CN112585298A

CN112585298A - Gasifier

Info

Publication number: CN112585298A
Application number: CN201980035271.1A
Authority: CN
Inventors: 小野弘文; 八木茂雄; 山本健太
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2018-07-24
Filing date: 2019-04-22
Publication date: 2021-03-30
Anticipated expiration: 2039-04-22
Also published as: KR20200140389A; JP2020020036A; JP6694093B2; TWI699495B; TW202007896A; KR102292156B1; CN112585298B

Abstract

Provided is a vaporizer in which bumping is suppressed and pressure fluctuation in a vaporization space is extremely small in a method without using a sprayer. The vaporizer (1) is composed of a container body (10), a porous member (30) which is provided in the vaporizer (1) and heated, an introduction pipe (40) which supplies a liquid raw material (L) to the porous member (30), and a gas discharge path (7) which discharges a vaporized raw material gas (G) to the outside. The outlet (41) of the introduction pipe (40) is disposed in contact with or in close proximity to the porous member (30). When the outlet (41) is disposed close to the porous member (30), the separation distance (H) from the outlet (41) to the porous member (30) is within a range not exceeding the size from the outlet (41) to the lower end of the liquid raw material (L) which drops as droplets from the outlet (41) due to surface tension.

Description

Gasifier

Technical Field

The present invention relates to a vaporizer that does not use a carrier gas for spraying for atomizing a liquid raw material before vaporization, and more particularly, to a vaporizer in which pressure fluctuation during vaporization is extremely small by bringing an introduction tube (capillary tube) for introducing a liquid raw material into a vaporizer into contact with or close to a porous member (sintered filter).

Background

In a manufacturing process of a semiconductor device, there are a film formation process, an etching process, a diffusion process, and the like, and in these processes, a gas is often used as a raw material. However, in recent years, liquid raw materials are often used instead of raw material gases.

The liquid raw material is converted into a gas by a vaporizer and supplied to a reaction step. When the raw material is a gas, the flow rate is controlled by a mass flow controller, and therefore, the flow rate stability is good.

On the other hand, in the case of a liquid raw material, the liquid raw material whose flow rate is controlled is introduced into a vaporizer, atomized by a spray gas inside the vaporizer, and then vaporized by heating, but the pressure fluctuation is large as compared with the case where the raw material is a gas. In order to stably produce a uniform film, it is necessary to suppress such pressure fluctuations as much as possible.

In such a semiconductor film formation process, the recent semiconductor film formation process often does not use a carrier gas. In such a gasification step without using a spray gas or a carrier gas, pressure fluctuations become significantly larger than those in the case of using a spray gas or a carrier gas for reasons described later.

Prior art documents

Patent document

Patent document 1: japanese patent No. 3650543

Patent document 2: japanese patent No. 4601535

Disclosure of Invention

Problems to be solved by the invention

In order to efficiently and stably vaporize the liquid material, a method of introducing the liquid material into the vaporization chamber by spraying the liquid material with a sprayer as described above is employed. This allows stable vaporization and suppresses pressure fluctuations inside the vaporization chamber.

However, in the latest method not using a sprayer, the liquid material is dropped from a relatively thin introduction pipe and introduced into the vaporization chamber in the state of large-sized droplets. The introduced liquid droplets are sequentially brought into contact with the inner wall of the heated vaporizing chamber and instantaneously vaporized. Therefore, bumping occurs continuously on the inner wall of the vaporization chamber, and the internal pressure of the vaporizer (internal pressure of the vaporization chamber) fluctuates greatly. This fluctuation causes unevenness in the source gas supplied to the film formation apparatus and appears. This is fatal to a film forming apparatus and prevents uniform film formation. This is a serious problem in the gasification step in the case where a sprayer is not used.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a vaporizer in which bumping occurring when a liquid material contacts a heating surface is suppressed and pressure fluctuation inside the vaporizer is extremely small, in a method not using a sprayer.

