JPH11186244A - Method of forming film and manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a piping system from clogging to stably form a high dielectric const. film or ferroelectric film by raising the temp. of a gasifier higher than the gasifying temp. of a liq. raw material to remove residues in the gasifier after forming the film. SOLUTION: The film forming method holds gasifier at a specified high temp. to avoid clogging by gasified residues after forming an SrBi2 Ta2 O9 . The temp. of the gasifier is set high enough to gasify a main material of the residues, Bi(C6 H5 )3 , Sr(DPM)2 but below the temp. for decomposing this material, thereby gasifying to avoid clogging. If the set temp. is not enough to gasify the material, the residue removing effect will be poor, but if higher than the decomposing temp. of the material, the material will be decomposed to precipitate metal elements in the gasifier. Thus the residues can be removed from the gasifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a solution-evaporated CV.
The present invention relates to a film forming method using a D apparatus and a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art With the large scale and high integration of semiconductor devices, high dielectric constant thin films and ferroelectric thin films for application to various memory devices are required. For example, for a DRAM, a high-quality dielectric thin film having a high dielectric constant is required to realize a large capacity with a small area. For a FRAM, a high-quality ferroelectric thin film having a remanent polarization characteristic is required. As a technique for forming such a high dielectric constant thin film or a ferroelectric thin film with good controllability, a solution vaporization type CVD method has recently attracted attention.

[0003] The solution vaporization type CVD method is a method that is a solid at room temperature.
The raw material dissolved in a solvent is immediately in front of the film forming chamber with a liquid pump.
To the vaporizer provided in the
The wafer is sent to the film chamber, where the raw materials are decomposed and formed on the wafer.
It is a method of filming. For example, SrBi which is a ferroelectric film
_TwoTa_TwoO₉Conventional film deposition methods for depositing films use solid raw materials.
Sr (DPM)_Two, Bi (C₆H_Five)_Three, Ta (O-
iC_ThreeH₇) _Four(DPM) dissolved in a solvent
Introduced into a vaporizer maintained above the vaporization temperature of these raw materials
The vaporized raw material is decomposed in the film forming chamber to form Sr
Bi _TwoTa_TwoO₉A film was formed.

[0004]

However, in the above-described conventional film forming method, the piping system for supplying the raw material is liable to be clogged, and it is difficult to stably form the film. An object of the present invention is to suppress clogging of a piping system, and to provide a solution-evaporated C
A film forming method capable of stably forming a high dielectric constant thin film or a ferroelectric thin film by a VD method, and a method of manufacturing a semiconductor device having a step of forming a high dielectric constant thin film or a ferroelectric thin film by the film forming method Is to provide.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide a film forming method in which a liquid material obtained by dissolving a solid material in a solvent is vaporized by a vaporizer and a film is formed by chemical vapor deposition. This is achieved by a film forming method, wherein the temperature of the vaporizer is raised to a temperature higher than a temperature at which the liquid raw material is vaporized, and residues in the vaporizer are removed. After film formation, the residue remaining in the vaporizer can be removed by raising the temperature of the vaporizer to a temperature higher than the temperature at which the liquid raw material is vaporized, so that the film can be stably formed while suppressing clogging of the piping system. It can be performed.

In the above-described film forming method, it is preferable that the residue is vaporized at a temperature lower than a decomposition temperature of the solid material constituting the residue. If the evaporator is heated to a temperature higher than the decomposition temperature of the solid raw material, the solid raw material constituting the residue may be decomposed and deposited. Therefore, it is necessary to remove the residue at a temperature lower than the decomposition temperature of the solid raw material. Further, the above-mentioned object is to provide a liquid raw material in which Sr (DPM) ₂ is dissolved in a solvent, a liquid raw material in which Bi (C ₆ H ₅ ) ₃ is dissolved in a solvent, and Ta (O-iC ₃ H ₇ ) ₄ (DPM) In a film forming method for forming a SrBi ₂ Ta ₂ O ₉ film by chemical vapor deposition with a liquid raw material in which is dissolved in a solvent and forming the SrBi ₂ Ta ₂ O ₉ film by a vaporizer, the vaporizer is replaced with the liquid It is also achieved by a film forming method characterized in that the temperature is raised to a temperature higher than the temperature at which the raw material is vaporized, and the residue in the vaporizer is removed. After film formation, the residue remaining in the vaporizer can be removed by raising the temperature of the vaporizer to a temperature higher than the temperature at which the liquid raw material is vaporized, so that the SrBi ₂ can be stably suppressed while suppressing the clogging of the piping system. A Ta ₂ O ₉ film can be formed.

