Vaporizer

Abstract

The vaporizer 10 is composed of a vaporizer main body 20, a spherical body 30, and a heater H. The vaporizer main body 20 is composed of a liquid raw material supply unit 12 that supplies a liquid raw material LM, a vaporization unit 22 that has a vaporization space K inside for vaporizing the liquid raw material LM, and a raw material gas discharge unit 40 that sends out the vaporized raw material gas VG to the next process. The spherical body 30 is filled inside the vaporization unit 22. The heater H emits infrared rays. The heater H is arranged with a gap d1 provided from the vaporization unit 22. The vaporization unit 22 and the spherical body 30 are composed of a transparent member that is infrared-transmittable. A liquid reservoir E into which the liquid raw material LM flows is provided in the vaporization unit 22 at a position lower than the flow path R of the liquid raw material LM flowing through the vaporization space K.

Description

Technical Field

[0001] The present invention relates to a vaporizer capable of efficiently and stably vaporizing a liquid raw material used in a semiconductor manufacturing process.

Background Art

[0002] In a semiconductor manufacturing process, there is equipment that vaporizes a liquid raw material to form a film, such as in an oxide film or thin film formation process, and supplies the raw material gas to the next processing apparatus. A vaporizer is used to vaporize a liquid raw material controlled to a constant flow rate and supply the raw material gas to the next processing apparatus. For example, in an oxide film formation process, in order to form an oxide film on the surface of a silicon wafer, a raw material gas for oxide film formation (specifically, an oxidizing gas such as water vapor or hydrogen peroxide vapor) is supplied into a high-temperature oxidation furnace, and an oxide film formation process is performed. Examples of using organic compounds include TEOS (tetraethoxysilane) and its derivative PhTES (triethoxyphenylsilane).

[0003] In this film formation process, it is required to stably send a raw material gas at a flow rate required at a temperature required by the processing apparatus to the vaporizer. In a film formation process, it is generally common to change the flow rate of the raw material gas. In a vaporizer, it is necessary to change the amount of heat for vaporizing the liquid raw material in accordance with a change in the flow rate of the liquid raw material. For this purpose, it is necessary to control the power supply to the heater. In addition, the vaporizer is also required to completely vaporize the supplied liquid raw material and supply it to the next processing apparatus in a steady state. In this case, it is also necessary that the apparatus shape does not become too large for complete vaporization of the liquid raw material.

[0004] As a conventional vaporizer (Patent Document 1), it is composed of a cylindrical metal casing extending in the vertical direction, a metal disk provided so as to close the metal casing and having a large number of fine holes penetrating through the front and back, a liquid raw material supply nozzle vertically provided toward the disk for supplying liquid raw material to the disk surface, and a heater provided on the outer periphery of the casing for heating the casing and the disk. In this vaporizer, the liquid raw material is dropped from the liquid raw material supply nozzle onto the disk surface, and the dropped liquid raw material spreads over the entire disk surface due to its surface tension and is efficiently vaporized by the heated disk. The vaporized raw material gas flows downward from the fine holes of the disk along with the carrier gas supplied from above to the casing.

[0005] However, in this vaporizer, for example, when vaporizing a liquid raw material using an organic compound, residues remaining unvaporized on the disk surface gradually block a large number of fine holes provided in the disk. Eventually, the amount of liquid raw material that can be vaporized decreases due to clogging, and finally, it becomes impossible to vaporize due to clogging. In other words, if clogging occurs, it is impossible to accurately vaporize the entire amount of the supplied liquid raw material within a specified time, and it becomes impossible to stably supply the raw material gas to the processing apparatus. Therefore, the vaporizer described in Patent Document 2 was proposed.

[0006] The vaporizer described in Patent Document 2 divides the casing of Patent Document 1 into two inner and outer casings, and stores a large number of opaque ceramics or granular bodies made of corrosion-resistant metal in the inner casing. A large number of holes with a larger diameter than the fine holes provided in the disk of Patent Document 1 are provided at the bottom of the inner casing. The portion where the granular bodies are stored becomes the vaporization part of the liquid raw material. The entire casing and the granular bodies are mainly heated by heat conduction from the heater.

[0007] The liquid raw material is supplied as droplets onto the granular bodies from the liquid raw material supply nozzle, and flows down through the gaps between the granular bodies as one or more flows while wetting the surface of the granular bodies. Since the granular bodies are heated through the casing, the liquid raw material flowing down while wetting the surface of the granular bodies is gradually vaporized. A carrier gas is supplied to the housing from above and flows downward through the gaps between the granular materials. During this process, the vaporized raw material gas flows downward from the holes at the bottom of the inner housing and then flows toward the next processing device. This heater is controlled so that the liquid raw material is completely vaporized before reaching the bottom of the housing. By adopting granular materials as the vaporization layer in this way and making the holes at the bottom larger than the micropores in Patent Document 1, the clogging of the micropores, which was a problem in the vaporizer described in Patent Document 1, is eliminated.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the vaporizer described in Patent Document 2, although the clogging problem of the vaporizer described in Patent Document 1 is eliminated because the vaporization part is composed of opaque spherical bodies and the holes at the bottom are larger than the micropores in Patent Document 1, there is a problem that it cannot flexibly respond to the increase or decrease of the liquid raw material.