Means for solving the problems

The invention described in claim 1 is a vaporizer 1 comprising a container body 10, a porous member 30, an introduction pipe 40, and a gas discharge path 7,

the container body 10 has a vaporization space 5 inside,

the porous member 30 is disposed in the vaporization space 5 and heated,

the introduction pipe 40 is inserted into the vaporization space 5 from the outside, and supplies the liquid material L to the porous member 30,

the gas discharge path 7 is configured to discharge the raw material gas G generated by the vaporization of the porous member 30 from the vaporization space 5 to the outside,

the outlet 41 of the inlet pipe 40 is disposed in contact with or close to the porous member 30,

the separation distance H from the outlet 41 to the porous member 30 when the outlet 41 is disposed close to the porous member 30 is within a range not exceeding the size from the outlet 41 to the lower end of the liquid raw material L hanging down as droplets from the outlet 41 due to surface tension.

The invention described in claim 2 is the gasifier 1 according to claim 1, characterized in that,

a minute through hole 45 is provided through a side surface of the inlet pipe 40 near the outlet 41.

The invention described in claim 3 is the gasifier 1 according to claim 1 or 2, characterized in that,

a recess 34 into which the outlet 41 of the introduction pipe 40 is inserted is formed in the surface of the porous member 30.

The invention described in claim 4 is the vaporizer 1 according to any one of claims 1 to 3,

the porous member 30 is made of a sintered metal body, a sintered ceramic body, a metal mesh laminate, or a sintered metal fiber nonwoven fabric.

The invention described in claim 5 is the gasifier 1 according to claim 1 or 2, characterized in that,

the porous member 30 is composed of a laminate of a plurality of

porous plates

30a, 30 b.

An invention described in claim 6 is the gasifier 1 according to claim 3, characterized in that,

the porous member 30 is composed of a laminate of a plurality of

porous plates

30a, 30b, the porous plate 30a on the outlet 41 side of the inlet pipe 40 is provided with through holes 34a for forming the recesses 34, and the porous plate 30b remote from the outlet 41 is formed in a flat plate shape.

An invention described in claim 7 is the gasifier 1 according to claim 1, characterized in that,

the notch 48 reaching the end face 42 of the outlet 41 of the introducing pipe 40 is provided in the vicinity of the outlet 41.

ADVANTAGEOUS EFFECTS OF INVENTION

Since the outlet 41 of the introduction pipe 40 of the vaporizer 1 of the present invention is disposed in contact with the porous member 30 or in proximity to the separation distance H within the above range, the liquid raw material L flowing out of the outlet 41 penetrates into the porous member 30 faster than vaporization while being in contact with the porous member 30, and rapidly diffuses around a point coincident with the outlet 41.

Around the point corresponding to the outlet 41 of the introduction pipe 40, the liquid material L gradually and continuously evaporates from the surface of the porous member 30. This greatly suppresses pressure fluctuations in the gasifier 1.

Drawings

FIG. 1 is a longitudinal cross-sectional view of a vaporizer of the present invention and a liquid flow control valve connected thereto.

Fig. 2 is a longitudinal sectional view of the inlet pipe in contact with the porous member of the present invention.

Fig. 3 is a cross-sectional view taken along line X-X of fig. 2.

FIG. 4 is a vertical cross-sectional view of the case where the outlet is closed and the liquid material flows out from the fine through-hole in FIG. 2.

Fig. 5 is a longitudinal sectional view of the inlet pipe and the porous member of the present invention in a state separated from each other.

Fig. 6 is a longitudinal sectional view of the porous member of the present invention with an introduction tube inserted into a recess.

Fig. 7 is a vertical cross-sectional view of the porous member of the present invention being a sintered body of a wire-mesh laminate.

Fig. 8 is a vertical cross-sectional view of the porous member of the present invention being a sintered metal fiber nonwoven fabric.

Fig. 9 is a vertical cross-sectional view of the porous member of the present invention in a state where the porous member is composed of a plurality of pieces.

Fig. 10 is a vertical sectional view of the porous member of the present invention in a state where the porous plate at the uppermost part is provided with through holes.

Fig. 11 is a longitudinal sectional view of the inlet tube of the present invention with a slit provided at the outlet end.

Detailed Description

The present invention is described below with reference to the drawings. Fig. 1 is a vertical sectional view of a vaporizer 1 of the present invention, and is composed of a container body 10, a porous member 30, an introduction pipe 40,

heaters

50a and 50b, and

thermocouples

60a and 60 b.

