JPH11345774A - Liquid-material vaporizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the fluctuation, etc., of film quality resulting from the abnormality of a liquid material surely, by transferring the liquid material up to a vaporizer by a liquid-feed line, and installing a state detecting means capable of detecting the state of the liquid material during device operation. SOLUTION: One ends of liquid-feed lines 4A-4D are disposed at places, where the liquid-feed lines are dipped in liquids in each material vessel 2A-2C or a solvent exclusive vessel 2D, the other ends are collected at a collecting place X, and flow-controllable proportional valves 5A-5D are interposed in the upstream of the collecting place X respectively and each liquid material A-D is transferred up to the vaporizer 12. The defective operation of a check valve for a pump 10 and the presence, etc., of the generation of bubbles in the liquid materials A-D and D are confirmed at the pressure of the liquid materials A-C and D monitored by a pressure sensor PS at that time. Attenuation in any extent in light transmitted through the liquid materials A-D from a light source having specified luminous intensity is obtained by detecting absorbance by a cell CL for spectrophotometric analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid material vaporizing apparatus capable of suitably supplying a liquid material to a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art In the manufacturing process of semiconductor devices, MoCVD has been widely used in recent years because it is superior to sputtering or the like in film quality, film forming speed, and step coverage. The gas supply method for CVD includes a bubbling method, a sublimation method, and the like, but in terms of controllability and stability,
A promising method is to evaporate a liquid organic metal or a liquid material at room temperature in which an organic metal is dissolved in a solvent immediately before a reaction layer.

[0003]

Incidentally, in such a liquid material vaporizer, it is desired to stably introduce the vaporized metal gas into CVD. However,
Conventional liquid material vaporizers are not equipped with a means for monitoring the state of the liquid material being fed, so bubbles are mixed in the liquid material, or the liquid material is altered by hydrolysis, etc. It was not possible to elucidate the cause of a change in film quality caused by an abnormality in the liquid material, such as a case where the mixing ratio of the liquid material was not as set. In addition, since the film quality fluctuation is found for the first time in the inspection after the film formation, there is a possibility that defective products may be generated in lot units.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a liquid material vaporizing apparatus capable of reliably preventing a change in film quality due to an abnormality in a liquid material. .

[0005]

In order to achieve the above object, the present invention takes the following measures.
That is, the liquid material vaporizing apparatus of the present invention is for vaporizing one or a plurality of liquid materials quantitatively and supplying them to the CVD film forming apparatus. A vaporizer, a liquid sending line for transferring the liquid material from the container to the vaporizer, and a state detecting means provided on the liquid sending line and capable of detecting the state of the liquid material during operation of the apparatus. It is characterized by having. Here, the state of the liquid material refers to, for example, the mixing ratio of each liquid material (in the case of mixing a plurality of liquids), the presence or absence of bubbles in the liquid material, the degree of deterioration of the liquid material, and the like.

In such a case, it is possible to detect the occurrence of an abnormality in the liquid material during the operation of the apparatus. In this case, the production is interrupted, and the production failure is detected before the film formation. Can be prevented. In addition, by accumulating the data of the liquid material output from the state detecting means, it is possible to use it for investigating the cause when an abnormality occurs in the film quality. As a result, efficient and stable film formation can be performed.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. The liquid material vaporizer shown in FIG. 1 is for mixing, vaporizing and supplying a liquid material to a CVD reactor 1 which is a component of a CVD film forming apparatus.
C, material containers 2A, 2B, and 2C, a solvent-only container 2D, and liquid supply lines 4A, 4B, 4C, 4D, and 4E.
And a vaporizer 12 for vaporizing the liquid materials A to C and the like sent through the liquid sending lines 4A to 4E, so that the mixed gas that has passed therethrough is supplied to the CVD reactor 1. It was done.

The material containers 2A, 2B, and 2C are filled with liquid materials A, B, and C, which are organic metals in which raw materials are dissolved at a predetermined ratio using a common solvent. The raw materials of the liquid materials A, B, and C include, for example, Pb, Zr, and Ti for forming a ferroelectric thin film, and Ba, Sr, and Ti for forming a high-dielectric thin film. However, if a superconducting thin film is further formed, Bi, Sr, Cu or the like is used. Of course, it goes without saying that the number of material containers prepared according to the number of raw materials may be two or four or more.