[0010] That is, this vaporizer has a vaporization part filled with opaque spherical bodies as described above, and is designed to completely vaporize the supplied liquid raw material during its flow downward. However, when the supply amount of the liquid raw material increases and becomes excessive compared to the calorific value of the heater, the unvaporized liquid raw material will leak out from the holes at the bottom as it is. When unvaporized liquid occurs, the film formation will be poor.

[0011] Conversely, when configuring the vaporization section according to the supply amount of the liquid raw material, the size of the vaporization section must be determined according to the maximum supply amount, so there is a risk that the vaporizer itself will become too large. On the contrary, if the shape of the vaporizer is restricted, the maximum supply amount of the liquid raw material has to be restricted. In other words, in the vaporizer of Patent Document 2, a large amount of liquid raw material could not be vaporized, and it was difficult to flexibly respond to changes in the required gas amount.

[0012] In addition, for temperature adjustment of the heater, a thermocouple is usually installed in the housing. However, the liquid raw material flowing down the spherical layer flows in one or a plurality of streaks. When the thermocouple is installed near the flow of the liquid raw material at a low temperature, the detected temperature appears low, and the heater is overheated. As a result, the temperature of the raw material gas supplied to the processing device becomes higher than the required temperature, and it also has an adverse effect on the liquid raw material.

[0013] Moreover, in the vaporizer of Patent Document 2, since the opaque spherical bodies are mainly heated by heat conduction by the inner housing, the spherical bodies in the peripheral portion in contact with the inner housing become a high temperature close to the inner housing, and the spherical bodies in the central portion become a low temperature because heat is difficult to conduct, and temperature unevenness occurs inside and outside. As described above, the flow path of the liquid raw material flowing through the spherical layer is not constant, and it may pass through the central portion or the peripheral portion, and the vaporization state varies depending on the flow path of the liquid raw material. Such variations prevent the raw material gas from being supplied to the next processing device in a steady state.

[0014] The present invention has been made in view of such conventional problems, and the first problem is to be able to flexibly respond to changes in the required raw material gas amount of the processing device and supply the raw material gas, without causing clogging, completely vaporize the supplied liquid raw material and not generate unvaporized liquid raw material, and provide a vaporizer that can constantly supply the raw material gas to the processing device at the required temperature. And the second problem is to provide a vaporizer in which the temperature of the heater is accurately measured in order to achieve the first problem.

Means for Solving the Problems

[0015] In order to solve the above problems, the vaporizer 10 of the present invention (Claim 1) is configured as follows. A vaporizer body 20 composed of a liquid raw material supply unit 12 that supplies a liquid raw material LM for semiconductor manufacturing, a vaporization unit 22 having a vaporization space K inside for vaporizing the supplied liquid raw material LM, and a raw material gas discharge unit 40 that sends out the vaporized raw material gas VG to the next process; Spherical bodies 30 filled in the vaporization unit 22; A vaporizer 10 composed of a heater H that emits infrared rays and vaporizes the liquid raw material LM, The heater H is arranged with a gap d1 of width M1 provided from the vaporization unit 22, The vaporization unit 22 and the spherical bodies 30 are composed of a transparent member through which infrared rays can pass, A liquid reservoir E into which the liquid raw material LM flows is provided in the vaporization unit 22 at a position lower than the flow path R of the liquid raw material LM flowing through the vaporization space K.

[0016] Claim 2 is characterized in that, in the vaporizer 10 of Claim 1, the vaporization unit 22 is composed of a bent pipe material.

[0017] Claim 3 is characterized in that, in the vaporizer 10 of Claim 1, a reflecting member 28 is arranged to surround the vaporization unit 22 outside the heater H, and the inner surface facing the vaporization unit 22 is formed as a mirror surface 28k that reflects infrared rays.

[0018] Claim 4 is provided with an auxiliary reflecting member 89 on the heater H (Figs. 3 and 5). In the vaporizer 10 according to Claim 1 or 3, the auxiliary reflecting member 89 is provided on the surface of the heater H on the side opposite to the vaporizer body 20, and the surface of the auxiliary reflecting member 89 that reflects infrared rays toward the vaporizer body 20 is a mirror surface 89k.

[0019] Claim 5 relates to the arrangement of the temperature detector 70 (Fig. 2). In the vaporizer 10 according to Claim 1 or 3, A temperature detector 70 for measuring the amount of infrared radiation is arranged such that gaps d2 and d3 with widths M2 and M3 are provided between the vaporizer body 20 and the heater H between the vaporization section 22 and the heater H.

[0020] Claim 6 relates to the specific structure of the temperature detector 70 (Fig. 2). In the vaporizer 10 according to claim 5, the temperature detector 70 is characterized by being composed of a graphite infrared absorber 78 that absorbs infrared rays and is heated, and a temperature detection element 71 embedded in the infrared absorber 78 for detecting the temperature of the infrared absorber 78.

Advantages of the Invention

[0021] According to the present invention (claim 1), since the vaporization section 22 and the spherical body 30 are made of a transparent member that transmits infrared rays, the infrared rays radiated from the heater H pass through the whole of them. As a result, the liquid raw material LM supplied to the vaporization section 22 is uniformly and directly heated by infrared rays while flowing down between the spherical bodies 30 regardless of the flow path R taken.

