JP2003324070A - Method and device of manufacturing thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a high-grade thin film by an atomic layer deposition method under atmospheric pressure without using an expensive device such as a vacuum device or a valve and complicated processes. <P>SOLUTION: A method of manufacturing a thin film includes a process of forming a region 3 comprising a first raw material gas atmosphere, a region 4 comprising a second raw material gas atmosphere and a region 5 dividing an area between the two regions and comprising a purge gas atmosphere in a film forming reaction part 1; and a process of manufacturing a thin film by alternately supplying each raw material gas onto a base material across the region 5 of the purge gas atmosphere while moving the base material 10 to each region in the film forming reaction part 1. A thin film manufacturing device includes a base material support 11, a base material moving means, a gas supplying means A of the raw material gas containing a metal halide, a gas supplying means B of the raw material gas containing oxygen and a purging means C supplying a purge gas. <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 thin film manufacturing method and a thin film manufacturing apparatus by an atomic layer deposition method under atmospheric pressure.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductors and the like, very high demands have been made on device performance and manufacturing technology, and controllability at the atomic layer level is desired for thin film production. The atomic layer deposition method is a thin film growth method that utilizes the property of a self-stopping mechanism in which the growth is saturated in a monoatomic layer with respect to one supply of raw material. Instead of supplying all the raw materials at the same time as in the normal thin film manufacturing method, different raw material gases are alternately supplied corresponding to the atomic layers, so that the reaction of the raw material gases on the work (base material) is simple. Control at the molecular layer level,
The feature is that each layer is grown. Therefore,
The substance and film thickness can be controlled with atomic layer accuracy. Further, the film thickness is uniform on the entire surface of the substrate, and it is possible to grow the film uniformly along the irregularities on the surface. Among them, the atomic layer epitaxy method is a method of epitaxially growing a thin film on a base material, and since a higher quality single crystal thin film can be produced, research and practical application have been widely promoted in recent years.

However, since the conventional atomic layer deposition method is carried out under a reduced pressure or high vacuum atmosphere as shown in, for example, Japanese Patent Laid-Open Nos. 5-234899 and 5-29219, an expensive and large-scale vacuum system is used. Equipment was required and was not suitable for industrial production. Further, when an oxide thin film is produced, since it is a process under reduced pressure, oxygen defects are likely to occur, which has been a factor of deteriorating the quality of the thin film. Furthermore, since H ₂ 0 and 0 ₃ are used as oxygen raw materials, there have been problems with the film quality such as the problem of smoothness due to promotion of three-dimensional growth and the incorporation of OH groups in the film.

Further, in the atomic layer deposition method, the feed material must be switched every time one atomic layer is deposited. However, as shown in, for example, Japanese Patent Laid-Open Nos. 5-234899 and 5-190455, this feed material is conventionally used. Is switched by switching the valve installed in the feed route of each raw material. However, this method has a problem that not only the apparatus becomes complicated, but also it takes time to switch the gas, so that the production efficiency becomes low.

As another method, a method of spatially shielding different source gases with a barrier gas is used. This method has the advantage of high productivity because it does not require gas switching time.
With only the barrier gas, there is a problem that different raw material gases are mixed and the film quality is deteriorated. Therefore, Japanese Patent Publication Sho-48-331
50 proposes a method of providing an isolation chamber for purification, and Japanese Patent Laid-Open No. 5-270997 proposes a method of combining gas switching and barrier gas techniques. However, in these methods, the apparatus and the process are complicated, and in the method of spatially shielding different raw material gases only with a barrier gas, there is a problem that different raw material gases are mixed and contained to deteriorate the film quality.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the inventors of the present invention have realized a high-quality atomic layer deposition method under atmospheric pressure without using expensive equipment such as vacuum equipment and valves and complicated steps. We have made extensive studies to develop a method for producing a thin film. As a result, the present inventors provided a purge gas supply unit between different raw material gas supply units and arranged them alternately, and further, the outer peripheral portion of the base material support was projected from the base material upper surface, It has been found that such a problem can be solved by generating a convection region of the source gas or the purge gas on the material. The present invention has been completed from this point of view.

