Raw material supplying device and film forming apparatus

A raw material supplying device includes a raw material supplying pipe including a vertically extending rising pipe. The device further includes a first raw material discharging pipe which is provided to branch from the lower end of the rising pipe. The device further includes a cleaning fluid supplying pipe configured to supply one of purge gas and cleaning solution in order to extrude and discharge liquid raw material in the raw material supplying pipe to the first raw material discharging pipe. The device further includes a first raw material supplying valve and a first raw material discharging valve which are respectively provided in the side of the repository and the first raw material discharging pipe other than a connection portion of the raw material supplying pipe with the first raw material discharging pipe. The device further includes a cleaning fluid supplying valve provided in the cleaning fluid supplying pipe.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2010-293207, filed on Dec. 28, 2010, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a raw material supplying device for supplying liquid material and a film forming apparatus including the raw material supplying device.

BACKGROUND

Gas produced by vaporizing liquid raw material such as metal organic compounds by means of a vaporizer has been often used as process gas used for film forming processes in semiconductor manufacturing apparatuses. An example of film forming process may include a process of using liquid raw material, for example, tetrakis(ethylmethylamino)zirconium (TEMAZ), tetrakis(ethylmethylamino)hafnium (TEMAH), strontium bis(tetramethyl-heptanedionate) (Sr(THD)2) or the like, to form a high-permittivity film on a semiconductor wafer (hereinafter abbreviated as “wafer”). In this system, a vacuum pump to vacuumize the interior of a reaction container (reaction tube) in which the film forming process is performed and a raw material tank which is a repository of liquid material are, for example, installed below a vaporizer or the reaction tube (at a height position of operation by an operator or in the underground) in order to make a foot print of the system as small as possible. A raw material supplying device including raw material supplying pipes, valves and so on supplies liquid material from the raw material tank into the vaporizer upward.

In some case, the vaporizer and/or the raw material tank may be removed for maintenance of the vaporizer and/or exchange of the raw material tank with a new one. In this case, if the liquid material contacts the air, toxic gas such as diethylamine (C2H5)2NH), dimethylamine (CH3)2NH) or the like may be generated or there is a possibility that the raw material supplying pipe is blocked by reaction products generated by reaction of the liquid material with water contained in the air. Accordingly, when the vaporizer or the raw material tank is removed from the system, the liquid material is removed in advance from the raw material supplying pipe. Specifically, for example, the liquid material is extruded upward against a force of gravity by purging inert gas such as nitrogen (N2) or the like from below (the side of the raw material tank) into the raw material supplying pipe and is discharged from a vent pipe provided in the front of the reaction tube (in the side of the raw material supplying pipe) through the raw material supplying pipe in the side of the vaporizer. Thereafter, for example, the interiors of the raw material supplying pipe and the vaporizer are cleaned by flowing the cleaning solution such as octane or the like from below through the raw material supplying pipe, the cleaning solution is discharged from the vent pipe by the inert gas, and then the interior of the raw material supplying pipe is vacuumized and dried by the vaporizer.

However, since the liquid material has a specific gravity higher (i.e., is heavier) than that of water or the like, when the liquid material is to be extruded downward by the gas, the liquid material stays in the raw material supplying pipe and is in a so-called bubbling state where bubbles are to rise in the liquid material. This makes it difficult to remove the liquid material from the raw material supplying pipe even with increase in a gas pressure. In addition, since such liquid material has a vapor pressure lower than that of water or the like, for example, the liquid material is hard to be volatilized even when the interior of the raw material supplying pipe is vacuumized before the cleaning solution is supplied. In addition, since the interior of the raw material supplying pipe is not opened, it is not possible to directly confirm whether or not the liquid material is completely removed from the raw material supplying pipe.

If any liquid material is left in the raw material supplying pipe when the cleaning solution is supplied into the raw material supplying pipe, there may be a case where some water contained in the cleaning solution reacts with the liquid material, which may result in attachment (adhesion) of reaction products on a surface of a diaphragm (valve body) of a valve disposed on the raw material supplying pipe, for example. This may require frequent exchange of the diaphragm or the valve, which results in increase in running costs of the system.

Accordingly, when the vaporizer and/or the raw material tank are removed from the system, the liquid material has to be removed from the raw material supplying pipe by continuously flowing gas through the raw material supplying gas for, for example, a few days in order to secure a period of time for liquid removal (a period of time for supply of gas) slightly longer than a period of time for discharging of the liquid material even if the amount of liquid material left in the raw material supplying pipe is only several tens cc. Accordingly, operation hours (film forming time) of the system are shortened as much as time required for the removal of liquid from the raw material supplying pipe, and cost of nitrogen gas increases. In addition, even when such gas is supplied into the raw material supplying pipe for a long time, some liquid material may still be left in the raw material supplying pipe. In addition, likewise, even the cleaning solution is hard to be discharged from the raw material supplying pipe since it is extruded by the gas directing from below to above. In addition, when the liquid material is to be returned to the raw material tank by the gas supplied into the raw material supplying pipe from above (the side of the vaporizer), there is a possibility of contamination of the liquid material in the raw material tank through the inner wall of the raw material supplying pipe.

There is no document addressing the above-described problems although some techniques regarding a raw material supplying pipe and a valve are arranged to flow liquid from above to below have been known.

SUMMARY

According to one embodiment of the present disclosure, there is provided a raw material supplying device for vaporizing liquid raw material contained in a repository using a vaporizer, and supplying vaporized gas into a reaction container for semiconductor manufacture, including a raw material supplying pipe including a vertically extending rising pipe having an upper end and a lower end to which the vaporizer and the repository are connected respectively; a first raw material discharging pipe which is provided to branch from the lower end of the rising pipe; a cleaning fluid supplying pipe which is connected to the upper end of the rising pipe and supplies one of purge gas and cleaning solution in order to extrude and discharge liquid raw material in the raw material supplying pipe to the first raw material discharging pipe; a first raw material supplying valve and a first raw material discharging valve which are respectively provided in the side of the repository and the first raw material discharging pipe other than a connection portion of the raw material supplying pipe with the first raw material discharging pipe; and a cleaning fluid supplying valve which is provided in the cleaning fluid supplying pipe, wherein, when the liquid raw material is supplied into the vaporizer, the first raw material supplying valve is opened and the first raw material discharging valve and the cleaning fluid supplying valve are closed, and when the liquid raw material is discharged, the first raw material supplying valve is closed and the first raw material discharging valve and the cleaning fluid supplying valve are opened.

