JP2003324100A - Method for forming ferroelectric film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ferroelectric film forming method capable of forming a ferroelectric film whose composition and film quality are uniform by an MOCVD method. <P>SOLUTION: When a combination of organic metal materials formed by dissolving Pb(DPM)<SB>2</SB>, Zr(DPM)<SB>4</SB>and Ti(t-Am)<SB>2</SB>(DMHD)<SB>2</SB>into a solvent is used, a substrate is held at the temperature of 500 to 600°C which is a supply rate- determining area common to these organic metal materials. When the combination of organic metal materials formed by dissolving organic metal materials Pb(DPM)<SB>2</SB>, Zr(DMHD)<SB>4</SB>and Ti(s-Am)<SB>2</SB>(DMHD)<SB>2</SB>into the solvent is used, the substrate is held at the temperature of 450 to 550°C which is the supply rate- determining area common to these organic metal materials. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a ferroelectric film mainly used in a non-volatile memory device.

[0002]

2. Description of the Related Art PZT (Pb (Zr, Ti) O ₃ ) is a material having a perovskite type crystal structure having a ferroelectric property and an electro-optical property and having a large spontaneous polarization.
(Ferroelctric Random Access Memory) and other nonvolatile memory devices and electro-optical devices.

Ferroelectric thin films have been conventionally formed by various methods. Generally, a thin film forming technique is divided into a physical vapor deposition (PVD) technique and a chemical treatment technique. PVD techniques include electron beam evaporation, sputtering and laser ablation as methods used to form ferroelectric thin films.
Chemical solution deposition method (CSD: Chemical Sodium)
Solution Deposition Method) and Chemical Vapor Deposition Method (CVD:
Chemical Vapor Deposition method).

In PVD, film formation is mainly performed under a low pressure of 10 ^-2 Pa or less. The PVD technique has the advantages that a high-purity film can be obtained, a film with a high degree of cleaning can be obtained, and that the PVD technique is a technique that is widely used in the formation of semiconductor integrated circuits. However, the film forming rate is slow, it is difficult to control the number ratio of elements in the case of a multi-component compound, and
It has drawbacks such as high temperature of the formed anneal.

The CSD method has advantages such as high film formation rate, uniform distribution of molecules in the film, reproducibility of film composition, and easy introduction of dopant. With. However, cracks are generated in the film by heat treatment after formation, impurities are mixed in to form the film without using a vacuum chamber, and the composition of the starting material must be changed in order to change the composition. It has drawbacks such as not being possible.

Among the CVD methods, MOCVD (Metal Organi
c Chemical Vapor Deposition) method, the film formation rate is high, a high density film can be obtained, the film uniformity is excellent, the film composition controllability is excellent, and the film step There are advantages such as excellent coverage. In particular,
The excellent step coverage of the film is an advantage over the other methods described above. In addition, for example, Pb (Zr _X Ti _1-X )
In the case of O ₃ , even if the same raw material is used, the composition can be easily changed by changing the flow rate of each raw material.

As described above, since the MOCVD method has many advantages, it is most expected as a method for forming a ferroelectric thin film.

When forming a ferroelectric thin film by the MOCVD method, a bubbling method is generally used in which a liquid raw material is bubbled with a gas and the vaporized raw material is sent to a reaction chamber with a carrier gas. However, the bubbling method has a problem that the film forming speed is slow.

Further, when a ferroelectric thin film made of PZT is formed, only a toxic tetraethyllead-based raw material exists as a Pb liquid raw material. There is also a sublimation method in which a solid organic material is sublimated and sent to a reaction chamber as a method using a nontoxic raw material, but this method is poor in reproducibility of composition and film thickness.

By the way, it is generally known that in the CVD method, the deposition rate of each element forming the thin film changes with the temperature of the substrate.

FIG. 1 is a diagram showing the relationship between the deposition rate and the substrate temperature when a thin film is formed by the CVD method, with the horizontal axis representing the reciprocal of the substrate temperature and the vertical axis representing the deposition rate. Figure 1
As shown in, the deposition rate increases as the substrate temperature increases in a relatively low temperature region. In such a temperature range, the reaction state on the substrate surface is rate-determining the deposition rate,
This region is called the reaction rate-determining region.

When the temperature is further raised from the reaction rate-determining region, the deposition rate becomes almost independent of the substrate temperature. In such a temperature range, the deposition rate is controlled by the supply amount of the raw material, and thus this range is referred to as a supply rate-determining range.

When the temperature is further raised from the supply rate controlling region, the raw material is decomposed by heat before reaching the substrate. Such a temperature region is called a vapor phase decomposition region, and in this region, the deposition rate decreases as the substrate temperature rises.

However, in reality, the above-mentioned respective regions are not accurately divided, and for example, an intermediate region between these regions exists between the reaction rate-determining region and the supply rate-determining region.

As described above, it is extremely difficult to form a thin film in the vapor phase decomposition region from the viewpoint of composition controllability during thin film formation and crystallinity of the formed thin film. Therefore, generally, the thin film is formed in the reaction rate-controlled region or the supply rate-controlled region.

In the reaction-controlled region, a high quality film can be obtained when the desired crystallization temperature of the thin film is within this region. However, when forming a multi-component thin film, if the activation energy of each elemental raw material is different, the composition of the thin film changes depending on the substrate temperature. For example, when a thin film is formed on a substrate having a large area of 6 inches or 8 inches, if the temperature in the substrate is uneven, the composition and quality of the thin film become poor,
This leads to variations in characteristics.

On the other hand, in the feed rate controlling region, if the feed rate controlling regions of the respective raw materials are overlapped at a certain temperature, a thin film having excellent uniformity in composition and film quality can be obtained, so that the combination of these raw materials becomes important.