The solvent dedicated container 2D is filled with the same solvent D as that used for each of the liquid materials A, B, and C. In this case, the solvents D are not necessarily the same as long as they do not chemically affect the CVD process, and the same type of solvent having the same property can be used. Liquid sending line 4A
4D are arranged such that one end is immersed in the liquid of each of the material containers 2A to 2C or the solvent dedicated container 2D, and the other end is gathered at the gathering position X, and each is upstream of the gathering position X. Flow rate adjustable proportional valves 5A, 5B, 5C,
5D is interposed. These proportional valves 5A, 5A
B, 5C and 5D correspond to a vaporizer controller 17 described later.
The flow rate can be adjusted by output signals a, b, c, and d from the above. The liquid sending line 4E is a flow path from the collecting position X to the vaporizer 12, and is provided on the liquid sending line 4E in order from the upstream in order to control the flow rate.
0, a mixer 11 for mixing liquids is provided. The liquid sending pump 10 employs a series double plunger pump with high precision and low pulsation.
D is sequentially opened for a distribution time corresponding to a preset mixing ratio so that the liquid material or the solvent is sucked into the plunger. The total flow rate is controlled through the driving speed of the liquid feed pump 10.

In this embodiment, the external supply lines 6A, 6B, 6C and 6D, the purge line 7, the vacuum line 8 and the solvent bypass line 9 are used as much as possible in addition to the liquid feed lines 4A to 4E. A number of valves (not shown) are incorporated around the contact. Briefly describing these, the external supply lines 6A to 6D
Is filled with liquid materials A to C and a solvent D from a supply source (not shown) to the inlet side of each container 2A through a required valve operation.
To replenish. The purge line 7 is provided for each container 2A-
2D pressurizes the liquid surface for sending liquid, or
This is for purging the inside of the peripheral pipes in A to 2D. The vacuum line 8 is for evacuating the inside of the containers 2A to 2D and the surrounding piping. The solvent bypass line 9 is for performing solvent cleaning in a pipe located on the container outlet side.

The solvent dedicated container 2D is designed to be able to directly transfer the solvent to the inlet of the vaporizer 12 through a solvent transfer line 13 and an auxiliary pump 14 separately provided for cleaning the vaporizer. It is also possible to introduce an inert carrier gas into the vaporizer 12 through the carrier gas introduction system 15 from outside. In the liquid material vaporizer configured as above, in the present embodiment, the mixed liquid materials A, B, and C are placed on the liquid sending line 4E for supplying the mixed liquid materials A, B, and C. A state detecting means capable of always detecting the state in-line is provided.
The liquid materials A, B, and C are organic metals or organic metals dissolved in an organic solvent. The liquid materials A, B, and C are easily hydrolyzed and deteriorate. In addition, since the vapor pressure of the solvent is high, bubbles are generated in the piping. It's easy to do. From these points, in this embodiment,
As the state detecting means of the liquid materials A, B, and C, an absorption analysis cell CL for detecting the degree of alteration and a pressure sensor PS for detecting the presence or absence of air bubbles are employed.

The pressure sensor PS is disposed on the liquid sending line 4E and between the pump 10 and the mixer 11 (preferably near the pump outlet), and monitors the mixed liquid materials A, B, This is for confirming the malfunction of the check valve of the pump 10 and the occurrence of bubbles in the mixed liquid materials A, B, C, and the like by the pressure of C. That is, if the monitored pressure is normal, the mixed liquid materials A, B,
If C is flowing normally and the pressure is unstable, malfunction of the check valve of the pump 10 or mixed liquid materials A, B, C
It can be confirmed that air bubbles are generated therein. The output signal g of the pressure sensor PS is sent to a vaporizer controller 17 described later. In addition to the pressure sensor PS, the same operation can be performed using a flow meter. However, since the piping at the pump outlet is relatively thin and the dead volume is to be minimized, the usable flow meter is used in the mass flow controller. Limited to the thermal type. However, the thermal type has a problem that calibration is necessary for each material, and there is a problem that it is difficult to use for a material that is unstable to heat. Easy to handle and reliable operation pressure sensor P
S is adopted. Further, a similar pressure sensor PS is provided near the outlet of the pump 14, and the pressure of the solvent D is output from the output signal h.
It is configured so that it can be monitored.

The absorption analysis cell CL is provided on the liquid sending line 4E and between the mixer 11 and the vaporizer 12 (preferably immediately before the vaporizer 12), and is emitted from a light source having a predetermined luminous intensity, for example. It is based on the principle of detecting the absorbance of light transmitted through a liquid material based on the degree of attenuation. Since the liquid materials A, B, and C are organic metals and their absorbance changes when they are altered by hydrolysis or the like, the reference liquid materials A, B, and C that are not altered are changed.
Is compared with the actually measured absorbances of the liquid materials A, B, and C in the liquid sending line 4E to confirm the degree of deterioration of the liquid materials A, B, and C in the liquid sending line 4E. It is possible. In the present embodiment, the output signal i of the cell CL for absorption analysis is transferred to the vaporizer controller 17 via the amplifier AMP.

