JPH11106921A - Bubbling-type liquid raw material vaporizer and operating method for starting transport of the raw material vapor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bubbling-type liq. material vaporizer of a chemical vapor growth device by which the back flow of a liq. raw material is prevented at all times and to furnish an operating method for starting the transport of the raw material vapor. SOLUTION: This bubbling-type liq. material vaporizer 33 consists of a raw material vessel 41 provided with a carrier gas inlet 42 internally furnished with an immersed pipe 46 in which one end is immersed in a liq. raw material 45 filled in a vessel leaving a void 44 and externally furnished with an inlet valve 47 and a raw material vapor outlet 43, of a carrier gas transport pipe 51 connecting the inlet valve and the supply port of a carrier gas supply source 49, of a raw material vapor transport pipe 54 connecting an outlet valve and a raw material vapor introducing port, a bypass valve 55 connecting the carrier gas transport pipe and the raw material vapor transport pipe and of a thermostatic bath 56. In this case, a back pressure detecting means 57 is also provided to discriminate whether or not the difference between the internal pressure in the carrier gas transport pipe and the internal pressure in the raw material vessel is negative (back pressure).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bubbling type liquid source vaporizer used as a component of a chemical vapor deposition (hereinafter, CVD) apparatus or a chemical vapor epitaxy (hereinafter, CBE) apparatus, and a raw material vapor thereof. The present invention relates to a transportation start operation method. Note that CBE is considered to be a form of CVD performed under high vacuum, so it is not considered separately from CVD, and in the following description, CVD is assumed to include CBE.

[0002]

2. Description of the Related Art In CVD, one or more raw (chemical) vapors are transported to a reactor maintained at a predetermined pressure, and supplied to a substrate maintained at a predetermined temperature in the reactor to perform chemical reaction. Is a method of depositing a thin film.
Already used in a wide range of industrial fields. Since the type and number of raw materials that are gaseous at around room temperature are very limited,
In VD, the use of liquid raw materials is often forced. At this time, how to stably generate (vaporize) the raw material vapor is a technically important issue. The same applies to the case where the solid raw material is heated and liquefied for use.

FIG. 5 shows an apparatus for vaporizing a liquid material called a bubbler widely used in CVD (hereinafter referred to as Conventional Example 1).
Is shown. Reference numeral 111 denotes a sealed raw material container filled with a liquid raw material 112. 113 is the raw material container 1
11 is a carrier gas inlet 113, and the carrier gas inlet 113 passes through the liquid surface
An immersion tube 114 reaching one bottom is provided. A carrier gas transport pipe L1 is connected to the upper portion of the carrier gas inlet 113 via a valve 115. Reference numeral 116 denotes a raw material vapor outlet conveyed by the carrier gas.
2 is open in the upper space of the raw material container 111 that is not occupied. The raw material vapor outlet 116 is connected to a raw material vapor transport pipe L2 via a valve 117. Reference numeral 118 denotes a raw material vapor transport pipe L which does not pass the carrier gas through the raw material container 111.
2 is a bypass valve for sending to 2. The other end of the carrier gas transport pipe L1 is connected to the flow controller 119 and the valve 120.
Is connected to the carrier gas supply source 121 via the.
On the other hand, the raw material vapor transport pipe L2 is connected to the raw material introduction port of the CVD reactor 124 via a pressure adjusting valve 122 installed for adjusting the internal pressure of the raw material container 111 and a normal valve 123. The entire raw material vaporizer including a part of the carrier gas transport pipe L1 and a part of the raw material vapor transport pipe L2 is housed in a thermostat 125 maintained at a predetermined temperature as shown in the figure. The transport of the raw material vapor to the CVD reactor 124
The valve 118 is closed, and the valves 120, 115, 117,
This is achieved by opening 123 and supplying carrier gas from 121. The flow rate of the carrier gas flowing through the carrier gas transport pipe L1 is adjusted by the flow rate regulator 119 and released into the raw material from the tip of the immersion pipe 114 of the raw material container 111, and rises as bubbles while absorbing the vapor of the raw material on the way. ,
In the upper space of the raw material container 111, the material is repelled and diffused. The raw material vapor mixed with the carrier gas is transported together with the carrier gas from the raw material vapor outlet 116 to the CVD reactor 124 through the raw material vapor transport pipe L2. The transport rate of the raw material vapor per minute is determined by the flow rate of the carrier gas, the pressure in the raw material container 111, and the temperature of the thermostat 125.

