprises .Iaddend.an arithmetic unit which is connected to
the .[.sensor and, based on the detected temperature, surmises
mathematically the amount of heat supplied to the each portions of
the substrate to be treated.]. .Iadd.sensors.Iaddend.; .Iadd.and
.Iaddend. .[.wherein.]. the controlling means .[.is.].
.Iadd.comprises .Iaddend.a control unit which is connected to the
arithmetic unit .[.and, and based on the surmised temperatures of
the each portions, controls the output of the each heaters so that
the amount of heat supplied to the substrate to be treated is
uniform.]. .
25. The heat treatment apparatus as set forth in claim 10.Iadd.,
wherein.Iaddend.: .Iadd.the surmising means comprises an arithmetic
unit which is connected to the sensors; and the control means
comprises a control unit which is connected to the arithmetic
unit.Iaddend. .[.wherein each of the heaters disposed to the heat
treatment table are disposed concentric, and sensors are disposed
in one line in a diameter direction.]. .
26. The heat treatment apparatus as set forth in claim 3, further
comprising: .[.a first heating means for heating a lower surface of
a substrate to be treated to a predetermined temperature; and.].
.[.a second heating means for.]. .Iadd.an upper heater unit
.Iaddend.heating an upper surface of the substrate to be treated at
a temperature higher than .[.the first heating means.]. .Iadd.a
temperature of the heaters.Iaddend..
27. The heat treatment apparatus as set forth in claim 26,
.[.which.]. further .[.comprises.]. .Iadd.comprising.Iaddend.:
.[.a.]. means for controlling the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.to a temperature where the
substrate to be treated is exposed to heat treatment at an aimed
temperature.
28. The heat treatment apparatus as set forth in claim 27,
.[.which.]. further .[.comprises.]. .Iadd.comprising.Iaddend.:
.[.a.]. means for detecting .[.the.]. .Iadd.a .Iaddend.temperature
of the substrate to be treated; wherein .[.the controlling means is
a means for controlling the second heating means,.]. .Iadd.the
upper heater unit controlling means controls the upper heater unit
.Iaddend.based on the detected temperature of the substrate to be
treated, so that a temperature of heat treatment of the substrate
to be treated is an aimed temperature.
29. The heat treatment apparatus as set forth in claim 27.Iadd.,
further comprising a cover assembly which is disposed opposite to
the heat treatment table above the heat treatment table and
evacuates a gas heated by the heat treatment table,
wherein.Iaddend.: .[.wherein the first heating means is a heating
plate thereon a substrate to be treated is disposed, and which
comprises further a cover assembly which is disposed opposite to
the heating plate above the heating plate and evacuates a gas
heated by the heating plate;.]. the .[.second heating means is.].
.Iadd.upper heater unit comprises .Iaddend.at least one heater
disposed on a surface of the cover assembly opposed to .[.heating
plate.]. .Iadd.heat treatment table.Iaddend.; and the controlling
means comprises .[.a first control unit for maintaining the heating
plate at a predetermined temperature, and a second control unit.].
.Iadd.the upper heater unit controlling means .Iaddend.for
adjusting the heater to a temperature which is higher than .[.the
heating plate.]. .Iadd.a temperature of the heat treatment table
.Iaddend.and under which the substrate to be treated is treated at
an aimed temperature.
30. The heat treatment apparatus as set forth in claim 27.Iadd.,
further comprising.Iaddend.: .Iadd.a cover assembly which is
disposed opposite to the heat treatment table above the heat
treatment table and evacuates a gas heated by the heat treatment
table; and means for detecting a temperature of the substrate to be
treated, wherein:.Iaddend. .[.wherein the first heating means is a
heating plate thereon a substrate to be treated is disposed, and
which comprises further a cover assembly which is disposed opposite
to the heating plate above the heating plate and evacuates a gas
heated by the heating plate, and a sensor for detecting the
temperature of the substrate to be treated;.]. the .[.second
heating means is.]. .Iadd.upper heater unit comprises .Iaddend.at
least one heater disposed on a surface of the cover assembly
opposed to the .[.heating plate.]. .Iadd.heat treatment
table.Iaddend.; and the controlling means comprises .[.a first
control unit for maintaining the heating plate at a predetermined
temperature, and a second control unit.]. .Iadd.the upper heater
unit controlling means .Iaddend.for adjusting the heater, based on
the detected temperature of the substrate to be treated, to a
temperature which is higher than .[.the heating plate.]. .Iadd.a
temperature of the heat treatment table .Iaddend.and under which
the substrate to .[.he.]. .Iadd.be .Iaddend.treated is treated at
an aimed temperature.
31. The heat treatment apparatus as set forth in claim 29: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is divided into a plurality of
heaters capable of turning on and off an electric power source
independently.
32. The heat treatment apparatus as set forth in claim 29: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is disposed concentric.
33. The heat treatment apparatus as set forth in claim 32: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is divided into two or more parts
along a diameter direction.
34. The heat treatment apparatus as set forth in claim 29: wherein
.[.the.]. at least one heater of the .[.second heating means.].
.Iadd.upper heater unit .Iaddend.is a gradation heater of which
heating capacity is continuously inclined from the center of the
cover assembly to the periphery portion.
35. The heat treatment apparatus as set forth in claim 29: wherein
the .[.heating plate is a thermal surface plate which maintains.].
.Iadd.heat treatment table is maintained at .Iaddend.a
predetermined temperature by heating medium vapor circulating
inside thereof.
36. The heat treatment apparatus as set forth in claim 29: wherein,
on a lower surface side of the cover assembly, a flat surface
opposite to the .[.heating plate.]. .Iadd.heat treatment table
.Iaddend.is formed.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat treatment apparatus such as
a heater or a pre-heater to be assembled in a semiconductor
manufacturing system for manufacturing semiconductor elements by
use of a photomechanical process, for instance.
2. Description of the Related Art
Conventionally, in a semiconductor manufacturing system which
employs a photomechanical process, various kinds of treatment units
such as a resist coating unit, a drying unit, a heating unit and
the like are assembled in one system. And, a string of treatments
are carried out while transferring among these various kinds of
treatment units in turn.
FIG. 12 shows a vertical cross section of a typical heat treatment
unit 500.
In this heat treatment unit 500, a semiconductor wafer (hereinafter
simply refers to as "wafers") W is disposed on an upper surface of
a heat treatment table 501, and the wafer W is heated by heat
evolved from the heat treatment table 501. In this heat treatment
table 501, a heating mechanism which is not shown in the figure is
integrated, the heat treatment table 501 is heated by heat supplied
from this heating mechanism. On the upper surface of the heat
treatment table 501, there are disposed a plurality of small
projections which are not shown in the figure, the wafer W is
disposed on the tops of these small projections, thus the lower
surface of the wafer W is designed to be prevented from being
scratched or stuck by dust due to contact between the lower surface
of the wafer W and the upper surface of the heat treatment table
501. Therefore, between the lower surface of the wafer W and the
upper surface of the heat treatment table 501, minute gaps are
formed, and, from the upper surface of the heat treatment table
501, heat is supplied to the lower surface of the wafer W through a
gas, for instance, a nitrogen gas in the gaps. The gas heated by
the heat treatment table 501 and the wafer W, being smaller in its
specific gravity than that of the surrounding air of lower
temperature, ascends within the heat treatment unit 500, is
collected in a cover assembly 502 disposed oppositely above the
heat treatment table 501, and is evacuated through a piping 504
connected to the top 503 of the cover assembly 502.
Now, an wafer W is liable to be affected by heat. Thus, when the
heat treatment temperature goes out of its allowed range, the
quality of the semiconductor products deteriorates to lead to a
lower yield, resulting in an increase of the manufacturing cost.
Therefore, in such the heat treatment unit 500 as described above,
a temperature sensor such as a thermocouple is inserted within the
heat treatment table 501, temperature control is carried out based
on the temperature detected thereby.
However, the temperature distribution of the heat treatment table
is not necessarily uniform, thus correct detection of the
temperature is difficult. To be correct, the temperatures are
required to be measured directly of the respective parts by
disposing a plurality of heaters and temperature sensors for the
respective parts. However, since many temperature sensors are
necessary, there are such problems that the (manufacturing cost of
the apparatus goes up and the structure of the apparatus becomes
complicated.
In addition, in such the conventional heat treatment unit 500 as
described above, in order to heat enough the gas between the upper
surface of the heat treatment table 501 and the lower surface of
the wafer W, the temperature of the heat treatment table 501 is
required to be heated higher than the treatment temperature of the
wafer W.
However, heat transmission from the heat treatment table 501 to the
wafer W is not uniform, accordingly the heat tends to linger above
the center of the wafer W, affecting a higher temperature there
than the surroundings.
As the result, the heat treatment becomes nonuniform, the quality
of the semiconductor elements formed on the wafer W tends to
fluctuate, thereby produces problems that the yield of the
semiconductor elements becomes low and the manufacturing cost of
the semiconductor elements goes up.
The present invention was made to solve such problems. The
objective of the present invention is to provide a heat treatment
apparatus which is capable of implementing a uniform heat treatment
all over the whole wafer W.