According to another embodiment of the present disclosure, there is provided a film forming apparatus including: the above-described raw material supplying device; a vaporizer which vaporizes liquid material supplied from the raw material supplying device; and a reaction container which supplies process gas obtained by vaporizing the liquid material in the vaporizer to substrates accommodated in the reaction container.

DETAILED DESCRIPTION

An embodiment of a vertical heat processing apparatus to which a raw material supplying device of the present disclosure is applied will now be described in detail with reference toFIGS. 1 to 10. This vertical heat processing apparatus is configured as a film forming apparatus including a vaporizer11which vaporizes liquid material including film forming species, for example, tetrakis(ethylmethylamino)zirconium (TEMAZ), and a reaction tube (reaction container)12which performs a film forming process by supplying process gas obtained by the vaporization of liquid material in the vaporizer11onto a wafer W. A raw material supplying device13supplies the liquid material from a raw material repository14disposed below the vaporizer11and the reaction tube12to the vaporizer11via a raw material supplying pipe (a rising duct)15. As will be described later, when a liquid in the raw material supplying pipe15is removed (removal of liquid material) for maintenance of the vaporizer11and exchange of the raw material repository14, for example, the raw material supplying device13is configured to easily and quickly discharge the liquid material out of the raw material supplying pipe15.

First, the reaction tube12and the vaporizer11will be described in brief. As shown inFIG. 1, the reaction tube12is made of cylindrical quartz, its bottom is opened as a furnace hole, and an exhaust port12afor vacuumizing the internal atmosphere of the reaction tube12is formed in the central portion of the top of the reaction tube12. In addition, the reaction tube12is supported to a base plate22such that the bottom of the reaction tube12is located at a height position apart by, for example, 2 mm or so from a level of floor, so that a wafer boat21loading wafers W in the form of a shelf can be airtightly inserted from below. One end portion of a gas injector23for introducing process gas into the reaction tube12is airtightly inserted in a flange of the bottom of the reaction tube12. A heater24for heating the wafer W in the reaction tube23is circumferentially provided in the outside of the reaction tube12. An exhaust pipe25extending from the exhaust port12ais connected to a vacuum pump27which is a vacuum exhauster provided below the reaction tube12, for example, in a portion (underground) lower than the floor level, via a pressure regulator such as a butterfly valve26or the like. InFIG. 1, reference numeral28denotes a motor for rotating the wafer boat21around a vertical axis. The reaction tube12and the vaporizer11are drawn briefly inFIG. 1.

The vaporizer11of a cylindrical shape is provided to be adjacent to the reaction tube12in the lateral side of the reaction tube12and a nozzle (two-fluid nozzle)31for discharging (spraying) liquid material or cleaning solution into the vaporizer11is placed on the top surface of the vaporizer11. A liquid supplying pipe41for supplying liquid material and a gas supplying pipe42for supplying purifying gas, for example, nitrogen (N2) gas, as carrier gas of the liquid material are connected from the outside (upper side) via respective valves V. In the liquid supplying pipe41, a flow rate regulator (liquid mass flow controller)41ais disposed in the upstream of the vaporizer11(that is, at the side of raw material repository14).

A heater (not shown) for vaporizing the liquid material discharged into the vaporizer11is buried in the inner wall of the vaporizer11, thereby forming an internal region of the vaporizer11as a heating chamber11a. A taking-out port32for taking out process gas obtained by vaporization of the liquid material in the vaporizer11is provided in the side of a lower end of the vaporizer11, and a base end of the gas injector23is connected to a gas raw material supplying pipe35extending from the taking-out port32. A vent pipe36connected to the exhaust pipe25is connected to the gas raw material supplying pipe35via a valve V. A buried cylindrical heat exchanger33of the heater (not shown) is placed to face the nozzle31within the vaporizer11. InFIG. 1, reference numeral34denotes a drain hole for discharging droplets, which are not vaporized in the vaporizer11and falls on the floor of the vaporizer11, to a discharging part, and V denotes a valve. InFIG. 1, reference numeral16adenotes a flow rate regulator. A vaporization system30is constituted by the vaporizer11, the valves V at the side of the vaporizer11, which are provided in the liquid supplying pipe41and the gas supplying pipe42, respectively, and the flow rate regulator41a.

Subsequently, the above-mentioned raw material supplying device13will be described in detail. The raw material repository14storing the liquid material is placed below the reaction tube12and the vaporizer11, for example, in the underground, like the vacuum pump27in order to make a foot print of the device as small as possible. Accordingly, the raw material supplying device13is configured to deliver the liquid material from the underground to the vaporizer11, as will be described later. A supplying pipe14aconnected to the lower part of the raw material supplying pipe15is placed in the raw material repository14and a lower end of the supplying pipe14ais opened in a portion lower than a liquid level of the raw material supplying pipe15. In the underground are placed a gas repository16storing the above-mentioned purifying gas (purge gas) supplied into the raw material supplying pipe15and a cleaning solution repository (supplying part)17storing the cleaning gas such as octane or the like in order to easily and quickly remove liquid from the raw material supplying pipe15for maintenance of the device. An auxiliary storage tank17astoring the cleaning solution is provided to be adjacent to the raw material repository14in order to supply the cleaning solution into the supplying pipe14a. InFIG. 1, reference numeral7denotes a liquid feeding gas line for pumping the liquid material toward the supplying pipe14aby supplying He gas or the like to a portion higher than the liquid level in the raw material supplying pipe15and reference numeral8denotes an auxiliary cleaning solution supplying pipe for supplying the cleaning solution from the auxiliary storage tank17ato the supplying pipe14a. InFIG. 1, reference numeral9denotes an auxiliary gas supplying pipe for supplying the purifying gas from the gas repository16to the supplying pipe14aand reference numeral10denotes a filter for removing water from the purifying gas.