[0004] One of the serious problems that such a conventional raw material vaporizing apparatus has and is required to solve is the backflow of the liquid raw material 112 and various problems that accompany it. More specifically, the pressure in the raw material container 111 is P0, and the pressure in the carrier gas transport pipe L1 is P1. Pressure is P0> P
When it is 1, if the valve 115 of the vaporizer is opened by mistake, the liquid raw material 112 will be sucked into the carrier gas transport pipe L1. Such a backflow is caused by (1) liquid raw material 1
(2) When forming a film at a certain pressure and then trying to form a film at a lower pressure, (3) CV stopped for a long time
It often occurs when the D apparatus is operated after a long time. In addition, since the operation of the valve is performed by a person who is apt to make a mistake, the valve may be accidentally opened during a period when the valve should not be opened, and as a result, a backflow may be caused. When the backflow occurs, the flow regulator 119 and the valve 115 connected to the carrier gas transport pipe L1 may be damaged or the operation may be unstable. The economic damage caused by the expenditure for restoring the function of these parts and the production delay due to the stoppage of the equipment in the meantime is not small. At the actual site of CVD, the carrier gas transport pipe L1 is often removed for refilling the raw materials and weighing the remaining amount. It is extremely dangerous to perform this operation while the ignitable liquid raw material (for example, alkyl gallium) or the highly toxic liquid raw material (4-ethyl lead) stays in the carrier gas transport pipe L1, and is not allowed in terms of safety and health. If the worker performs the removal work without noticing the backflow, a serious accident such as a fire, explosion or acute poisoning may occur.

As a method for solving such a problem of the backflow of the raw material, Japanese Patent Application Laid-Open No. Hei 5-343339 proposes a raw material container of a raw material vaporizer having a novel structure shown in FIG. According to this conventional example (hereinafter referred to as “Conventional example 2”), the inside of the raw material container body 201 is divided into two chambers A and B by a central partition 202. Each of the two chambers is electrically connected by a pore 203 provided at the bottom of the partition 202. The diameter of the pores 203 may be smaller than the diameters of the chambers A and B. However, it is preferable that the diameter be equal to or less than 1/5 of the diameter of these chambers in order to reliably prevent the liquid material from flowing backward. Each of the chambers A and B has gas introduction pipes 204a and 204b which are respectively connected to an upper space in the chamber.
04a and 204b have valves 205a and 205b, respectively.
Is interposed. The volume of the chamber A is desirably equal to or larger than the volume of the chamber B, and the filling amount of the liquid raw material 206 is set to be smaller than the volume of the chamber B. Before use, the liquid level of the liquid raw material is at the same level in both the chambers A and B. In use, the valve 205
When a is opened, the liquid raw material 206 moves from the chamber B to the chamber A even if the carrier gas inlet side is lower than the outlet side pressure (in other words, a reverse pressure).
There is no backflow to the upper piping through 05a. Thus, Japanese Patent Application Laid-Open No. Hei 5-343339 clearly solves the problem of the liquid material flowing backward in the conventional example 1 of the related art.

[0006] However, the conventional example 2 is very excellent in solving the backflow, but has the following disadvantages. The first disadvantage is the instability of the raw material vapor concentration and the gas flow rate which occur at the initial stage of film formation. According to the detailed description described in the conventional example 2, “the gas introduction pipe 204a
When the carrier gas is introduced into the chamber A, all the organic metal (= liquid raw material) in the chamber A moves to the chamber B, and the liquid level of the organic metal in the chamber B rises. " That is, in the conventional example 2, even if the carrier gas is introduced into the raw material container body 201, the bubbling is not started until all the liquid raw materials in the chamber A are transferred to the chamber B. That is, the raw material vapor transported from the raw material container body 201 to the reactor during this period is the vapor that has accumulated in the upper space of the chamber B, and its concentration and gas flow rate are significantly different from those after the start of bubbling. I have to do it. And the period is long. In addition, there is a drawback that the actual start time of bubbling is not clear and fluctuates due to a change in film forming conditions such as a pressure and a flow rate of a carrier gas. In this respect, in Conventional Example 1, since there is substantially no space corresponding to the room A, bubbling is started immediately after the introduction of the carrier gas, and the instability of the raw material concentration and the gas flow rate at the initial stage of film formation are far less than those in Conventional Example 2. It is. Another problem which the conventional example 2 has is a problem of clogging occurring in the pores 203. This occurs over time based on the following long-term mechanism: Particles and foreign substances generated by a reaction with a small amount of impurity gas (for example, oxygen) contained in the carrier gas or the leak gas gradually accumulate in the liquid raw material, and settle at the bottom of the container with the passage of time. In Conventional Example 2, since the raw material in the chamber A passes through the pores 203 provided at the lowermost part of the partition 202 between the chamber A and the chamber B each time a film is formed, particles and foreign substances settled at the bottom are also included. Pore 20
It is conveyed to room B through 3. While repeating this, the pores 203 are gradually closed by the attached particles and foreign substances,
Eventually, it becomes completely clogged, making bubbling impossible. One solution to this problem is to increase the diameter of the pores 203. However, if the diameter is widened, it becomes difficult to generate bubbles having a small diameter, and the concentration of the raw material vapor conveyed from the vaporizer and the gas flow rate are unsatisfactory. This countermeasure cannot be a drastic one, as it creates a new problem of stability. As described above, the conventional example 2 is very excellent in solving the major problem of backflow of the raw material of the conventional example 1, but it is a new technique which is not a problem in the conventional example 1. Technical contradictions that cause serious problems.