In the above-mentioned film forming method, the temperature at which the liquid material is vaporized is Sr (DPM) ₂ , Bi (C ₆ H).
_{5) 3} and _{Ta (O-iC 3 H 7} ) 4 ( below the decomposition temperature of the DPM), the temperature for removing the residue, Bi (C ₆ H ₅₎
It is desirable to be lower than the decomposition temperature of ₃ and Sr (DPM) ₂ . The vaporization temperature of the liquid raw material needs to be lower than the decomposition temperature of all solid raw materials, but the temperature for removing the residue may be set to be lower than the decomposition temperature of the main raw material constituting the residue. It is desirable to set as described above.

In the above-mentioned film forming method, the temperature at which the liquid material is vaporized is preferably 200 to 220 ° C. In the above-described film forming method, the temperature for removing the residue is desirably 230 to 250 ° C. Further, the above object is to vaporize a liquid raw material obtained by dissolving a solid raw material in a solvent by a vaporizer and form a film on a base substrate by chemical vapor deposition, and to carry out the vaporizer at a temperature at which the liquid raw material is vaporized. A step of raising the temperature to a higher temperature and removing the residue in the vaporizer. By manufacturing a semiconductor device in this manner, a solution-evaporated CV
By the method D, a film can be formed with good controllability and in a stable manner.

In the above method for manufacturing a semiconductor device, the solid raw material may be Sr (DPM) ₂ , Bi (C
₆ H ₅₎ is _3, and _{Ta (O-iC 3 H 7} ) 4 (DPM),
The film is preferably a SrBi ₂ Ta ₂ O ₉ film. The method of manufacturing a semiconductor device is, for example, a DRAM
And the formation of a ferroelectric film of an FRAM capacitor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A film forming method and a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating a solution vaporization type CVD apparatus, FIG. 2 is a diagram illustrating a cause of clogging of a piping system, and FIG. 3 is a graph illustrating a temperature of a vaporizer in a film forming method according to the present embodiment.

First, a solution evaporation type CVD apparatus will be described with reference to FIG. In the following description, SrBi ₂ T
Although an example in which an a ₂ O ₉ ferroelectric thin film is formed is shown, the present invention can be applied to a case in which another high dielectric constant thin film or ferroelectric thin film is formed. The solution vaporization type CVD apparatus shown in FIG. 1 mainly includes a liquid material supply device 10 for supplying a material.
And a vaporizer 24 for vaporizing a liquid material, and a film forming chamber 36 for growing a thin film.

The liquid raw material supply device 10 is a raw material container 12 in which a liquid obtained by dissolving Sr (DPM) ₂ which is a raw material of Sr (strontium) in THF (tetrahydrofuran), and a raw material of Bi (bismuth). Bi (C
A raw material container 14 in which a liquid in which ₆ H ₅ ) ₃ is dissolved in THF is sealed, and a raw material of Ta (tantalum), Ta (O-iC).
A raw material container 16 in which a liquid in which ₃ H ₇ ) ₄ (DPM) is dissolved in THF is provided. An N ₂ gas supply pipe 18 is connected to these source containers, and the liquid source can be introduced into the pipe 20 by pressing the liquid surface of the liquid source with the N ₂ gas. A liquid pump 22 is connected to the pipe 20, and the liquid raw material is supplied to the pipe 20.
From the vaporizer 24.

The vaporizer 24 is connected to a carrier N ₂ gas supply pipe 26 serving as a carrier for the raw material.
A heater 28 for keeping the inside of the vaporizer at a predetermined temperature is provided. Inside the vaporizer 24, a porous metal plate 30 for vaporizing the liquid material passing therethrough is provided.
Note that the pipe 32 can be maintained at a predetermined temperature by a heater 34 in order to prevent the vaporized raw material from being deposited.

A pipe 32 for supplying a raw material vaporized by the vaporizer 24, an O ₂ gas and N ₂
A gas supply pipe 38 for supplying gas is connected.
The introduced gas is supplied into the film forming chamber 36.
There is provided a shower head 40 for uniformly supplying the wafer inside, and a susceptor 44 for mounting a wafer 42 on which a film is to be formed. The susceptor 44 is provided with a heater (not shown) for heating the wafer 42 during film formation.
A vacuum pump 46 is connected to the film forming chamber 36 so that the inside of the film forming chamber 36 can be depressurized.

Next, the film forming method according to the present embodiment will be explained with reference to FIG. First, after the inside of the film forming chamber 36 is depressurized by the vacuum pump 46, the wafer 42 placed on the susceptor 44 is heated by the heater. This heating is for decomposing the raw material on the wafer 42 and depositing the SrBi ₂ Ta ₂ O ₉ film, and is performed at a temperature of, for example, 400 to 500 ° C.