A plurality (for example, four) of liquid removal mechanisms, each of which includes a plurality of valves, is provided in the raw material supplying device13. As shown inFIG. 1, the liquid removal mechanisms are respectively disposed in the side of the raw material repository14and the vaporizer11in the raw material supplying pipe15, the side of the cleaning solution repository17in a cleaning solution supplying pipe (cleaning fluid supplying pipe)19supplying the cleaning solution from the cleaning solution repository17to the vaporizer11, and a first raw material discharging pipe61extending from a drainage60, which is a discharging destination of the liquid material and the cleaning solution, to an upper part (the side of the vaporizer11). These liquid removal mechanisms in the side of the raw material repository14, the side of the vaporizer11and the side of the drainage60are hereinafter called “first liquid removal mechanism50a,” “second liquid removal mechanism50b”and “third liquid removal mechanism50c,”respectively. The liquid removal mechanism provided in the cleaning solution supplying pipe19is also called “first liquid removal mechanism50a”since it has the same configuration as the first liquid removal mechanism50a. InFIG. 1, the valves of these liquid removal mechanisms are schematically (enlarged) shown to be simplified. In addition, since the first liquid removal mechanism50ais placed near the floor in actuality, the supplying pipe14abetween the raw material repository14and the first liquid removal mechanism50ais significantly shorter than the raw material pipe15extending form the first liquid removal mechanism50ato the second liquid removal mechanism50b, althoughFIG. 1schematically shows a length dimension of the supplying pipe14aand the raw material supplying pipe15.

The valves used in these liquid removal mechanisms include 2-way valves18aconfigured to open/close a vertically extending passage53and 3-way valves18bformed with the vertically extending passage53and other passage (bypass passage54) connected from the lateral side of the passage53. The 3-way valves18bare configured to switch between an open state where the passage53and the bypass passage54communicate to each other and a close state where one of an opening end of a lower part of the passage53and an opening end of the bypass passage54is closed. The 2-way valves18aand the 3-way valves18bare implemented with electromagnetic valves which can be opened/closed by an instruction from a control unit1which will be described later.

Each of the first liquid removal mechanisms50ais provided with two 2-way valves18aand one 3-way valve18band the second liquid removal mechanism50bis provided with one 2-way valve18aand five 3-way valves18b. The third liquid removal mechanism50cis provided with one 2-way valve18aand two 3-way valves18b. Valves in portions other than the liquid removal mechanisms50are denoted by “V” as described above, and distinguished from valves (valves71to82which will be described later) constituting the liquid removal mechanisms.

Subsequently, a layout of the valves in the liquid removal mechanisms will be described in more detail. First, the first liquid removal mechanism50awill be described. As shown inFIG. 2, the first liquid removal mechanism50aincludes a valve71constituted by a 2-way valve18a, a first raw material supplying valve72constituted by a 3-way valve18b, and a first raw material discharging valve73constituted by a 2-way valve18a, which are arranged in order from top to bottom. One end (lower end) of the raw material supplying pipe15and the first raw material discharging pipe61are connected to an upper end of the valve71and a lower end of the first raw material discharging valve73, respectively.FIG. 3schematically shows the first liquid removal mechanism50a.

As schematically shown inFIG. 4, the first raw material supplying valve72is formed with the vertically extending passage53via a valve room51of the first raw material supplying valve72, and the above-mentioned valve71and first raw material discharging valve73are connected to the upper end and lower end of the passage53, respectively. One end of the bypass passage54is openably/closably opened by a valve body52in the valve room51and the other end of the bypass passage54is bent downward and connected to the supplying pipe14aat a position lower than the first raw material discharging valve73. Accordingly, under a state where the first raw material supplying valve72is closed (a state where an opening end of the bypass passage54is blocked by the valve body52), the supply of the liquid material from the supplying pipe14ais stopped as shown inFIG. 5, whereas, under a state where the first raw material supplying valve72is opened, the liquid material is supplied into the valve room51as shown inFIG. 6. By opening/closing the valve71and the first raw material discharging valve73along with the first raw material supplying valve72, the liquid material is supplied into the side of the vaporizer11(the side of the second liquid removal mechanism50b) or the liquid material is discharged out of the vaporizer11. The upper end of the valve71, the lower end of the first raw material discharging valve73and the opening end in the lower end of the bypass passage54are arranged to face the same direction (the left side inFIG. 2).

The first liquid removal mechanism50ais also provided in the side of the cleaning solution repository17in the cleaning solution supplying pipe19, and supplying pipes19aextending respectively from the cleaning solution supplying pipe19and the cleaning solution repository17are connected to the upper end of the valve71and the bypass passage54of the first raw material supplying valve72, respectively. The above-mentioned first raw material discharging pipe61is connected to the lower end of the first raw material discharging valve73.

Subsequently, the second liquid removal mechanism50bwill be described with reference toFIGS. 7 and 8. The second liquid removal mechanism50bis configured to supply purifying gas into the raw material supplying pipe15from an upper side and discharge the liquid material and the cleaning solution to a lower side. That is, the second liquid removal mechanism50bis connected with the raw material supplying pipe15, the cleaning solution supplying pipe19and the gas supplying pipe43extending from the gas repository16, and includes five 3-way valves18band one 2-way valve18aarranged such that the opening end of the gas supplying pipe43is located above the opening ends of the raw material supplying pipe15and the cleaning solution supplying pipe19.

Specifically, the second liquid removal mechanism50bincludes a vertically extending passage53and a second raw material supplying valve74constituted by a 3-way valve18bcomprising a bypass passage54connected from the lateral side of the passage53, like the above-described first raw material supplying valve72. The other end (upper end) of the raw material supplying pipe15is connected to the bypass passage54of the second raw material supplying valve74and a lower end of a cleaning solution supplying valve75constituted by a 2-way valve18ais connected to the upper end of the passage53of the second raw material supplying valve74. An upper end of a passage53in a second raw material discharging valve76constituted by a 3-way valve18bis connected to the lower end of the passage53of the second raw material supplying valve74. The above-mentioned liquid supplying pipe41is connected to a bypass passage54in the second raw material discharging valve76via a discharging valve V and a second raw material discharging pipe62extending toward the third liquid removal mechanism50cis connected to the lower end of the passage53of the second raw material discharging valve76.