[0007]

SUMMARY OF THE INVENTION The present invention has solved the above-mentioned problems of the conventional example 2, and the object is to solve the problem of the conventional example 1.
It is an object of the present invention to provide a bubbling type liquid source vaporizer of a CVD apparatus which can prevent a backflow of a liquid source at any time without lowering the function of the above.

[0008]

Means for Solving the Problems In order to achieve the above object, according to the present invention, a liquid material vaporizing apparatus of a CVD apparatus and a configuration of an operation method thereof are described in the respective claims. . In other words, in the bubbling type liquid material vaporizer according to claim 1 or 6, a immersion pipe in which one end is immersed in the filled liquid material with leaving a gap is provided inside, and a first valve is provided outside. A hermetically sealed raw material container having one opening and a second opening which is open to the gap and has a second valve provided outside, and connects the first valve of the raw material container to a supply port of a carrier gas supply source; A first pipe, a second pipe connecting the second valve of the raw material container and the raw material vapor inlet of the reactor, and a third valve connecting the first pipe and the second pipe (claim 1 only) And a constant-temperature bath provided so as to enclose the source container, in the bubbling type liquid source vaporizer of the chemical vapor deposition apparatus, the internal pressure P of the first pipe.
A bubbling type liquid raw material vaporizer comprising: a pressure difference P1-P2 between the pressure vessel 1 and the internal pressure P2 of the raw material container; did. Claims 2 to 5 are the bubbling type liquid raw material vaporizers according to claim 1.
Numeral 0 indicates a specific mode of the bubbling type liquid raw material vaporizer according to the sixth aspect. That is, in claim 2, the back pressure detecting means according to claim 1 monitors any one of a change in the internal pressure of the raw material container, a change in the internal pressure of the first pipe, and a change in the internal pressure of the second pipe. Configuration. According to a third aspect of the present invention, the back pressure detection means of the first and second aspects is configured to discriminate the back pressure by closing the first valve and closing the second valve and the third valve.
According to a fourth aspect of the present invention, the back pressure state is identified by the back pressure detecting means by detecting an increase in the first pipe internal pressure. According to a fifth aspect of the present invention, there is provided a method for starting operation of transporting a raw material vapor of a bubbling type liquid raw material vaporizer according to any one of the first to fourth aspects, comprising the steps of simultaneously or sequentially opening a second valve and a third valve, And a step of opening the first valve and a step of closing the third valve. In claim 7, claim 6
The described back pressure detecting means is the first pipe and the raw material container, or
The internal pressure of one set of the first pipe and the second pipe was monitored. According to a ninth aspect of the present invention, the back pressure detection means of the sixth and seventh aspects is configured to identify the back pressure when the first valve is closed and the second valve is open. The bubbling type liquid source vaporizer according to claim 6 is characterized in that the identification of the back pressure state by the back pressure detecting means is based on the internal pressure of the first pipe and the internal pressure of the liquid source container or the internal pressure of the second pipe. The configuration was made by comparison.

According to a tenth aspect of the present invention, there is provided a method of starting a raw material vapor transport of a bubbling type liquid raw material vaporizer according to a sixth aspect of the present invention, comprising the steps of: opening a second valve; The method includes a step of checking a pressure state and a step of opening the first valve. In the eleventh aspect of the present invention, in the bubbling type liquid material vaporizer according to the first to fourth or sixth to ninth aspects, when the back pressure detecting means indicates a back pressure state. The first valve is provided with opening prohibiting means for prohibiting opening of the first valve.