[0016] Then, the N ₂ gas from the N ₂ gas supply line 18 to the liquid surface is pressed is introduced into the source container 12, 14, 16, the liquid material to the vaporizer 24 from the pipe 20 via a liquid pump 22 Supply. At this time, the supply amount of the raw material introduced into the vaporizer 24 is, for example, 0.1 to 0.2 cc / min. Subsequently, the liquid raw material introduced into the vaporizer 24 is vaporized by the vaporizer 24. The liquid raw material introduced into the vaporizer 24 is vaporized while passing through the porous metal plate 30, and the vaporized raw material is supplied to the pipe 32.

When the liquid raw material is vaporized, the vaporizer is set to a predetermined temperature by the heater 28 according to the raw material. That is, if the vaporization temperature is too high, the raw material may be decomposed and precipitated, and if it is too low, the raw material cannot be sufficiently vaporized. Therefore, the temperature of the vaporizer 24 is higher than the vaporization temperature of the raw material and lower than the decomposition temperature. There is a need. Sr (DPM) ₂ , Bi
In the above system using (C ₆ H ₅ ) ₃ and Ta (O-iC ₃ H ₇ ) ₄ (DPM) as raw materials, Ta (O-
The upper limit of the vaporization temperature is determined by iC ₃ H ₇ ) ₄ (DPM), and the vaporization temperature is desirably about 220 ° C. or less.
On the other hand, the lower limit of the vaporization temperature is about 2 to which these raw materials can be vaporized.
Desirably, the temperature is not lower than 00 ° C.

The vaporized source gas is supplied to the carrier N_TwoWith gas
Both are supplied to the pipe 32 and supplied from the gas supply pipe 38
Done O_TwoGas, N_TwoIntroduced into the film forming chamber 36 together with the gas.
It is. For example, the total flow rate of the introduced gas is set to 500 to 150.
0 sccm, carrier N _Two300 sc gas flow
cm, O_TwoGas is introduced into the deposition chamber at a rate of 20-80%
Then, the pressure in the film forming chamber 36 is set to 3 to 7 Torr.

The raw material gas thus introduced is decomposed and reacted on the wafer 42, and SrBi
_{A 2} Ta ₂ O ₉ film is formed. When the SrBi ₂ Ta ₂ O ₉ film is deposited by the solution evaporation type CVD method in this way, it is empirically recognized that clogging occurs in a piping system for supplying the raw material. As a result of the present inventors' intensive studies on the causes of clogging, it is clear that clogging of the piping system has occurred between the tip of the vaporizer introduction pipe (pipe 20) and the porous metal plate 30. It became. This is because not all of the liquid raw material 48 supplied on the porous metal plate 30 is vaporized, and a part thereof becomes a residue 50 and remains on the porous metal plate 30. It is conceivable that the layered structure blocks the tip of the vaporizer introduction pipe and causes clogging (FIG. 2).

The cause of the residue is mainly
Sr (DPM)_Two, Bi (C₆H_Five)_Three, Ta (O
-IC_ThreeH₇)_Four(DPM) has different vaporization temperatures
It is thought to be possible. Sr (DPM)_Two, Bi (C₆
H_Five)_Three, Ta (O-iC_ThreeH₇)_Four(DPM) as raw material
In the above system, Ta (O-iC) having the lowest decomposition temperature is used.
_ThreeH₇)_Four(DPM) does not decompose about 200-220 ° C
The liquid material is vaporized depending on the temperature. However,
Bi (C at this temperature₆H_Five)_Three, Sr (DPM)_Twoof
The vaporization is not enough, and Bi (C₆H_Five)_Three,
Sr (DPM) _TwoAre considered to remain as residues.

Therefore, in the film forming method according to the present embodiment,
In order to evaporate the residue and eliminate clogging, SrBi ₂ T
After the formation of the a ₂ O ₉ film, the vaporizer is kept at a high temperature at a predetermined temperature (FIG. 3). Specifically, the temperature of the vaporizer is controlled by adjusting Bi (C ₆ H ₅ ) ₃ ,
By keeping the vaporizer at a temperature higher than the temperature at which r (DPM) ₂ is sufficiently vaporized and lower than the temperature at which this raw material decomposes, the residue is vaporized and clogging is eliminated.
When the temperature of the vaporizer is set in this manner, the effect of residue removal is small at a temperature at which the raw material is not sufficiently vaporized, and at a temperature higher than the decomposition temperature of the raw material, the raw material is decomposed and the metal element is contained in the vaporizer. This is because they are deposited. Bi (C ₆
H ₅ ) ₃ and Sr (DPM) ₂ are sufficiently vaporized at about 230 ° C. or higher, while decomposed at a temperature higher than about 250 ° C.
It is desirable to be in the range of ° C.