Next, the handling method of this embodiment will be described. First, when attaching empty containers 2A to 2D, their inlet side and outlet side are connected to the nearest piping to which each of the containers 2A to 2D is to be connected via a joint Z, respectively. Next, all the valves are opened to operate the vacuum line 8 to evacuate the containers 2A to 2D and the pipes at various locations, and then the containers 2A to 2D are filled with the liquid materials A to C and the solvent D. When the pump 10 is operated and an inert gas is introduced along the purge line 7 to the inlet side of each of the containers 2A to 2D and the liquid surface is pressurized, the liquid filled in these containers 2A to 2D is Materials A to C and solvent D
Is sent to the liquid sending lines 4A to 4D, and the proportional valve 5A
After 5D, they are gathered at the gathering position X at a predetermined mixture ratio. This mixing ratio can be changed through the setting of each of the proportional valves 5A to 5D even during operation.
The liquid mixture thus produced is supplied to the pump 1 shown in FIG.
After passing through 0, the mixture is homogeneously mixed by the mixer 11 and vaporized by the vaporizer 12.

At this time, the mixed liquid material A in the liquid feed line 4E is
The states of B and C are monitored and these data are sent to the vaporizer controller 17 by output signals g and i, as shown in FIG.
This is sent to a higher-level computer (not shown). The higher-level computer analyzes the transferred data and, for example, if the value is out of a certain predetermined range, stops the production line as abnormal and prevents the occurrence of defective products. On the other hand, these data are stored and provided for analysis of the cause when a defective product occurs.

The vaporizer 12 is provided with a vent line 16 in addition to the CVD reactor 1, and the mixed gas is sent to the CVD reactor 1 only during the film formation. Escape to 16 side. At this time, the pump 10 is turned off and the pump 14 is turned on, the solvent is directly transferred from the solvent transfer line 13 to the vaporizer 12, and the inside is cleaned.

As described above, the mixed liquid materials A, B,
The state of C can be continuously detected in-line during operation. Therefore, according to the present embodiment, it is possible to detect when an abnormality has occurred in the mixed liquid materials A, B, and C, thereby preventing production defects before film formation. Further, by accumulating (logging) the data of the mixed liquid materials A, B, and C output from the state detecting means, it is possible to use for investigating the cause when an abnormality occurs in the film quality.

The present invention is not limited to the above embodiment, but can be variously modified. For example, FIG. 2 shows a modified example in which the concentration of the liquid material to be supplied to the CVD reactor 1 is high and the concentration cannot be measured by the absorption-analysis cell CL if the concentration is unchanged. Here, the same reference numerals are given to members corresponding to the above embodiment. In this modified example, a six-way valve 20 is provided on a liquid sending line 4E that exits the mixer 11 and reaches the vaporizer 12, and is branched from the six-way valve 20 into a measurement-specific mixer 22, an absorption analysis cell CL, and the like. The circuit that leads to it is provided. More specifically, in the normal position, the six-way valve 20 is in a connection state shown by a solid line in FIG. That is, the mixer 11 and the vaporizer 12 are directly connected, and the pipe 4F into which the diluting solvent is fed is connected to the measurement-specific mixer 22 via the quantitative loop section 21 that can hold a fixed amount of liquid. It is like that. On the other hand, the mixer 11 and the carburetor 1
2 and the pipe 4F are connected to the mixer 22 dedicated to measurement. In the figure, reference numeral 24 indicates a drain.

The handling method is, for example, as follows. That is, during the film formation, the six-way valve 20
Is set to the normal position, and the six-way valve 20 is switched to the measurement position for a certain period of time between film formations. After filling the fixed amount loop section 21 with the mixed liquid materials A, B and C in this way, the 6-way valve 20 is switched to the normal position again. As a result, the mixed liquid materials A, B, and C, which have been cut out by the predetermined amount in the fixed amount loop section 21 together with the solvent for dilution, are mixed with the dedicated mixer 2
2 where it is stirred with a solvent for dilution and diluted at a predetermined ratio. After that, the diluted mixed liquid materials A, B, and C are measured by the absorption analysis cell CL provided downstream of the measurement mixer 22.

