U.S. patent application number 14/952784 was filed with the patent office on 2016-06-23 for heating type vaporizing device.
The applicant listed for this patent is HORIBA STEC, Co., Ltd.. Invention is credited to Akihiro Taguchi, Hidetaka Yada.
Application Number | 20160178187 14/952784 |
Document ID | / |
Family ID | 56128971 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160178187 |
Kind Code |
A1 |
Taguchi; Akihiro ; et
al. |
June 23, 2016 |
HEATING TYPE VAPORIZING DEVICE
Abstract
This invention is a continuous type vaporizing device that makes
it possible to output a large flow rate of the material gas stably
while the vaporizing device is downsized. The vaporizing device
comprises a vaporizing tank that has a vaporizing chamber and that
outputs a material gas that is produced by vaporizing the liquid
material that is introduced into the vaporizing chamber, a heater
that promotes vaporization of the liquid material in the vaporizing
chamber by heating the vaporization tank, and a partition wall that
partitions a lower space of the vaporizing chamber into a first
lower space into which the liquid material is introduced first and
a second lower space into which the liquid material that overflows
from the first lower space is introduced.
Inventors: |
Taguchi; Akihiro;
(Kyoto-shi, JP) ; Yada; Hidetaka; (Kyoto-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HORIBA STEC, Co., Ltd. |
Kyoto-shi |
|
JP |
|
|
Family ID: |
56128971 |
Appl. No.: |
14/952784 |
Filed: |
November 25, 2015 |
Current U.S.
Class: |
392/397 |
Current CPC
Class: |
F22B 1/282 20130101;
F22B 1/30 20130101; F22B 15/00 20130101 |
International
Class: |
F22B 15/00 20060101
F22B015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2014 |
JP |
2014-259536 |
Claims
1. A vaporizing tank that has a vaporizing chamber heated by a
heater and that outputs a material gas that is vaporized by heating
a liquid material that is introduced into the vaporizing chamber,
wherein comprising a partition wall that partitions a lower space
of the vaporizing chamber into a first lower space into which the
liquid material is introduced first and a second lower space into
which the liquid material that overflows from the first lower space
is introduced.
2. The vaporizing tank described in claim 1, wherein a liquid
surface height at which the liquid material starts overflowing into
the second lower space is set within a target liquid surface height
range or at a height higher than the target liquid surface height
range.
3. The vaporizing tank described in claim 1, wherein comprising a
plurality of thermal conductors that project from an internal wall
surface of the vaporizing chamber.
4. The vaporizing tank described in claim 3, comprising a block
shaped body where a bottomed hole that opens in a predetermined
surface is formed and a cap body that forms the vaporizing chamber
by closing the opening of the bottomed hole, wherein the bottomed
hole is formed by boring multiple portions of the predetermined
surface of the body, and a remaining wall portion formed between
the bottomed holes is so configured to perform a function as the
thermal conductor.
5. The vaporizing tank described in claim 1, wherein a wall body
that forms the vaporizing chamber is so configured that the heater
to apply the heat to the liquid material can be buried.
6. A vaporizer comprising a vaporizing tank that has a vaporizing
chamber and that outputs a material gas produced by vaporizing a
liquid material introduced into the vaporizing tank, a heater that
applies heat to the vaporizing tank so as to promote vaporization
of the liquid material in the vaporizing tank, and a partition wall
that partitions a lower space of the vaporizing chamber into a
first lower space into which the liquid material is introduced
first and a second lower space into which the liquid material that
overflows from the first lower space is introduced.
7. A vaporizing device comprising the vaporizer described in claim
6, a liquid surface sensor that detects a liquid surface height of
a liquid material stored in a vaporizing chamber, a flow rate
adjusting valve that is arranged on a liquid material introducing
flow channel that communicates with the vaporizing chamber, and a
control mechanism that controls the flow rate adjusting valve so as
to make the liquid surface height detected by the liquid surface
sensor within a predetermined target liquid surface height range,
wherein the liquid surface height at which the liquid material
overflows into the second lower space is set within or above the
predetermined target liquid surface height range.
Description
FIELD OF THE ART
[0001] This invention relates to a heating type vaporizing device
that gasifies a liquid semiconductor material.
BACKGROUND ART
[0002] Some semiconductor materials are liquid at a normal
temperature such as a material containing no fluorocarbon. For a
semiconductor manufacturing system, in case of using the liquid
semiconductor material that is liquid at a normal temperature, a
heating type vaporizing device that gasifies the liquid by applying
heat to the liquid may be utilized.