One end (upper end) of a passage53of a gas supplying valve77constituted by a 3-way valve18bis connected to the upper end of the cleaning solution supplying valve75via a pipe (cleaning solution supplying pipe)63and both ends of the pipe63are bent downward such that the one end of the passage53directs upward. An upper end of a passage53in a cleaning solution supplying valve78constituted by a 3-way valve18bis connected to the other end (lower end) of the passage53of the gas supplying valve77and the gas supplying pipe43is connected to a bypass passage54of the gas supplying valve77. An upper end of a passage53in a valve79constituted by a 3-way valve18bis connected to the lower end of the passage53of the cleaning solution supplying valve78and the cleaning solution supplying pipe19is connected to a bypass passage54of the cleaning solution supplying valve78. The above-mentioned second raw material discharging pipe62also used as a cleaning solution discharging pipe is connected to the lower end of the passage53of the valve79and a branch pipe44branching and extending from the liquid supplying pipe41is connected to a bypass passage54of the valve79. These valves74,77and78are each configured such that their passages53and bypass passages54communicate to each other in their opened state while their bypass passages54are closed in their closed state. The valves76and79are each configured such that their passages53and bypass passages54communicate to each other in their opened state while their downward-directing passages53are closed (i.e., the upper ends of the passages53communicate to the bypass passages54) in their closed state.FIG. 8schematically shows the second liquid removal mechanism50bshown inFIG. 7. InFIG. 7, the second liquid removal mechanism50bis shown to be horizontally reversed to that ofFIG. 1

Subsequently, the third liquid removal mechanism50cwill be described with reference toFIG. 9. The third liquid removal mechanism50cincludes a first fluid discharging valve80constituted by a 3-way valve18b, a drainage suction valve81constituted by a 3-way valve18b, and a second fluid discharging valve82constituted by a 2-way valve18a, which are arranged in order from top to bottom, and passages53of the valves80to82are formed to extend vertically. The first raw material discharging pipe61is connected to an upper end of the first fluid discharging valve80and the second raw material discharging pipe62directing from the second liquid removal mechanism50bto a lower part is connected to a bypass passage54of the first fluid discharging valve80. A vacuum pump56as an exhaustion mechanism is connected to a bypass passage54of the drainage suction valve81via a pressure regulator55such as a butterfly valve or the like. The drainage60is connected to a lower end of the second fluid discharging valve82. These valves80and81are each configured such that their passages53and bypass passages54communicate to each other in their opened state while their bypass passages54are closed in their closed state.FIG. 10schematically shows the third fluid removal mechanism50c.

A valve V is disposed in the first raw material discharging pipe61between the third fluid removal mechanism50cand the above-described first fluid removal mechanism50aand one ends of drain pipes64discharging liquid out of the first raw material discharging pipe61are connected to the side of the third liquid removal mechanism50cand the first fluid removal mechanism50avia valves V, respectively. The other ends of these drain pipes64are connected to a drain tank65together. A pressure detector66for measuring an internal pressure of the first raw material discharging pipe61is disposed in the first raw material discharging pipe61in the side of the third fluid removal mechanism50cother than these drain pipes64. As will be described later, based on an output value of the pressure detector66, it is determined by the control unit1whether or not liquid within the raw material supplying pipe15, the cleaning solution supplying pipe19, the first raw material discharging pipe61and the second raw material discharging pipe62has been completely removed (or liquid has been individually removed from the exteriors of the raw material supplying pipe15, the cleaning solution supplying pipe19, the first raw material discharging pipe61and the second raw material discharging pipe62). Liquids such as the above-mentioned liquid material, cleaning solution and drain are collected in one site (in the underground) below the reaction tube12and the vaporizer11, for example, in reality, although they are separately shown inFIG. 1.

This vertical heat processing apparatus is provided with a valve opening/closing device5for outputting signals to open/close various valves, and the control unit1implemented with a computer for controlling the entire operation of the apparatus including the valve opening/closing device5. In a memory of the control unit1are stored a film forming program for supplying process gas obtained by vaporizing the liquid material in the vaporizer11into the reaction tube12and performing a film forming process for the wafer W, and a liquid removal program for removing liquid from the raw material supplying pipe15for maintenance of a device (for example, the vaporizer11) or exchange of the raw material repository14, for example. These programs are installed from a storage unit2, which is a storage medium such as a hard disk, compact disk, magneto-optical disk, memory card, flexible disk or the like, into the control unit1.

Next, operation of the above-described embodiment will be described. First, a process of forming films on wafers W in the reaction tube12will be described. Initially, an empty wafer boat21is positioned below the reaction tube12and, at the same time, a plurality of wafers W are loaded on the wafer boat21in the form of a shelf by means of a carrying arm (not shown). Subsequently, the wafer boat21is airtightly inserted in the reaction12tube, the interior of the reaction tube12is vacuumized by the vacuum pump27to set a process pressure, and the wafers W are heated while the wafer boat21is being rotated. In addition, the vaporizer11is heated to vaporize the liquid material in the vaporizer11.

Subsequently, as shown inFIG. 11, while purifying gas as carrier gas is being supplied from the gas repository16into the heating chamber11aof the vaporizer11, gas is supplied from the liquid feeding gas line7into the raw material repository14and then liquid material is supplied into the nozzle by means of the raw material supplying pipe15via the first liquid removal mechanism50aand the second liquid removal mechanism50b. That is, as shown inFIG. 12, in the first liquid removal mechanism50a, the first raw material discharging valve73is set to a closed state while the valve71and the first raw material supplying valve72are set to an opened state. Accordingly, as indicated by thick lines inFIG. 12, with the liquid material filled in the bypass passage54, the passage53between the first raw material supplying valve72and the first raw material discharging valve73, and the passage53extending from the first raw material supplying valve72and the upper end of the valve71, the liquid material is rising from the upper end of the valve71toward the second liquid removal mechanism50b. InFIG. 12, the opened and closed states of each valve71to73are indicated by circles describing “opened” or “closed.” InFIGS. 11 and 12, places where fluid (the purifying gas or the liquid material) flows are indicated by thick lines.FIG. 11schematically shows the apparatus, which is true of later figures.

As shown inFIG. 13, in the second liquid removal mechanism50b, the second raw material supplying valve74is set to the opened state while the cleaning fluid supplying valve75and the second raw material discharging valve76are set to the closed state. The liquid material supplied from the first liquid removal mechanism50ato the second liquid removal mechanism50bfalls from the second raw material supplying valve74toward the second raw material discharging valve76and flows through the liquid supplying pipe41toward the nozzle31via the bypass passage54of the second raw material discharging valve76and the discharging valve V. Thus, when the liquid material is sprayed from the nozzle31into the vaporizer11, the liquid material is vaporized by heat generated by a heater (not shown) provided in the inner wall of the vaporizer11and, along with the carrier gas, flows into the reaction tube12via the taking-out port32and the gas injector23. When the process gas contacts surfaces of the wafers W, the process gas is thermally decomposed, thereby forming thin films made of, for example, zirconium oxide (ZrO), on the surfaces of the wafers W.