FIG. 3 shows a modification which is effective when quantitative analysis is performed for each of the liquid materials A, B and C. This variant is
Mixer 22 dedicated to measurement and cell CL for absorption analysis in FIG.
The second 6-way valve 20A and the column 25 are arranged in series in this order from the upstream. Second 6-way valve 2
In the normal position indicated by the solid line 0A, the dedicated measurement mixer 22 communicates directly with the drain 24, while one end of the second quantitative loop section 21A communicates with the column 25, and the other end connects to a pipe 4G through which the pressure fluid is fed. It is made to communicate with. At the measurement position indicated by the broken line, the dedicated mixer 22 for measurement and the drain 24 are connected to the second quantitative loop section 21A.
And the pipe 4G is directly connected to the column 25.

The handling method is, for example, as follows. First, by setting the second six-way valve 20A to the measurement position, the mixed liquid materials A, B, and C that are diluted by the same operation as in the above-described modification and discharged from the measurement-specific mixer 22 are subjected to the second measurement. Is filled in the quantitative loop section 21A. Thereafter, the second 6-way valve 20A is switched to the normal position. As a result, the mixed liquid materials A, B, and C cut by a predetermined amount in the second fixed amount loop section 21A are pushed into the column 25 by the pressure fluid. As is well known in the field of liquid chromatography, the column 25 includes each liquid material A, B,
Separation is performed by making the passage time different for each C. Therefore, if the output value of the absorption cell CL provided downstream of the column 25 is continuously monitored, as shown in FIG. 4, for example, each liquid material A, B, and C has peaks at different times. A simple curve graph is required. The peak time of each peak AA, BB, CC in this graph is the same as the liquid material A,
The types of B and C are shown, and the area of each of the liquid materials A, B,
This indicates the content of C. Therefore, according to such a method, it is also possible to check whether or not the mixing ratio is as set based on the detected amounts of the liquid materials A, B, and C. In addition, when monitoring off-line as shown in FIG. 2 and FIG. 3, it is possible to use not only the absorption analysis but also other analysis means such as TOF-MS, which is suitable for the material. The method can be selected.

The present invention can be variously modified in addition to the above. For example, in FIG. 1, a bypass flow path that bypasses the light absorption analysis cell CL is provided, and a valve that allows the liquid material to pass through the light absorption analysis cell or the bypass flow path is provided so that the light absorption is performed only during monitoring. A liquid material may be passed through the analysis cell. In this way, contamination of the absorption spectroscopy cell can be reduced as much as possible, and measurement accuracy can be improved. In this case, when not monitoring, the circuit may be configured so that only the solvent is guided to the absorption spectroscopy cell to clean the inner part. In the above-described embodiments and modifications, a plurality of liquid materials are mixed. However, the present invention has an advantage that the state of the material itself can be monitored. of course,
Even in the case of mixing two or more liquids, it is needless to say that each liquid material can be monitored by connecting an absorption analysis cell to each valve outlet. Further, it is also possible to feedback-control the liquid mixing ratio and the like based on the state data of the liquid material.

[0023]

As described above, according to the present invention, the mixing ratio of each liquid material (in the case of mixing a plurality of liquids), the presence or absence of bubbles in the liquid material, The apparatus is provided with state detecting means capable of detecting the state of the liquid material typified by the degree of deterioration of the liquid material during operation of the apparatus. Therefore, it is possible to detect the occurrence of an abnormality in the liquid material during the operation of the apparatus. In this case, it is possible to prevent production failure before film formation, for example, by interrupting production. In addition, by accumulating the data of the liquid material output from the state detecting means, not only can it be useful for investigating the cause when an abnormality has occurred in the film quality, but also the state data of the liquid material can be used as the basis. In this way, the liquid mixing ratio and the like can be feedback-controlled to constantly supply a stable liquid material. As described above, according to the present invention, efficient and stable film formation can be performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a main part circuit diagram showing a modification of the present invention.

FIG. 3 is a main part circuit diagram showing another modification of the present invention.

FIG. 4 is a measurement result diagram showing an example of a measurement result of the modification.

[Explanation of symbols]

 A, B, C: liquid material 2A, 2B, 2C: container 4A, 4B, 4C, 4D, 4E: liquid sending line 12: vaporizer PS: pressure sensor (state detecting means) CL: absorption analysis cell (state detecting means) )

Claims (1)

[Claims] 1. The method of claim 1, wherein one or a plurality of liquid materials are quantitatively vaporized to obtain a CV.
D, which is to be supplied to the film forming apparatus, wherein a container containing the liquid material, a vaporizer for vaporizing the liquid material, and a liquid sending line for transferring the liquid material from the container to the vaporizer And a state detecting means provided on the liquid sending line and capable of detecting the state of the liquid material during operation of the apparatus.