[0003] A store type vaporizing device wherein a liquid material
that is sufficiently required for a predetermined process is stored
in a vaporizing tank, the liquid material is vaporized and the
vaporized material gas is output, or a continuously introducing
type vaporizing device wherein a liquid material is continuously or
intermittently introduced into the vaporizing tank, the liquid
material is vaporized and the vaporized gas is output as the
material gas can be represented as a typical vaporizing device for
this purpose.
[0004] Since the store type vaporizing device only requires
sufficient amount of the liquid material stored in the vaporizing
tank, there is no need of a complicated flow rate structure or a
valve control to introduce the liquid material. In addition, with
regard to controlling the temperature to heat the vaporizing tank,
so much fast response is not required. As a result of this, the
store type vaporizing device has a merit that it is easy to output
a large flow rate of the material gas stably. On the other hand,
the vaporizing tank of this type is prone to be enlarged so that
there is a demerit that it is difficult to downsize the vaporizing
device.
[0005] Whereas, although the continuously introducing type
vaporizing device has a merit that the vaporizing tank can be
downsized, it has a demerit that it is difficult to output a large
flow rate of the material gas stably. The reason is that it is
necessary to introduce a new liquid material one after another
continuously by an amount that is vaporized in the vaporizing tank
and output from the vaporizing tank so that a controlled
responsiveness of the liquid material introducing amount is
required. For example, if it takes too much time to control the
responsiveness, too much liquid material is introduced into the
vaporizing tank and the liquid material that fails to vaporize
overflows from the vaporizing tank and is output from the output
port of the material gas. As a result of this, there might be a
risk that an unexpected failure occurs.
[0006] On the other hand, if an emergency output halt mechanism is
added in order to prevent the liquid material from overflowing due
to an excessive input of the liquid material, the state of halting
the output occurs frequently and a harmful influence is exerted on
the semiconductor process itself. Then this arrangement can not be
a fundamental solution.
[0007] In addition, these problems will occur not a little also for
the store type vaporizing device.
PRIOR ART DOCUMENTS
Patent Document
[0008] Patent document 1: Japanese Unexamined Patent Application
Publication No. 2004-157719
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0009] The present claimed invention intends to solve all of the
problems and a main object of this invention is to make it possible
to provide a vaporizing device used for semiconductor manufacturing
system that is downsized and that can output a large flow rate of a
material gas stably.
Means to Solve the Problems
[0010] More specifically, a vaporizing tank in accordance with this
invention has a vaporizing chamber heated by a heater and outputs a
material gas that is vaporized by heating a liquid material that is
introduced into the vaporizing chamber, and is characterized by
comprising a partition wall that partitions a lower space of the
vaporizing chamber into a first lower space into which the liquid
material is introduced first and a second lower space into which
the liquid material that overflows from the first lower space is
introduced.
[0011] In accordance with this arrangement, since the liquid
surface height is kept generally constant for a little while after
the liquid material that first flows in the first lower space
starts overflowing from the partition wall into the second lower
space, it is possible to control the liquid surface height by
making use of this time. As a result of this, it is possible to
keep the liquid material amount (the liquid surface height) in the
vaporizing chamber within an appropriate range without making use
of an expensive and highly responsive mechanism to control the
liquid surface height so that it is possible to attain an object of
this invention that downsizing the device while increasing the flow
rate of the liquid material.
[0012] If a liquid surface height at which the liquid material
starts overflowing into the second lower space is set within a
target liquid surface height range or at a height higher than the
target liquid surface height range, it becomes easy to control the
liquid surface height so that the above-mentioned effect becomes
conspicuous.
[0013] In order to stably supply the large flow rate of the
material gas in a compact vaporizing chamber, it is preferable that
not only the liquid surface height is controlled in order to
introduce the liquid material into the vaporizing chamber
accurately whose amount meets an amount that is output as the
material gas but also the temperature of the liquid material in the
vaporizing chamber is kept at a vaporization promoting temperature
at which the liquid material is securely vaporized.
[0014] In order to attain the object, it is more preferable to
comprise a plurality of thermal conductors that project from an
internal wall surface of the vaporizing chamber. The reason is
since the heat from the heater is efficiently transmitted to the
liquid material by means of multiple thermal conductors, even
though the liquid material is introduced into the compact
vaporizing chamber one after another so as to increase the flow
rate of the liquid material by speeding up the velocity of
replacing the liquid material, it is possible to keep the
temperature to promote the vaporization by heating the liquid
material quickly so as to offset the temperature drop due to the
increased flow rate.