Another objective of the present invention is to provide a heat
treatment apparatus which is capable of carrying out an accurate
temperature control during the heat treatment of the wafer W.
SUMMARY OF THE INVENTION
The present invention was made to solve such problems. Still
another objective of the present invention is to provide a heat
treatment apparatus which is capable of controlling accurately the
temperature with a small number of temperature sensors, accordingly
capable of carrying out a uniform heat treatment all over the whole
wafer W.
Further, still another objective of the present invention is to
provide a heat treatment apparatus which is capable of carrying out
an accurate temperature control during the heat treatment of the
wafer W.
A heat treatment apparatus of the first invention, comprises: a
heat treatment table thereon a substrate to be treated is disposed;
two or more heaters for heating the each areas of the heat
treatment table divided into two or more areas; at least a sensor
detecting the temperature of the predetermined area of the heat
treatment table; a means for predicting the temperatures of the
each areas of the heat treatment table based on the detected
temperature; and a means for controlling the output of the each
heaters based on the temperatures predicted for the each areas so
that the temperature of the whole heat treatment table becomes
uniform.
Further, another embodiment of a heat treatment apparatus of the
first invention, comprises: a heat treatment table thereon a
substrate to be treated is disposed; two or more heaters for
heating the each areas of the heat treatment table divided into two
or more areas; at least one sensor for detecting the temperature of
the predetermined area of the heat treatment table; a means for
predicting an amount of heat to be supplied to the each area of the
substrate to be heat treated based on the detected temperatures;
and a means for controlling the output of the each heaters based on
the predicted amount of heat so that the amount of heat to be
supplied to the substrate to be treated becomes uniform.
The heat treatment apparatus of the second invention comprises a
heating means for heating the lower surface of the substrate to be
treated, and a means for cooling the gas heated to the
predetermined temperature or more by the heating means above the
substrate to be treated.
The heat treatment apparatus involving another embodiment of the
second invention comprises a heating means for heating a lower
surface of a substrate to be treated, a means for evacuating the
gas heated by the heating means from an above portion of the
substrate to be treated, a means for detecting the temperature
affecting on the substrate to be treated, and a means for cooling,
based on the detected temperature, the gas passing the above
portion of the substrate to be treated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view showing an entire structure of a
coating/developing system involving the embodiment of the first
invention.
FIG. 2 is a front view of a coating/developing system involving the
embodiment of the first invention.
FIG. 3 is a rear view of a coating/developing system involving the
embodiment of the first invention.
FIG. 4 is a plan view showing a constitution of a heat treatment
unit involving the embodiment of the first invention.
FIG. 5 is a cross-section of a heat treatment unit involving the
embodiment of the first invention.
FIG. 6 is a plan view of a heat treatment table involving the
embodiment of the first invention.
FIG. 7 is a vertical cross section of a heat treatment table
involving the embodiment of the first invention.
FIG. 8 is a block diagram showing a control system of a heat
treatment unit involving the embodiment of the first invention.
FIG. 9 is a vertical cross section of a heat treatment unit
involving another embodiment of the first invention.
FIG. 10 is a plan view showing a state seen from the lower side of
a cover assembly and involving another embodiment of the first
invention.
FIG. 11 is a block diagram illustrating a control system of a heat
treatment unit involving another embodiment of the first
invention.
FIG. 12 is a vertical cross section of a conventional heat
treatment unit.
FIG. 13 is a vertical cross section of a cover assembly involving
the embodiment of the second invention.
FIG. 14 is a plan view of a state seen from the lower side of a
cover assembly and involving the embodiment of the second
invention.
FIG. 15 is a vertical cross section showing schematically a
structure in the neighborhood of a thermal surface plate involving
the embodiment of the second invention.
FIG. 16 is a block diagram showing a control system of a heat
treatment unit involving the embodiment of the second
invention.
FIG. 17 is a diagram showing relation between the temperature of
heat treatment of a heat treatment unit, temperature of wafer W,
and temperature of jacket involving the embodiment of the second
invention.
FIG. 18 is a vertical cross section of a cover assembly involving
the embodiment of the third invention.
FIG. 19 is a plan view of a state seen from the lower side of a
cover assembly and involving the embodiment of the third
invention.
FIG. 20 is a vertical cross section showing schematically a
structure of the surroundings of a thermal surface plate involving
the embodiment of the third invention.
FIG. 21 is a block diagram illustrating a control system of a heat
treatment unit involving the embodiment of the third invention.
FIG. 22 is a diagram showing relation between temperature of heat
treatment of the heat treatment unit, temperature of wafer W, and
temperature of heater involving the embodiment of the third
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
EXAMPLE 1
In the following, the detailed description of the embodiments of
the present invention will be given based on the drawings.
Incidentally, the scope of the present invention should not be
construed to be restricted to that of the following
embodiments.
FIG. 1 is a plan view showing the entire of a coating/developing
system 1 of semiconductor wafers (hereinafter simply refer to as
"wafer") which is provided with a resist coating unit (COT)
involving one embodiment of the present invention.
In this coating/developing system 1, a cassette station 10 which
carries in/out wafers, subjects to be treated, from the
outside/inside by a wafer cassette CR by a plurality of pieces,
that is, by a unit of 25 pieces for instance, or which carries
in/out the wafers W to/from the wafer cassette CR, a treatment
station 11 in which various kinds of treatment units of sheet-fed
type which carry out the predetermined treatments to the respective
wafers during the coating/development process are disposed
multistage, and an interface portion 12 which delivers the wafers W
between an exposure device (not shown in the figure) disposed
adjacent to the treatment station 11, are connected integrally.
In this cassette station 10, at the place of a positioning
projection 20a on a cassette stage 20, a plurality of pieces, up to
4 pieces for instance, of wafer cassettes CR are disposed directing
the inlet/outlet of the respective wafers towards the treatment
station 11 side in one line in X direction (the up and down
direction in FIG. 1). And a wafer carrier 21 capable of moving in
the direction where the cassettes are arranged (X direction) and in
the direction where the wafers W accommodated in the wafer cassette
CR are arranged (Z direction; vertical direction) makes a selective
approach to the respective wafer cassette CR.
This wafer carrier 21 is capable of rotating freely in .theta.
direction and also can make an approach to an alignment unit (ALM)
disposed to the multistage unit portion of the third treatment unit
group G.sub.3 on the treatment station 11 side which will be
described later or an extension unit (EXT).
To the treatment station 11, a main wafer carrying mechanism 22 of
vertically carrying type provided with a wafer carrier is disposed,
the entire treatment units are disposed multistage in the
surrounding thereof in one set or a plurality of sets.
FIG. 2 is a front view of the aforementioned coating/developing
system 1.
In the first treatment unit group G.sub.1, two sets of spinner type
treatment unit for carrying out the predetermined treatment while
holding an wafer W on a spin chuck in a cup CP, for instance a
resist coating unit (COT) and a developing unit (DEV), are stacked
in two stages from the bottom. In the second treatment unit group
G.sub.2, two sets of treatment unit of spinner type, for instance a
resist coating unit (COT) and a developing unit (DEV) are stacked
in two stages from the bottom. These resist coating units (COT),
since the waste liquid of the resist liquid is troublesome from the
mechanism and maintenance points of view, are preferable to be
disposed at the lower stage. However, as the need arises, they can
be disposed appropriately on the upper stage.
FIG. 3 is a rear view of the aforementioned coating/developing
system 1.
In the main wafer carrying mechanism 22, inside a cylindrical
supporter 49, an wafer carrier 46 is equipped movable freely in the
up and down direction (Z direction). The cylindrical holder 49 is
connected to a rotating axis of a motor (not shown in the figure),
and, by the rotating driving force of this motor, rotates together
with the wafer carrier 46 with the rotating axis as a center,
thereby the wafer carrier 46 is made capable of rotating freely in
the .theta. direction. Incidentally, the cylindrical supporter 49
may be constituted to be connected to another rotating axis (not
shown in the figure) which is rotated by the motor.
To the wafer carrier 46, a plurality of holding members which are
movable freely in the forward and backward direction of a carrier
base 47 are disposed, these holding members 48 enable delivery of
the wafers between the respective treatment units.
Further, as shown in FIG. 1, in this coating/developing system 1 5
groups of treatment unit G.sub.1, G.sub.2, G.sub.3, G.sub.4, and
G.sub.5 are possible to be disposed, multistage units of the first
and the second groups of treatment unit G.sub.1 and G.sub.2 are
disposed in a front (this side in FIG. 1) side of the system, a
multistage unit of the third group of treatment unit G.sub.3 is
disposed adjacent to the cassette station 10, a multistage unit of
the fourth group of treatment unit G.sub.4 is disposed adjacent to
an interface portion 12, and a multistage unit of the fifth group
of treatment unit G.sub.5 can be disposed on the rear side.