[0010]

In the present invention, the opening of the first pipe, that is, the first valve connecting the carrier gas transport pipe and the immersion pipe of the raw material container, must be performed in advance by a series of operations for eliminating the back pressure. Since the pressure detection unit is configured to execute the process after confirming the non-back pressure state, the problem of the first conventional example that the liquid material flows backward through the carrier gas transport pipe at the start of bubbling does not occur. Further, in some embodiments of the present invention, this configuration is developed to establish conduction between the immersion tube of the raw material container and the carrier gas transport tube when the back pressure detecting means indicates the back pressure state. Since the reverse pressure conduction inhibiting means for inhibiting is provided, it is possible to prevent the reverse flow of the raw material even when an operator or the like erroneously conducts the operation of conducting the first valve when the liquid material vaporizer is in the reverse pressure state. it can. Further, according to the structure of the present invention, the liquid raw material filled in the two chambers A and B of the raw material container body partitioned by the partition as in Conventional Example 2 is provided at the bottom of the partition each time bubbling starts / ends. Since the configuration is completely different from the configuration of going back and forth through the provided pores, the problem of Conventional Example 2 does not occur, and therefore, this problem can be solved.

[0011]

FIG. 1 shows a configuration of a chemical vapor deposition (CVD) apparatus including a bubbling type liquid source vaporizer of the present invention. 30 is a substrate 2 heated to a predetermined temperature
This is a reactor containing 7. An exhaust system 31 is connected to the reactor 30. The exhaust system 31 exhausts the residual gas, the raw material gas, and the generated gas in the reactor 30 to the outside of the reactor, and also forms the gas in the reactor 30 during film formation. It has a function of maintaining the pressure at a predetermined pressure. Reference numeral 32 denotes a chemical vapor supply system, which has a role of supplying liquid raw material vapor, gaseous raw material, diluent gas, carrier gas, and the like to the reactor 30 via a transport pipe. The chemical vapor supply system 32 includes at least one or more bubbling-type liquid source vaporizers 33 according to the present invention. One or more gas source supply devices 34 and dilution gas supply devices 35 are provided. As described above, the basic configuration of the CVD apparatus used in the present embodiment is wide, and the configuration of the CVD apparatus used in Conventional Example 1 or Conventional Example 2 is not different at all. That is, when the present invention is applied, the change required for the CVD apparatus is limited to the change of the bubbling type vaporizer, and does not extend to the change of the entire CVD apparatus. This is one of the excellent features of the present invention. Now, a specific embodiment of a bubbling type liquid source vaporizing apparatus for a CVD apparatus according to the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 4 shows the structure of Embodiment 1 of a bubbling type liquid raw material vaporizer of the present invention. Reference numeral 41 denotes two openings, that is, a carrier gas inlet (=
(First opening) 42 and raw material vapor outlet (= second opening) 43
, And is filled with a desired liquid raw material 45 leaving a space 44 inside. An immersion pipe 46 having one end immersed to the depth of the liquid raw material 45 is provided inside the carrier gas inlet 42, and an inlet valve (= first valve) 47 is provided outside the carrier gas inlet 42. On the other hand, the raw material vapor outlet 43 opens into a gap 44 and an outlet valve (= second valve) 4
8 is provided outside. 49 is a carrier gas supply source. An inlet valve 47 of the raw material container 41 and a supply port of the carrier gas supply source 49 are connected by a carrier gas transport pipe (= first pipe) 51 via a flow rate controller 50 on the way. On the other hand, the outlet valve 48 of the raw material container 41 is connected to the raw material vapor transport pipe (= second pipe) 54 via the pressure adjusting valve 52 (normally open) and the raw material introduction valve 53 of the raw material container 41.
To the raw material vapor inlet of the reactor 30 (FIG. 3). The carrier gas transport pipe 51 and the raw material vapor transport pipe 54 are connected via a bypass valve (= third valve) 55 as shown in the figure. Reference numeral 56 denotes a constant temperature bath provided so as to include the raw material container 41, and holds the raw material container 41 and the liquid raw material 45 therein at a predetermined temperature. The transport rate of the liquid raw material vapor per minute is determined by the flow rate of the carrier gas, the internal pressure of the raw material container 41, and the temperature of the thermostat 56. 57 is an internal pressure P of the carrier gas transport pipe before the inlet valve 47 is opened.
This is a back pressure detecting means for identifying and notifying that the pressure difference P1-P2 between the pressure vessel 1 and the internal pressure P2 of the raw material container is negative, that is, a back pressure. The purpose of the back pressure detecting means 57 is that the inlet valve 47 is closed, the outlet valve 48 and the bypass valve 55
Is open, one of the following internal pressures: (a) the internal pressure of the raw material container 41, or (b) the internal pressure of the carrier gas transport pipe 51, or (c) the pressure adjusting valve 52 and the outlet valve 48, the raw material vapor transport pipe 54
This is achieved by monitoring any one of the changes in the internal pressure, determining whether the change is a pressure increase (or a pressure decrease), and reporting the result. In order to achieve this object, the back pressure detecting means 57 compares at least the pressure gauge, a storage device capable of constantly storing / updating two or more data of the pressure gauge, and two temporally consecutive data stored in the storage device. It is provided with a comparator and a notifier for notifying the worker or other devices of the result of the comparison by displaying, warning, signal output, or the like. When the back pressure detecting means 57 is configured to monitor (a) a change in the internal pressure of the raw material container 41, the pressure gauge (P) is installed at a position where the internal pressure of the container can be measured, for example, at a position S1. I do. Similarly, the back pressure detecting means 57 detects (b) a change in the internal pressure of the carrier gas transport pipe 51 or (c) a change in the internal pressure of the raw material vapor transport pipe 54 between the pressure adjusting valve 52 and the outlet valve 48. In the case of a configuration for monitoring, it is assumed that the pressure gauge is installed at, for example, S2 or S3, respectively. It is sufficient that one pressure gauge is provided in S1, S2, or S3.