[0015] In order to facilitate the manufacture of the vaporizing
tank, it is preferable to comprise a block shaped body where a
bottomed hole that opens in a predetermined surface is formed and a
cap body that forms the vaporizing chamber by closing the opening
of the bottomed hole, and the bottomed hole is formed by boring
multiple portions of the predetermined surface of the body, and a
remaining wall portion formed between the bottomed holes is so
configured to perform a function as the thermal conductor.
[0016] In order to effectively transmit the heat from the heater to
the liquid material, it is preferable that a wall body that forms
the vaporizing chamber is so configured that the heater to apply
heat to the liquid material can be buried.
[0017] In addition, the vaporizer in accordance with this invention
is characterized by comprising a vaporizing tank that has a
vaporizing chamber and that outputs a material gas produced by
vaporizing a liquid material introduced into the vaporizing tank, a
heater that applies heat to the vaporizing tank so as to promote
vaporization of the liquid material in the vaporizing tank, and a
partition wall that partitions a lower space of the vaporizing
chamber into a first lower space into which the liquid material is
introduced first and a second lower space into which the liquid
material that overflows from the first lower space is
introduced.
[0018] Furthermore, the vaporizing device in accordance with this
invention comprises the vaporizer, a liquid surface sensor that
detects a liquid surface height of a liquid material stored in a
vaporizing chamber, a flow rate adjusting valve that is arranged on
a liquid material introducing flow channel that communicates with
the vaporizing chamber, and a control mechanism that controls the
flow rate adjusting valve so as to make the liquid surface height
detected by the liquid surface sensor within a predetermined target
liquid surface height range, and is characterized by that the
liquid surface height at which the liquid material overflows into
the second lower space is set within or above the predetermined
target liquid surface height range.
Effect of the Invention
[0019] In accordance with the present claimed invention having the
above-mentioned arrangement, since the liquid surface height is
kept generally constant for a little while after the liquid
material that first flows in the first lower space overflows from
the partition wall into the second lower space, it is possible to
control the liquid surface height by making use of this time. As a
result of this, it is possible for the continuously introducing
type evaporation device to be downsized while increasing the flow
rate of the liquid material stably.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a pattern diagram showing an overall configuration
of a vaporizing device in accordance with one embodiment of this
invention.
[0021] FIG. 2 is a perspective view showing a vaporizing tank of
this embodiment.
[0022] FIG. 3 is a plane view showing a body of the vaporizing tank
of this embodiment.
[0023] FIG. 4 is a right side view showing a body of the vaporizing
tank of this embodiment.
[0024] FIG. 5 is a cross-sectional view taken along A-A line in
FIG. 3.
[0025] FIG. 6 is a cross-sectional view taken along B-B line in
FIG. 3.
[0026] FIG. 7 is a perspective view showing a preheating tank in
this embodiment.
[0027] FIG. 8 is a front view showing an arrangement configuration
of the vaporizer, a preheater, and a flow rate control valve of the
vaporizer in this embodiment.
BEST MODES OF EMBODYING THE INVENTION
[0028] One embodiment of this invention will be explained with
reference to drawings.
(1) Summary of a Vaporizing Device 100 in Accordance with this
Embodiment
[0029] The vaporizing device 100 of this embodiment is incorporated
into, for example, a semiconductor manufacturing system, and to
supply a material gas of a predetermined flow rate to a process
chamber of the semiconductor manufacturing system.
[0030] As shown in FIG. 1, the vaporizing device 100 comprises a
vaporizer 1 that vaporizes the introduced liquid material and
outputs the material gas, a preheater 2 that preheats the liquid
material in advance and that introduces the preheated liquid
material to the vaporizer 1, an introducing amount control
mechanism 3 that controls a flow rate of the liquid material that
is introduced from the preheater 2 into the vaporizer 1 and a mass
flow controller 7 that is connected to an output port of the
vaporizer 1 and that controls a mass flow rate of the material
gas.
[0031] Next, each component of this vaporizing device 100 will be
explained.
(2) Configuration of the Vaporizer 1
[0032] The vaporizer 1 comprises, as shown in FIG. 1, a vaporizing
tank 11 inside of which a vaporizing chamber 11a is provided, and a
vaporizing chamber temperature control mechanism 12 that controls
the temperature of the liquid material in the vaporizing chamber
11a so as to keep it at a predetermined vaporization promoting
temperature at which vaporization is promoted.