As shown in FIG. 3, in the third group of treatment unit G.sub.3,
an oven type treatment unit for carrying out the predetermined
treatment while holding the wafer W on a holding stage (not shown
in the figure), for instance, a cooling unit (COL) for cooling, an
adhesion unit (AD) for carrying out a so called hydrophobic
treatment in order to heighten fixing property of the resist, an
alignment unit for aligning (ALIM), an extension unit (EXT), a
pre-baking unit (PREBAKE) for carrying out heat treatment preceding
the exposure and a post-baking unit (POBAKE) for carrying out heat
treatment after exposure are stacked in turn, in eight stages for
instance, from the bottom. Even in the fourth group of treatment
unit G.sub.4, an oven type treatment unit, for instance a cooling
unit (COL), an extension cooling unit (EXTCOL), an extension unit
(EXT), a cooling unit (COL), a pre-baking unit (PREBAKE) and a
post-baking unit (POBAKE) are stacked in turn, in eight stages, for
instance, from the bottom.
By disposing the cooling unit (COL) and extension cooling unit
(EXTCOL) of low treatment temperature at the lower stage as
described above, and by disposing the pre-baking unit (PREBAKE),
post-baking unit (POBAKE) and adhesion unit (AD) of higher
treatment temperature at the upper stage, thermal interference
between units can be made small. Naturally, random multistage
disposition may be adopted.
As shown in FIG. 1, in the interface position 12, the depth
direction (X direction) possesses the dimension identical with the
aforementioned treatment station 11, however the breadth direction
(Y direction) possesses a smaller size. Or the front portion of
this interface portion 12, a portable pickup cassette CR and a
fixed buffer cassette BR are disposed in two stages, whereas, on
the rear portion, a periphery exposing device 23 is disposed,
further, in the central portion, an wafer carrier 24 is disposed.
This wafer carrier 24 makes an approach to both cassettes CR and
BR, and the periphery exposing apparatus 23 by moving in the X
direction and Z direction.
The wafer carrier 24 is capable of rotating freely even in .theta.
direction, and can make an approach to an extension unit (EXT)
disposed to the multistage unit of the fourth group of treatment
unit G.sub.4 on the treatment station 11 side, or an wafer delivery
table (not shown in the figure) on the side of the adjacent
exposing device.
Further, in the coating/developing treatment system 1, as described
above, even to the rear side of the main wafer carrying mechanism
22, a multistage unit of the fifth group of treatment unit G.sub.5
shown by the dotted lines in FIG. 1 may be disposed, however, the
multistage unit of the fifth group of treatment unit G.sub.5 can be
moved in Y direction along a guide rail 25. Therefore, even in the
case of the multistage unit of the fifth group of treatment unit
G.sub.5 being disposed as shown in the figure, by travelling along
the guide rail 25, a space can be secured. Therefore, a maintenance
operation to the main wafer carrying mechanism 22 can be carried
out readily from the back.
Next, with reference to FIG. 4 and FIG. 5, constitutions and
operations of the heat treatment unit such as baking units
(PREBAKE) and (PROBAKE) and a cooling unit (COL) and (EXTCOL) which
are included in the multistage units of the third and fourth groups
G.sub.3 and G.sub.4 in the treatment station 11 will be
described.
FIG. 4 and FIG. 5 are a plan view and a cross-sectional view
showing a constitution of a heat treatment unit involving the
present embodiment. Incidentally, in FIG. 5, a horizontal
separating plate 55 is omitted for an illustration.
A treatment room 50 of this heat treatment unit is formed of both
side walls 53 and the horizontal separating plates 55, and the
front side (the side of main wafer carrying mechanism 24) and the
rear side of the treatment room 50 are openings 50A and 50B,
respectively. At the central portion of the separating plate 55, a
circular opening 56 is formed, inside this opening 56, a disc like
heat treatment table 58 is disposed as a stage for setting an wafer
W.
To this heat treatment table 58, three holes 60, for instance, are
bored, inside the each hole 60, a supporting pin 62 is pierced with
play, and, when a semiconductor wafer W is loaded or unloaded, the
each supporting pin 62 projects or ascends above the front surface
of the heat treatment table 58, thereby delivery of the wafer W is
carried out between the holding member 48 of the main wafer
carrying mechanism 22.
On the exterior periphery of the heat treatment table 58, a shutter
66 consisting of a belt plate of ring shape in which many air holes
64 are formed with 2.degree. apart in a circumference direction is
disposed. This shutter 66 normally stays receded at a position
below the heat treatment table 58, however, during heat treatment,
ascends to the position higher than the upper surface of the heat
treatment table 58 as shown in FIG. 5, thereby forms a side wall of
ring shape between the heat treatment table 58 and the cover
assembly 68, thereby a down-flow inert gas, nitrogen gas for
instance, sent in from a gas supplying system not shown in the
figure, can be flowed in uniformly in the circumference direction
from the air holes 64.
At the central portion of the cover assembly 68, an exhausting
opening 68a is disposed to evacuate the gas evolved from the
surface of the wafer W during heat treatment, and, to this
exhausting opening 68a, an exhausting pipe 70 is connected. This
exhausting pipe 70 communicates with a duct 53 (or 54) of the front
side of the apparatus (the side of the main wafer carrying
mechanism 22) or a duct not shown in the figure.
Below the separating plate 55, a machine room 74 is formed out of
the separating plate 55, both side walls 53 and a bottom plate 72,
therein, a heat treatment table holding plate 76, a shutter arm 78,
a supporting pin arm 80, a cylinder 82 for driving the shutter arm
going up and down, and a cylinder 84 for driving the supporting pin
arm going up and down are disposed.
As shown in FIG. 4, on a surface position of the heat treatment
table 58 thereon the exterior periphery of the wafer W is placed, a
plurality of pieces, four pieces for instance, of supporting
projections 86 for guiding the wafer W are disposed.
Further, there are a plurality of small projections, which are not
shown in the figure, on a part, thereon an wafer W is placed, of a
upper surface of the heat treatment table 58, and the lower surface
of the wafer W is placed on the tops of these small projections.
Accordingly, there are formed minute spaces between the lower
surface of the wafer W and the upper surface of the heat treatment
table 58, thereby the lower surface of the wafer W is prevented
from touching directly with the upper surface of the heat treatment
table 58, thus even in the case of there being dust and the like,
the wafer W is prevented from contamination or scratching taking
place.
In addition, as will be described later, there are disposed a
plurality of heaters inside the heat treatment table 58, by heating
these heaters, the heat treatment table 58 can be maintained at the
predetermined temperature.
FIG. 6 is a plan view depicting schematically a structure of the
heat treatment table 58 involving an embodiment corresponding to
the first invention, and FIG. 7 is a vertical cross section
depicting schematically a structure of the same heat treatment
table 58.
As shown in FIG. 6, this heat treatment table 58 is formed of five
regions of from P1 through P5 of doughnut shape. These regions P1
through P5 are formed concentric, and, inside of P1 through P5,
there are disposed heaters H1 through H5 which are independent each
other, for instance, Nichrome heaters (not shown in the figure) are
formed in the doughnut shape as identical as the respective regions
P1 through P5. The heaters are wired independently each other,
thereby the amount of heat to be supplied to the respective regions
of P1 through P5 can be controlled independently each other.
To the second region P2 and the fourth region P4 from the outside
of the heat treatment table 58, holes for attaching sensors are
bored vertical, and into these holes, the sensor S1 and sensor S2
are attached vertical, respectively. These sensors detect the
temperature distribution in the horizontal direction of the heat
treatment table 58.
Further, from the direction of the right side surface in FIG. 6 of
the heat treatment table 58, there are bored holes of the
horizontal direction in parallel at two places up and down, these
holes reach up to the midway of the region P2 piercing through the
region P1.
As shown in FIGS. 6 and 7, also to these holes, sensors S3 and S4
are attached. These sensors S3 and S4 detect the temperature
distribution in the vertical direction of the heat treatment table
58.
FIG. 8 is a block diagram illustrating a control system of a heat
treatment unit involving the present embodiment.
As shown in FIG. 8, inside the respective regions of P1 through P5
of the heat treatment table 58, there are disposed heaters H1
through H5, respectively. These heaters H1 through H5 are connected
to a control unit 90, by this control unit 90 their output is
controlled. Further, the sensors S1 through S4 are also connected
to this control unit 90, thereby the temperatures of the respective
parts of the heat treatment table 58 are recognized by the control
unit 90.
Next, the way how to control the heat treatment unit involving the
present embodiment will be described.
In the heat treatment unit involving the present embodiment, the
temperatures of the predetermined parts of the heat treatment table
58 are detected, from these temperatures the temperature
distribution of the entire heat treatment table 58 is surmised.
Then, based on this surmised result, the output of the heaters H1
through H5 is controlled to prevent the thermal non-uniformity from
occurring.
In the concrete, concerning the temperature distribution in the
horizontal direction of the heat treatment table 58, the
temperature distribution of the entire heat treatment table is
surmised from the temperatures detected by the sensor S1 which is
disposed in the region P2 second from the periphery of the heat
treatment table 58 and the sensor S2 which is disposed in the
region P4 fourth from the periphery of the heat treatment
table.