Next, the liquid raw material vaporizer 3 of the present embodiment will be described.
The function and effect of No. 3 will be described together with the process of CVD film formation.
After accommodating the substrate 27 in the reactor 30 maintained at a predetermined growth temperature, the reactor 30 is once evacuated to a vacuum, and when the pressure is sufficiently reduced, the bypass valve 55 and the source introduction valve of the bubbling type liquid source vaporizer 33. 53 was opened,
The carrier gas adjusted to a predetermined flow rate by the flow rate controller 50 is introduced into the reactor 30. Chemical vapor supply system 3 to be used
In the case where 2 has a dilution gas supply device 35, the dilution gas supplied to the reactor 30 is also supplied from the dilution gas supply device 35 at a predetermined flow rate. Subsequently, the outlet valve 48
And at the same time, the function of the back pressure detecting means 57 is operated to continuously monitor the change of the internal pressure at any one of the points S1, S2 and S3 in the figure. Identification of whether or not there is a back pressure state is performed as follows. Measured at a certain time t1, the back pressure detecting means 5
The pressure data stored in the storage device of No. 7 is P (t1), t
The pressure data measured at time t2 following 1 and stored in the storage device is P (t2). By opening the outlet valve 48 when the raw material container 41 is in the reverse pressure state, the pressure decreases at the point S1, and increases at the points S2 and S3.

When the measurement of the pressure is performed at the point S1, when the relationship of P (t1)> P (t2) holds, it is the reverse pressure state. At this time, the comparator determines that the pressure is the reverse pressure, and instructs the alarm to output. Eventually, the pressure relationship becomes P (t
1) When ≤P (t2), the comparator determines that the back pressure state has been released, and stops the output of the alarm device. Similarly, when the pressure is measured at the point S2 or S3, the comparator determines that the pressure is back when P (t1) <P (t2), and instructs the back pressure alarm to output. Eventually the pressure relationship becomes P
When (t1) ≧ P (t2), the comparator determines that the back pressure state has been released, and stops the output of the alarm device. The time from when the outlet valve 48 is opened until the back pressure state of the raw material container 41 is released is several seconds at most. When the raw material container 41 is in the back pressure state, the back pressure detecting means 57 stops the output of the alarm and confirms that the back pressure state has been released. Otherwise, after confirming that the alarm is not output, the bypass valve 55 is shut off and the inlet valve 47 is opened at the same time, and the carrier gas is delivered to the immersion pipe 46 to start bubbling. If the chemical vapor supply system 32 to be used has a gas source supply device 34, the gas source adjusted to a predetermined flow rate is supplied to the reactor 30 at this time. When the film formation is completed, the valves 47, 48 and 53 are shut off, the reactor 30 is set to the atmospheric pressure, and the substrate 27 is taken out of the chamber. Thus, the CVD film formation using the bubbling type liquid source vaporizer 33 of the present embodiment is completed.

As is apparent from the above description, in the bubbling type liquid raw material vaporizer 33 of the present embodiment, the internal pressure of the raw material container 41 and the carrier gas transport pipe 51 are opened by opening the bypass valve 55 and the outlet valve 48. The inlet valve 47 is opened after the step of equalizing the internal pressure of the raw material and the step of confirming that the back pressure state has been eliminated by the back pressure detecting means 57. Regardless of the value of the internal pressure, bubbling can be started without backflow of the liquid raw material 45. The configuration of the raw material container 41 of the bubbling type liquid raw material vaporizer 33 according to the present embodiment is such that the liquid raw material 45 filled in the two chambers A and B of the main body of the raw material container 41 partitioned by partitions as in Conventional Example 2 is bubbled. The structure is completely different from the structure in which the structure moves back and forth through a pore provided at the lowermost portion of the partition every time the start / end of the partition is started. Therefore, the problems of Conventional Example 2 do not originally occur, and as a result, these problems can be solved.