The container body 10 is composed of an outer block 11 and an inner block 21, which are made of a corrosion resistant material resistant to the liquid material L. The outer block 11 has a receiving hole 12 with an open lower surface, and an insertion hole 13 extending from the upper surface of the outer block 11 to the top surface of the receiving hole 12 is formed therethrough. One or more heaters 50a are embedded in the side wall 14 of the outer block 11 surrounding the housing hole 12 to heat the outer block 11 to a set temperature. A thermocouple 60a for measuring the temperature of the outer block 11 is attached to the top plate portion of the outer block 11. In order to correctly measure the temperature of the gasification space 5 in contact with the ceiling portion, the front end of the thermocouple 60a is inserted into a portion close to the ceiling portion.

The inner block 21 is composed of a base 22 and a table portion 23 projecting from the center of the upper surface of the base 22, and one or more heaters 50b for the inner block 21 are attached to a portion extending from the bottom of the inner block 21 to the vicinity of the upper surface of the table portion 23.

A space is provided between the upper surface of the table portion 23 and the top surface of the housing hole 12 of the outer block 11, and this space is defined as the vaporization space 5. Further, a gap is provided over the entire circumference between the inner circumferential surface of the housing hole 12 and the outer circumferential surface of the table portion 23, and this gap is defined as a gas discharge gap 17 constituting a part of the gas discharge path 7.

Further, a center hole 24 having an open lower surface is provided in the inner block 21 from the lower surface toward the upper surface of the table portion 23. The lower surface of the center hole 24 is closed by a cover member 27. A gas introduction hole 25 communicating with the gas discharge gap 17 from the side surface of the upper end portion of the center hole 24, and a gas discharge hole 26 communicating with the tip of a gas discharge nozzle 29 from the side surface near the bottom of the center hole 24 are provided, and the gas discharge nozzle 29 is provided on the side surface of the base 22. The gas discharge gap 17, the gas introduction hole 25, the center hole 24, and the gas discharge hole 26 form a gas discharge path 7. In this case, in order to detect the temperature in the vaporizing space 5 and measure the temperature near the upper surface of the table portion 23, a thermocouple 60b is attached from the bottom of the inner block 21 to the vicinity of the upper surface of the table portion 23.

When the temperature in the vaporizing space 5 can be sufficiently maintained at the vaporizing temperature by the heater 50a of the outer block 11, the heater 50b of the inner block 21 is omitted. Conversely, when the temperature in the vaporizing space 5 can be sufficiently maintained at the vaporizing temperature by the heater 50b of the inner block 21, the heater 50a of the outer block 11 is omitted.

The porous member 30 is a thick plate-shaped member in a disc shape, and sintered bodies of particles 31 of alloys such as stainless steel, Hastelloy (Hastelloy) alloy, Permalloy (Permalloy) and the like having excellent corrosion resistance can be used.

The gaps 38 between the particles 31 provided in the porous member 30 communicate with each other (so-called continuous bubble type), and the surface of the porous member 30 (further, the inner peripheral surface and the bottom surface of the recessed portion 34 described later) has numerous openings. The thickness is smaller than the height of the vaporization space 5 (the height from the table portion 23 to the top surface of the storage hole 12), and the maximum size is a size covering the entire upper surface of the table portion 23. Of course, the upper surface of the table portion 23 may be smaller as long as evaporation of the permeated liquid raw material L is not hindered.

Other examples of the porous member 30 include a sintered body 32 of a wire mesh laminate excellent in corrosion resistance and chemical resistance shown in fig. 7, and a thick nonwoven fabric-like sintered body 33 of metal fibers excellent in corrosion resistance and chemical resistance shown in fig. 8. Their height and area are the same as those of the sintered body of the particles 31. The gaps between these wires and fibers become gaps 38, and the liquid material L gradually permeates therethrough.

As a modification of the shape of the porous member 30, as shown in fig. 6, there is a porous member 30 in which a recess 34 is formed in the center of the upper surface of the porous member 30. An outlet 41 at the lower end of an introduction pipe 40 described later is inserted into the recess 34. As described above, numerous gaps 38 are opened in the inner peripheral surface and the bottom surface of the recess 34. The concave portion 34 is also formed in the sintered body 32 of the wire mesh laminate and the thick nonwoven fabric-like sintered body 33 of the metal fiber. The porous member 30 is fixed to the upper surface of the base 23 of the inner block 21.