[0033] As shown in FIG. 2.about.FIG. 5, the vaporizing tank 11 has
the vaporizing chamber 11a that is provided inside of an elongated
block shape metal body (more concretely, a rectangular
parallelepiped), and an introducing port 11b for introducing the
liquid material into the vaporizing chamber 11a and an output port
11c for outputting the material gas from the vaporizing chamber 11a
are open on one end surface that is orthogonal to a longitudinal
direction of the elongated block shape metal body. The vaporizing
tank 11 is arranged with its longitudinal direction set as a
horizontal direction in a posture wherein the output port 11c is
located at an upper part of the introducing port 11b. The liquid
material that is introduced from the introducing port 11b is stored
in a lower space of the vaporizing chamber 11a, and the material
gas that is made by vaporizing the liquid material is filled into
an upper space of the vaporizing chamber 11a and then is output
from the output port 11c.
[0034] The vaporizing chamber temperature control mechanism 12
comprises, as shown in FIG. 1, a heater 121 that is mounted on the
vaporizing chamber 11a, a temperature sensor 123 that directly or
indirectly measures a temperature of the liquid material in the
vaporizing chamber 11a and a heater control circuit 122 that
controls the heater 121 so as to make the temperature measured by
the temperature sensor 123 at the vaporization promoting
temperature. The heater 121 is rod-shaped, and is inserted into a
bore 11d for heater that opens on the one end surface of the
vaporizing tank 11 and that extends in the longitudinal
direction.
(3) Configuration of the Preheater 2
[0035] The preheater 2 comprises, as shown in FIG. 1 and FIG. 7, a
preheating tank 21 inside of which a preheating chamber 21a is
provided, and a preheating chamber temperature control mechanism 22
that controls the temperature of the liquid material in the
preheating chamber 21a to be kept at a predetermined preheating
temperature that is lower than the vaporization promoting
temperature. The preheater 2 outputs the preheated liquid material
to the vaporizer 1.
[0036] Similar to the vaporizing tank 11, the preheating tank 21
has the preheating chamber 21a that is provided inside of an
elongated block shape metal body (more concretely, a rectangular
parallelepiped), and an introducing port 21b for introducing the
liquid material into the preheating chamber 21a and an output port
21c for outputting the preheated material gas from the preheating
chamber 21a are open on one end surface that is orthogonal to a
longitudinal direction of the elongated block shape metal body.
[0037] As shown in FIG. 7, the preheating tank 21 is arranged with
its longitudinal direction set as a horizontal direction and the
output port 21c is arranged to be located at an upper part of the
introducing port 21b. In addition, the preheating chamber 21a
comprises multiple (four, in this embodiment) extending flow
channels 21d, 21e, 21f, 21g that extend in the longitudinal
direction and connecting channels 21h, 21i, 21j each of which
connects an end part of each of the extending flow channels 21d,
21e, 21f, 21g so as to connect the extending flow channels 21d,
21e, 21f, 21g in serial. A starting end of the extending flow
channel 21d located in the most upstream side becomes the
introducing port 21b and an ending end of the extending flow
channel 21g located in the most downstream side becomes the output
port 21c. These extending flow channels 21d, 21e, 21f, 21g are so
arranged that the extending flow channels 21d, 21e, 21f, 21g in the
more upstream side is located at the upper part than the extending
flow channels 21d, 21e, 21f, 21g in the more downstream side. This
is to make the material gas naturally go toward the output port 21c
in order to avoid the material gas from remaining in the preheating
chamber 21a, even though the liquid material is vaporized and
becomes the material gas in the preheating chamber 21a.
[0038] The preheating chamber temperature control mechanism 22
comprises, as shown in FIG. 1, a second heater 221 that is mounted
on the preheating chamber 21a, a temperature sensor 223 that
directly or indirectly measures a temperature of the liquid
material in the preheating chamber 21a and a second heater control
circuit 222 that controls the second heater 221 so as to make a
temperature measured by the temperature sensor 223 at the
preheating temperature. The second heater 221 is rod-shaped, and as
shown in FIG. 7, is inserted into a bore 21k for second heater that
opens in a center of the other end surface of the preheating tank
21 and that extends in the longitudinal direction. The extending
flow channels 21d, 21e, 21f, 21g are arranged to surround the bore
21k for second heater viewed from the end surface. This is to
transmit the heat generated by the second heater 221 extremely
efficiently to the liquid material in the preheating chamber 21a.
Furthermore, in this embodiment, the extending flow channel 21g
located in the most downstream side and the extending flow channel
21d located in the most upstream side are arranged to face across
the bore 21k for second heater. This is to prevent the temperature
drop as much as possible because the liquid material, whose
temperature becomes the highest, in the extending flow channel 21g
located in the most downstream side is influenced by the liquid
material, whose temperature becomes the lowest, in the extending
flow channel 21d located in the most upstream side.