(Embodiment 2) FIG. 3 shows a configuration of Embodiment 2 of a bubbling type liquid raw material vaporizer of the present invention. In this figure, components having the same reference numerals as those in FIG. 2 are the same as those in FIG. 2 and have the same functions, so that detailed description will be omitted. Reference numeral 60 denotes the internal pressure P1 of the carrier gas transport pipe 51 and the raw material container 4 before the inlet valve 47 is opened.
This is a reverse pressure detecting means for identifying and reporting that the pressure difference P1-P2 from the internal pressure P2 is negative, that is, a reverse pressure. The purpose of the back pressure detecting means 60 is to set any one of the following two combinations of the internal pressures in a state where the inlet valve 47 is closed and the outlet valve 48 is open, namely, (d) S2 of the carrier gas transport pipe 51. Internal pressure at the point and raw material container 41
Or (e) the internal pressure at point S2 of the carrier gas transport pipe 51 and the internal pressure at point S2 of the raw material vapor transport pipe 54.
This is achieved by monitoring any one pair of the internal pressures at the points, determining whether the internal pressure at the point S2 is lower than the internal pressure at the points S1 or S3, and reporting the result. In order to achieve this object, the back pressure detecting means 60 includes at least two pressure gauges installed at the S2 point and the S1 or S3 point, a comparator for constantly comparing the pressure data at the two points indicated by the pressure gauge, and a S2 point. Is displayed when the internal pressure P (S2) is lower than the internal pressure P (S1) or P (S3) at the point S1 or S3.
Raw material container 41 for workers and other equipment by alarm, signal output, etc.
And a notifying device for notifying that the device is in a back pressure state.

Next, the operation and effect of the bubbling type liquid source vaporizer 33 of this embodiment will be described together with the process of CVD film formation. After accommodating the substrate 27 in the reactor 30 maintained at a predetermined growth temperature, the reactor 30 is once evacuated to a vacuum, and when the pressure is sufficiently reduced, the bypass valve 55 and the source introduction valve of the bubbling type liquid source vaporizer 33. 53
Is opened, and the carrier gas adjusted to a predetermined flow rate by the flow rate controller 50 is introduced into the reactor 30. When the chemical vapor supply system 32 to be used includes the dilution gas supply device 35, the dilution gas supplied to the reactor 30 is also adjusted to a predetermined flow rate from the dilution gas supply device 35. Then,
When the outlet valve 48 is opened, the back pressure detecting means 60
, And measure the internal pressure at points S2 and S1 or at points S2 and S3 with a pair of pressure systems, P (S2)
When <P (S1) or P (S2) <P (S3), the comparator determines that the pressure is opposite, sends a signal to the alarm, and instructs the alarm to output. After a while, the back pressure condition disappears,
P (S2) ≧ P (S1) or P (S2) ≧ P (S
In 3), the comparator 30 cancels the signal transmission to the alarm, and stops the output of the alarm. The time from when the outlet valve 48 is opened until the back pressure state of the raw material container 41 is released is several seconds at most. After confirming that the back pressure detecting means 60 stops the output of the alarm and cancels the notification of the back pressure state, it is confirmed that the alarm is not output when the raw material container 41 is not in the back pressure state. After that, the bypass valve 55 is shut off and the inlet valve 47 is opened at the same time, and the carrier gas is delivered to the immersion pipe 46 to start bubbling. When the chemical vapor supply system 32 to be used includes the gas material supply device 34, the gas material adjusted to a predetermined flow rate is supplied to the reactor 30 at this time. Thereafter, film formation is started in the reactor 30. When the film formation is completed, the valves 47, 48 and 53 are shut off, the reactor 30 is set to the atmospheric pressure, and the substrate 27 is taken out of the chamber. Thus, the CVD film formation using the bubbling type liquid source vaporizer 33 of the present embodiment is completed.

Also in the present embodiment, as in the first embodiment, a step of opening the bypass valve 55 and the outlet valve 48 to equalize the internal pressure of the raw material container 41 and the internal pressure of the carrier gas transport pipe 51, Since the inlet valve 47 is opened after a step of confirming that the liquid material has been eliminated by the back pressure detecting means 60, the liquid material 45 is supplied to the liquid material 45 regardless of the internal pressure of the material container 41 before the start of CVD. Bubbling can be started without causing backflow. It is apparent that the problems of the second conventional example can be solved for the same reason as in the first embodiment.