Fig. 9 shows an example in which the porous member 30 is constituted by a laminate of a plurality of

porous plates

30a and 30 b. The number of the upper and lower blocks in the drawing is not limited to this, and three or more blocks may be used. The porosity of the

porous plates

30a, 30b may be the same, or the porosity of the uppermost porous plate (the porous plate 30a near the inlet pipe 40) may be increased (i.e., made sparse) so that the porosity of the following porous plate 30b is smaller than the porosity of the uppermost porous plate 30a (i.e., made dense). Therefore, the raw materials (shown above) that make up the

porous plates

30a, 30b can also be varied.

Since the uppermost porous plate 30a is more likely to be clogged than the following porous plates 30b, only the uppermost porous plate 30a may be replaced when clogging occurs.

Fig. 10 is a modification of fig. 6, in which a through hole 34a for forming the concave portion 34 is provided in an upper porous plate 30a (on the outlet 41 side of the introduction pipe 40) among the plurality of

porous plates

30a and 30b, and the lower porous plate 30b (on the side away from the outlet 41) may be configured in a flat plate shape such that the concave portion 34 shown in fig. 6 is positioned directly below the outlet 41 of the introduction pipe 40.

The introduction pipe 40 is a capillary tube led out from a device, such as the liquid flow control valve 9, which is provided above the vaporizer 1 and supplies the liquid material L at a set mass flow rate to the downstream vaporizer 1. In fig. 1, the introduction pipe 40 is shown as one member, but a plurality of members may be joined. The inlet pipe 40 is also made of a material having excellent corrosion resistance and chemical resistance, as in the porous member 30.

The introduction tube 40 may be formed integrally with a single capillary tube, or may be provided with a minute through-hole 45 in a side surface of the distal end portion as shown in fig. 2 and 3. In the figure, four minute through holes 45 are provided.

The introduction pipe 40 is provided with the outlet 41 at the tip end thereof in contact with the surface of the porous member 30 as shown in fig. 2, or with a slight separation distance H between the surface of the porous member 30 and the outlet 41 as shown in fig. 5. In principle, when the liquid raw material L is easily thermally decomposed and the deposit 70 in the reaction product is easily formed, the liquid raw material L is provided with a slight separation distance H, and is not used in such a case by being brought into contact with each other.

The separation distance H is usually about 0.5mm to 1.0mm, and the maximum separation distance H is set to a size from the outlet 41 to the lower end of the liquid droplet when the liquid raw material L is dropped from the outlet 41 of the introduction pipe 40. When the separation distance H is too large, the liquid raw material L is dropped from the inlet pipe 40, and the liquid droplets are separated from the outlet, and the droplets collide with the upper surface of the porous member 30, so that bumping occurs at the moment of collision, and a large pressure fluctuation occurs in the vaporization space 5. That is, when the separation distance H is set to the size of the liquid droplets of the liquid raw material L, the liquid droplets of the liquid raw material L dropped from the outlet 41 come into contact with the surface of the porous member 30 before leaving the outlet 41, and penetrate into the porous member 30 at that moment without causing bumping as described above.

Fig. 11 shows another example of the introduction pipe 40, and one or more notches 48 reaching the end face 42 of the outlet 41 of the introduction pipe 40 are provided in the vicinity of the outlet 41 (in a range of 1mm to 5mm from the end face 42). The slit 48 may be a triangle having an enlarged slit width toward the end face 42 of the outlet 41 as viewed from the front as shown in the drawings, or may be a line having a constant slit width.

Next, an example of use of the vaporizer 1 of the present invention will be described. When the heater 50a for the outer block 11 of the vaporizer 1 is energized, the outer block 11 is heated to a set temperature. The temperature is controlled by feedback control using a thermocouple 60a provided in the outer block 11. Thereby, the inside of the vaporization space 5 is maintained at a temperature suitable for vaporization, and the porous member 30 is also maintained at the temperature.