[0018]

In the MOCVD method, a liquid supply vaporization method in which a liquid raw material is gasified in a vaporization chamber and sent to a CVD reaction chamber has been studied in recent years. With this liquid supply vaporization method, the film formation rate is high and a thin film can be formed with good reproducibility.

However, many problems remain, such as the combination of the organometallic raw materials and the selection of the solvent that dissolves the organometallic raw materials, which provides good composition controllability during thin film formation. The current situation is that the body thin film has not yet been formed.

From the above, it is an object of the present invention to provide a method for forming a ferroelectric film by MOCVD, which can form a ferroelectric film having a uniform composition and film quality.

[0021]

A method of forming a ferroelectric film according to the present invention is performed by using an organometallic material Ti (t-Am).
₂ (DMHD) ₂ ((tertial amyl alkoxide)
(Dimethylheptanedionate) titanium), Pb
And a ferroelectric film containing Ti as a main component or a ferroelectric film containing Pb, Zr and Ti as a main component is formed.

The method for forming a ferroelectric film according to the present invention is performed by using the organometallic material Ti (s-Am) ₂ (DMHD).
₂ ((Secondary amyl alkoxide) (dimethylheptanedionate) titanium) is used to form a ferroelectric film containing Pb and Ti as main components or a ferroelectric film containing Pb, Zr and Ti as main components. Is characterized by.

The method of forming a ferroelectric film according to the present invention is a method of forming a ferroelectric film containing Pb, Zr and Ti as main components on a semiconductor circuit substrate by using a metal organic chemical vapor deposition method. In the method of forming a body film, a step of heating the semiconductor circuit substrate in a CVD reaction chamber, and introducing a metalorganic source gas and an oxidizing gas into the CVD reaction chamber to form a ferroelectric film on the semiconductor circuit substrate. Pb (DPM) ₂ ((dipivaloylmethanate) lead), Zr (DPM) ₄ ((dipivaloylmethanate) zirconium) and Ti (t-Am) as the organic metal raw material. )
A liquid raw material formed by dissolving ₂ (DMHD) ₂ in a solvent is used, and the semiconductor circuit substrate is maintained at a temperature of 500 to 600 ° C.

In the present invention, a combination of the above-mentioned organometallic raw materials is used. All of these organometallic raw materials are in the rate-determining region at a temperature of 500 to 600 ° C.
Therefore, the film formation rate and the film composition are determined by the supply amount of the raw material, and the influence of the substrate temperature is small. As a result, a ferroelectric film having a uniform composition and a uniform film thickness can be formed if the amount of raw material supplied is constant. In this case, if the temperature distribution (variation in temperature) of the substrate is 17 ° C. or less, the composition and film thickness uniformity of the ferroelectric film can be kept within ± 3%. Further, if the temperature distribution of the substrate is 6 ° C. or less, the composition and film thickness uniformity of the ferroelectric film can be kept within ± 1%.

The method of forming a ferroelectric film according to the present invention is a method of forming a ferroelectric film containing Pb, Zr and Ti as main components on a semiconductor circuit substrate by using a metal organic chemical vapor deposition method. The method for forming a body film includes the steps of heating the semiconductor circuit substrate in a CVD reaction chamber and introducing an organometallic source gas and an oxidizing gas into the CVD reaction chamber to form the ferroelectric film. , Pb (DPM) ₂ , Zr (DMHD) ₄ ((dimethylheptanedionate) zirconium) and Ti (s-A) as the organic metal raw material.
m) ₂ (DMHD) ₂ is dissolved in a solvent to form a liquid raw material, and the semiconductor circuit board is maintained at a temperature of 450 to 550 ° C.

In the present invention, a combination of the above-mentioned organometallic raw materials is used. All of these organometallic raw materials are in the rate-determining region at a temperature of 450 to 550 ° C.
Therefore, the film formation rate and the film composition are determined by the supply amount of the raw material, and the influence of the substrate temperature is small. As a result, a ferroelectric film having a uniform composition and a uniform film thickness can be formed if the amount of raw material supplied is constant. In this case, if the temperature distribution of the substrate is 20 ° C. or less, the composition and film thickness uniformity of the ferroelectric film can be kept within ± 3%. If the temperature distribution of the substrate is 6.5 ° C. or less, the composition and film thickness uniformity of the ferroelectric film can be kept within ± 1%.

In the present invention, as the oxidizing gas, oxygen gas, a mixed gas of oxygen gas and dinitrogen monoxide gas, or a mixed gas of oxygen gas and nitrogen gas can be used.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

In the present invention, a ferroelectric thin film having a perovskite type structure containing Pb, Zr and Ti as main components is formed on a semiconductor circuit substrate by MOCVD. At this time, a safe and stable organometallic material Pb (D
PM) ₂ , Zr (DPM) ₄ , Zr (DMHD) ₄ , T
i (t-Am) ₂ (DMHD) ₂ and Ti (s-Am)
THF (Tetrahydorofur) is used as a solid raw material of ₂ (DMHD) _2.
Use a liquid raw material dissolved in an organic solvent such as an).

FIG. 2 shows the results of examining the relationship between the substrate temperature and the deposition rate of a liquid source using Pb (DPM) _2, with the horizontal axis being the reciprocal of the substrate temperature and the vertical axis being the deposition rate. It is a figure.

As shown in FIG. 2, the liquid raw material using Pb (DPM) ₂ has a wide temperature range of 450 to 600 ° C. (see FIG. 2).
Then, the supply rate-controlling region exists in the range of 1.15 × 10 ^{−3 to} 1.38 × 10 ⁻³ (1 / K).