(4) Configuration of the Introducing Amount Control Mechanism 3
[0039] The introducing amount control mechanism 3 comprises, as
shown in FIG. 1, a flow rate adjusting valve 31 that is arranged on
a connecting flow channel between the preheating tank 21 and the
vaporizing tank 11, a liquid surface sensor 32 as being a liquid
material detecting device that detects an amount of the liquid
material stored in the vaporization chamber 11a, and a valve
control circuit 33 that controls the flow rate of the liquid
material that is introduced into the vaporizing tank 11 by driving
the flow rate adjusting valve 31 in order to make the flow rate of
the liquid material detected by the liquid surface sensor 32 within
a predetermined target range.
[0040] The flow rate adjusting valve 31 is in a cylindrical shape
comprising a laminated piezoelectric element, not shown in
drawings, and a valve body that is driven by the laminated
piezoelectric element, and is of an ON/OFF open close valve type
that takes only a full open state and a full close state. In this
embodiment, as shown in FIG. 8, the flow rate adjusting valve 31,
the vaporizing tank 11 and the preheating tank 21 are arranged
vertically in a posture of its longitudinal direction being
horizontal on one side surface of an upstanding plate shape block
body 4. The plate shape block body 4 is so called a manifold block
wherein forming a first flow channel 4a for supplying the liquid
material to the introducing port 21b of the preheating tank 21, a
second flow channel 4b for communicating the output port 21c of the
preheating tank 21 with the flow rate adjusting valve 31, a third
flow channel 4c for communicating the flow rate adjusting valve 31
with the introducing port 11b of the vaporizing tank 11 and a forth
flow channel 4d for outputting the vaporized material gas from the
output port 11c of the vaporizing tank 11. As mentioned above, the
plate shape block body 4 where the internal flow channel
4a.about.4d are formed is arranged to be upright. The preheating
tank 21, the flow rate adjusting valve 31 and vaporizing tank 11
each of which is placed in a horizontal posture are mounted in this
order from the bottom on the upright block body 4 so as to downsize
the vaporizing device 100.
[0041] The liquid surface sensor 32 is of a float type that detects
a liquid surface height of the liquid material stored in a first
lower space 11e, and as shown in FIG. 5, a probe of the liquid
surface sensor 32 is mounted on the vaporizing tank 11 by being
inserted from an upper wall surface of the vaporizing tank 11 to
downward.
[0042] More concretely, the valve control circuit 33 receives an
output from the liquid surface sensor 32. In case that the liquid
surface height detected by the liquid surface sensor 32 exceeds a
predetermined target liquid surface height range, the valve control
circuit 33 closes the flow rate adjusting valve 31, and in case
that the detected liquid surface height is lower than the
predetermined target liquid surface height range, the valve control
circuit 33 opens the flow rate adjusting valve 31. The
predetermined target liquid surface height range may have a width,
or may be a point.
[0043] As shown in FIG. 1, the valve control circuit 33 is formed
as a physically integrated electric circuit together with the
heater control circuit 112 and the second heater control circuit
22. The electric circuit has, for example, a digital electronic
circuit comprising a CPU, a memory, and a communication port, and
an analog electronic circuit comprising an ADC, DAC, an amplifier
and a buffer. The electric circuit produces functions as the valve
control circuit 33, the heater control circuit 122 and the second
heater control circuit 222 by operating the peripheral circuits
according to the predetermined programs stored in the memory.
(5) Configuration of the Mass Flow Controller 7
[0044] The mass flow controller 7, although its detail is not shown
in drawings, is of, for example, a differential pressure type
connected to the output port 11c of the vaporizer 1, and controls a
mass flow rate of the material gas output by the vaporizer 1 by
controlling the flow rate adjusting valve arranged inside so as to
make a difference between before and after a flow resistance
element, not shown in drawings, at the target value, more
specifically, the target mass flow rate.
(6) Characteristic Configuration of the Vaporizing Device 100
[0045] Then, in this embodiment, the vaporizing tank 11 has the
following characteristic configuration.
[0046] More specifically, as shown in FIG. 2, FIG. 3 and FIG. 5,
provided is a partition wall 6 that partitions the lower space of
the vaporizing chamber 11a into the first lower space 11e as being
a space located in one end surface side where the introducing port
11b opens and a second lower space 11f as being a space located in
the other end surface side. A volume of the first lower space 11e
is set to be more than 8 to 10 times of the volume of the second
lower space 11f. The upper space of the vaporizing chamber 11a is
not divided and is continuous. In addition, the liquid surface
sensor 32 is arranged just above the first lower space 11e so as to
make it possible to detect the liquid surface height of the first
lower space 11e.
[0047] Next, these characteristic points will be described.