Subsequently, when the film forming process is completed, the supply of the liquid material into the vaporizer11is stopped, that is, for example, the valve V between the vaporizer11and the reaction tube12is closed while the second raw material supplying valve74is closed, thereby vacuumizing the interior of the reaction tube12to discharge the process gas. Subsequently, inert gas is supplied from a purge gas source (not shown) into the reaction tube12in order to return the interior of the reaction tube12to the air atmosphere. Then, the wafer boat21is descended to carry the wafers W out of the wafer boat21by means of carrying arms (not shown). Thus, after a plurality of batch processes (carrying the wafers W into the wafer boat21, film forming, and taking the wafers W out of the wafer boat21) are performed, the liquid material is removed for maintenance of the vaporizer11or exchange of film forming species (replacement of the raw material repository14with a new one), as will be described below. This removal process will be described in detail below with reference to a flow chart ofFIG. 14.

<Removal of Liquid from Vaporizer>

First, as shown inFIG. 15, liquid raw material is discharged from the second liquid removal mechanism50band the vaporizer11by a cleaning solution. That is, supply of the liquid raw material into the second liquid removal mechanism50bis stopped by closing the second raw material supplying valve74(Step S1) and the valve V of the vent pipe36is opened while closing the valve V between the vaporizer11and the reaction tube12. In addition, as shown inFIG. 16, the cleaning fluid supplying valve75and the cleaning solution supplying valve78are opened and the second raw material discharging valve76, the gas supplying valve77and the valve79are closed. Liquid raw material remaining in the second liquid removal mechanism50bis pumped toward the nozzle31by the cleaning solution supplied from the cleaning solution supplying pipe19and, along with the cleaning solution, is atomized in the vaporizer11by purifying gas (carrier gas) supplied from the gas supplying pipe42. Mixed gas generated by the vaporization of the liquid raw material and the cleaning solution is exhausted toward the vacuum pump27via the above-mentioned vent pipe36.

Subsequently, as shown inFIGS. 17 and 18, the cleaning solution supplying valve78is closed and the gas supplying valve77are closed, and a cleaning solution remaining in the second liquid removal mechanism50band the vaporizer11is discharged to the vacuum pump27via the vent pipe36by the purifying gas supplied from the gas supplying pipe43. Then, as shown inFIGS. 19 and 20, the valve V of the gas supplying pipe42in the vicinity of the nozzle31and the gas supplying valve77are closed to vacuumize the interiors of the second liquid removal mechanism50band the vaporizer11. At this time, the cleaning fluid supplying valve75may be opened. Subsequently, the supply of the purifying gas into the second liquid removal mechanism50band the vaporizer11(seeFIGS. 17 and 18) and the vacuumization of the interiors of the second liquid removal mechanism50band the vaporizer11(seeFIGS. 19 and 20) are repeated, for example, four times. Thus, the cleaning solution (or a mixture of the cleaning solution and the liquid raw material) is removed out of the interior of the vaporizer11and the neighborhood of the vaporizer11(the side of the second liquid removal mechanism50bof the vaporizer11and the side of the reaction tube12).

Subsequently, it is checked whether or not the removal of liquid out of the vaporizer11has been completed. Specifically, as shown inFIGS. 21 and 22, the valve V of the vent pipe36is closed and, at the same time, the second raw material discharging valve76and the valve79are opened. In addition, the valve V of the first raw material discharging pipe61between the drain pipes64and the valve V of the drain pipe64in the side of the third liquid removal mechanism50care closed. Then, as shown inFIG. 23, in the third liquid removal mechanism50c, when the first fluid discharging valve80and the drainage suction valve81are opened and the second fluid discharging valve82is closed, the interiors of the second liquid removal mechanism50band the vaporizer11are vacuumized through the interior of the second raw material discharging pipe62extending from the second liquid removal mechanism50bto the third liquid removal mechanism50c. Thus, as shown inFIG. 24, the drainage suction valve81is closed and, at the same time, a valve (not shown) provided in the side of the first raw material discharging pipe61of the pressure detector66is opened to read an output value of the pressure detector66. At this time, if the output value increases (i.e., a degree of vacuum becomes lower) with the lapse of time, then it means that a cleaning solution is left in the vaporizer11, for example, and, if the output value remains stabilized without increasing, then it means that the removal of liquid from the vaporizer11is completed (Step S2). Since no liquid raw material and cleaning solution is left in the vaporizer11and in the vicinity thereof by the above-described process, for example even if the vaporizer11is removed after the valve (hand valve) V in the side of the second liquid removal mechanism50bother than the flow rate regulator41ain the liquid supplying pipe41is closed, the reaction tube12and the second liquid removal mechanism50bremains airtight, thereby preventing the liquid raw material and the cleaning solution from being leaked out.

<Removal of Liquid from Raw Material Supplying Pipe>

Since any liquid raw material is still left in the raw material supplying pipe15as shown inFIG. 25, the liquid raw material is removed from the raw material supplying pipe15as follows. First, the valve V of the supplying pipe14ais closed and, subsequently, as shown inFIG. 26, the second raw material discharging valve76in the second liquid removal mechanism50bis opened. In addition, as shown inFIG. 27, in the third liquid removal mechanism50c, the first fluid discharging valve80and the second fluid discharging valve82are opened and, at the same time, the drainage suction valve81is set to a closed state.

Subsequently, as shown inFIGS. 28 and 29, while the purifying gas is supplied from the gas supplying pipe43toward the second liquid removal mechanism50b, the second raw material supplying valve74, the gas supplying valve77and the cleaning fluid supplying valve75in the second liquid removal mechanism50bare opened and the cleaning solution supplying valve78, the valve79and the second raw material discharging valve76in the second liquid removal mechanism50bare closed. Since a passage below the gas supplying valve77(the cleaning solution supplying valve78, the valve79and the discharging valve V in the branch pipe44) is closed, the purifying gas supplied into the gas supplying valve77rounds into the upper end of the cleaning fluid supplying valve75via the pipe63above the gas supplying valve77and flows toward the second raw material supplying valve74via the cleaning fluid supplying valve75. In addition, since the second raw material discharging valve76and the discharging valve V in the liquid supplying pipe41are closed and the second raw material supplying valve74is opened, the purifying gas reaching the second raw material supplying valve74from above flows through the raw material supplying pipe15toward below (the side of the first liquid removal mechanism50a) via the bypass passage54of the second raw material supplying valve74. Accordingly, for example, the liquid material filled in the bypass passage54of the second raw material supplying valve74and the raw material supplying pipe15is returned to below by the purifying gas.