In FIG. 3, the horizontal axis represents the reciprocal of the substrate temperature, and the vertical axis represents the deposition rate. Zr (DPM) ₄ and Zr (DM)
FIG. 6 is a diagram showing the results of examining the relationship between the deposition rate of a liquid source using HD) ₄ and the substrate temperature. In FIG.
Square plots show Zr (DPM) ₄ results and diamond plots show Zr (DMHD) ₄ results.

As shown in FIG. 3, Zr (DMHD) ₄ has a temperature range of at least 400 to 550 ° C. (1.
In the range of 21 × 10 ^{−3 to} 1.48 × 10 ⁻³ (1 / K)), there is a supply rate controlling region, and Zr (DPM) ₄ is 550 to 6
Temperature range of 50 ° C. (1.08 × 10 ^{−3 to} 1.2 in FIG. 3)
In the range of 1 × 10 ⁻³ (1 / K)), there is a supply rate controlling region. From FIG. 3, when a thin film is formed in a relatively low temperature region, a liquid raw material using Zr (DMHD) ₄ is suitable,
It can be seen that the liquid raw material using Zr (DPM) ₄ is suitable in a relatively high temperature region.

In FIG. 4, the horizontal axis represents the reciprocal of the substrate temperature, and the vertical axis represents the deposition rate. Ti (t-Am) ₂ (DMHD)
FIG. 3 is a diagram showing the results of examining the relationship between the deposition rate of a liquid source using ₂ and Ti (s-Am) ₂ (DMHD) ₂ and the substrate temperature. In FIG. 4, the square plot is T
The results for i (s-Am) ₂ (DMHD) ₂ and the diamond plots show the results for Ti (t-Am) ₂ (DMHD) ₂ .

As shown in FIG. 4, Ti (s-Am)
Liquid raw material using ₂ (DMHD) ₂ is 450 to 550 ° C.
Temperature range (1.21 × 10 ^{−3 to} 1.38 × 1 in FIG. 4)
In the range of 0 ^-3 (1 / K)), there is a supply rate controlling region, and Ti
The liquid raw material using (t-Am) ₂ (DMHD) ₂ is 50
Temperature range of 0 to 600 ° C. (1.15 × 10 ^{−3 in} FIG. 4)
In the range of 1.29 × 10 ⁻³ (1 / K)), there is a supply rate controlling region. From FIG. 4, a liquid raw material using Ti (s-Am) ₂ (DMHD) ₂ is suitable for forming a thin film in a relatively low temperature region, and Ti (t-
It can be seen that a liquid raw material using Am) ₂ (DMHD) ₂ is suitable.

From the above results, Pb (DPM) ₂ , Zr (DMHD) ₄ and T can be used for forming a thin film in a relatively low temperature region.
A combination of liquid raw materials of i (s-Am) ₂ (DMHD) ₂ is suitable, and Pb (DP) for forming a thin film in a relatively high temperature region.
M) ₂ , Zr (DPM) ₄ and Ti (t-Am) ₂ (D
A combination of MHD) ₂ liquid sources is suitable.

In FIG. 5, the horizontal axis represents the reciprocal of the substrate temperature, and the vertical axis represents the deposition rate. Pb (DPM) ₂ , Zr (DMH)
It is the figure which showed the result of having investigated the relationship between the deposition rate and the substrate temperature by the combination of the liquid raw materials of D) ₄ and Ti (s-Am) ₂ (DMHD) ₂ . In FIG. 5, the rhombus plots show the results for Pb (DPM) ₂ , the square plots show the results for Zr (DMHD) ₄ , and the triangle plots for Ti (s-Am) ₂ (DMHD) ₂ . The results are shown.

From FIG. 5, a temperature range of 450 to 550 ° C. (in FIG. 5, 1.21 × 10 ^{−3 to} 1.38 × 10 ⁻³ (1 /
In the range K)), it can be seen that all of these liquid raw materials are in the rate-controlling region. Therefore, when a thin film is formed in this temperature range, a wide margin for the substrate temperature distribution and its reproducibility can be obtained, and a thin film having good composition uniformity can be formed.

In FIG. 6, the horizontal axis represents the reciprocal of the substrate temperature and the vertical axis represents the deposition rate, and Pb (DPM) ₂ , Zr (DP
It is the figure which showed the result of having investigated the relationship between the deposition rate and the substrate temperature by the combination of the liquid raw materials of M) ₄ and Ti (t-Am) ₂ (DMHD) ₂ . In FIG. 6, the diamond plot is the result of Pb (DPM) ₂ and the square plot is Z.
The result of r (DPM) ₄ and the triangular plot are Ti
The result of (t-Am) ₂ (DMHD) ₂ is shown.

From FIG. 6, a temperature range of 500 to 600 ° C. (in FIG. 6, 1.15 × 10 ^{−3 to} 1.29 × 10 ⁻³ (1 /
In the range K)), it can be seen that all of these liquid raw materials are in the rate-controlling region. Therefore, when a thin film is formed in this temperature range, a wide margin for the substrate temperature distribution and its reproducibility can be obtained, and a thin film having good composition uniformity can be formed.

As described above, a thin film having good composition uniformity can be obtained in a wide substrate temperature range of 450 to 600 ° C. by combining the above liquid raw materials.

FIG. 7 is a schematic view showing an example of a PZT thin film forming apparatus.

As shown in FIG. 7, the PZT thin film forming apparatus comprises a raw material supply section 1, a vaporization chamber 2, a CVD apparatus 3 and an exhaust apparatus 4.