[0048] The vaporizing tank 11 in this embodiment comprises a block
shape body 111 wherein a bottomed hole 11h is formed on a
predetermined surface (upper surface, in this embodiment) along a
longitudinal direction and a plate shape cap body 112 that forms
the vaporizing chamber 11a by closing the bottomed hole 11h.
[0049] The first lower space 11e of the bottomed hole 11h and its
above space are formed by cutting (drilling) a top surface of, for
example, a metal block material at multiple portions in a matrix
shape. Each of the bores 11g has the same diameter and a pitch to
punch the bores 11g is made a little larger than the diameter of
the bore 11g. As a result of this, in case of punching the bores
11g by means of a drill, no punched portion remains between the
bores 11g. However, in accordance with this embodiment, multiple
remaining wall portions 5 that are lined at even intervals in the
longitudinal direction and that extends in a width direction
(orthogonal to the longitudinal direction) viewed from the top are
formed by punching a part of the no punched portion.
[0050] The remaining wall portions 5 produce a function as a
thermal conductor 5. A top end height of the thermal conductor 5 as
being the remaining wall portion is made to be lower than the
opening surface of the bottomed hole 11h so that the thermal
conductor 5 does not extend to the upper space of the vaporizing
chamber 11a. This arrangement secures a gas circulation in the
upper space. In addition, each of the thermal conductors 5 is
arranged to be separated from an inner side surface of the bottomed
hole 11h so as to store the liquid material in whole of the first
lower space 11e smoothly.
[0051] In this embodiment, a number of the bores 11g arranged in
the width direction is three, and a depth of the bore 11g located
in the center is made shallower than the depth of the bores 11g
located in both ends. This is because that the bore 11d for the
heater into which the heater 121 is inserted is formed in the lower
area of the bore 11g located in the center.
[0052] Meanwhile, the partition wall 6 extends in the width
direction and each end of the partition wall 6 is continuous to the
inner side surface of the bottomed hole 11h, and the top end height
of the partition wall 6 is set to be near or over the upper limit
of the target liquid surface height range by the introducing amount
control mechanism 3.
[0053] The top end height of the remaining wall portion 5 is set to
be generally the same as or a little lower than the top end height
of the partition wall 6. In addition, the introducing port 11b is
set to be lower than the top end height of the partition wall 6,
and the output port 11c is set to be both higher than the top end
height of the partition wall 6 and higher than the upper limit of
the target liquid surface height range.
(7) Operation Explanation of the Vaporizing Device 100
[0054] Next, an operation of the vaporizing device 100 will be
explained.
[0055] The liquid material introduced into the preheating tank 21
is preheated, and then the preheated liquid material is introduced
into the vaporizing tank 11 and stored. The stored liquid material
in the vaporizing tank 11 is heated and vaporized so as to be the
material gas. The material gas is continuously output from the
output port 11c of the vaporizing tank 11 while the flow rate of
the material gas is controlled by the mass flow controller located
in the downstream of the output port 11c.
[0056] Meanwhile, the liquid material in the vaporizing tank 11a
gradually decreases because the material gas is output from the
vaporizing tank 11a, and the liquid surface height is lowered. When
the liquid surface height becomes below the target liquid surface
height range, the introducing amount control mechanism 3 detects
that the liquid surface height is below the predetermined target
liquid surface height range and opens the flow rate adjusting valve
31. Then, the liquid material enters the vaporizing chamber 11a so
that the liquid surface height rises. When the liquid surface
height becomes over the target liquid surface height range, the
introducing amount control mechanism 3 detects that the liquid
surface height exceeds the predetermined target liquid surface
height range and closes the flow rate adjusting valve 31.
[0057] As mentioned above, the material gas is continuously output
from the vaporizing chamber 11a while the liquid material is
intermittently introduced into the vaporizing chamber 11a. In
addition, during this period, the liquid material temperature in
the vaporizing chamber 11a is controlled to be at the predetermined
vaporization promoting temperature at which the vaporization of the
liquid material is promoted by the vaporizing chamber temperature
control mechanism 12.
(8) Effect by the Vaporizing Device 100
[0058] Usually, in order to output a large flow rate of the
material gas stably while downsizing the vaporizing chamber 11a, it
is necessary to introduce a large flow rate of the liquid material
into the vaporizing chamber 11a so that a fast response is required
for controlling the flow rate. More specifically, since fluctuation
velocity of the liquid surface height of the liquid material in the
vaporizing chamber 11a becomes big, unless the response speed of
the introducing amount control mechanism 3 comprising the liquid
surface sensor 32, the control circuit 33 and the flow rate
adjusting valve 31 is increased, the introducing amount control
mechanism 3 fails to catch the fluctuation velocity of the liquid
surface height, resulting in a problem that the liquid material
that is not vaporized overflows from the output port 11c.