(Embodiment 3) FIG. 4 shows Embodiment 3 of a bubbling type liquid source vaporizer 33 of the CVD apparatus of the present invention.
Is shown. This device is an extension of one of the second embodiment. Reference numeral 61 denotes an electromagnetically driven or pneumatically driven inlet valve. Reference numeral 62 denotes a drive circuit for the inlet valve 61.
An / OFF switch 63 and a normally closed output contact 64 built in the alarm of the back pressure detecting means 60 are inserted in series. The output contact 64 is open when the back pressure detecting means 60 detects the back pressure, and is closed otherwise.

Next, the operation and effect of the bubbling type liquid source vaporizer 33 of this embodiment will be described together with the process of CVD film formation. After accommodating the substrate 27 in the reactor 30 maintained at a predetermined growth temperature, the reactor 30 is once evacuated to a vacuum, and when the pressure is sufficiently reduced, the bypass valve 55 and the source introduction valve of the bubbling type liquid source vaporizer 33. 53
Is opened, and the carrier gas adjusted to a predetermined flow rate by the flow rate controller 50 is introduced into the reactor 30. When the chemical vapor supply system 32 to be used includes the dilution gas supply device 35, the dilution gas supplied to the reactor 30 is also adjusted to a predetermined flow rate from the dilution gas supply device 35. Then,
When the outlet valve 48 is opened, the back pressure detecting means 60
, And measure the internal pressure at points S2 and S1 or at points S2 and S3 with a pair of pressure systems, P (S2)
When <P (S1) or P (S2) <P (S3), the comparator determines that the pressure is reverse, sends a signal to the alarm, and instructs the alarm to open the output contact 64. . As soon as the back pressure detecting means 60 is operated, the ON / OFF switch 63 is turned ON to adjust the posture for opening the inlet valve 61. When the raw material container 41 is in the back pressure state, the output contact 64 of the back pressure detecting means 60 is open, so that the opening of the inlet valve 61 is suspended for a while until the back pressure state is released. The time from when the outlet valve 48 is opened until the back pressure state of the raw material container 41 is released is several seconds at most. When the raw material container 41 is not in the reverse pressure state, the ON / OFF switch 63 is turned ON and the inlet valve 61 is opened at the same time. Thereafter, when the bypass valve 55 is shut off, the carrier gas is delivered to the immersion pipe 46, and bubbling starts. Chemical vapor supply system 3 to be used
When the apparatus 2 includes the gas source supply device 34, the gas source adjusted to a predetermined flow rate is supplied to the reactor 30 at this time. Thereafter, film formation is started in the reactor 30.
When the film formation is completed, the valves 61, 48 and 53 are shut off, the reactor 30 is set to the atmospheric pressure, and the substrate 27 is taken out of the chamber. Thus, the CVD film formation using the bubbling type liquid source vaporizer 33 of the present embodiment is completed.

In the present embodiment, as in the first embodiment, the process of opening the bypass valve 55 and the outlet valve 48 to equalize the internal pressure of the raw material container 41 and the internal pressure of the carrier gas transport pipe 51 is the same as in the first embodiment. Since the inlet valve 61 is opened after a step of confirming that the liquid material has been canceled by the back pressure detecting means 60, the liquid material 45 can be supplied no matter what value the internal pressure of the material container 41 has before the start of CVD. Bubbling can be started without causing backflow. It is apparent that the problems of the second conventional example can be solved for the same reason as in the first embodiment. In this embodiment, the operation can be shifted to the operation of opening the inlet valve 61 without the operator confirming whether or not the inside of the raw material container 41 is under the back pressure. This is where the present embodiment is functionally different from the second embodiment. Such a function is extremely useful when the CVD apparatus is automatically operated by sequential control.

[0022]

As described above, according to the bubbling type liquid source vaporizer of the present invention, even if the internal pressure of the liquid source container is any value before the start of chemical vapor deposition (CVD), Since bubbling can be started without backflow of the liquid raw material, serious accidents such as fire, explosion, and acute poisoning damage caused by backflow and damage to valves and the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a chemical vapor deposition apparatus including a bubbling type liquid source vaporizer according to the present invention.

FIG. 2 is a diagram showing a configuration of a bubbling type liquid source vaporizer according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a bubbling type liquid raw material vaporizer according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a bubbling type liquid raw material vaporizer according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional example 1 of a liquid source vaporizer.

FIG. 6 is a diagram showing a configuration of a second conventional example of a liquid source vaporizer.