The temperature maintained at a high temperature is Ta (O-i
Although it is higher than the decomposition temperature of C ₃ H ₇ ) ₄ (DPM), Ta (O-iC ₃ H ₇ ) ₄ (DP
Since the amount of M) is small, it is considered that a sufficient effect of removing the residue can be obtained by holding at a high temperature of 230 to 250 ° C. If the residue is removed after the predetermined film formation is performed in this manner, the film can be formed continuously while keeping the film formation conditions such as the film formation speed stable. Note that the frequency and time for removing the residue by holding at a high temperature are desirably adjusted as appropriate according to the film forming conditions such as the raw material, the flow rate of the raw material, and the thickness of the film to be formed.

When the amount of the residue on the porous metal plate 30 increases, the flow of the raw material and the carrier N ₂ gas becomes difficult, so that the pressure in the vaporization chamber 24 deteriorates as the residue is generated. Therefore, the state of the residue can be estimated by measuring the pressure in the vaporization chamber 24. Therefore, before and after film formation,
After the high temperature was maintained, the pressure inside the vaporizer 24 was measured.
As a result, although the pressure before film formation was about 25 Torr, the pressure had deteriorated to about 40 Torr after film formation.
By maintaining the temperature at 0 to 250 ° C., the pressure could be recovered to about 25 Torr, which is almost the same as before the start of growth. Thereby, it became clear that the residue can be removed by holding at a high temperature.

As described above, according to the present embodiment, in the film forming method for forming a film by the solution vaporization type CVD method, the vaporizer is kept at a predetermined temperature after the film is formed, so that the residue in the vaporizer is kept. Can be removed. Thereby, clogging of the pipe in the vaporizer can be suppressed, and the film can be stably formed. In the above embodiment, SrBi ₂ T
Although the case of forming the a ₂ O ₉ film has been described, the present invention can be widely applied to a film forming method of forming a film by a solution vaporization type CVD method. For example, SrBi ₂ (Ta, Nb)
₂ O ₉ , Sr ₂ (Ta, Nb) ₂ O ₇ , Bi ₄ Ti ₃ O ₁₂ ,
The present invention can be applied to the formation of a high dielectric constant thin film such as (BaSr) TiO ₃ and Pb (Zr, Ti) O ₃ and a ferroelectric thin film. In particular, it is suitable for a solution vaporization type CVD method using a plurality of solid raw materials having different vaporization temperatures and decomposition temperatures.

As the Ta source, Ta (O-iC _{3
H 7) 5, Ta (O} -C 2 H 5) 5 and the like, as the Bi source, or the like can be used _{Bi (O-tC 4 H 9} ) 3. Further, the film forming method according to the above embodiment is applied to a manufacturing process of a high dielectric constant thin film or a ferroelectric thin film for forming a capacitor of a DRAM, and a manufacturing process of a ferroelectric thin film for forming a capacitor of an FRAM. By doing
A high dielectric constant thin film and a ferroelectric thin film can be formed stably.

[0026]

As described above, according to the present invention, a film is formed in a film forming method in which a liquid material obtained by dissolving a solid material in a solvent is vaporized by a vaporizer and a film is formed by chemical vapor deposition. Thereafter, the temperature of the vaporizer is raised to a temperature higher than the temperature at which the liquid raw material is vaporized, and the residue in the vaporizer is removed, so that the film can be stably formed while suppressing clogging of the piping system.

In the above-described film forming method, if the residue is vaporized at a temperature lower than the decomposition temperature of the solid material constituting the residue, the solid material is removed while preventing the solid material from being decomposed and deposited. Can be. Further, a liquid raw material in which Sr (DPM) ₂ is dissolved in a solvent, a liquid raw material in which Bi (C ₆ H ₅ ) ₃ is dissolved in a solvent, and Ta (O-iC ₃ H ₇ ) ₄ (DP
In a film forming method of forming a SrBi ₂ Ta ₂ O ₉ film by chemical vapor deposition with a liquid material obtained by dissolving M) in a solvent and forming the SrBi ₂ Ta ₂ O ₉ film by a vaporizer, the vaporizer is connected to a liquid Since the temperature is raised to a temperature higher than the temperature at which the raw material is vaporized and the residue in the vaporizer is removed, the film can be stably formed while suppressing clogging of the piping system.