In addition, as shown inFIG. 30, in the first liquid removal mechanism50a, when the valve71and the first raw material discharging valve73are opened and, at the same time, the first raw material supplying valve72is closed, the liquid material falling from the raw material supplying pipe15as described above is discharged to the first raw material discharging pipe61in the lower part via the passages53of these valves71to73by a pressure of the purifying gas. Here, since the first raw material supplying valve72is closed, the liquid material stays in the bypass passage54of the first raw material supplying valve72, thereby forming liquid retention.

In the third removal mechanism50c, since the second fluid discharging valve82is opened and the first fluid discharging valve80and the drainage suction valve81are closed as described above, the liquid material pumped from the first liquid removal mechanism50ainto the first raw material discharging pipe61is discharged to the drainage60(seeFIG. 28) via the passages53of these valves80to82, as shown inFIG. 31. Thus, the liquid material is quickly removed out of the raw material supplying pipe15between the second liquid removal mechanism50band the first liquid removal mechanism50afrom above to below without going against a force of gravity.

Subsequently, as shown inFIG. 32, the cleaning solution is supplied from the cleaning solution repository17into the second liquid removal mechanism50bvia the first liquid removal mechanism50a. That is, in the first liquid removal mechanism50a, an opened/closed state of the valves71to73is set likeFIG. 12. In addition, as shown inFIG. 33, in the second liquid removal mechanism50b, the cleaning solution valve78is opened while the gas supplying valve77is closed. The cleaning solution rounds from the cleaning solution supplying valve78into the gas supplying valve77and the cleaning fluid supplying valve75in the upper part and reaches the second raw material supplying valve74. Then, the cleaning solution is discharged to the drainage60via the raw material supplying pipe15along a pass shown inFIGS. 30 and 31described above. Accordingly, even if any liquid material is adhered to the inner wall of the raw material supplying pipe15and so on, the inner wall is cleaned by the cleaning solution.

Subsequently, as shown inFIG. 34, the cleaning solution is discharged out of the first liquid removal mechanism50aand the second liquid removal mechanism50b. That is, after the supply of the cleaning solution is stopped (i.e., the valve V of the supplying pipe19ais closed), the gas supplying valve77in the second liquid removal mechanism50bis opened to supply the purifying gas into the second liquid removal mechanism50b. Since the purifying gas flows through the raw material supplying pipe15and the cleaning supplying pipe19toward below as shown inFIG. 35, the cleaning solution in the raw material supplying pipe15and the cleaning supplying pipe19is discharged to the drainage60. Here, as shown inFIG. 36, in the first liquid removal mechanism50aof the raw material supplying pipe15, since the first raw material supplying valve72keeps closed, any liquid material remains left in the bypass passage54of the first raw material supplying valve72.

As an alternative, one of the second raw material supplying valve74and the cleaning solution supplying valve78may be first opened and, subsequently, while the one valve is closed, the other valve may be opened to supply the purifying gas into the raw material supplying pipe15and the cleaning supplying pipe19in order. In addition, if the liquid material is only removed out of the apparatus (i. e, the cleaning solution is left in the apparatus), the liquid material may not be removed out of the cleaning solution supplying pipe19. Accordingly, if the cleaning solution remains left in the cleaning solution supplying pipe19, the cleaning solution supplying pipe19remains filled with the cleaning solution without the interior of the cleaning solution supplying pipe19being vacuumized in the subsequent processes.

Thereafter, as shown inFIG. 37, the interior of each of the liquid removal mechanisms50is vacuumized Specifically, as shown inFIG. 38, in the second liquid removal mechanism50b, the valves74,75,76,78and79are opened and the gas supplying valve77is closed. In addition, as shown inFIG. 39, in the third liquid removal mechanism50c, the valves80and81are opened and the second fluid discharging valve82is closed. Accordingly, for example, even if some cleaning solution is left in the interiors of the raw material supplying pipe15, the cleaning solution supplying pipe19and the raw material discharging pipes61and62, the interiors become vacuumized by the vacuum pump56connected to the bypass passage54of the drainage suction valve81through the first liquid removal mechanism50aand the second liquid removal mechanism50b, thereby volatilizing the cleaning solution. It is detected by the pressure detector66whether or not the cleaning solution from the raw material supplying pipe15, the cleaning solution supplying pipe19and the raw material discharging pipes61and62is removed (volatilized). That is, a valve (not shown) of the pressure detector66provided in the side of the first raw material discharging pipe61is opened and an output value of the pressure detector66is read. Then, for example, if the drainage suction valve81is closed and the output value increases (i.e., a degree of vacuum becomes lower) with the lapse of time, then it means that any cleaning solution is left in the raw material supplying pipe15, for example, and, if the output value remains stabilized without increasing, then it means that the cleaning solution is discharged. Thus, the removal of liquid from the raw material supplying pipe15, the cleaning solution supplying pipe19and the raw material discharging pipes61and62between the first liquid removal mechanism50a, the second liquid removal mechanism50band the third liquid removal mechanism50cis completed to clean the interiors thereof (Step S3).

<Removal of Liquid from Raw Material Repository>

Next, removal of liquid from the supplying pipe14ain the side of the raw material repository14other than the first liquid removal mechanism50aand cleaning of the supplying pipe14aare performed (Step S4). That is, as shown inFIGS. 40 and 41, the valve73in the first removal mechanism50ais closed and the first raw material supplying valve72is opened. In addition, an opened/closed state of the valves (74to79) is set likeFIG. 29. When the valve V of the supplying pipe14ain the side of the raw material repository14is opened, the liquid material left in the bypass passage54of the first raw material supplying valve72is returned to the raw material repository14by a pressure of the purifying gas.

Then, the valve V is closed after the liquid material is returned to the raw material repository14other than the valve V of the supplying pipe14a. In addition, in the first liquid removal mechanism50a, the valve71is closed and the first raw material discharging valve73is opened. Subsequently, as shown inFIG. 42, the valve V of the drain pipe64in the side of the first liquid removal mechanism50ais opened to supply the cleaning solution from the auxiliary repository17ainto the drain tank65via the supplying pipe14a, the first raw material discharging pipe61and the drain pipes64. The interior of the bypass passage54of the first raw material supplying valve72is cleaned by this cleaning solution. Then, as shown inFIG. 43, one V of the two valves V of the drain pipes64in the vacuum pump56is opened and the other valve V (in the side of the first liquid removal mechanism50a) is closed. In addition, the valve V disposed on the first raw material discharging pipe61between the drain pipes64is closed. Thus, after a region above the level of liquid in the drain tank65is made vacuous through the vacuum pump56, as shown inFIG. 44, the valves V are switched likeFIG. 42to supply the purifying gas from the gas repository16into the drain tank65via the supplying pipe14a, the first raw material discharging pipe61and the drain pipes64. As shown inFIG. 45, for example, the cleaning solution in the bypass passage54of the first raw material supplying valve72is discharged by this purifying gas. Thereafter, the valves V of the drain pipes64are closed and the valve V of the first raw material discharging pipe61is opened. Then, when the supply of the purifying gas into the supplying pipe14a, the first liquid removal mechanism50aand the first raw material discharging pipe61shown inFIG. 46and the vacuumization of the supplying pipe14a, the first liquid removal mechanism50aand the first raw material discharging pipe61shown inFIG. 47are repeated several times, the interior of the supplying pipe14ais cleaned. Even in this case, whether or not the removal of liquid from the first raw material discharging pipe61has been completed is determined based on the output value of the pressure detector66.