In the case of fig. 2, the inlet pipe 40 is provided with a minute through hole 45 at its distal end portion, and in the case of fig. 11, the inlet pipe 40 is provided with a slit 48 at its distal end portion, and the outlet 41 is provided so as to be in contact with the upper surface of the porous member 30. The liquid raw material L is selected from raw materials that are difficult to generate reaction products by heating.

In this state, when the liquid material L, for example, mass-controlled by the liquid flow rate control valve 9 is supplied from the introduction pipe 40 to the porous member 30, the liquid material L reaching the outlet 41 of the introduction pipe 40 instantly penetrates into the gap 38 from the surface of the porous member 30 without being vaporized, and rapidly diffuses toward the surroundings.

Since the porous member 30 is fixed to the upper surface of the table portion 23 of the inner block 21 and is maintained at the set temperature as described above, the liquid material L permeated into the porous member 30 is heated in the porous member 30. The heated liquid raw material L is gradually vaporized in a static state in order from the gap 38 exposed on the surface of the porous member 30 around the introduction pipe 40 without causing bumping. As a result, the pressure fluctuation in the vaporization space 5 becomes extremely small, and stable vaporization is performed. The gasified raw material gas G is sent to the next step through the gas discharge passage 7 constituted by the gas discharge gap 17 between the outer block 11 and the inner block 21, the gas introduction hole 25, the center hole 24, and the gas discharge hole 26. This enables highly accurate film formation.

In the above description, only the heater 50a is used for the outer block 11, but the heater 50b of the inner block 21 is used in combination when the liquid material L is supplied beyond the capacity of the heater 50a or is not easily vaporized due to the characteristics of the liquid material L. Since the porous member 30 is fixed to the upper surface of the table portion 23 of the inner block 21, when power is supplied to the heater 50b of the inner block 21, the heat is transferred to the porous member 30.

Of course, since the two

heaters

50a and 50b are thermally managed by the

thermocouples

60a and 60b, the two

heaters

50a and 50b can be used together even in the initial case.

When the vaporization operation is performed for a long time, even in the case of the liquid raw material L in which the reaction product is less likely to be generated, the reaction product may be accumulated in the outlet 41 of the introduction pipe 40, and eventually the outlet 41 may be closed. In this case, the liquid material L is pushed out from the fine through-holes 45 on the side surface near the outlet 41, flows down to the porous member 30 statically along the outer surface of the introduction pipe 40, and immediately permeates into the porous member 30. When the fine through-holes 45 are provided in the vicinity of the outlet as described above, the gasification operation can be performed without interruption even when the outlet 41 is closed.

The slit 48 shown in FIG. 11 is opened at a portion of the slit 48, which is not less than the deposition height of the reaction product, similarly to the fine through-holes 45, even if the reaction product is deposited on the outlet 41, and the liquid raw material L flows down statically from this portion and immediately permeates into the porous member.

In contrast, fig. 5 shows a case where the outlet 41 of the introduction pipe 40 is disposed apart from the surface of the porous member 30. The liquid raw material L can be used even if it is likely to form a reaction product.

In this case, even if the reaction product gradually deposits in the range from the outlet 41 of the introduction pipe 40 to the gap 38 of the porous member 30 as described above, a gap through which the liquid raw material L flows out is secured between the deposit 70 and the outlet 41 of the introduction pipe 40, and therefore, the vaporization operation can be performed without interruption. The discharged liquid raw material L is absorbed by the porous member 30 before vaporization, and is vaporized while maintaining a stable state as in the case of no gap.

Here, although the distance H between the outlet of the introduction pipe 40 and the porous member 30 is set to be too long, when the distance H between the outlet of the introduction pipe 40 and the porous member 30 is too long, the liquid raw material L flowing out of the outlet 41 becomes spherical due to its surface tension, falls on the surface of the porous member 30, and instantaneously vaporizes to generate bumping, and a large pressure fluctuation occurs in the vaporization space 5. Therefore, the separation distance H becomes an important element in performing the static gasification operation.

The separation distance H is usually set to 0.5mm to 1.0mm, and is a distance from the outlet 41 to the lower end of the droplet hanging from the outlet 41 at the maximum. This value is not fixed depending on the surface tension of the liquid material L, and a value smaller than this value may be selected, and the value as described above is actually selected. In this sense, the above numerical values have important meanings in the present invention.