In the above-mentioned film forming method, the liquid raw material
Temperature at which Sr (DPM) evaporates _Two, Bi (C₆H_Five)_Three
And Ta (O-iC_ThreeH₇)_FourFrom the decomposition temperature of (DPM)
The temperature at which the residue is removed is low, Bi (C₆H_Five)_ThreeAnd S
r (DPM)_TwoLower than the decomposition temperature of
The residue can be removed. Also, dissolve solid raw materials in a solvent.
The vaporized liquid raw material is vaporized by a vaporizer for chemical vapor deposition.
The process of forming a film on the underlying substrate and the vaporizer
The temperature rises to a temperature higher than the temperature at which the raw material evaporates, and
Manufacturing semiconductor devices using the process of removing residues
With this, the controllability is improved by the solution evaporation type CVD method and
In addition, a film can be formed stably.

In the above method for manufacturing a semiconductor device,
And Sr (DPM) as a solid material _Two, Bi (C₆H_Five)_Three
And Ta (O-iC_ThreeH₇)_FourSrBi using (DPM)_Two
Ta _TwoO₉If a film is formed, this film can be
The dielectric film of the capacitor of FRAM and the strength of the capacitor of FRAM
It can be applied to a dielectric film.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a solution vaporization type CVD apparatus.

FIG. 2 is a diagram illustrating a cause of a clogging of a piping system.

FIG. 3 is a graph showing a temperature of a vaporizer in a film forming method according to an embodiment of the present invention.

[Explanation of symbols]

10 ... liquid material supply device 12 ... Sr (DPM) ₂ material container _{14 ... Bi (C 6 H 5} ) 3 source container _{16 ... Ta (O-iC 3} H 7) 4 (DPM) material container 18 ... N ₂ gas supply piping 20 ... pipe 22 ... liquid pump 24 ... carburetor 26 ... carrier N ₂ gas supply line 28 ... heater 30 ... porous metal plate 32 ... pipe 34 ... heater 36 ... film forming chamber 38 ... gas supply pipe 40 ... showerhead 42 ... wafer 44 ... susceptor 46 ... vacuum pump 48 ... liquid raw material 50 ... residue

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/8247 29/788 29/792

Claims (8)

[Claims] 1. A film forming method for forming a film by chemical vapor deposition by vaporizing a liquid raw material obtained by dissolving a solid raw material in a solvent and forming a film by chemical vapor deposition. A film forming method comprising: elevating the temperature to a temperature higher than a temperature at which the gas is vaporized; and removing a residue in the vaporizer. 2. The film forming method according to claim 1, wherein said residue is vaporized at a temperature lower than a decomposition temperature of said solid raw material constituting said residue. 3. Sr (DPM)_TwoIn a solvent
Raw materials and Bi (C₆H _Five)_ThreeRaw material in which is dissolved in a solvent
And Ta (O-iC_ThreeH₇)_Four(DPM) in a solvent
Liquid raw material is vaporized by a vaporizer for chemical vapor deposition.
More SrBi_TwoTa_TwoO₉In the film forming method to form the film
After forming a film, the vaporizer is used to vaporize the liquid raw material.
Temperature to a temperature higher than the temperature of
A film forming method characterized by removing. 4. The film forming method according to claim 3, wherein the temperature at which the liquid material is vaporized is Sr (DPM) ₂ , B
lower than the decomposition temperature of i (C ₆ H ₅ ) ₃ and Ta (O-iC ₃ H ₇ ) ₄ (DPM), and the temperature at which the residue is removed is Bi (C ₆ H ₅ ) ₃ and Sr
(DPM) A film formation method characterized by being lower than the decomposition temperature of ₂ . 5. The film forming method according to claim 3, wherein a temperature at which the liquid raw material is vaporized is 200 to 220 ° C. 6. The film forming method according to claim 3, wherein a temperature at which the residue is removed is 230 to 250 ° C. 7. A step of vaporizing a liquid raw material obtained by dissolving a solid raw material in a solvent by a vaporizer and forming a film on an undersubstrate by chemical vapor deposition, and controlling the vaporizer by a temperature at which the liquid raw material is vaporized. The temperature of the vaporizer is also raised to a high temperature to remove the residue in the vaporizer. 8. The method for manufacturing a semiconductor device according to claim 7, wherein the solid material is Sr (DPM) ₂ , Bi (C ₆ H ₅ ) ₃ and Ta (O-iC ₃ H ₇ ) ₄ (DPM). Wherein the film is a SrBi ₂ Ta ₂ O ₉ film.