In the raw material supply section 1, Pb-based liquid raw material, Zr
Raw material tanks 5, 6, 7, and 8 in which a system liquid material, a Ti system liquid material, and a solvent such as THF are stored are arranged. Pipes 13 and 1 from the raw material tanks 5, 6, 7 and 8 respectively
4, 15, 16 extend. These pipes 13, 1
Liquid mass flow meters 9, 4, 15 and 16
10, 11, 12 are attached, and the flow rates of the liquid raw materials and the solvent can be individually adjusted.

The pipes 13, 14, 15 and 16 and the pipe 17 through which the carrier gas flows merge to form a pipe 18, which is connected to the vaporization chamber 2.

In the vaporizing chamber 2, a heating device (not shown) for heating the internal space of the vaporizing chamber 2 and a nozzle for spraying the liquid raw material sent through the pipe 18 into the internal space of the vaporizing chamber 2. (Not shown) are provided. The liquid raw material sent through the pipe 18 is gasified in the vaporization chamber 2 to become a raw material gas.

A pipe 19 extending from the vaporization chamber 2 branches in the middle, one pipe 20 is connected to the CVD device 3 via a valve 21, and the other pipe 22 is connected to the exhaust device 4 via a valve 23. Connected.

A gas mixing chamber 24 is provided above the CVD apparatus 3. A pipe 20 through which the source gas flows and a pipe 25 through which the oxidizing gas flows are connected to the gas mixing chamber 24. In this gas mixing chamber 24, the source gas and the oxidizing gas (O
₂ gas, mixed gas of O ₂ gas and N ₂ O gas, or O ₂
Gas and a mixed gas of N ₂ gas) are mixed. The gases mixed in the gas mixing chamber 24 are introduced into the reaction chamber 27 via the shower head 26.

A heating part 28 is arranged in the reaction chamber 27, and a susceptor 29 is arranged on the heating part 28. The substrate 30 is placed on the susceptor 29. Heating part 28
Is provided with a resistor arranged so as to form a concentric circle from the center of the surface on which the susceptor 29 is placed, and electric power can be controlled independently at the center and the outer periphery of the resistor. .

A pipe 31 for exhausting gas is connected to the reaction chamber 27. The pipe 31 is connected to the exhaust device 4.

Next, a method of forming a PZT thin film using the apparatus constructed as described above will be described.

First, the substrate 30 is placed on the susceptor 29, and electric power is supplied to the resistor of the heating section 28 to heat it to a constant temperature. At this time, the electric power supplied to the resistors in the central portion and the outer peripheral portion of the heating unit 28 is individually controlled to adjust the temperature distribution of the substrate 30.

On the other hand, Pb-based liquid raw material, Zr-based liquid raw material, Ti-based liquid raw material and THF solvent are supplied to the vaporization chamber 2 from the liquid raw material tanks 5, 6, 7 and the solvent tank 8. The Pb-based liquid raw material, the Zr-based liquid raw material, the Ti-based liquid raw material, and the THF solvent are supplied in the liquid mass flow meters 9 and 1.
Adjust with 0, 11, and 12. These liquid raw material and solvent are supplied to the vaporization chamber 2 together with the carrier gas (N ₂ ) and are gasified in the vaporization chamber 2 to become the raw material gas.

Until the temperature of the substrate 30 in the CVD apparatus 3 stabilizes, the valve 21 is closed and the valve 23 is opened so that the source gas is not supplied to the CVD apparatus 3.

When the temperature of the substrate 30 in the CVD apparatus 3 becomes stable, the valve 23 is closed and the valve 21 is opened to supply the source gas to the CVD apparatus 3.

In the CVD apparatus 3, the source gas and the oxidizing gas are mixed in the gas mixing chamber 24, and this mixed gas is introduced into the reaction chamber 27 via the shower head 26.

In the reaction chamber 27, the source gas is decomposed and a PZT film is formed on the substrate 30. Further, the remaining gas is discharged through the pipe 31 and the exhaust device 4.

The results of actually forming the PZT thin film by the above method will be described below.

(Embodiment 1) In this embodiment, the liquid raw materials are the organometallic materials Pb (DPM) ₂ and Zr (DMHD).
₄ and Ti (s-Am) ₂ (DMHD) ₂ respectively
A liquid formed by dissolving it in an HF solvent at a rate of 0.3 mol / L (liter) was used.

The substrate temperature is 500 at the center of the substrate.
℃, the difference between the highest and lowest values in the temperature distribution of the substrate is 5
° C (hereinafter referred to as Δ5 ° C) or Δ1
The PZT thin film was formed under the conditions of 0 ° C. and the respective substrate temperature distributions.

Further, the substrate 3 for forming the PZT thin film
For 0, a 6-inch Si substrate was used. A SiO ₂ oxide film having a film thickness of 100 nm was formed on the Si substrate, and an Ir film having a film thickness of 150 nm was formed on the SiO ₂ oxide film by a sputtering method.

First, the substrate 30 was placed on the susceptor 29, and the heating portion 28 was heated for 240 seconds to stabilize the temperature of the substrate 30.

Next, the organometallic material Pb (DPM) ₂ , Z
r (DMHD) ₄ and Ti (s-Am) ₂ (DMHD)
Each of the liquid raw materials formed by dissolving ₂ in THF solvent at a ratio of 0.3 mol / L has a flow rate of Pb / (Zr + T
i) It was introduced into the vaporization chamber 2 while controlling the flow rate ratio to be 0.98 and the Zr / (Zr + Ti) flow rate ratio to be 0.42.

Next, these liquid raw materials were made into a raw material gas in the vaporization chamber 2 heated to 260 ° C., and this raw material gas was introduced into the CVD apparatus 3 by using a carrier gas having a flow rate of 300 sccm. However, until the temperature of the substrate 30 was stabilized, the raw material gas was directly introduced into the exhaust device 4 without being introduced into the CVD device 3.