[0022] And in this vaporization section 22, a liquid reservoir E is provided at a position lower than the flow path R of the liquid raw material LM flowing through the vaporization space K. When the supply amount of the liquid raw material LM supplied from the liquid raw material supply section 12 is large and not all of it vaporizes by the time it reaches the liquid reservoir E, the unvaporized liquid raw material LM accumulates in the liquid reservoir E. The unvaporized liquid raw material LM accumulated in the liquid reservoir E is heated therein and sequentially vaporizes efficiently without leaking from the liquid reservoir E. Therefore, a large amount of the liquid raw material LM can be efficiently processed with a vaporization section 22 of a small capacity, and it is possible to flexibly cope with fluctuations in the supply amount of the liquid raw material LM.

[0023] In the present invention (claim 2), since the vaporization section 22 is composed of a bent pipe material, the bent portion 22e serves as the liquid reservoir E, and the vaporizer 10 can flexibly cope with fluctuations in the supply amount of the liquid raw material LM.

[0024] According to the present invention (Claim 3), the infrared rays radiated from the heater H are repeatedly reflected in innumerable and random directions by the reflecting member 28 surrounding the vaporizing portion 22. Therefore, the transparent vaporizer body 20 and the spherical body 30 are uniformly exposed to the infrared rays throughout. Then, the liquid raw material LM flowing down through the gaps of the transparent spherical body 30 is smoothly vaporized by the efficient absorption of the main infrared rays.

[0025] According to the present invention (Claim 4), the infrared rays radiated from the heater H to the opposite side of the vaporizer body 20 are reflected toward the vaporizer body 20 by the auxiliary reflecting member 89, and thus the infrared rays radiated from the heater H gather toward the vaporizer body 20 accordingly.

[0026] According to the present invention (Claim 5), since the temperature detector 70 is arranged in a non-contact manner with respect to the vaporizing portion 22 and the heater H, the temperature detector 70 can detect the temperature without being affected by the vaporizing portion 22 or the heater H. The temperature detection of the temperature detector 70 depends only on the infrared rays absorbed by the temperature detector 70, and the accuracy of the temperature detection is improved.

[0027] According to the present invention (Claim 6), as the infrared absorber 78 of the temperature detector 70, graphite having a high absorption rate for infrared rays and a high thermal conductivity is adopted. Therefore, the infrared rays incident on the infrared absorber 78 are almost absorbed and heat is transferred, and the amount of infrared ray radiation from the heater H can be accurately and quickly measured.

Brief Description of the Drawings

[0028]

Figure 1

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Figure 15

Mode for Carrying Out the Invention

[0029] Hereinafter, the present invention will be described with reference to the drawings. The vaporizer 10 is a device that vaporizes the liquid raw material LM supplied from the upstream side into the raw material gas VG and supplies this raw material gas VG to various semiconductor manufacturing apparatuses on the downstream side that use it. The vaporizer 10 is roughly composed of a vaporizer body 20, a heater H, a temperature detector 70, and a reflecting member 28 that serves as a casing for housing these components. The liquid raw material LM includes various substances as described above, and is appropriately selected according to the raw material gas VG used in various semiconductor manufacturing apparatuses. Here, as representative examples, water, hydrogen peroxide, TEOS (tetraethoxysilane), and PhTES (triethoxyphenylsilane) are taken up. These liquid raw materials LM efficiently absorb mid-infrared rays in the wavelength range of 2.5 μm to 4 μm. In the case of water, when the film thickness is 10 μm or more, it efficiently absorbs mid-infrared rays in the above range. When the film thickness is 1 mm, it almost completely absorbs mid-infrared rays in the above range.

[0030] The supply method of the liquid raw material LM is supplied to the vaporizer main body 20 in a mist form, droplet form, or liquid form. The carrier gas CG may be supplied to the vaporizer main body 20 together with the liquid raw material LM, or only the liquid raw material LM may be supplied to the vaporizer main body 20 without the carrier gas CG. When the liquid raw material LM is supplied to the vaporizer main body 20 in a mist form, something like an atomizer 12a is used (Fig. 9).

[0031] The vaporizer main body 20 has various structures for achieving the above problems, and all are characterized in that a liquid reservoir E into which the liquid raw material LM flows is provided in the vaporization section 22 at a position lower than the flow path R of the liquid raw material LM flowing through the vaporization space K. (Embodiment 1: Figs. 1 to 8) In the vaporizer 10 of Embodiment 1, it is the case where the liquid raw material LM is supplied to the vaporizer main body 20 in a liquid or droplet form. The vaporizer main body 20 includes a liquid raw material supply section 12 that supplies the liquid raw material LM to the vaporization space K, a vaporization section 22 that has the vaporization space K inside for vaporizing the supplied liquid raw material LM, and a raw material gas discharge section 40 that sends out the vaporized raw material gas VG to the next process.

[0032] In the case of Fig. 1, the vaporizer main body 20 is such that the liquid raw material supply section 12 and the raw material gas discharge section 40 are integrated with the vaporization section 22. Of course, as will be described later, there may be a case where the liquid raw material supply section 12, the raw material gas discharge section 40, and the vaporization section 22 are separate bodies (Fig. 9). The vaporizer main body 20 is a member formed by bending a pipe material having a circular cross-section made of, for example, transparent quartz glass that transmits infrared rays. The vaporization section 22 of this embodiment is a bent portion in a U shape, and is composed of a bent portion 22e and straight pipe portions 22f and 22g extending upward from this bent portion 22e.