For instance, when the same electric power is supplied to the
heaters H1 through H5, in the case of the heat treatment table 58
having a tendency that the temperature is the minimum at the region
P1, and as goes inside as P2, P3, . . . , goes up to the maximum at
the region P5, the correspondence between the respective
temperatures of the regions P2 and P4 where the sensors S1 and S2
are disposed and other regions P1, P3 and P5 than these is obtained
from the measured values or theoretical values. And, by formulating
a table which enables to specify the respective temperatures of the
regions P1, P3 and P5 through specification of the temperatures of
the sensors of S1 and S2 and the power supplies to the heaters of
H1 through H5, this is memorized in the memory elements of the
control unit.
Similarly, also in the case of the power supply to the heaters H1
through H5 being varied, the similar table is formulated, thereby
enables to specify the respective temperatures of the region P1, P3
and P5 by specifying the temperatures of the sensors S1 and S2 and
the respective power supplies tD the heaters H1 through H5.
Thus, from the temperature signals detected by the sensors S1 and
S2 and the power supply signals to the heaters H1 through H5, the
temperature distribution of the entire heat treatment table 58
including the regions P1, P3 and P5 is surmised.
Next, based on the surmised temperature distribution of the entire
heat treatment table 58, the electric power to be supplied to the
each heater H1 through H5 is adjusted to control the output of the
each heater of H1 through H5 so that the temperature of the enter
heat treatment table 58 becomes uniform.
In the concrete, based on the aforementioned table, the power
supply to the each heater is adjusted to control the output of the
each heater of H1 through H5 so that the regions P1 through P5
become uniform.
For instance, as mentioned above, in the case of the temperature of
the region P1 being the minimum and, as goes inside as P2, P3, . .
. , the temperature becoming higher to the maximum at the region
P5, the output of the each heater of the heaters H1 through H5 is
controlled to cancel such a thermal non-uniformity. That is, the
output of the heater H1 is made high, that of the heater H5 is made
low, and the output of the heaters H2 through H4 intervening them
is made incline to connect continuously from the heater H1 to the
heater H5. These output values of the heaters H1 through H5 also
are obtained based on the aforementioned table by use of the
temperatures of the regions P2 and P4 as the indicators.
Further, in the heat treatment unit involving the present
embodiment, also in the vertical direction of the heat treatment
table 58, the sensors S3 and S4 are disposed. And, based on the
temperatures detected by these sensors S3 and S4, the temperature
distribution in the vertical direction of the entire heat treatment
table 58 is surmised, thereby the temperature of the heat treatment
table 58 is administered.
In the concrete, with the sensors S3 and S4, the temperatures in
the vertical direction of the region P2 are detected. On the other
hand, the correspondence between the detected temperatures of the
sensors S3 and S4 and the temperature distribution in the vertical
direction of the each region of the P1 through P5 of the heat
treatment table 58, and the relation with the output of the each
heater of H1 through H5 are obtained in advance from the measured
values or the theoretically calculated values, they are memorized
as identically as the above in the memory part of the control
unit.
Then, with the temperatures detected by the sensors S3 and S4 at
two places, high and low, of the region P2 as the indicators, the
temperature distribution of the surface to the heat treatment table
58 is surmised. That is, from the temperatures of the region P2
detected by the sensors S3 and S4, by use of the aforementioned
table, the temperatures in the neighborhood of the surface of the
other region P1 and P3 through P5 are surmised. Then, in the case
of the surface temperature of each region of the regions P1 through
P5 being irregular, the output of the heaters H1 through H5 is
controlled by use of the aforementioned tables so that the surface
temperature of the heat treatment table 58 becomes uniform and
adequate.
Next, operation in the case of this heat treatment unit being
employed as a baking unit (PREBAKE) and cooling unit (COL) will be
described in the followings.
First, from inside an wafer cassette CR which is set on a stage 20,
an wafer W is pulled out by an wafer carrier 21, then the wafer W
is delivered from the wafer carrier 21 to a main wafer carrying
mechanism 22. The main wafer carrying mechanism 22 carries the
delivered wafer W into a resist coating unit (COT) and sets, here
resist coating is carried out on the wafer W. Then, the wafer W is
pulled out from inside the resist coating unit (COT) by the main
wafer carrying mechanism 22, carried into the aforementioned heat
treatment unit, and set on the heat treatment table 58.
On the other hand, at the same time with power input to the heat
treatment unit, power is began to be input to the heaters H1
through H5 within the heat treatment table 58. When the temperature
of the heat treatment table 58 becomes stable after the
predetermined time period elapsed, the control unit 90 starts to
operate to adjust the output of the heaters H1 through H5.
That is, with the sensors S1 and S2 disposed at the regions P2 and
P4, the temperature adjustment of the horizontal direction of the
heat treatment table 58 is carried out, thereby the heat treatment
table 58 is controlled so that the temperature is maintained
adequate and uniform.
For instance, in the case of the temperature being low in the
region P1, and, as the region goes inside as P2, P3, . . . ,
becoming high to be the maximum at the region P5, the output of the
heater H1 is made high, and, as the heater goes inside as H2, H3, .
. . , the output is made low to be the minimum at the heater
H5.
On the contrary, in the case of the temperature being high at the
region P1, and, as the region goes inside as P2, P3, . . . ,
becoming low to be the minimum temperature at the region P5, the
output of the heater H1 is made low, and, as the heater goes inside
as H2, H3, . . . , the output is increased to be the maximum at
heater H5.
Similarly, in the case of the temperatures of the regions P1 and P5
being low and the these of the regions P2 through P4 being high,
whereas the output of the heaters H1 and H5 are made high, the
output of the heaters H2 through H4 are made low. Here, for the
output value of the each heater of the aforementioned each case,
the most adequate value are obtained based on the aforementioned
tables, the output value being adjusted to these values.
Further, also as to the temperature distribution in the vertical
direction of the heat treatment table 58, similarly, based on the
temperature detected from the sensors S3 and S4 and the
aforementioned table, the temperature distribution on the surface
of the heat treatment table 58 is surmised, thereby the output of
the heaters H1 through H5 is controlled so that the temperature of
the entire surface of the heat treatment table 58 becomes adequate
and uniform.
Incidentally, in this embodiment, by controlling only the output of
the heaters H1 through H5, the temperature control of the heat
treatment table 58 is carried out, however, by other method than
this, for instance, by controlling the gas flow rate of the gas
supply system which supplies a gas such as a nitrogen gas from the
side direction of the heat treatment table 58, the temperature
control of the heat treatment table 58 can be carried out.
Thus, in the heat treatment unit involving the present embodiment,
whereas the heat treatment table is divided into a plurality of
regions to dispose a heater for every region, the sensors detecting
the temperatures of the heat treatment table are disposed only for
the predetermined parts. On the other hand, the thermal
correspondence as to the heat transmission state between the region
where the sensors are disposed and other parts of the heat
treatment table than these are obtained from the measured values or
the theoretical values to memorize in the memory part of the
control unit. When the temperature control of the heat treatment
table is actually carried out, for the predetermined parts, the
temperatures are actually detected by the sensors, and, for the
other parts than these, the temperatures are obtained by surmising
from the data of the thermal correspondence memorized in the memory
part.
In the case of, as the result of this surmise, the surface
temperature of the heat treatment table being expected to be
non-uniform, the output of the heaters is controlled based on the
aforementioned data so that the temperature of the heat treatment
table is adequate and uniform.
Thus, in the heat treatment unit involving the present embodiment,
the sensors are disposed only to the predetermined parts, and other
parts than these are constituted so that the temperature
distribution is surmised with the mathematical method by use of the
measured values or theoretical values. Therefore, the temperature
control of the heat treatment table can be carried out with a
smaller number of sensors against a plurality of heaters.
Further, in the heat treatment unit involving the present
embodiment, in the case of, from the above surmised results, the
thermal irregularity being liable to occur as to the temperature
distribution of the heat treatment table, the output of the heaters
is controlled based on the data of the thermal correspondence so
that this thermal irregularity is cancelled. Therefore, the
temperature control can be carried out with high accuracy.
Incidentally, the present invention is not restricted to the
content of the aforementioned embodiments.
For instance, though, in the aforementioned embodiment, the
temperature distribution of the entire heat treatment table is
surmised from the temperatures detected for the predetermined parts
of the heat treatment table, by surmising further the heat amount
affecting the wafer W placed on the heat treatment table, the
heaters can be controlled so that the amount of heat affecting the
wafer W is made uniform.
Further, in the above embodiments, the heat treatment table is
divided into a plurality of concentric regions, and a heater formed
in doughnut shape is incorporated in every region. However, the
heat treatment table can be divided in the diameter direction or in
various forms such as a sector form heater or the like.
Further, also as to the number of the sensor, only one sensor can
be disposed or the sensors of the same number as that of the heater
or more can be disposed.
Further, in the above embodiments, description is carried out of
the coating/developing system 1 of the wafer W as an example,
however, the present invention can be applied also to the treatment
apparatus other than this, for instance, an LCD substrate treatment
apparatus and the like.
EXAMPLE 2
Next, another embodiment involving the first invention will be
described.