Next, after the temperature of the substrate 30 is stabilized, C
In the gas mixing chamber 24 of the VD device 3, a source gas and O ₂ gas as an oxidizing gas are mixed, and this gas is showered by a shower head 26.
It was introduced into the reaction chamber 27 via. On the substrate 30, about 3
About 100 nm PZT thin film was formed at a deposition rate of 0 nm / min.

When the composition of the central portion of this PZT thin film was examined, the Pb / (Zr + Ti) composition ratio was 1.15, and Zr /
The (Zr + Ti) composition ratio was 0.45.

When the compositional uniformity of the PZT thin film formed under the condition that the substrate temperature distribution was Δ5 ° C. was examined, Pb was ± 0.8%, Zr was ± 0.4%, and Ti was ± 0.7%. %Met. Furthermore, the film thickness uniformity of this PZT thin film is ± 0.5%.
Met.

When the compositional uniformity of the PZT thin film formed under the condition of the substrate temperature distribution Δ10 ° C. was examined, Pb was ± 1.
5%, Zr ± 1.0%, Ti ± 1.3%.
Further, the film thickness uniformity of this PZT thin film was ± 1.0%.

As in this example, Pb was added to the organometallic raw material.
(DPM) ₂ , Zr (DMHD) ₄ and Ti (s-A
m) ₂ (DMHD) ₂ dissolved in a solvent is used, and the substrate temperature is 450 ° C. to 5 including the temperature range of the substrate temperature distribution.
By forming the PZT thin film while controlling the temperature in the range of 50 ° C., it is possible to obtain the PZT thin film having excellent composition and film thickness uniformity.

Example 2 In this example, the organometallic materials Pb (DPM) ₂ , Zr (DPM) ₄ and Ti (t-A) are used.
m) ₂ (DMHD) ₂ in THF solvent
A liquid formed by melting at a ratio of ol / L was used.

The substrate temperature is 550 at the center of the substrate.
C. and the substrate temperature distribution was .DELTA.5.degree. C. or .DELTA.10.degree. C., and the PZT thin film was formed under the respective substrate temperature distribution conditions. Also,
As the substrate 30, the substrate formed by the method shown in Example 1 was used.

First, the substrate 30 was placed on the susceptor 29, and the heating portion 28 was heated for 240 seconds to stabilize the temperature of the substrate 30.

Next, the organometallic material Pb (DPM) ₂ , Z
r (DPM) ₄ and Ti (t-Am) ₂ (DMHD) ₂
Of the liquid raw material formed by dissolving each of them in a THF solvent at a ratio of 0.3 mol / L and a flow rate of Pb / (Zr + Ti).
Flow rate ratio 0.35, Zr / (Zr + Ti) flow rate ratio 0.76
It was introduced into the vaporization chamber 2 by controlling so that

Next, these liquid raw materials were made into a raw material gas in the vaporizing chamber 2 heated to 260 ° C., and this raw material gas was introduced into the CVD apparatus 3 using a carrier gas having a flow rate of 300 sccm. However, until the temperature of the substrate 30 was stabilized, the raw material gas was directly introduced into the exhaust device 4 without being introduced into the CVD device 3.

Next, after the temperature of the substrate 30 is stabilized, C
In the gas mixing chamber 24 of the VD device 3, a source gas and O ₂ gas as an oxidizing gas are mixed, and this gas is showered by a shower head 26.
It was introduced into the reaction chamber 27 via. On the substrate 30, about 2
About 100 nm PZT thin film was formed at a deposition rate of 0 nm / min.

When the composition of the central portion of this PZT thin film was examined, the Pb / (Zr + Ti) composition ratio was 1.15, and Zr /
The (Zr + Ti) composition ratio was 0.45.

When the compositional uniformity of the PZT thin film formed under the condition of the substrate temperature distribution Δ5 ° C. was examined, Pb was ±
0.2%, Zr was ± 0.9%, and Ti was ± 0.5%. Further, the film thickness uniformity of this PZT thin film was ± 0.2%.

When the compositional uniformity of the PZT thin film formed under the condition of the substrate temperature distribution Δ10 ° C. was examined, Pb was ± 0.
5%, Zr was ± 1.8%, and Ti was ± 0.9%.
Further, the film thickness uniformity of this PZT thin film was ± 0.5%.

As in this example, Pb was added to the organometallic raw material.
(DPM) ₂ , Zr (DPM) ₄ and Ti (t-Am)
₂ (DMHD) ₂ was used as a solvent, and the substrate temperature was set to 500 ° C to 600 ° C including the temperature range of the substrate temperature distribution.
By forming the PZT thin film by controlling in the range of ℃,
It is possible to obtain a PZT thin film having excellent composition and film thickness uniformity.

(Method for Forming Ferroelectric Thin Film Other Than PZT Thin Film) In the above-described Examples 1 and 2, Pb (Zr, Ti) O was used as the ferroelectric thin film containing Pb, Zr and Ti as main components.
This is an example in which the present invention is applied to the case where ₃ is formed.
b, La) (Zr, Ti) O ₃ , (Pb, La, Ca)
(Zr, Ti) O ₃ and (Pb, La, Ca, Sr)
The present invention can also be applied to the case of forming a ferroelectric thin film containing Pb, Zr and Ti as main components such as (Zr, Ti) O ₃ .

For example, (Pb, La) (Zr, Ti)
In order to form a thin film of O ₃ , that is, a PLZT film, an organometallic material La (DPM) ₃ ((dipivaloylmethanate) lanthanum) was used as a organometallic raw material of La as a Pb dopant in a solvent of 0.1 mol / mol. A liquid dissolved at a ratio of L is used.