[0033] The liquid raw material supply section 12 is integrally connected to one straight pipe portion 22f, is formed in an inverted L shape, and has a shape in which the inlet portion extends in the horizontal direction. The raw material gas discharge section 40 is integrally connected to the other straight pipe portion 22g, and has a shape in which the outlet portion is drawn out in the horizontal direction. The vaporization section 22 configured in a U shape by the bent portion 22e and the straight pipe portions 22f and 22g is filled with a spherical body 30 made of, for example, transparent quartz that is infrared transmissive. The spherical body 30 is, for example, a sphere with a diameter of 2 mm to 5 mm. Inside this vaporization section 22, the portion filled with the spherical bodies 30 is the vaporization space K. The spherical bodies 30 are in point contact with each other, and a gap P serving as a flow path for the liquid raw material LM is formed between the spherical surfaces of the spherical bodies 30.

[0034] In the embodiment of FIG. 1, the vaporization section 22 has a bent shape in a U shape. However, the shape of the vaporization section 22 is not limited to a U shape as will be described later. The bent portion 22e constituting the bottom of the vaporization section 22 becomes the liquid reservoir E of the liquid raw material LM. The present invention only requires that this liquid reservoir E be configured at a position lower than the flow path R of the liquid raw material LM flowing through the vaporization space K. For example, an example in which a bent portion 22e positioned below these is provided between the straight pipe portions 22f and 22g extending in the horizontal direction as will be described later (FIG. 12), a substantially n-shaped one (FIG. 13), a W-shaped one (FIG. 14), or a horizontally installed spiral pipe (FIG. 15) is also included.

[0035] On the spherical bodies 30 filled in the straight pipe portions 22f and 22g, porous filters 23f and 23g are installed as required. As the porous filters 23f and 23g, any material can be used as long as it is not affected by the liquid raw material LM and can allow it to pass through smoothly. Here, a porous semi-molten quartz glass body in which quartz glass powder particles are in a semi-molten state and the contact portions are fusion-bonded is used so that infrared rays radiated from the heater H can pass through and welding fixation to the vaporizer body 20 is possible. Although not shown, in order to keep the discharged raw material gas VG at a constant temperature, a cylindrical heater block with a built-in heating heater may be attached to the outer periphery of the tubular raw material gas discharge portion 40.

[0036] The reason why transparent quartz glass is used as the material of the vaporizer body 20 and the spherical bodies 30 is that infrared rays radiated from the heater H can pass through and the infrared rays can pass through to the center of the vaporization portion 22. In this embodiment, the shape of the spherical bodies 30 is spherical, but it is not limited to a sphere. For example, granular quartz may be used. This is preferable in terms of increasing the surface area and thus enhancing the vaporization efficiency of the liquid raw material. However, those that are likely to chip due to vibration or other external forces and generate particles are not adopted.

[0037] On both sides of the vaporizer body 20, a plurality of heaters H (two in this embodiment) are erected. It is preferable that the straight pipe portions 22f and 22g of the vaporization portion 22 and the heater H are parallel, and the center lines of the heater H and the straight pipe portions 22f and 22g coincide with each other front and back and are parallel. The heater H is configured to cover at least the straight pipe portions 22f and 22g and the bent portion 22e of the vaporization portion 22 and radiate infrared rays evenly to these portions. A gap d1 with a width M1 is provided between each heater H and the side wall 22h of the vaporizer body 20. This blocks heat transfer from the heater H to the vaporizer body 20. However, since gas (air) exists in this gap d1, the heat of the heater H is transferred to the vaporizer body 20. Therefore, as will be described later, it is conceivable to use the gap d1 as a flow path for gas replacement.

[0038] The first embodiment of the heater H is as shown in Fig. 4(a). The heater H is composed of a pair of two transparent quartz tubes 80, closing plugs 82 and 83 provided at both ends of the transparent quartz tubes 80, a connection terminal 85 provided on the upper closing plug 82, a heater coil 88 stretched in the transparent quartz tube 80, and an auxiliary reflection member 89. For example, a Kanthal wire is used for the heater coil 88. The pair of heater coils 88 are connected inside the lower closing plug 83. The upper ends of the heater coils 88 are respectively connected to the connection terminal 85. An inert gas is enclosed in the transparent quartz tube 80. When the heater coil 88 is a Kanthal wire, its peak wavelength is 2.6 μm. The wavelengths of 50% or more of the specific radiant power of the Kanthal wire are medium infrared rays in the region of about 1.5 μm to 4 μm. The second embodiment of the heater H is shown in Fig. 4(b). In this case, the heater coil 88 is formed of graphite processed into a zigzag. In the case of graphite, it emits the same infrared rays as the Kanthal wire.

[0039] Fig. 5(b) shows an example in which the auxiliary reflection member 89 is used for the heater H. Since there is a main reflection member 28 surrounding the vaporizer body 20 as will be described later, this auxiliary reflection member 89 is not always necessary. This auxiliary reflection member 89 is provided on the back side of the transparent quartz tube 80, that is, the entire surface on the opposite side of the side wall 22h of the vaporizer body 20. The surface of the auxiliary reflection member 89 facing the vaporizer body 20 is a mirror surface 89k.

[0040] The reflecting member 28 is a cylindrical member provided for reflecting the infrared rays radiated from the heater H toward the vaporization space K. The inner surface of the reflecting member 28 is finished to a mirror surface 28k by means such as metal (for example, gold, etc.) plating or vapor deposition with a high infrared reflectance, or an aluminum foil is attached to form the mirror surface 28k. As shown in FIG. 3, the reflecting member 28 is provided so as to surround the vaporizer body 20 outside the heater H. A ceiling plate 21 is attached to the upper end of the reflecting member 28, and a bottom plate 27 is attached to the lower end thereof. The inner surfaces of the ceiling plate 21 and the bottom plate 27 are also the mirror surface 28k.