Incidentally, the parts repeating the aforementioned example 1 will
be omitted from the following description.
FIG. 9 is a vertical cross section of the heat treatment table 158
and cover assembly 168 of the heat treatment unit involving the
present embodiment, and FIG. 10 is a plan view showing a state seen
from the bottom of the cover assembly 168.
As shown in FIG. 9, on a wall surface 168b formed conical on the
lower surface side of the cover assembly 168, upper heaters of
sector shape h1 through h20 are disposed. As shown in FIG. 10,
these upper heaters h1 through h20 are disposed in such a manner
that the five concentric circles, large and small, are divided into
four, respectively, on the wall surface 168b.
FIG. 11 is a block diagram showing a heating system of the heat
treatment unit involving the present embodiment. As shown in FIG.
11, for each upper heater of h1 through h20, wiring is given
independently each other, by the control unit 190 thereto each
heater is connected, the operation or the amount of heat of
evolution thereof can be controlled.
In the heat treatment unit involving the present embodiment, in
addition to the heat treatment table 158 of the utterly identical
structure as that of the heat treatment table 58 involving the
aforementioned first embodiment, a cover assembly 168 thereon the
upper heaters h1 through h20 are disposed is given.
In this heat treatment unit, from the temperatures of the regions
P11 and P12 which are detected by the sensors S11 and S12 disposed
to the regions P12 and P14 of the heat treatment table 158 and the
output of the respective heaters H11 through H15, whether the
temperature distribution is adequate or not, or uniform or not, is
judged.
That is, as identical as the aforementioned first embodiment, from
the thermal correspondence of the each regions of the heat
treatment table which is memorized in the memory part of the
control unit 190, the temperature distribution of the entire heat
treatment table 158 is surmised, thereby whether the state of the
temperature distribution is adequate or not, uniform or not, is
judged.
And, in the case of the temperature distribution being judged to be
inadequate, and the thermal non-uniformity being judged to be
present, in order to cancel this thermal non-uniformity, the
heaters H11 through H15 are controlled. At the same time, the
amounts of heat of evolution of the upper heaters h1 through h20
disposed on the lower surface of the cover assembly 168 are
controlled to cancel the thermal non-uniformity.
For instance, in the case of the periphery portion of the exterior
circumference of the heat treatment table being low in its
temperature, the amount of the heat of evolution of the upper
heaters h17 through h20 on the side of the periphery of the
exterior circumference is increased, and in the case of there
occurring partly the portion of lower temperature, the amount of
the heat of evolution of the upper heaters positioning immediately
above those portions is increased to accomplish the uniform heat
treatment of the wafer W.
Further, in the case of the cover assembly 168 involving the
present embodiment being adopted, the amount of the heat of
evolution of the heat treatment table 158 is controlled so that the
temperature becomes a little bit lower than that of the heat
treatment of the wafer W, on the other hand, the amount of the heat
of evolution of the upper heaters h1 through h20 is controlled so
as to make the temperature higher than the temperature of heat
treatment of the wafer W, thereby the temperature gradient is
formed such that the temperature varies vertically toward the upper
direction from a low temperature to a high temperature. By carrying
out the heat treatment like this, the thermal convection can be
prevented from occurring above the neighborhood of the center of
the wafer W. Thus, an effect characteristic to the present
embodiment such that the control of the temperature of the heat
treatment can be carried out readily is obtained.
As described above in detail, according to the first invention,
whereas the heaters are disposed on the two or more regions,
respectively, which are formed by dividing the heat treatment
table, the sensors are disposed on the predetermined positions of
the heat treatment table. Based on the temperatures detected by
these sensors, the temperature of the each position of the heat
treatment table is surmised. Therefore, the temperature control can
be carried out with a small number of sensors.
Further, based on thus surmised temperature, the output of the each
heater is controlled so that the temperature of the entire heat
treatment table becomes uniform. Thus, all over the heat treatment
plate, the uniform heat treatment can be carried out.
With an arithmetic unit, based on the temperature detected above,
if the temperature of the each position of the heat treatment table
is surmised mathematically, the temperature control during heat
treatment of the substrate to be treated can be carried out with
high accuracy.
In the case of a plurality of the upper heaters which are disposed
divided concentric being disposed above the heat treatment table,
on the surface, opposing to the heat treatment table, of the cover
assembly which is disposed opposite to the heat treatment table,
since the heating is carried out from above and below the wafer,
heating efficiency is good and the uniform heat treatment can be
carried out.
Further, by setting the temperature of the upper heater side at the
higher temperature with respect to the lower heater, or by
controlling the lower heaters or upper heaters so as to cancel the
thermal unbalance, the temperature control during heat treatment of
the substrate to be treated can be carried out with high
accuracy.
Further, by disposing the respective heaters concentric on the heat
treatment table, with respect to the diameter direction of the heat
treatment table in which direction the thermal non-uniformity tends
to occur, a more delicate temperature control can be carried out,
thus all over the substrate to be treated, the uniform heat
treatment can be carried out.
Further, by disposing the sensors in one line in the diameter
direction of the heat treatment table, a small number of the
sensors can realize an accurate temperature control.
Further, by disposing the sensors in the thickness direction of the
heat treatment table, the time lag due to the thermal transmission
in the thickness direction can be readily corrected, thereby
management of the temperature of heat treatment or the temperature
control during the heat treatment of the substrate to be treated
can be carried out with high accuracy.
EXAMPLE 3
FIG. 13 is a vertical cross section of a cover assembly 268
involving one embodiment corresponding to the second invention, and
FIG. 14 is a plan view showing a state seen from the bottom side of
the cover assembly 268. As shown in FIG. 13, on the lower surface
side of the cover assembly 268, a conical concave portion 168b is
formed, and at the summit of the cone, an exhaust outlet 268a is
disposed, and a lower end of an exhausting pipe 270 is connected to
this exhaust outlet 268a. The other end side of the exhausting pipe
270 is connected to a not shown exhausting system, the heating gas
(nitrogen gas) which is heated by the thermal surface plate and
went up is collected by the conical concave portion 268b, and
evacuated through the exhaust outlet 268a and exhausting pipe
270.
On the central portion of the conical concave 268b, a through hole
268c is disposed, and to this through hole 268c, a jacket for
cooling a gas (hereinafter refers simply as "jacket") 290 is
attached.
This jacket is a cooler for cooling the heating gas (nitrogen gas)
which is heated by the thermal surface plate 258 and ascended the
space between the thermal surface plate 258 and the cover assembly
268. The jacket 290 has an appearance of a disc in the center of
which the exhaust outlet 268a is bored, the upper surface thereof
is a plane, and, on the lower surface thereof, the conical concave
268b is formed. The size of its diameter is nearly equal with that
of the through hole 268c of the cover assembly 268, and that is
designed just to be accommodated in the through hole 268c.
The jacket 290 is made out of materials of high thermal
conductivity such as light alloys of aluminum or copper, and inside
thereof a path 291 for circulating a coolant is formed.
In the jacket 290 involving the present embodiment, as shown in
FIG. 14, the circulation path 291 has a shape formed in spiral with
the exhaust outlet 268a as its center, at the both ends of the
circulation path 291, pipes 292, 293 for letting in or out the
coolant are connected. The other end sides of these pipes 292, 293
are connected to a coolant supplier 294, and the coolant cooled to
the predetermined temperature by this coolant supplier 294 is
circulated inside the circulation path 291 through the pipes 292
and 293.
Incidentally, in the jacket 290 of the present embodiment, there is
explained a method in which the coolant is circulated inside the
jacket, however, one in which no coolant is used, for instance, air
cooling type, or an electrical one employing a Peltier element can
be employed.
FIG. 15 is a vertical cross section showing schematically a
structure of a thermal surface plate 258 involving the present
embodiment and its neighborhood. As shown in this FIG. 15, the
inside of the thermal surface plate 258 forms a sealed cavity 258a,
and, on a part of the bottom portion, a reservoir 258b of heating
medium of which the cross section is formed in a V character shape
is disposed. Within the reservoir 258b of the heating medium, a
heater 293 made out of Nichrome wire or the like is disposed in a
direction perpendicular to the plane of the paper of FIG. 15, and
to this heater 293, electric power is supplied from an electric
power source 295 controlled by a control unit not shown in the
figure.
When the power is supplied to the heater 293 from the electric
power source 295, the heater 293 starts to evolve heat, and the
heating medium reserved in the reservoir 258b of heating medium
through condensation is heated by the heater 293. The heated
heating medium is vaporized/evaporated to circulate inside the
cavity 258a. When the vapor of the heating medium collides the
cooled part inside the cavity 258a, the vapor of the heating medium
gives the amount of heat to this cooled portion, at the same time,
is condensed to liquefy. The amount of heat given at this time from
the heating medium to the thermal surface plate 258 is the heat of
vaporization of the heating medium, being determined by the kind of
the heating medium. Therefore, when a sequence of a cycle from the
vaporization of the heating medium to condensation thereof becomes
stable to establish a stable state, the temperature of the thermal
surface plate can be maintained at the almost constant
temperature.