[Explanation of symbols]

 S1 Installation position of pressure gauge of back pressure detection means S2 Installation position of pressure gauge of back pressure detection means S3 Installation position of pressure gauge of back pressure detection means 27 Substrate 30 Reactor 31 Exhaust system 32 Chemical vapor supply system 33 Bubbling type Liquid source vaporizer 34 Gas source supply device 35 Dilution gas supply device 41 Source container 42 Carrier gas inlet 43 Source vapor outlet 44 Void 45 Liquid source 46 Immersion tube 47 Inlet valve 48 Outlet valve 49 Carrier gas supply source 50 Flow rate controller 51 Carrier Gas transport pipe 52 Pressure regulating valve 53 Raw material introduction valve 54 Raw material vapor transport pipe 55 Bypass valve 56 Constant temperature bath 57 Reverse pressure detecting means 60 Reverse pressure detecting means 61 Inlet valve 62 Drive circuit 63 ON / OFF switch 64 Output contact L1 Carrier gas transport Pipe L2 Raw material vapor transport pipe 111 Raw material container 11 2 Liquid raw material 113 Carrier gas inlet 114 Immersion pipe 115 Valve 116 Raw material vapor outlet 117 Valve 118 Bypass valve 119 Flow rate regulator 120 Valve 121 Carrier gas supply source 122 Pressure regulating valve 123 Valve 124 CVD reactor 201 Raw material container body 202 Partition 203 Fine Hole 204a Gas inlet tube 204b Gas inlet tube 205a Valve 205b Valve 206 Liquid raw material

Claims (11)

[Claims] 1. A dip tube, one end of which is immersed in a liquid material filled with a gap left inside, a first valve outside the first valve, and a first opening outside the gap, and a first opening outside the gap. A sealed raw material container having a second opening externally provided with two valves, a first pipe connecting the first valve of the raw material container and a supply port of a carrier gas supply source, A second pipe connecting the two valves to the raw material vapor inlet of the reactor, a third valve connecting the first pipe and the second pipe, and a thermostat provided so as to include the raw material container. A bubbling type liquid source vaporizer for a chemical vapor deposition apparatus comprising: a pressure difference P1-P2 between the internal pressure P1 of the first pipe and the internal pressure P2 of the source container is negative, that is, A bubbling type liquid source, comprising back pressure detecting means for identifying the presence thereof Vaporizer. 2. The method according to claim 1, wherein the back pressure detecting means achieves its purpose by changing one of the internal pressure of the raw material container, the internal pressure of the first pipe, and the internal pressure of the second pipe. 2. The bubbling type liquid raw material vaporizer according to claim 1, wherein the bubbling is monitored. 3. The bubbling according to claim 1, wherein the back pressure is detected by the back pressure detecting means when the first valve is closed and the second valve and the third valve are open. Liquid material vaporizer. 4. The bubbling type liquid source vaporizer according to claim 1, wherein the back pressure state is identified by the back pressure detecting means by detecting an increase in the first pipe internal pressure. 5. A step of simultaneously or sequentially opening a second valve and a third valve, a step of confirming a non-back pressure state by a back pressure detecting means, a step of opening a first valve, and a step of closing a third valve. 5. A method for starting a raw material vapor transport of a bubbling type liquid raw material vaporizer according to claim 1, comprising: 6. A immersion tube having one end immersed in the filled liquid material leaving a gap therein, and a first opening outside the first valve outside the immersion tube, and a first opening outside the first valve outside the gap. A hermetically sealed raw material container having a second opening externally provided with two valves, a first pipe connecting the first valve of the raw material container, and a supply port of a carrier gas supply source, and a second pipe of the raw material container. A bubbling type liquid source vaporizer of a chemical vapor deposition apparatus, comprising: a second pipe connecting the two valves and the reactor; and a constant temperature bath provided so as to enclose the source vessel. Internal pressure P1 and pressure P2 in the upper space of the raw material container
A back pressure detecting means for identifying that the pressure difference P1-P2 is negative, that is, a back pressure. 7. The back pressure detecting means monitors an internal pressure of any one of a first pipe and a raw material container or a first pipe and a second pipe in order to achieve the object. The bubbling type liquid raw material vaporizer according to claim 6. 8. The bubbling type liquid according to claim 6, wherein the back pressure detection means detects the back pressure while the first valve is closed and the second valve is opened. Raw material vaporizer. 9. The method according to claim 1, wherein the identification of the state of the back pressure by the back pressure detecting means is performed by comparing the internal pressure of the first pipe with the internal pressure of the liquid material container or the internal pressure of the second pipe. The bubbling type liquid raw material vaporizer according to any one of claims 6 to 8. 10. A step of opening the second valve, a step of confirming a non-back pressure state by the back pressure detecting means,
The method for starting operation of transporting raw material vapor of a bubbling type liquid raw material vaporizer according to claim 6, comprising a step of opening a valve. 11. The apparatus according to claim 1, further comprising an opening prohibiting unit that prohibits opening of the first valve when the back pressure detecting unit indicates a back pressure state.
10. A bubbling type liquid source vaporizer according to claim 6.