[0041] The bottom plate 27 is provided with holes, which are used as the replacement gas supply part 25. The ceiling plate 21 is also provided with holes, which are used as the replacement gas discharge part 26. Thus, the replacement gas (air) flows through the internal space of the reflecting member 28 in which the heater H is disposed. As a result, the gas (air) around the heater H heated by the heater H rises and is discharged from the replacement gas discharge part 26. Instead, the outside air at room temperature flows in from the replacement gas supply part 25, and the space in which the heater H is disposed is maintained at the temperature of the replacement gas (air). As a result, as will be described later, most of the thermal influence on the vaporizer body 20 and the temperature detector 70 by the heater H in the internal space of the reflecting member 28 is removed.

[0042] In FIGS. 1 to 3, an example considering the heat transfer to the vaporizer body 20 in the space where the heater H is disposed is shown. When the heater H is heated, the temperature of the gas (air) around it rises. The side wall 22h of the vaporizer body 20 is heated through this heated gas (air). Therefore, the width M1 of the gap d1 is devised or the gap d1 is used as the flow path for the replacement gas. This can be applied to all the embodiments.

[0043] In this case, the width M1 of the above-mentioned gap d1 becomes a problem. The room-temperature outside air flowing in from the replacement gas supply unit 25 as described above rises along the heater H and gradually increases in temperature. When the space (width M1) between the heater H and the side wall 22h of the vaporizer body 20 is close and smaller than the thickness δ of the temperature boundary layer T, the replacement gas that flows along the heater H and is heated by the heater H will touch the side wall 22h of the vaporizer body 20. As a result, the temperature of the side wall 22h will be affected by the heater H. Therefore, as shown in Fig. 7(b), when the space (width M1) between the heater H and the side wall 22h of the vaporizer body 20 is made larger than the thickness δ of the temperature boundary layer T, the unheated replacement gas will flow along the side wall 22h between the heated temperature boundary layer T and the side wall 22h, blocking the heat influence of the heated temperature boundary layer T. As a result, the influence of the heated temperature boundary layer T in the space where the heater H is arranged will be surely removed.

[0044] The temperature detector 70 is composed of a temperature detection element 71 and an infrared absorber 78. The temperature detection element 71 is one in which a pair of thermocouple element wires 71a and 71b, which are the temperature detection elements 71, are embedded in a stainless-steel sheath 74 via an insulating layer 72. In this embodiment, a sheath-shaped infrared absorber 78 is covered so as to surround the joint 73 of the thermocouple element wires 71a and 71b and to be in close contact with the sheath 74. Graphite, which has a better thermal conductivity than metal, is used for the infrared absorber 78. The thinner the infrared absorber 78 is, the more sensitive it is to changes in the absorbed infrared rays.

[0045] As shown in Fig. 2, the temperature detector 70 is arranged with gaps d2 and d3 of widths M2 and M3 so as to be non-contact with respect to the vaporizer body 20 and the heater H between the vaporizer body 20 and the heater H. In the vaporizer body 20, particularly in the straight pipe portion 22f on the inlet side of the vaporization section 22, the liquid raw material LM that has passed through the porous filter 23f becomes one or more meandering streaks (flow paths R) and flows down between the spherical bodies 30. When the amount of infrared heat from the heater H is sufficient for the liquid raw material LM, the entire amount of the liquid raw material LM vaporizes within the straight pipe portion 22f on the inlet side. On the other hand, when the amount of infrared heat from the heater H is insufficient for the liquid raw material LM, the entire amount of the liquid raw material LM does not vaporize within the straight pipe portion 22f on the inlet side, and the unvaporized liquid raw material LM accumulates in the bent portion 22e.

[0046] Since the portion where the liquid raw material LM is flowing and the portion where it has accumulated are at a lower temperature than other portions, if a temperature detector 70 is installed in this portion, the detected temperature will appear low. If the temperature detector 70 is installed so as to be non-contact with the vaporizer body 20 and the heater H, it will not be affected by both of them, absorb the infrared rays from the heater H and be heated, and detect the amount of infrared radiation from the heater H.

[0047] Here, strictly speaking, the widths M2 and M3 of the gaps d2 and d3 become a problem. As described above, the reflection member 28 incorporates the vaporizer body 20 and the heater H inside. The internal temperature of the reflection member 28 and the temperature of the side wall 22h of the vaporizer body 20 gradually increase as they rise along the heater H. Even if the outside air with a low temperature flows into the reflection member 28 from the replacement gas supply portion 25 of the reflection member 28 as described above, passes through the gaps d2 and d3, and exits from the replacement gas discharge portion 26 of the ceiling portion, if the space (widths M2 and M3) between the infrared absorber 78 of the temperature detector 70 and the side wall 22h of the heater H and the vaporizer body 20 is close and smaller than the thickness δ of the temperature boundary layer T, the heated replacement gas will touch the infrared absorber 78. As a result, the temperature measurement of the temperature detector 70 will be affected.

[0048] As shown in FIG. 7(a), when the gaps d2 and d3 (widths M2 and M3) are made larger than the thickness δ of the temperature boundary layer T, the unheated replacement gas flows along the infrared absorber 78 between the heated temperature boundary layer T and the infrared absorber 78, and blocks the thermal influence of the heated temperature boundary layer T on the temperature detector 70. As a result, the influence of the heated temperature boundary layer T in the space where the infrared absorber 78 is disposed is surely removed. As a result, accurate temperature measurement of the heater H becomes possible.