Thereafter, as shown inFIG. 48, the process of supplying the cleaning solution from the auxiliary repository17ainto the second liquid removal mechanism50bvia the supplying pipe14aand the raw material supplying pipe15and discharging the cleaning solution from the second raw material discharging pipe62and the process of vacuumizing the interiors of the supplying pipe14a, the raw material supplying pipe15and the second raw material discharging pipe62are repeated several times, thereby completing a series of liquid removal processes as described above. Thereafter, the raw material supplying pipe15and the vaporizer11are removed from the apparatus and the vaporizer11and so on may be maintained or the raw material repository14and the vaporizer11may be replaced with new ones for supplying new or different liquid material. In addition, in the second liquid removal mechanism50b, if any liquid material or cleaning solution is left in the side of the discharging valve V other than the valve79and the second raw material discharging valve76, the cleaning solution or the purifying gas is supplied to the side of the discharging valve V to discharge the left liquid material or cleaning solution to the vent pipe36via the vaporizer11.

According to the above-described embodiment, when the liquid material is supplied from the raw material repository14into the vaporizer11via the raw material supplying pipe15, the first raw material discharging pipe61is placed below the raw material supplying pipe15and the purifying gas and the cleaning solution are supplied through the raw material supplying pipe15from above to below. Then, the gas supplying valve77for supplying the purifying gas is placed above the second raw material supplying valve74and the cleaning solution supplying valve78for supplying the liquid material and the cleaning solution, respectively. In addition, in each of the liquid removal mechanisms50a,50band50c, the valves50are arranged such that liquid retention is not formed or is minimized. Accordingly, since the liquid material and the cleaning solution are discharged from above to below without going against a force of gravity, even if the liquid material is TEMAZ or the like which is hard to be volatilized due to its specific gravity larger than water, the liquid material can be quickly and easily discharged out of the raw material supplying pipe15. That is, while conventional methods of supplying purifying gas through the raw material supplying pipe15from below to above for liquid removal required a few days for liquid removal and further might provide insufficient cleaning (a low level of cleaning), the present disclosure makes it possible to halve time taken for liquid removal and provide a very high level of cleaning for portions where liquid is removed.

Thus, operation hours (film forming time) of the apparatus can be lengthened (prolonged). In addition, since the liquid material makes little or no contact with the air when the raw material supplying pipe15is removed, it is possible to prevent toxic gas such as diethylamine (C2H5)2NH), dimethylamine (CH3)2NH) or the like from being generated. In addition, since it is possible to prevent reaction products from being generated by reaction of liquid material with water contained in the air, it is possible to prevent the raw material supplying pipe15from being blocked due to the reaction products. Accordingly, the reaction products can be prevented from being adhered to the valve bodies52(seeFIG. 4) of the valves, which may result in long life of the valves. In addition, usage of purifying gas can be greatly reduced. In addition, since the valves V are arranged such that only the bypass passage54of the first raw material supplying valve72corresponds to a portion where the liquid material of the first liquid removal mechanism50ais left when liquid is removed from the raw material supplying pipe15, it is possible to easily and quickly achieve removal of liquid from the portion and cleaning of the portion. In addition, in case of the liquid removal in the above-described Step S1for maintenance of the vaporizer11, the present disclosure can reduce time taken for liquid removal to several hours although conventional methods required several tens hours for liquid removal.

When the liquid removal mechanisms are installed as described above, since the valves are generally vertically arranged in each of the liquid removal mechanisms and the bypass passage54uses the 3-way valve18bopened below the first raw material discharging valve73, it is possible to reduce an extending (contacting) region of the liquid material as compared to when the valves are horizontally arranged. This can result in reduction of time required for liquid removal and cleaning and reduction of foot prints of the liquid removal mechanisms to the minimum. In addition, since a space where the pressure detector66and the filter10are formed can be secured as much as the foot prints of these liquid removal mechanisms are reduced, end point detection of liquid removal and removal of water from purifying gas (prevention of reaction products in the raw material supplying pipe15) can be achieved. Accordingly, for example, when the vaporizer11is removed, there is no leakage of residual liquid (liquid material and cleaning solution) out of the vaporizer11. In addition, when the liquid material and the cleaning solution are discharged from the first raw material discharging pipe61or the second raw material discharging pipe62, since they are once discharged without the pipes being directly vacuumized by the vacuum pump56, deterioration (load) of the vacuum pump56can be suppressed, which can result in long life of the vacuum pump56.

In addition, for example, in the second liquid removal mechanism50b, the liquid material encounters the cleaning solution through two or more valves. For example, the cleaning fluid supplying valve75and the gas supplying valve77are interposed between the second raw material supplying valve74for supplying the liquid material and the cleaning solution supplying valve78for supplying the cleaning solution. Accordingly, for example, even if the cleaning solution is a little leaked to the liquid material through the cleaning solution supplying valve78, reaction of water contained in the cleaning solution with the liquid material can be suppressed to prevent reaction products from being adhered to the interior of the valves.

In addition, since the liquid material in the second liquid removal mechanism50bis discharged to the third liquid removal mechanism50cthrough the second raw material discharging valve76provided in the second liquid removal mechanism50b, fast liquid removal can be achieved as compared to when the liquid material is discharged to the vaporizer11through the nozzle31. In addition, as shown inFIG. 45, when the cleaning solution is discharged from the bypass passage54of the first raw material supplying valve72, since the valve71near the upper part of the first raw material supplying valve72is closed, leakage of the cleaning solution into the side of the raw material supplying pipe15can be suppressed. In addition, for example, while heaters were often wound on the raw material supplying pipe15and the cleaning solution pipe19in order to volatilize any cleaning solution left in the raw material supplying pipe15and the cleaning solution pipe19in a conventional valve configuration where the liquid material is discharged from below to above, the present disclosure can save a space without providing such heaters.