Upon the gas (nitrogen gas) of room temperature being sent from the
side direction of the thermal surface plate 258 maintained at a
constant temperature through an airhole 301, the gas is heated at
the surface of the thermal surface plate 258 to be the heating gas,
and due to collision of the heating gas against the wafer W
disposed on the thermal surface plate 258, the amount of heat is
supplied to the wafer W.
FIG. 16 is a block diagram illustrating a control system of a heat
treatment unit involving the present embodiment. As shown in FIG.
16, in the heat treatment unit involving the present embodiment, an
electric power supply 295 which supplies the electric power to the
thermal surface plate 258 and a coolant supplier 294 are connected
to a control unit 296. To this control unit 296, there are further
connected a sensor S11 which detects the temperature of the gas
(nitrogen gas) in the neighborhood of the center of the lower
surface of the jacket 290, and a sensor S12 which detects the
temperature of the wafer W disposed on the thermal surface plate
258. The control unit 296, based on the temperature of the heating
gas and the temperature of the wafer W detected by these sensors
S11 and S12 respectively, controls the thermal surface plate 258
and the jacket 290.
For the sensors S11 and S12, the various kinds of known temperature
sensors can be employed appropriately, however, in order to detect
the temperature of the wafer W, a sensor which can detect the
temperature in a non-contact state such as a sensor of a mechanism
which detects the temperature from the radiated infra-red light or
the like, for instance, is preferable.
Further, for the temperature of the thermal surface plate 258, as
identical as the aforementioned jacket 290 and the wafer W, a
sensor is disposed to detect directly the temperature, and the
detected temperature can be sent to the control unit 296, however,
the temperature of the thermal surface plate 258 can be controlled
from the temperature of the heating medium of the power supply 295
or the supplied power.
Next, a method for controlling the heat treatment unit involving
the present embodiment will be described.
The thermal surface plate 258 is controlled to maintain a constant
temperature a little bit higher than that of the heat treatment of
the wafer W.
As described above, the temperature of the thermal surface plate
258 is controlled based on a temperature sensor (not shown in the
figure) disposed exclusively or the supplied power from the
electric power supply 295.
The temperature actually affecting the wafer W which is exposed to
the heat treatment is detected by the sensor 12.
The gas (nitrogen gas) heated by the thermal surface plate 258
ascends up and gathers in the neighborhood below the exhaust outlet
268a of the jacket 290, accordingly by the sensor S11 disposed in
the neighborhood thereof, the temperature of the heating gas can be
detected.
In the case of this temperature being higher than the predetermined
temperature, together with adjusting the temperature of the thermal
surface plate 258, the coolant supply 294 is operated to circulate
a cold coolant inside the jacket 290, thereby cools the overheated
gas (air or an inert gas such as a nitrogen gas or the like). The
gas cooled here becomes high in specific gravity and descends to
collide the neighborhood of the center of the wafer W which is
liable to be overheated, thereby preventing this part from being
overheated.
On the other hand, in the case of the wafer temperature being
liable to get lower than the temperature necessary for the heat
treatment, the coolant supply 294 is ceased in operation or lowered
in its output, thereby overcooling is prevented from occurring.
Further, the temperature of the thermal surface plate 258 is
adjusted as the necessity arises thereby the temperature affecting
the wafer W can be prevented from lowering.
In general, it is known that, when the jacket 290 is operated in a
state where the thermal surface plate 258 is maintained at the
temperature a little bit higher than the temperature necessary for
the heat treatment of the wafer W, the temperature affecting the
wafer W is the most suitable temperature for the heat treatment.
Accordingly, based on the measured data, the temperatures of the
thermal surface plate 258 and the jacket 290 are adjusted to
stabilize at these temperatures.
More concrete, when the aimed value of the temperature of the heat
treatment of the wafer W is T.sub.W, the temperature of the thermal
surface plate 258 is T.sub.H, and the temperature (the average
temperature) of the jacket 290 is T.sub.L, there is a relation of
T.sub.L<T.sub.W<T.sub.H between these T.sub.W, T.sub.L, and
T.sub.H. In FIG. 17, this relation is depicted.
As shown in FIG. 17, by maintaining the temperature T.sub.H of the
heating plate at a constant value and the temperature of the jacket
290 at the predetermined temperature T.sub.L lower than the aimed
value T.sub.W of the heat treatment of the wafer W, the temperature
affecting the wafer W can be maintained at the value close to the
aimed value T.sub.W of the heat treatment. The temperature T.sub.H
of the heating plate and the value of the temperature T.sub.L
thereto the jacket 290 should be maintained can be obtained based
on the measured data.
Further, the temperature T.sub.L thereat the jacket 290 should be
maintained may be controlled based on the temperature of the
thermal surface plate 258 detected by the temperature sensor (not
shown in the figure), or the temperature of the heating medium or
the power supplied to the heating medium supplier. Further, based
on both temperatures of the wafer W and the thermal surface plate
258, the temperature of the jacket 290 may be controlled.
Incidentally, the present embodiment adopted a jacket 290
incorporating a spiral circulation path 291, however, by using,
other than this, a cooler which is formed concentric and has a
plurality of cooling portions capable of cooling to the
respectively different temperatures by the electric power, or a
cooler which has a plurality of sector-shaped cooling portions
which are obtained by further dividing the aforementioned
concentric cooling portions in the diameter direction, and of which
the each part can be cooled independently, a particular effect can
be expected.
For instance, in the case of the thermal non-uniformity occurring
in the horizontal direction from the center of the thermal surface
plate 258 to the periphery portion thereof, by cooling the each
sector-shaped cooling portion so as to cancel the thermal
non-uniformity on the thermal surface plate 258, the wafer W can be
exposed to the uniform heat treatment.
That is, in the case of there being such a temperature gradient
that the temperature is low in the neighborhood of the center of
the thermal surface plate 258 and rises toward the periphery
portion thereof, while cooling strongly the sector-shaped cooling
portions on the exterior periphery side, the cooling portions in
the neighborhood of the center are cooled weak, the intervening
cooling portions therebetween are cooled to the intervening
temperature.
On the contrary, in the case of there being such a temperature
gradient that the temperature is high in the neighborhood of the
center of the thermal surface plate 258 and goes down toward the
periphery portion, whereas the cooling portions in the neighborhood
of the center of the cover assembly 268 are cooled strong, the
cooling portions on the periphery portion is cooled weak, and the
intervening cooling portions therebetween are cooled at the
intervening temperature. Further, in the case of the temperature
being low at both the neighborhood of the center and the periphery
portion of the thermal surface plate 258, and the intervening
portion between the neighborhood of the center and the periphery
portion thereof being high, only the cooling portions positioning
immediate above the portion which tends to be high temperature are
cooled strong, and the other cooling portions are cooled weak or
stopped to cool.
Further, in the case of there occurring some parts of high
temperature or low temperature on the thermal surface plate 258, so
as to cancel the thermal non-uniformity of that region, some of the
cooling portions can be cooled to the different temperatures from
the other portions.
Next, the operation will be described for the case of the heat
treatment unit being used as a baking unit (PREBAKE) and a cooling
unit (COL).
First, from inside the wafer cassette CR set on the stage 20, an
wafer W is pulled out by an wafer carrier 21, thereafter the pulled
out wafer W is delivered from the wafer carrier 21 to the main
wafer carrying mechanism 22. The main wafer carrying mechanism 22
delivers and sets the delivered wafer W into the resist coating
unit (COT), where the resist coating is carried out on the wafer W.
Next, the main wafer carrying mechanism 22 pulls out the wafer W
from inside the resist coating unit (COT), carries the same inside
the heat treatment unit and set it on the thermal surface plate
258.
On the other hand, simultaneously with input of power to the heat
treatment unit, the heating medium supplier 295 of the thermal
surface plate 258 and a circulating system begin to operate, and,
after the predetermined time period, the thermal surface plate 258
is maintained at the predetermined temperature, that is, at the
temperature a little bit higher than the aimed value of the
temperature of the heat treatment of the wafer W. Similarly, also
to the cooling medium supplier 294 of the jacket 290 disposed in
the central portion of the cover assembly 268, the electric power
is inputted to start cooling. Incidentally, in the thermal surface
plate 258 involving the present embodiment, there is a tendency
that the temperature is high in the vicinity of the center and low
in the exterior periphery portion. Accordingly, so as to cancel
this, temperature control is carried out so that the heating gas
(nitrogen gas) passing through the neighborhood of the center
thereof is cooled by the jacket 290 disposed in the neighborhood of
the center of the cover assembly 268.
Thus, in the heat treatment unit involving the present embodiment,
upon setting the wafer W between the thermal surface plate 258 and
cover assembly 268 both of which are controlled in their amount of
heat, the gas heated above the temperature of heat treatment of the
wafer W by the thermal surface plate 258 tends to linger in the
lower side of the vicinity of the center of the cover assembly 268.