[0049] Since the heater H has the heater coil 88 covered with the transparent quartz tube 80 as described above, the temperature detector 70 cannot be installed in the heater coil 88. If the temperature detector 70 is to be installed in the transparent quartz tube 80, the transparent quartz tube 80 will be damaged, so the temperature detector 70 cannot be installed in the transparent quartz tube 80.

[0050] The temperature detector 70 is connected to an external infrared heater temperature controller 90. The infrared heater temperature controller 90 is connected to a power source 91 and is configured to control the power supplied to the heater H according to the output from the temperature detector 70.

[0051] Next, a method for vaporizing the liquid raw material LM using the vaporizer 10 of the present invention will be described. When the heater H is energized, infrared rays having a mountain shape spreading to the short wavelength side and the long wavelength side, including mid-infrared rays in the region of about 1.5 μm to 4 μm with a peak wavelength of 2.6 μm, are radially radiated from the heater coil 88. On the surface of the heater H facing the vaporizer body 20 side, a considerable portion of the infrared rays travels toward the vaporizer body 20. The infrared rays emitted to the back side are reflected by the auxiliary reflection member 89 on the back of the heater H (when there is no auxiliary reflection member 89, they are reflected by the cylindrical main reflection member 28) and travel toward the vaporizer body 20.

[0052] Since the vaporizer body 20 is formed of a transparent quartz glass that transmits infrared rays, the infrared rays that have traveled toward the vaporizer body 20 pass through the side wall 22h of the vaporizer body 20 while refracting. Since the inside of the vaporizer body 20 is filled with the spherical bodies 30, the infrared rays that have reached the vaporization space K inside the vaporizer body 20 pass through these spherical bodies 30 while refracting and reach the opposite side wall 22h, and further pass through this while refracting. The figure becomes complicated, so the infrared rays are shown as straight lines.

[0053] Most of the infrared rays that have passed through the vaporizer body 20 are reflected by the mirror surface 28k on the opposite side of the cylindrical reflecting member 28 and pass through the vaporizer body 20 again. The remaining infrared rays are reflected by the auxiliary reflecting member 89. The infrared rays will be instantaneously and infinitely repeated within the cylindrical reflecting member 28.

[0054] The state of the infrared rays in the vaporization space K of the vaporizer body 20 is uniform because the infinite reflections are instantaneously repeated as described above. When the temperature in the vaporization space K rises to a uniform temperature at the set temperature and becomes in a state where the liquid raw material LM can be vaporized, the liquid raw material LM is supplied to the liquid raw material supply unit 12. The liquid raw material LM flows down onto the porous filter 23f on the inlet side through the liquid raw material supply unit 12. The flowing-down liquid raw material LM soaks into the porous filter 23f and oozes out from its lower surface. The spherical bodies 30 are in contact with the lower surface of the porous filter 23f, and the oozed liquid raw material LM becomes one or a plurality of streaks (flow paths R) and randomly flows down along the surface of the spherical bodies 30.

[0055] The spherical bodies 30 are in point contact with adjacent spherical bodies 30 to support each other, and a substantially triangular gap P formed by a complex concave spherical surface is formed therebetween in plan view (Fig. 8(a)). Most of the flowing-down liquid raw material LM flows down while wetting the surface of the spherical bodies 30, and the remaining liquid raw material LM accumulates in the gap P due to the surface tension of the liquid raw material LM to form a liquid film of the liquid raw material LM. When the film thickness of the liquid raw material LM is 10 μm or more, it efficiently absorbs medium infrared rays of 2.5 μm to 4 μm. In particular, when the film thickness is 1 mm or more, it absorbs almost 100% of the medium infrared rays.

[0056] Most of the infrared rays used here are mid-infrared rays. As described above, their wavelength is 2.5 μm to 4 μm, including the absorption peak wavelength (3 μm) of the liquid raw material LM. Therefore, a part of the mid-infrared rays reaching the vaporization section 22 is absorbed by the thin film of the liquid raw material LM formed on the surface of the spherical body 30, or is absorbed by the liquid film of the liquid raw material LM accumulated in the gap P, converted into heat, and vaporizes the liquid raw material LM. If the film thickness of the thin film of the liquid raw material LM is too small, the infrared rays will pass through directly. Since the spherical body 30 is formed of transparent quartz glass that transmits infrared rays, the infrared rays not absorbed by the liquid raw material LM pass through the spherical body 30 and exit to the opposite side.

[0057] The infrared rays not absorbed by the liquid raw material LM successively pass through the spherical bodies 30 filled in the vaporizer main body 20, pass through the side wall 22h on the opposite side of the vaporizer main body 20, and emit light to the outside. The infrared rays emitted from the vaporizer main body 20 are reflected by the mirror surface 28k on the opposite side of the reflecting member 28 (or a part of it is the auxiliary reflecting member 89), and then head towards the vaporizer main body 20 again. In this way, the liquid raw material LM flowing down in the vaporization space K (that is, the straight pipe portion 22f on the inlet side) is mainly heated by uniform mid-infrared rays, and the liquid raw material LM that has absorbed this mid-infrared ray and increased in temperature gradually vaporizes. On the other hand, the heating of the liquid raw material LM by heat conduction from the spherical body 30 due to point contact is small.