FIG. 49shows a result of measurement on the quantity of particles adhered to upper, middle and wafers S in the reaction tube12when liquid material vaporized in the vaporizer11is actually used to perform a film forming process for the wafers W in the reaction tube12in a conventional pipe and valve connection configuration (configuration where purifying gas is supplied into the raw material supplying pipe15from below) and a configuration of the present disclosure. It can be seen fromFIG. 49that the quantity of particles in the present disclosure is substantially the same as conventional. That is, it can be seen that the raw material supplying device13of the present disclosure has no adverse effect on properties of the wafers W. InFIG. 49, the present disclosure has the same process conditions as conventional, and, therefore, detailed explanation of which will be omitted.

FIGS. 50A to 50Gshow photographs of diaphragms used in the present disclosure and a conventional example, where valve names are given to photographs of the present disclosure. Specifically,FIGS. 50A to 50Dshow a cleaning fluid supplying valve75, a second raw material supply valve74, a gas supplying valve77, and a cleaning solution supplying valve78of the present disclosure respectively.FIGS. 50E to 50Gshow valves in a conventional example, whereinFIG. 50Eshows a diaphragm of a valve contacting liquid raw material, andFIGS. 50F and 50Gshow diaphragms of valves distanced from the valve ofFIG. 50Eto the right side, i.e., from the valve ofFIG. 50Eto the side of a passage through which the cleaning solution flows. After the valves in the conventional configuration and valves in the configuration of the present disclosure were used for a long time, the conventional configuration showed white attachments A1, A2and A3such as Zr—O based compounds on a surface of a valve body (diaphragm) as shown inFIGS. 50E to 50G, whereas the inventive configuration showed little or no attachment on the diaphragm surface as shown inFIGS. 50A to 50D. While white attachments were found in any diaphragms in the conventional example, little or no attachment was found in any diaphragms in the present disclosure.

Herein, although liquid material from the raw material supplying pipe15was discharged by purifying gas, the liquid material may be discharged by a cleaning solution. That is, after a film forming process is stopped, the cleaning solution may be supplied into the raw material supplying pipe15from above. In this case, after the liquid material is discharged by the cleaning solution, the cleaning solution may be discharged by the purifying gas and then the cleaning solution may be supplied into the raw material supplying pipe15. In the case of such discharging of the liquid material by the cleaning solution, after the cleaning solution is supplied into the raw material supplying pipe15, the interior of the raw material supplying pipe15may be vacuumized through the internal atmospheres of the vaporizer11and the reaction tube12in order to volatilize any cleaning solution left in the raw material supplying pipe15(without supplying the purifying gas).

Although in the first liquid removal mechanism50athe bypass passage54used the 3-way valve18bopened below the first raw material discharging valve73, the bypass passage may use the 3-way valve18bopened in the lateral side of the valve73, like the second liquid removal mechanism50band the third liquid removal mechanism50c. In addition, the second liquid removal mechanism50band the third liquid removal mechanism50cmay use the 3-way valve18bhaving the same structure as the first liquid removal mechanism50a.

Although the above-described example is illustrated with maintenance of the vaporizer11and exchange of the raw material repository14with a new one storing different raw material when liquid is removed from the raw material supplying pipe15, the liquid may be removed from the raw material supplying pipe15even when the raw material repository14is exchanged with a new one storing the same raw material. In this case, after the removal of the liquid material from the raw material supplying pipe15and the cleaning of the raw material supplying pipe15are performed as described above, the liquid material in the bypass passage54of the first raw material supplying valve72is returned to the raw material repository14by the purifying gas. Subsequently, after the processes ofFIGS. 42 to 47are performed, the raw material repository14is exchanged. Thereafter, the interior of the supplying pipe14ain the air atmosphere is vacuumized by the vacuum pump56.

Herein, when liquid is removed from the vaporizer11in Step S1, instead of the processes ofFIGS. 15 to 24, the second raw material supplying valve74, the cleaning solution supplying valve78and the valve V in the side of the nozzle31other than the side of the flow rate regulator41ain the liquid supplying pipe41may be closed, and, at the same time, the gas supplying valve77, the second raw material discharging valve76, the first fluid discharging valve80and the drainage suction valve81may be opened to discharge the liquid raw material by means of the vacuum pump56through the second raw material discharging pipe62, along with the purifying gas. Although in the above-described example the pressure detector66is provided in the first raw material discharging pipe61, the pressure detector66may be provided in one of the raw material supplying pipe15and the second raw material discharging pipe62, instead of the first raw material discharging pipe61, or may be provided in at least one of the raw material discharging pipe61, the raw material supplying pipe15and the second raw material discharging pipe62.

In addition, although in the above-described example TEMAZ is used as the liquid material, other liquid material such as tetrakis(ethylmethylamino)hafnium (TEMAH), strontium bis(tetramethyl-heptanedionate) (Sr(THD)2) or the like may be used. Instead of or in addition to octane, hexane or alcohol-based liquid may be used as the cleaning solution.

In addition, two sets of vaporizers11and two sets of raw material supplying devices13may be provided to alternately supply different liquid materials to the wafers W to form films thereon. Also, although in the above-described example the four liquid removal mechanisms50are provided, at least the second liquid removal mechanism50bmay be only provided.

Further, although in the above-described example the removal of liquid from the raw material supplying pipe15and the cleaning of the raw material supplying pipe15are performed by the control unit1, an operator may perform such liquid removal and cleaning according to an operating manual. In this case, the operator may progress the above-described steps by pushing valve opening/closing buttons (not shown) corresponding to the valves, which are arranged on an operating screen or an operating panel, based on an operation sequence manual or the like describing a sequence of opening/closing of the valves.

According to some embodiments of the present disclosure, when liquid material is supplied from a repository storing the liquid material into a vaporizer in an upper part through a raw material supplying pipe, a discharging pipe is provided in the side of a lower end of the raw material supplying pipe in the side of the repository and a cleaning fluid supplying pipe for supplying one of purge gas and cleaning solution is connected to the side of an upper end of the raw material supplying pipe. In addition, since the liquid material is discharged from the side of the upper end of the raw material supplying pipe to the discharging pipe by one of the purge gas and the cleaning solution when the liquid material is discharged from the raw material supplying pipe, the liquid material can be extruded from above to below without going against a force of gravity, which can result in easy discharging of the liquid material from the raw material supplying pipe.