However, since the cover assembly 268 is provide with the jacket
290 in the center portion, if the temperature of the gas (nitrogen
gas) passing through this portion is above the predetermined
temperature, the cooling medium is circulated to the jacket 290 to
cool the superheated gas passing through the lower side of the
jacket 290. The cooled gas collides against the neighborhood of the
center of the wafer W and prevents the temperature of this portion
from rising. Accordingly, the wafer W which is set therebetween and
is exposed to heat treatment is always given uniform amount of
heat, thereby the uniform heat treatment is carried out all over
the wafer W.
Further, according to the heat treatment unit involving the present
embodiment, the temperature control is carried out while detecting
the temperatures of the wafer W by sensors, accordingly, a delicate
temperature control is possible, thereby the temperature control
during the heat treatment of the wafer W can be carried out with
high accuracy.
Incidentally, the present invention is not restricted to the
content of the aforementioned embodiment.
For instance, in the aforementioned embodiment, description was
given to a apparatus in which an wafer W is heated by use of a
thermal surface plate which is heated uniform by circulating the
heating medium inside the same, however, a heating plate which
controls the temperature by a temperature sensor or the like by
incorporating a nichrome heater inside can be employed.
Another to the second invention, whereas the lower surface of the
substrate to be treated being heated, the gas heated by a heating
means above the predetermined temperature is cooled at the upper
portion of the substrate to be treated, accordingly, the gas of
high temperature does not tend to linger at the upper portion of
the substrate to be treated, thereby, all over the entire substrate
to be treated the uniform heat treatment can be carried out.
In the aforementioned apparatus for heat treatment, a means for
detecting the temperature affecting the substrate to be treated may
be disposed. Based on the temperature detected by the detecting
means and affecting the substrate to be treated, the gas passing
the upper portion of the substrate to be treated is cooled.
Thereby, the temperature control during heat treatment of the
substrate can be carried out with high accuracy.
Further, when the gas heated by the heating plate is cooled by the
cooler disposed around the exhaust outlet of the cover assembly,
the gas of high temperature does not tend to linger in the space
between the substrate to be treated and the cover assembly, thereby
all over the entire substrate to be treated uniform heat treatment
can be carried out.
Around the exhaust outlet of the cover assembly, the sensor for
detecting the temperature around there may be disposed. Based on
the temperature, detected by the sensor, of the gas in the
neighborhood of the exhaust outlet, the heating plate and cooler
are controlled. Thereby, the temperature control during the heat
treatment of the substrate to be treated can be carried out with
high accuracy.
A sensor may be disposed for detecting the temperature of the
substrate to be treated. Based on the detected temperature of the
substrate to be treated, the heating plate and cooler are
controlled. Thereby, the temperature control during the heat
treatment of the substrate to be treated can be carried out with
high accuracy.
A sensor may be disposed for detecting the temperature of the
heating plate. Based on the detected temperature of the heating
plate, the heating plate and cooler are controlled. Thereby, the
temperature control during the heat treatment of the substrate to
be treated can be carried out with high accuracy.
The first sensor for detecting the temperature of the gas around
the exhaust outlet and the second sensor for detecting the
temperature of the heating plate may be disposed. Based on the
temperatures, detected by these sensors, of the gas around the
exhaust outlet and the heating plate, the heating plate and cooler
are controlled. Thereby, the temperature control during the heat
treatment of the substrate to be treated can be carried out with
high accuracy.
The first sensor for detecting the temperature of the gas around
the exhaust outlet and the second sensor for detecting the
temperature of the substrate to be treated may be disposed. Based
on the temperatures, detected by these sensors, of the gas around
the exhaust outlet and the substrate to be treated, the heating
plate and cooler are controlled. Thereby, the temperature control
during the heat treatment of the substrate to be treated can be
carried out with high accuracy.
The first sensor for detecting the temperature of the gas around
the exhaust outlet, the second sensor for detecting the temperature
of the substrate to be treated and the third sensor for detecting
the temperature of the heating plate may be disposed. Based on the
respective temperatures, detected by these sensors, of the gas
around the exhaust outlet, the substrate to be treated and the
heating plate, the heating plate and cooler are controlled.
Thereby, the temperature control during the heat treatment of the
substrate to be treated can be carried out with high accuracy.
EXAMPLE 4
FIG. 18 is a vertical cross section of a cover assembly 368
involving the embodiment corresponding to the third invention, and
FIG. 19 is a plan view showing a state seen from the bottom side of
the cover assembly 368. As shown in FIG. 18, on the lower surface
side of the cover assembly 368, a conical concave portion 368b is
formed, and at a portion corresponding to the top of the cone, an
exhaust outlet 368a is disposed, to this exhaust outlet 368a an
lower end of an exhausting pipe 370 is connected. The other end
side of the exhausting pipe 370 is connected the not shown
exhausting system, the heating gas (air or inert gas such as
nitrogen or the like) which ascended heated by the heating plate
358 is collected at the conical concave portion 368b and evacuated
through the exhaust outlet 368a and exhausting pipe 370.
On the side wall 368c of the conical concave portion 368b, a
plurality of heaters H21 through H32 are disposed forming
concentric circles. In the cover assembly 368 involving the present
embodiment, twelve sheets of sector type heaters H21 through H32
are disposed, each four sheets of heaters of H21 through H24,
heaters H25 through H28, and heaters H29 through H32 are disposed
to form three concentric circles different in their diameters,
large, medium, and small. These twelve sheets of heaters of H21
through H32 are wired so that electric power is supplied through
the respective control unit (not shown in the figure).
FIG. 20 is a vertical cross section showing schematically a
structure of a thermal surface plate 358 involving the present
embodiment and its surroundings. As shown in FIG. FIG. 20, the
inside of the thermal surface plate 358 is a closed cavity 358a,
and, on a part of the bottom portion, a heating medium reservoir
358b of which the cross section is formed in a V character shape is
disposed. In the heating medium reservoir 358b, a heater such as
Nichrome wire or the like 393 is disposed in a direction vertical
to the plane of the paper of FIG. 20, to this heater 393, electric
power from the power source is supplied controlled by the control
unit.
Upon supplying the electric power form the power source 395 to the
heater 393 after control by the control unit, the heater 393 starts
to evolve heat, thereby the heating medium reserved in the heating
medium reservoir 358b due to condensation is heated. The heated
heating medium vaporizes and circulates inside the cavity 358a.
When the vapor of the heating medium collides against the cold
portion in the cavity 358a, the heating medium gives the heat to
this cold portion and at the same time condenses to liquefy. At
this time, the heating medium heats the entire interior wall of the
cavity 358a to a uniform temperature, accordingly the entire
thermal surface plate is maintained at a constant temperature.
FIG. 21 is a block diagram illustrating a control system of a heat
treatment unit involving the present embodiment. As shown in FIG.
21, to the thermal surface plate 358 an electric power supply 395
for supplying electric power to the heater 393 disposed within the
thermal surface plate 358 is connected, the electric power supply
395 is controlled by a control unit 390 and controls the
temperature of the thermal surface plate 358. Similarly, twelve
sheets of heaters H21 through H32 are also connected to the control
unit 390, and turning on/off of these heaters H21 through H32 or
the amount of heat of evolution of heaters H32 through H32 can be
controlled independently.
Next, the way of control of the heat treatment unit involving the
present embodiment will be described.
The thermal surface plate 358 is controlled so as to maintain a
constant temperature. The temperature thereto the thermal surface
plate 358 is maintained is a temperature convenient for controlling
the temperature of heat treatment of the wafer W disposed on the
thermal surface plate 358, for instance, a temperature close to the
heat treatment temperature of the wafer W and a little bit lower
than this heat treatment temperature.
In contrast to the aforementioned thermal surface plate 358 being
controlled so as to keep a given temperature, the heaters H21
through H32 are maintained to such temperatures that the
temperature to which the thermal surface plate 358 is maintained as
well as the heat treatment temperature of the wafer W are
maintained constant. For instance, it is a temperature close to the
aimed value of the heat treatment temperature of the wafer W and a
little bit higher than the aimed value of the temperature of the
heat treatment.
In general, the aforementioned temperature of the thermal surface
plate is determined based on the aimed value of the heat treatment
temperature, and the temperatures of the heaters H21 through H32
are obtained based on the aimed value of the heat treatment
temperature of the wafer W and the temperature of the thermal
surface plate.
That is, in the case of the temperature of the thermal surface
plate 358 being maintained at a little bit lower temperature with
respect to the aimed value of the heat treatment temperature and
the wafer W being heated from the upper surface in this state, the
temperature where the temperature actually affecting the wafer W
becomes the closest to the aimed value is obtained, to these
temperatures, the temperatures of the heaters H21 through H32 are
controlled.
In the more concrete, when the aimed value of the temperature of
the heat treatment of the wafer W is T.sub.W, the temperature of
the thermal surface plate 358 is T.sub.L, and the temperature (the
average temperature) of the heaters H21 though H32 is T.sub.H,
there is a relation of T.sub.L<T.sub.W<T.sub.H between these
T.sub.W, T.sub.L, and T.sub.H. In FIG. 22, this relation is
depicted.