The PLZT thin film is formed by the method shown in the first or second embodiment. At this time, La
Flow rate of the liquid raw material of La / (Pb + La) is 0.
It is controlled so as to be 06 to 0.2.

Similarly, (Pb, La, Ca) (Z
r, Ti) O ₃ or (Pb, La, Ca, Sr) (Z
A thin film of r, Ti) O ₃ can also be formed.

At this time, with Ca and Sr organometallic raw materials
Then, the organometallic material Ca (DPM) ₂((Gipivaloyl
Methanate) calcium) or Sr (DPM)₂((
Pivaloylmethanate) strontium)
A liquid dissolved in a medium is used. The flow rate of these liquid raw materials is
Ca / (Pb + Ca) flow rate ratio 0.1 to 0.3 or
Is a Sr / (Pb + Sr) flow rate ratio of 0.06 to 0.2
To control.

In addition, Pb such as PbTiO ₃ is used.
The present invention can also be applied to the case of forming a ferroelectric film containing Ti and Ti as a main component.

(Nonvolatile Ferroelectric Memory Device) When manufacturing a nonvolatile ferroelectric memory device (FRAM), especially FRA
By applying the ferroelectric film formed by the method described in the above embodiment to the capacitor portion of M, an FRAM having excellent characteristics can be formed.

FIG. 8 is a sectional view showing the structure of the FRAM.

On the surface of the silicon substrate 51, the source diffusion layer 52 and the drain diffusion layer 53 of the memory cell transistor are formed with the channel region sandwiched therebetween. An element isolation film 54 is formed adjacent to the source diffusion layer 52 or the drain diffusion layer 53.

A gate insulating film 56 is formed on the channel region of the silicon substrate 51, and a gate electrode 57 is formed on the gate insulating film 56.

A first interlayer insulating film 58 is formed on the silicon substrate 51 and the gate electrode 57. This first
A bit line 59 is formed on the interlayer insulating film 58. The bit line 59 is electrically connected to the source diffusion layer 52 via the first plug 60 embedded in the first interlayer insulating film 58.

A second interlayer insulating film 61 is formed on the first interlayer insulating film 58 and the bit line 59. A lower electrode 62 made of Ir is formed on the second interlayer insulating film 61.
Are formed. The lower electrode 62 is electrically connected to the drain diffusion layer 53 via the second plug 63 embedded in the first interlayer insulating film 58 and the second interlayer insulating film 61.

A ferroelectric thin film 64 of PZT is formed on the lower electrode 62, and I is formed on the ferroelectric thin film 64.
An upper electrode 65 made of r is formed. Lower electrode 6
2. The ferroelectric thin film 64 and the upper electrode 65 form a ferroelectric capacitor.

9 to 13 are sectional views showing the method of manufacturing the FRAM in the order of steps. 9 to 13, the same parts as those in FIG. 8 are designated by the same reference numerals.

First, as shown in FIG. 9A, the element isolation film 54 is formed on the silicon substrate 51 by the shallow trench method.

Next, as shown in FIG. 9B, a gate insulating film 56 is formed on the silicon substrate 51 by the CVD method. After that, the gate electrode 57 is formed on the gate insulating film 56 by the sputtering method and the photolithography technique.

Next, as shown in FIG. 9C, the source diffusion layer 52 and the drain diffusion layer which become the source / drain of the memory cell transistor are formed by introducing impurities into the surface of the silicon substrate 51 using the gate electrode 57 as a mask. 53 is formed.

Next, as shown in FIG. 10A, CVD
A first interlayer insulating film 58 made of a silicon oxide film is formed on the silicon substrate 51 and the gate electrode 57 by the method.
After that, a chemical mechanical polishing method (CMP: Chemical Mecha
The surface of the first interlayer insulating film 58 is planarized by the nical polishing method).

Next, as shown in FIG. 10B, a first contact hole 66 reaching the source diffusion layer 52 from the surface of the first interlayer insulating film 58 is formed by the photolithography technique and the etching technique.

Next, as shown in FIG. 10C, a W film is formed on the first interlayer insulating film 58 by the sputtering method,
Thereafter, the W film is polished by the CMP method until it reaches the surface of the first interlayer insulating film 58, and the first contact hole 66 is formed.
A first plug 60 is formed inside.

Next, as shown in FIG. 11A, a W film is formed on the first interlayer insulating film 58 by the sputtering method,
After that, the W film is patterned by the photolithography technique and the etching technique to form the bit line 59.
The bit line 59 is electrically connected to the source diffusion layer 52 via the first plug 60.

Next, as shown in FIG. 11B, CVD
A second interlayer insulating film 61 made of a silicon oxide film is formed on the first interlayer insulating film 58 and the bit line 59 by the method.

Next, as shown in FIG. 11C, a second contact hole 67 reaching the drain diffusion layer 53 from the surface of the second interlayer insulating film 61 is formed by the photolithography technique and the etching technique.

Next, as shown in FIG. 12A, a W film is formed on the second interlayer insulating film 61 by the sputtering method,
Then, the W film is polished by the CMP method until it reaches the surface of the second interlayer insulating film 61, and the second contact hole 67 is formed.
A second plug 63 is formed inside.

Next, as shown in FIG. 12B, the first Ir film 6 is formed on the second interlayer insulating film 61 by the sputtering method.
2a is formed. The first Ir film 62 a is electrically connected to the drain diffusion layer 53 via the second plug 63.

Next, as shown in FIG. 12C, the MOC
The PZT film 64a is formed on the first Ir film 62a by the VD method.
To form. At this time, Pb (DP
M) ₂ , Zr (DMHD) ₄ and Ti (iPrO)
₂ (DPM) ₂ is used to form the PZT film 64a by applying the method for forming a ferroelectric film of the present invention.