Especially, since the velocity of rising the liquid surface becomes
considerably fast, it is important to control the fast response
tailored to this.
[0059] Contrarily, in accordance with this vaporizing device 100,
the liquid material first flowing into the first lower space 11e of
the vaporizing chamber 11a overflows from the partition wall 6 and
flows into the second lower space 11f so that the liquid surface
height is kept constant for a while after the liquid material
overflows. In addition, since the liquid surface height is set at a
height that is a little higher than the upper limit of the target
liquid surface height range, it is possible to sufficiently control
the amount of the liquid material (the liquid surface height) in
the vaporizing chamber 11a at the appropriate value by making use
of the time while the liquid surface height is kept generally
constant without forcibly improving the responsiveness of the
introducing amount control mechanism 3.
[0060] Accordingly, there is no need of using the liquid surface
sensor 32 whose response velocity and the sensing performance are
high and that is expensive, and it is possible to use an
inexpensive ON/OFF open/close valve as the flow rate adjusting
valve 31 so that it is possible to produce an expected performance
such as enlarging the flow rate with a downsized vaporizing device
3 at low cost.
[0061] In addition, every time the liquid material is filled, the
liquid material overflows to the second lower space 11f and the
overflown liquid material remains and is stored in the second lower
space 11f and finally the second lower space 11f is filled with the
liquid material. Once it reaches this situation, the effect cannot
be expected that the liquid material overflows the partition wall 6
from the first lower space 11e and flows into the second lower
space 11f. As a result of this, it can be conceived to fail to
produce the effect of gaining the time to control the flow rate
adjusting valve 31 by keeping the liquid surface height constant
due to the liquid material that overflows to the second lower space
11f.
[0062] However, since the liquid material vaporizes, the liquid
material that overflows into the second lower space 11f in a
previous cycle vaporizes and almost disappears until the liquid
material overflows into the second lower space 11f again, the
above-mentioned problem will not be generated. Conversely, it is
necessary to set the introducing amount of the liquid material and
the liquid area of the second lower space 11f in order to make the
liquid material that overflows into the second lower space 11f in
the previous cycle vaporize and disappear until the liquid material
is filled again and climbs over the partition wall 6 and overflows
into the second lower space 11f again.
[0063] Meanwhile, in accordance with the vaporizing device 100 of
this embodiment, since multiple thermal conductors 5 that
integrally project from the inner wall of the vaporizing chamber
11a are provided inside of the vaporizing chamber 11a so that the
heat from the heater 121 can be transmitted to the liquid material
efficiently, even though a large flow rate of the liquid material
is introduced one after another into a compact vaporizing chamber
11a and a speed of exchanging the liquid material is increased, it
is possible to keep the temperature of the liquid material at the
vaporization promoting temperature by quickly applying the heat to
the liquid material so as to offset the temperature drop. As a
result of this, it is possible to output a large flow rate of the
material gas stably. Especially, in this embodiment, since the
thermal conductor 5 makes use of the remaining wall part formed by
being drilled and the cross-sectional shape of the thermal
conductor 5 is a variant shape having concave parts and convex
parts, a surface area of the thermal conductor 5 is considerably
big, which enables an extremely effective thermal conductivity.
[0064] In addition, since the heater 121 is embedded inside of the
metal wall that forms the vaporizing tank 11 (inserted into the
bore 11d for the heater 121), the above-mentioned effect is
promoted in a point that the heat from the heater 121 can be
effectively transmitted. In addition, a point that the preheating
device 2 is provided in the previous stage of the vaporizing device
1 also contributes to a stable output of the large flow rate of the
material gas. The reason is that the temperature fluctuation
becomes small at a time when the liquid material flows in the
vaporizing chamber 11a so that it becomes easy to keep the
temperature of the liquid material in the vaporizing chamber
11a.
(9) Modified Embodiment
[0065] The present claimed invention is not limited to the
above-mentioned embodiment.
[0066] For example, an elongated portion that elongates further
upward may be provided at the top end of the partition wall. In
this case, a bore may be provided for the elongated portion so that
the liquid material overflows from the first lower space to the
second lower space at the same height as that of the
above-mentioned embodiment.