[0058] When the supply amount of the liquid raw material LM is small, as described above, the entire amount of the liquid raw material LM vaporizes in the straight pipe portion 22f on the inlet side before reaching the bent portion 22e. The vaporized raw material gas VG rapidly increases in volume, passes through the bent portion 22e and the straight pipe portion 22g on the outlet side, and is discharged from the raw material gas discharge portion 40 towards the next process.

[0059] When the supply amount of the liquid raw material LM is large or when the supply amount of the liquid raw material LM fluctuates during the vaporization process and exceeds the supplied heat amount of the heater H, the entire amount of the liquid raw material LM does not vaporize in the straight pipe portion 22f on the inlet side, and the remaining unvaporized liquid raw material LM accumulates in the bent portion 22e. This portion is referred to as the liquid accumulation E. The liquid raw material LM accumulated in the liquid pool E is exposed to infrared rays and heated, and vaporizes within the narrow gaps P between the spherical bodies 30. On the other hand, the inflow of the unvaporized liquid raw material LM into the bent portion 22e will continue. Due to the presence of the liquid pool E, liquid leakage of the unvaporized liquid raw material LM does not occur, and it can be continuously vaporized rapidly and efficiently.

[0060] And, since there is a straight pipe portion 22g on the outlet side and a distance between the liquid pool E and the outlet 40d of the vaporizer body 20, the raw material gas VG rising from the liquid pool E will be uniformly heated in this portion regardless of its quantity.

[0061] Next, temperature measurement will be described. As described above, this liquid raw material LM flowing down along the surface of the spherical body 30 gradually vaporizes and flows down within the straight pipe portion 22f on the inlet side as one or a plurality of flows. When the liquid raw material LM accumulates in the liquid pool E which has a large flow rate and is the bent portion 22e, the temperature of that portion is lower than that of the spherical body 30 and the bent portion 22e, so the temperature of the portion in contact with the liquid raw material LM is naturally lower than the portion not in contact. That is, temperature unevenness will occur in the straight pipe portion 22f on the inlet side and the bent portion 22e.

[0062] Since the temperature detector 70 is held non - contact (at least at a distance of the temperature boundary layer δ or more) with respect to the vaporizing portion 22 and the heater H, it is not affected by temperature unevenness or the heater H. And since the temperature detector 70 has a graphite infrared absorber 78 as a sheath - like outer skin, the infrared rays incident on the infrared absorber 78 are almost absorbed and converted into heat, and this infrared absorber 78 is detected for its temperature. Since the amount of absorbed infrared rays is proportional to the amount of infrared rays radiated by the heater H, by measuring the temperature of the infrared absorber 78, the amount of infrared rays radiated by the heater H can be accurately measured.

[0063] In other words, the temperature detection by this temperature detector 70 does not depend on heat transfer, but only on the infrared rays absorbed by the infrared absorber 78. Therefore, it is not affected by the temperature unevenness of the vaporization section 22 or the heater H, and accurate temperature measurement becomes possible. Note that if the thickness of the infrared absorber 78 is made as thin as possible, the heat transfer to the joint portion 73 of the temperature detector 70 becomes rapid, and the responsiveness of the temperature control is improved.

[0064] (Modification 1 of Embodiment 1: FIG. 9) In the above, an example in which the liquid raw material LM is directly supplied to the vaporizer main body 20 has been shown, but it may be supplied in a mist form. In this case, the main part of the liquid raw material supply section 12 is constituted by an atomizer 12a. A liquid raw material supply pipe 12b is provided at the center of the atomizer 12a, and its tip is constricted into a conical shape to form a spray port 12d. A carrier gas supply pipe 12c is provided on the side surface of the atomizer 12a. An annular carrier gas supply path 12e that is connected to the spray port 12d and exhibits a Venturi effect is provided on the outer periphery of the liquid raw material supply pipe 12b. The space from the spray port 12d to the porous filter 23f on the inlet side serves as an atomization space S. The atomization space S is not filled with the spherical bodies 30.

[0065] When the liquid raw material LM is supplied to the liquid raw material supply pipe 12b and the carrier gas CG is supplied to the carrier gas supply pipe 12c, a Venturi effect is thereby generated, and the liquid raw material LM becomes misty and is uniformly dispersed into the atomization space S from the spray port 12d. The misty liquid raw material LM dispersed in the atomization space S is evenly poured onto the porous filter 23f and flows down toward the spherical bodies 30 side in one or a plurality of streaks. Thereafter, it is the same as in Embodiment 1.

[0066] (Embodiment 2: FIGS. 10 and 11) In this Embodiment 2, compared with Embodiment 1, the shapes of the vaporizer main body 20 and the reflection member 28, and the position of the heater H with respect to the vaporizer main body 20 are different. In FIG. 3, heaters H are erected before and after the vaporizer body 20. In contrast, in this modification, heaters H are erected on both sides of the vaporizer body 20. As a result, the front-rear width of the vaporizer 10 becomes thinner, and the reflecting member 28 can be formed into a rectangle with a thin front-rear width in a horizontal cross-section, enabling the vaporizer 10 to be made thinner. Along with this change, the liquid raw material supply section 12 and the raw material gas discharge section 40 connected to the straight pipe portions 22f and 22g extend upward as they are beyond the ceiling plate 21. The temperature detector 70 is installed between one of the heaters H and the straight pipe portions 22f and 22g on the inlet side or the outlet side. Otherwise, it is the same as in Embodiment 1.