Next, as shown in FIG. 13A, a second Ir film 65a is formed on the PZT film 64a by the sputtering method.

Next, as shown in FIG. 13B, the first I
The r film 62a, the PZT film 64a, and the second Ir film 65a are patterned to form the lower electrode 62, the ferroelectric thin film 64, and the upper electrode 65, respectively. In this way, a ferroelectric capacitor including the lower electrode 62, the ferroelectric thin film 64 and the upper electrode 65 is formed. In this way
FRAM is completed.

When the lower electrode is made of Pt, a barrier metal made of Ir is formed on the second interlayer insulating film, and an adhesion layer made of IrO _x is formed thereon. A lower electrode is formed on this adhesion layer. The upper electrode may be formed of Pt or IrO _x instead of Ir.

(Supplementary Note 1) Organic metal raw material Ti (t-Am)
₂ (DMHD) ₂ is used to form a ferroelectric film containing Pb and Ti as main components or a ferroelectric film containing Pb, Zr and Ti as main components. Method.

(Supplementary Note 2) Organic metal raw material Ti (s-Am)
₂ (DMHD) ₂ is used to form a ferroelectric film containing Pb and Ti as main components or a ferroelectric film containing Pb, Zr and Ti as main components. Method.

(Supplementary Note 3) In the method for forming a ferroelectric film, the ferroelectric film containing Pb, Zr, and Ti as a main component is formed on a semiconductor circuit substrate by a metal organic chemical vapor deposition method. The method includes heating a circuit board in a CVD reaction chamber, and introducing an organometallic source gas and an oxidizing gas into the CVD reaction chamber to form a ferroelectric film on the semiconductor circuit board. As a raw material, Pb (DP
M) ₂ , Zr (DPM) ₄ and Ti (t-Am) ₂ (D
Using a liquid raw material formed by dissolving MHD) ₂ in a solvent,
A method of forming a ferroelectric film, characterized in that the semiconductor circuit substrate is maintained at a temperature of 500 to 600 ° C.

(Supplementary Note 4) The method for forming a ferroelectric film according to Supplementary Note 3, wherein the temperature variation of the semiconductor circuit substrate during film formation is controlled to 17 ° C. or less.

(Supplementary Note 5) The method for forming a ferroelectric film according to Supplementary Note 3, wherein the temperature variation of the semiconductor circuit substrate during film formation is controlled to 6 ° C. or less.

(Appendix 6) Organometallization on a semiconductor circuit board
Using Pb, Zr and Ti as the main components using the vapor deposition method
Forming a ferroelectric film in a method of forming a ferroelectric film
And heating the semiconductor circuit board in a CVD reaction chamber
And a metalorganic source gas and an oxidizing gas to the CVD reaction chamber
To form a ferroelectric film on the semiconductor circuit substrate.
Pb (DP
M)₂, Zr (DMHD) _FourAnd Ti (s-Am)
₂(DMHD)₂The liquid raw material formed by dissolving
Using the semiconductor circuit board at a temperature of 450 to 550 ° C.
A method for forming a ferroelectric film, characterized in that

(Supplementary Note 7) The method for forming a ferroelectric film according to Supplementary Note 6, wherein the variation in the temperature of the semiconductor circuit substrate during film formation is controlled to 20 ° C. or less.

(Supplementary Note 8) The method for forming a ferroelectric film according to Supplementary Note 6, wherein the variation in temperature of the semiconductor circuit substrate during film formation is controlled to 6.5 ° C. or less.

(Supplementary Note 9) Oxygen gas as the oxidizing gas,
9. The method for forming a ferroelectric film according to any one of appendices 1 to 8, wherein a mixed gas of oxygen gas and dinitrogen monoxide gas or a mixed gas of oxygen gas and nitrogen gas is used.

(Supplementary Note 10) Pb (Zr, Ti) O ₃ , as the ferroelectric film containing Pb, Zr and Ti as main components,
(Pb, La) (Zr, Ti) O ₃ , (Pb, La, C
a) (Zr, Ti) O ₃ or (Pb, La, Ca, S
10. The method for forming a ferroelectric film as described in any one of appendices 1 to 9, characterized in that r) (Zr, Ti) O ₃ is formed.

(Supplementary Note 11) The method for forming a ferroelectric film according to any one of Supplementary Notes 1 to 11, wherein the ferroelectric film is formed as a capacitor portion of a nonvolatile ferroelectric memory.

[0120]

As described above, according to the method of forming a ferroelectric film of the present invention, Pb (DPM) ₂ , Zr (DP
M) ₄ and Ti (t-Am) ₂ (DMHD) ₂ are each dissolved in a solvent, and a combination of organometallic raw materials is used, and a temperature of 500 ° C. to 600 ° C. is a supply rate controlling region common to these organometallic raw materials. Hold the substrate with
If the amount of raw material supplied is constant, a ferroelectric film having a uniform composition and film thickness can be formed. As a result, MOCVD
The method can provide a method for forming a ferroelectric film, which can form a ferroelectric film having a uniform composition and film thickness.

According to another method for forming a ferroelectric film of the present invention, Pb (DPM) ₂ , Zr (DMHD) ₄ and Ti (s-Am) ₂ (DMHD) ₂ are dissolved in a solvent. Using the combination of the formed organometallic raw materials, 450 ° C., which is a supply rate-controlling region common to these organometallic raw materials
Since the substrate is held at a temperature of 550 ° C. to 550 ° C., it is possible to form a ferroelectric film having a uniform composition and a uniform film thickness if the amount of raw material supplied is constant. As a result, by the MOCVD method,
It is possible to provide a method for forming a ferroelectric film that can form a ferroelectric film having a uniform composition and film thickness.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a deposition rate and a substrate temperature when a thin film is formed by a CVD method.