In this case, when the porous plate 30a of the uppermost layer (and the upper layer including the uppermost layer) is formed to be thinner than the porous plate 30b of the lower layer, the penetration rate of the liquid material L into the porous plate 30a of the uppermost layer (and the upper layer including the uppermost layer) becomes faster, and the above-described bumping can be suppressed more favorably.

Fig. 6 shows a case where the recess 34 is provided in the center of the surface of the porous member 30, and the outlet 41 of the introduction pipe 40 is brought into contact with the bottom of the recess 34 or is inserted separately within the range of the separation distance H. In this case, in addition to the above-described operational effects, the liquid material L is accumulated in the concave portion 34, and therefore the liquid material L gradually permeates into the porous member 30 from the inner surface as well as the bottom of the concave portion 34, and the permeation area increases. This increases the permeation rate of the liquid material L into the porous member 30, as compared with the case where the recess 34 is not provided. The other points are the same as those described above.

In this case, the porous member 30 is constituted by the plurality of

porous plates

30a and 30b, and when the porous plate 30 in which the porous plate 30a in which the through holes 34a for the recessed portions 34 are formed and the porous plate in the uppermost layer of the flat porous plate 30b in which the through holes 34a for the recessed portions 34 are not formed are formed thinly as described above, and the porous plate below the porous plate in the uppermost layer of the flat porous plate 30b is made dense as described above, the permeation rate of the liquid material L becomes high in the thin portion, and bumping can be suppressed more favorably as described above.

Description of reference numerals

1: gasifier, 5: gasification space, 7: gas discharge path, 9: liquid flow control valve, 10: container body, 11: outer block, 12: receiving hole, 13: insertion-through hole, 14: side wall, 17: gas discharge gap, 21: inner block, 22: base station, 23: stage, 24: center hole, 25: gas introduction hole, 26: gas discharge hole, 27: cover member, 29: gas discharge nozzle, 30: porous members, 30a, 30 b: porous plate, 31: particle, 32: sintered body of wire-net laminate, 33: thick nonwoven-like sintered body of metal fiber, 34: recess, 34 a: through-hole, 38: gap, 40: introduction tube, 41: outlet, 42: end face, 45: micro through-hole, 48: incision, 50a, 50 b: heaters, 60a, 60 b: thermocouple, 70: deposit, G: raw material gas, H: separation distance, L: liquid feedstock

Claims

1. A vaporizer is composed of a container body, a porous member, an inlet pipe and a gas discharge path,

the container body has a vaporization space inside,

the porous member is provided in the vaporization space and heated,

the introducing pipe is inserted into the vaporizing space from the outside and supplies the liquid material to the porous member,

the gas discharge path discharges the raw material gas generated by the vaporization of the porous member from the vaporization space to the outside,

it is characterized in that the preparation method is characterized in that,

the outlet of the inlet pipe is disposed in contact with or close to the porous member,

when the outlet is disposed close to the porous member, the separation distance from the outlet to the porous member is within a range not exceeding the size from the outlet to the lower end of the liquid material hanging down as droplets from the outlet due to surface tension.

2. A gasifier in accordance with claim 1,

a minute through hole is provided through a side surface of the inlet pipe in the vicinity of the outlet.

3. A gasifier according to claim 1 or 2,

a recess into which the outlet of the inlet pipe is inserted is formed in the surface of the porous member.

4. A gasifier according to any one of claims 1 to 3,

the porous member is made of any one of a metal sintered body, a ceramic, a wire mesh laminate, and a sintered body of a metal fiber nonwoven fabric.

5. A gasifier according to claim 1 or 2,

the porous member is composed of a laminate of a plurality of porous plates.

6. A gasifier in accordance with claim 3,

the porous member is composed of a laminate of a plurality of porous plates, through holes for forming recessed portions are provided in the porous plate on the outlet side of the inlet pipe, and the porous plate remote from the outlet is formed in a flat plate shape.

7. A gasifier in accordance with claim 1,

a notch reaching the end face of the outlet of the introduction pipe is provided in the vicinity of the outlet.