As shown in FIG. 22, by maintaining the temperature T.sub.L of the
heating plate at a constant value and the temperature of the
heaters H21 through H32 at the predetermined temperature T.sub.H
higher than the aimed value T.sub.W of the temperature of the heat
treatment of the wafer W, the temperature affecting the wafer W can
be maintained at the value close to the aimed value T.sub.W of the
temperature of the heat treatment. The temperature T.sub.L of the
heating plate and the value of the temperature T.sub.H thereto the
heaters H21 through H32 should be maintained can be obtained based
on the measured data.
Incidentally, the temperature T.sub.H thereto the heaters H21
through H32 should be maintained may be controlled based on the
temperature of the wafer W detected by the temperature sensor (not
shown in the figure).
Further, in the case of the thermal non-uniformity occurring in the
horizontal direction from the central portion of the thermal
surface plate 358 toward the periphery thereof, by heating the
heaters H21 through H32 so that the thermal non-uniformity on the
thermal surface plate 358 is cancelled, the wafer W can be exposed
to the uniform heat treatment.
For instance, in the case of there being such a temperature
gradient that the temperature is low in the neighborhood of the
center of the thermal surface plate 358 and rises towards the
periphery portion, while heating the heaters H21 through H32 of the
center of the cover assembly 368 to high temperature, the heaters
H29 through H32 of the exterior periphery are heated at low
temperature, and intervening heaters H25 through H28 are maintained
at the intervening temperature.
On the contrary, in the case of there being such a temperature
gradient that the temperature is high in the neighborhood of the
center of the thermal surface plate 358 and goes down towards the
periphery portion thereof, while the heaters H21 through H24 in the
center of the cover assembly 368 are heated at low temperature, the
heaters H29 through H32 of the exterior periphery portion are
heated to high temperature, and the intervening heaters H25 through
H28 are maintained at the intervening temperature. Further, in the
case of the temperature being low in the neighborhood of the center
of this thermal surface plate 358 and the periphery thereof and
beings high in the intervening portion, the heaters H21 through H24
and heaters H29 through H32 are heated to high temperature and the
heaters H25 through H28 are heated to the low temperature. In the
case of there occurring partly high temperature or low temperature
portions due to the characteristic of the thermal surface plate
358, so as to cancel the non-uniformity, some of the heaters H21
through H32 can be heated to the temperatures different form the
other heaters.
Further, in the present embodiment, the twelve sheets of heaters
H21 through H32 which are divided into sector-shape as shown in
FIG. 19 are employed, however, a so-called gradation heater which
is a sheet of continuous heater and can vary local heating or
heating amount for each local portion can be employed. In that
case, while being a sheet of continuous heater, it can heat locally
as mentioned above. Accordingly, while maintaining the
aforementioned characteristics, the number of component can be
reduced or the manufacturing process can be simplified, resulting
in the reduction of the manufacturing cost.
Next, the operation in the case of this heat treatment unit being
employed as a baking unit (PREBAKE) and a cooling unit (COL) will
b)e described in the following.
First, from inside the wafer cassette CR set on the stage 20, an
wafer W is pulled out by an wafer carrier 21, thereafter the pulled
out wafer W is delivered from the wafer carrier 21 to the main
wafer carrying mechanism 22. The main wafer carrying mechanism 22
delivers and sets the delivered wafer W into the resist coating
unit (COT), where the resist coating is carried out on the wafer W.
Next, the main wafer carrying mechanism 22 pulls out the wafer W
from inside the resist coating unit (COT), carries the same into
the heat treatment unit and set the wafer W on the thermal surface
plate 358.
On the other hand, simultaneously with input of power to the heat
treatment unit, the electric power supply 395 of the thermal
surface plate 358 begins to operate, and, after the predetermined
time period, the thermal surface plate 358 is maintained at the
predetermined temperature, that is, at the temperature a little bit
lower than the aimed value of the temperature of the heat treatment
of the wafer W. Similarly, also the heaters H21 through H32
disposed on the lower surface side of the cover assembly 368, the
electric power is inputted to start heating. Incidentally, in the
thermal surface plate 358 involving the present embodiment, there
is a tendency that the temperature is high in the vicinity of the
center and low in the exterior periphery portion. Accordingly, in
order to cancel this, temperature control is carried out so that
the heating temperatures at the heaters H21 through h24 of the
cover assembly 368 are low, and as the heaters go to the heaters
H25 through H28 on the outside than these and heaters H29 through
H32 of further outside, the heating temperature gradually goes
up.
Thus, in the heat treatment unit involving the present embodiment,
upon setting the wafer W between the thermal surface plate 358 and
cover assembly 368 both of which are controlled in their amount of
heat, since the amount of heat of the heaters H21 through H32 of
the cover assembly 368 is controlled so as to cancel the thermal
non-uniformity of the amount of heat from the thermal surface plate
358, accordingly, the wafer W which is set therebetween and is
exposed to heat treatment is always given uniform amount of heat,
thereby the uniform heat treatment is carried out all over the
wafer W.
Further, since the temperatures of heaters H2 through H32 are
controlled to be high with respect to the temperature of the
thermal surface plate 358, the thermal gradient is constituted to
get high always from the lower side toward the upper side in the
vertical direction. Therefore, the gas heated by the thermal
surface plate 358 ascends straight up, and there does not occur
thermal convection in the space formed between the thermal surface
plate 358 and the heaters H21 and H32.
Therefore, the non-uniform supply of amount of heat induced by this
thermal convection can be prevented from occurring, thereby uniform
heat treatment of the wafer W is made possible.
Further, according to the heat treatment unit involving the present
embodiment, whereas the wafer W is heated from the lower surface
side while maintaining the thermal surface plate 358 at a
relatively low temperature close to the lower limit for the heat
treatment, the necessary amount of heat is supplied additionally
from the upper surface side of the wafer W by the heaters H21
through H32. Therefore, the delicate temperature control is made,
moreover, there is no possibility of occurrence of convection due
to the change of the amount of heat of the heaters H21 through H32.
Thus, the temperature control during the heat treatment can be
carried out with high accuracy.
Incidentally, the present invention is not restricted to the
contents Df the aforementioned embodiment.
For instance, in the aforementioned embodiment, the cover assembly
has a shape in which the lower surface of the cover assembly is cut
in a cone, however, the shape of the lower surface can be formed in
a level surface. In the case of the cover assembly having the lower
surface of the level plane, there are such advantages that
manufacture of the cover assembly is simple and the entire heat
treatment unit can be made compact due to the smaller cover
assembly. Incidentally, in the case of the lower surface of the
cover assembly being a level plane, by adequately combining the
shape, arrangement, and capacity of evolution of heat of the
heaters H21 through H32, the thermal convection is prevented from
occurring between the thermal surface plate 358 and the heaters H21
through H32.
Further, in the aforementioned embodiment, the heaters H21 through
32 are disposed concentric, other than this, various arrangement
such as spiral disposition can be adopted.
Similarly, in the aforementioned embodiment, the wafer W is heated
by use of the thermal surface plate which is heated uniformly by
circulating the heating medium inside, instead, a heating plate
which incorporates nichrome heater therein and controls the
temperature by the temperature sensor can be employed.
According to the third invention, while the lower surface of the
substrate to be treated is heated to the predetermined temperature
by the first heating means, the upper surface of the substrate to
be treated is heated to the temperature higher than that obtained
by the first heating means by the second heating means, thereby
such the temperature gradient is formed in the space where the heat
treatment is given to the substrate to be treated that the
temperature rises from below toward above. Thus, there does not
occur the thermal convection which makes irregular the flow of the
heating gas and the uniform heat treatment can be carried out all
over the substrate to be treated.
When the temperature of heat treatment of the substrate to be
treated is adjusted by controlling the second heating means which
heats the upper surface of the substrate to be treated, the flow of
the heating gas is not disturbed, thus the temperature control
during the heat treatment of the substrate to be treated can be
carried out with high accuracy.
When the second heating means is controlled so that the temperature
of heat treatment of the substrate to be treated becomes the aimed
temperature by further use of the aforementioned means for
detecting the temperature of the substrate to be treated, based on
the actually detected temperature of the substrate to be treated,
the temperature control during the heat treatment of the substrate
to be treated can be carried out with high accuracy.
While heating the lower surface of the substrate to be treated to
the predetermined temperature by use of the heating plate, the
upper surface of the substrate to be treated is heated to the
temperature higher than the heating plate by use of the heaters.
Thus, in the space where the heat treatment is carried out to the
substrate to be treated, such a temperature gradient is formed that
the temperature rises from below toward above. Thereby, the thermal
convection which makes irregular the flow of the heating gas does
not occur in this space, the uniform heat treatment can be carried
out all over the substrate to be treated. Further, when the heaters
are adjusted by the second control portion to the temperature where
the substrate to be treated is treated at the aimed temperature,
the flow of the heating gas is not disturbed, resulting in the
highly accurate temperature control during the heat treatment of
the substrate to be treated.
In the aforementioned apparatus of heat treatment, if such a heater
is adopted that is divided into a plurality of heaters capable of
turning on and off the electric power source independently, a
delicate temperature control can be carried out, resulting in the
further highly accurate temperature control during the heat
treatment of the substrate to be treated.
* * * * *