FIG. 2 is a diagram showing a result of examining a relationship between a deposition rate of a liquid source using Pb (DPM) ₂ and a substrate temperature.

FIG. 3 shows Zr (DPM) ₄ and Zr (DMH).
It is a figure showing the result of having investigated the relation between the deposition rate and the substrate temperature by the liquid source which used D) ₄ .

FIG. 4 shows the results of examining the relationship between the deposition rate of a liquid source using Ti (t-Am) ₂ (DMHD) ₂ and Ti (s-Am) ₂ (DMHD) ₂ and the substrate temperature. It is the figure shown.

FIG. 5 shows Pb (DPM) ₂ and Zr (DMHD).
FIG. 4 is a diagram showing the results of examining the relationship between the deposition rate and the substrate temperature for combinations of liquid raw materials of ₄ and Ti (s-Am) ₂ (DMHD) ₂ .

FIG. 6 shows Pb (DPM) ₂ and Zr (DPM) ₄
FIG. 5 is a diagram showing a result of examining a relationship between a deposition rate and a substrate temperature by combining liquid raw materials of Ti and (Ti-Am) ₂ (DMHD) ₂ .

FIG. 7 is a schematic view showing an example of a PZT thin film forming apparatus.

FIG. 8 is a sectional view showing a structure of an FRAM.

FIG. 9 is a cross-sectional view (1) showing the method of manufacturing the FRAM in the order of steps.

FIG. 10 is a sectional view (No. 2) showing the method of manufacturing the FRAM in the order of steps.

FIG. 11 is a cross-sectional view (3) showing the method of manufacturing the FRAM in the order of steps.

FIG. 12 is a cross-sectional view (4) showing the method of manufacturing the FRAM in the order of steps.

FIG. 13 is a cross-sectional view (5) showing the method of manufacturing the FRAM in the order of steps.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Raw material supply part, 2 ... Vaporization chamber, 3 ... CVD apparatus, 4 ... Exhaust device, 5, 6, 7, 8 ... Raw material tank, 9, 10, 11, 12 ... Liquid mass flow meter, 13, 14, 15, 16, 17, 18, 19, 20, 2
2, 25, 31 ... Piping, 21, 23 ... Valve, 24 ... Gas mixing chamber, 26 ... Shower head, 27 ... Reaction chamber, 28 ... Heating part, 29 ... Susceptor, 30 ... Substrate, 51 ... Silicon substrate, 52 ... Source diffusion layer, 53 ... Drain diffusion layer, 54 ... Element isolation film, 56 ... Gate insulating film, 57 ... Gate electrode, 58 ... First interlayer insulating film, 59 ... Bit line, 60 ... First plug, 61 ... Second interlayer insulating film, 62 ... Lower electrode, 62a ... First Ir film, 63 ... Second plug, 64 ... Ferroelectric thin film, 64a ... PZT film, 65 ... Upper electrode, 65a ... Second Ir Film, 66 ... First contact hole, 67 ... Second contact hole.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Wataru Nakamura             4-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 1 within Fujitsu Limited (72) Inventor Kenji Maruyama             4-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa             No. 1 within Fujitsu Limited F term (reference) 5F058 BA11 BA20 BC03 BC20 BF06                       BF27 BF29                 5F083 FR02 JA15 JA38 JA43 MA06                       MA17 NA01 NA08 PR21 PR40

Claims (6)

[Claims] 1. An organometallic material Ti (t-Am) ₂ (DM
HD) ₂ is used to form a ferroelectric film containing Pb and Ti as main components, or a ferroelectric film containing Pb, Zr and Ti as main components, and forming a ferroelectric film. 2. An organometallic material Ti (s-Am) ₂ (DM
HD) ₂ is used to form a ferroelectric film containing Pb and Ti as main components, or a ferroelectric film containing Pb, Zr and Ti as main components, and forming a ferroelectric film. 3. A method for forming a ferroelectric film, which comprises forming a ferroelectric film containing Pb, Zr, and Ti as a main component on a semiconductor circuit substrate by using a metal organic chemical vapor deposition method. In a CVD reaction chamber, and a step of introducing an organometallic raw material gas and an oxidizing gas into the CVD reaction chamber to form a ferroelectric film on the semiconductor circuit substrate. Pb (DPM) ₂ , Zr (DP
M) ₄ and Ti (t-Am) ₂ (DMHD) ₂ dissolved in a solvent are used as a liquid raw material, and the semiconductor circuit substrate is kept at a temperature of 500 to 600 ° C. Forming method. 4. The method for forming a ferroelectric film according to claim 3, wherein variation in temperature of the semiconductor circuit substrate during film formation is controlled to 17 ° C. or less. 5. A method for forming a ferroelectric film, which comprises forming a ferroelectric film containing Pb, Zr, and Ti as a main component on a semiconductor circuit substrate by using a metal organic chemical vapor deposition method. In a CVD reaction chamber, and a step of introducing an organometallic raw material gas and an oxidizing gas into the CVD reaction chamber to form a ferroelectric film on the semiconductor circuit substrate. Pb (DPM) ₂ , Zr (DM
A ferroelectric film, characterized in that a liquid raw material formed by dissolving HD) ₄ and Ti (s-Am) ₂ (DMHD) ₂ in a solvent is used to hold the semiconductor circuit substrate at a temperature of 450 to 550 ° C. Forming method. 6. The method for forming a ferroelectric film according to claim 5, wherein variation in temperature of the semiconductor circuit substrate during film formation is controlled to 20 ° C. or less.