[0067] In addition, the float type of the liquid surface sensor is
used in the above-mentioned embodiment, however, various types of
the liquid surface sensor may be used such as a thermal capacity
type, (for example, A resistive element where a certain electric
current flows becomes a sensor body. The resistive element is made
to generate the heat at a temperature higher than that of the
ambient environment. The temperature of the resistive element
changes due to a difference of the specific heat between a case
wherein the resistive element is in a gas and a case wherein the
resistive element is in a liquid. The liquid surface height is
detected based on the change of the resistance value resulting from
the change of the temperature of the resistive element.) an
ultrasonic wave type, an electrostatic capacity type, a pressure
type, an oscillating type or the like.
[0068] A platinum resistive element for temperature measurement (Pt
sensor) may be conceived as the thermal capacity type liquid
surface sensor.
[0069] In addition, as the thermal capacity type liquid surface
sensor conceived is a liquid surface sensor comprising a
thermocouple temperature sensor and a heating body that makes a
temperature measuring junction of the thermal capacity type liquid
surface sensor higher than that of a reference junction of the
thermal capacity type liquid surface sensor. The heating body is,
for example, a Pt sensor that is arranged around or near the
temperature measuring junction, and is to apply heat in advance to
the temperature measuring junction in order to make the temperature
of the temperature measuring junction higher than that of the
reference junction. The reference junction is arranged at a
position where no heat is applied by the heating body. With this
arrangement, it is possible to increase an output at a time when
the liquid material makes contact with the temperature measuring
junction (temperature of the temperature measuring
junction-temperature of the reference junction) so that the liquid
surface height of the liquid material can be detected with high
accuracy. Meanwhile, in case that no heat is applied to the
temperature measuring junction by the heating body, an output at a
time when the liquid material makes contact with the temperature
measuring junction (temperature of the temperature measuring
junction-temperature of the reference junction) is small so that it
is difficult to detect the liquid surface height of the liquid
material accurately. The reason is that the temperature of a liquid
phase (the liquid material) in the vaporizing chamber is generally
the same as that of a gaseous phase (vaporized material) in the
vaporizing chamber and it is difficult to generate the temperature
difference between the temperature measuring junction and the
reference junction even though the liquid material makes contact
with the temperature measuring junction.
[0070] From a point of downsizing the sensor and a point of
responsiveness, it is preferable that the above-mentioned two
thermal capacity type liquid surface sensors comprise a platinum
resistive element for temperature measurement (Pt sensor).
Meanwhile, from a point of measurement error reduction due to
fluctuation of the ambient temperature, it is preferable to
comprise a temperature sensor and a heating body.
[0071] Furthermore, a second liquid surface sensor may be provided
and detect that the liquid surface in the vaporizing chamber
exceeds the target liquid surface height range and the upper end
height of the partition wall and approaches near the output port.
In case that the liquid surface detected by the second liquid
surface sensor approaches near the output port, the flow rate
adjusting valve to introduce the liquid material into the
vaporizing chamber is closed and an emergency halt mechanism to
inform the emergency halt may be provided. In accordance with this
arrangement, it is possible to securely prevent overflow of the
liquid material that fails to vaporize in case of contingency (for
example, a failure of the liquid surface sensor).
[0072] The thermal conductor may project from any arbitrary portion
of the vaporizing tank. Similar to the above-mentioned embodiment,
the thermal conductor may project integrally from a back surface of
the cap body in consideration of facilitation of manufacturing.
[0073] In the above-mentioned embodiment, the remaining wall
portion by boring the bore 11g is the thermal conductor 5, however,
a shape of the thermal conductor 5 is not limited to this, and the
vaporizing tank and the thermal conductor may be integrally formed
by the use of a metal mold. In addition, every diameter of the bore
is set to be the same, however, it may differ each other.
[0074] The heater may be a type of surrounding the vaporizing tank
without being embedded into the vaporizing tank.
[0075] The flow rate adjusting valve is not limited to the ON/OFF
open/close valve, and may be a type wherein an opening degree
continuously changes.
[0076] In addition, it is a matter of course that the present
claimed invention is not limited to the above-mentioned embodiment
and may be variously modified without departing from a spirit of
the invention.
EXPLANATION OF CODES
[0077] 100 . . . vaporizing device [0078] 1 . . . vaporizer [0079]
11 . . . vaporizing tank [0080] 111 . . . body [0081] 112 . . . cap
body [0082] 121 . . . heater [0083] 11a . . . vaporizing chamber
[0084] 11e . . . first lower space [0085] 11g . . . bore [0086] 11f
. . . second lower space [0087] 11h . . . bottomed hole [0088] 3 .
. . control mechanism (introducing amount control mechanism) [0089]
31 . . . flow rate adjusting valve [0090] 32 . . . liquid surface
sensor [0091] 5 . . . thermal conductor
* * * * *