[0067] (Embodiment 3: FIG. 12) In the vaporizer body 20 of Embodiment 3, a bent portion 22e located below these is provided between the horizontally extending straight pipe portions 22f and 22g. The liquid raw material LM that has flowed through the gap P of the spherical body 30 in the straight pipe portion 22f on the inlet side flows into the liquid pool E, which is the bent portion 22e when the flow rate is high. Then, it is heated and vaporized here. This point is the same as in Embodiment 1. In FIG. 12, the bent portion 22e is formed in a small U shape, but Embodiment 2 is not limited to this shape. It is connected to the straight pipe portions 22f and 22g, and the lower surface of the boundary portion bulges downward in a hemispherical shape. This bulging portion may be used as the liquid pool E. The excess liquid raw material LM flowing in from the straight pipe portion 22f on the inlet side will accumulate in this liquid pool E.

[0068] (Embodiments 4 and 5: FIGS. 13 and 14) The vaporizer body 20 of Embodiment 4 is formed by bending a transparent quartz tube into a substantially n shape, and the vaporizer body 20 of Embodiment 5 is formed by bending a transparent quartz tube into a W shape. In this case, since the path from the liquid pool E to the outlet 40d can be made longer than in Embodiment 1, the uniform heating of the raw material gas VG can be further promoted. Otherwise, it is the same as in Embodiment 1.

[0069] (Embodiment 6: FIG. 15) The vaporizer body 20 of Embodiment 6 is formed by bending a transparent quartz tube into a spiral shape, arranging the spiral portion horizontally, and disposing a heater H at its center. Also in this case, a plurality of bending portions 22e are provided in the spiral portion, and more uniform heating of the raw material gas VG can be promoted. In this case, the liquid reservoir E becomes the first bending portion 22e. Also in this case, since the path from the liquid reservoir E to the outlet 40d can be made longer than that in Embodiment 1, more uniform heating of the raw material gas VG can be promoted. Other aspects are the same as those in Embodiment 1.

Explanation of Signs

[0070] CG: Carrier gas, d1·d2·d3: Clearance, E: Liquid reservoir, H: Heater, K: Vaporization space, LM: Liquid raw material, M1·M2·M3: Width of clearance, P: Void, R: Flow path, S: Atomization space, T: Temperature boundary layer, VG: Raw material gas, δ: Thickness of temperature boundary layer 10: Vaporizer, 12: Liquid raw material supply section, 12a: Atomizer, 12b: Liquid raw material supply pipe, 12c: Carrier gas supply pipe, 12e: Carrier gas supply path, 12d: Spray port, 20: Vaporizer body, 21: Ceiling plate:, 22: Vaporization section, 22e: Bending portion, 22f·22g: Straight pipe portion, 22h: Side wall, 23f·23g: Porous filter, 25: Substitution gas supply section, 26: Substitution gas discharge section, 27: Bottom plate, 28: Reflecting member, 28k: Mirror surface, 30: Spherical body, 40: Raw material gas discharge section, 40d: Outlet, 70: Temperature detector, 71: Temperature detection element, 71a·71b: Thermocouple wire, 72: Insulating layer, 73: Junction, 74: Sheath, 78: Infrared absorber, 80: Transparent quartz tube, 82·83: Blocking stopper, 85: Connection terminal, 88: Heater coil, 89: Auxiliary reflecting member, 89k: Mirror surface, 90: Infrared heater temperature controller, 91: Power supply

Claims

1. A vaporizer body 20 is constituted by a liquid source supplying section 12 for supplying a liquid source LM for semiconductor manufacturing, a vaporizing section 22 having a vaporizing space K therein for vaporizing the supplied liquid source LM, and a source gas exhausting section 40 for sending out the vaporized source gas VG to a next process, a spherical body 30 filled in the vaporizing section 22, and a heater H for emitting infrared rays to vaporize the liquid source LM, The heater H is disposed at a gap d1 of width M1 from the vaporizing section 22, The vaporizing section 22 and the spherical body 30 are made of a transparent material through which infrared rays can pass, A vaporizer characterized in that a liquid reservoir E into which the liquid source LM flows is provided in the vaporizing section 22 at a position lower than a flow path R of the liquid source LM flowing through a vaporization space K.

2. 2. The vaporizer according to claim 1, wherein the vaporizing section (22) is made of a bent pipe material.

3. The vaporizer described in claim 1, characterized in that it includes a reflective member 28 arranged to surround the vaporization section 22 outside the heater H, and whose inner surface facing the vaporization section 22 is formed into a mirror surface 28k that reflects infrared rays.

4. A vaporizer as described in claim 1 or 3, characterized in that an auxiliary reflection member 89 is provided on the surface of the heater H opposite the vaporizer main body 20, and the surface of the auxiliary reflection member 89 that reflects infrared rays toward the vaporizer main body 20 is a mirror surface 89k.

5. A vaporizer as described in claim 1 or 3, characterized in that a temperature detector 70 for measuring the amount of infrared radiation is arranged between the vaporization section 22 and the heater H with gaps d2 and d3 of widths M2 and M3 provided between the vaporizer main body 20 and the heater H.

6. The carburetor described in claim 5, characterized in that the temperature detector 70 is composed of an infrared absorbing body 78 made of graphite that absorbs infrared rays and heats up, and a temperature detection element 71 embedded in the infrared absorbing body 78 and detects the temperature of the infrared absorbing body 78.

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