[0007]

That is, according to the present invention, in a method for producing a thin film by an atomic layer deposition method under atmospheric pressure, a region consisting of a first source gas atmosphere and a region consisting of a second source gas atmosphere are provided. A step of forming a purge gas atmosphere region dividing the two regions in a film forming reaction section, and separating the purge gas atmosphere area while moving the substrate to each area in the film forming reaction section. And a step of alternately supplying each raw material gas onto the base material to form a thin film, the present invention provides a method for producing a thin film. As the first source gas atmosphere, for example, a source gas atmosphere containing a vaporized metal halide is suitable. Further, as the second source gas atmosphere, for example, a source gas atmosphere containing oxygen is preferably cited, and in addition, ammonia is used.
Examples include a source gas atmosphere containing (NH ₃ ). Here, "alternately supplying" means, for example, that the metal halide is first supplied in the source gas atmosphere region containing the metal halide, and then the purge bath is supplied in the purge gas atmosphere region, and then the source gas containing oxygen is supplied. After moving to the atmosphere region and being supplied with oxygen, it is shown that the metal halide is supplied in the source gas atmosphere region containing the metal halide through the purge gas atmosphere region. According to this method, it is possible to form a thin film at the atomic layer level controlled by the self-stopping mechanism. Further, since gas switching is not required, the process can be simplified and the production efficiency is high. Further, since the raw material gas is not mixed on the base material, a good quality thin film can be produced.

In the step of producing the thin film, it is preferable to form a region where the supplied gas convects on the substrate. For example, there is a mode in which the source gas and the purge gas are supplied in a direction substantially perpendicular to the surface of the base material so that the supplied gas is convected on the base material. According to this aspect, by supplying the gas vertically, uniform convection can be formed over the entire surface of the substrate, so that a homogeneous thin film can be produced over a wide range. In the step of producing the thin film, the base material can be gradually moved into each of the regions. The term "stepwise" as used herein means that the base material is allowed to remain in each region for a certain period of time and then moves in a stepwise manner. The time is arbitrarily determined depending on the manufacturing conditions. In each region, a monoatomic layer can be generated in each region by allowing it to exist for 0.1 seconds or more. Further, the present invention can further include a step of providing a buffer layer on the base material in a stage before the step of producing the thin film.

Further, the present invention is an apparatus for producing a thin film using an atomic layer deposition method under atmospheric pressure, comprising a base material support base and a base material for moving the base material support base in a film forming reaction section. A moving means, a gas supply means for supplying a source gas containing a vaporized metal halide to the film formation reaction section, a gas supply means for supplying a source gas containing oxygen to the film formation reaction section, and the two gas supplies A thin film manufacturing apparatus comprising: a purifying unit that is provided between the units and that supplies a purging gas to a film forming reaction unit. As a result, it is possible to form an atomic layer level thin film controlled by the self-stopping mechanism by a simple and inexpensive device that does not have an expensive vacuum device or gas supply valve.

Here, it is preferable that the base support has a shape in which the supplied gas convects on the base. For example, there is a mode in which the outer peripheral portion of the base support is formed so as to protrude from the top surface of the base so that the supplied gas convects on the base. According to this aspect, it is possible to easily form the high-quality convection region of the raw material gas without mixing the raw material gases on the base material. Further, there may be mentioned a mode in which the gas supply means and the purification means supply the source gas and the purge gas in a substantially vertical direction with respect to the base material so that the supplied gas convects on the base material.

Furthermore, the present invention provides a thin film produced by any one of the above-described thin film production methods or thin film production apparatuses. In the present invention, a metal oxide thin film formed by thin film atomic layer epitaxy by an atomic layer deposition method under atmospheric pressure without using an expensive device such as a vacuum device or a valve and a complicated process is used. It is possible to grow each. Hereinafter, embodiments of the present invention will be described in detail.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the thin film manufacturing method of the present invention, a region consisting of a purge gas atmosphere that divides both regions is formed in the film formation reaction section between two regions of the source gas atmosphere. Here, the purge gas serves to remove the raw material deposited in excess of one atomic layer on the base material after the raw material gas is supplied. Further, since different raw material gas supply units are continuously present, a purge gas supply unit is provided between them to also serve as a barrier gas that suppresses mixing of different raw material gases. As the source gas, one first source gas is a source gas containing a vaporized metal halide or the like, and the other second source gas is a source gas containing oxygen or ammonia. Here, as the metal halide,
For example, zinc chloride (ZnCl ₂ ) and the like can be mentioned.

In the step of forming a thin film according to the present invention, each gas is alternately supplied onto the base material while moving the base material to each of the above-mentioned regions in the film formation reaction section. At this time, due to the existence of the convection region, it is possible to uniformly promote the growth of the film in a wide range when the source gas is supplied, and it is possible to efficiently purify the excessive deposit even when the purge gas is supplied. Therefore, thin film growth accompanied by a self-stopping mechanism under atmospheric pressure can be realized with simple equipment. At this time, the length t of the outer peripheral portion of the base material support protruding from the top surface of the base material is 0.
It is desirable that t <0.5 l. l indicates the length of the portion of the base material supporting portion on which the base material is placed.

In the present invention, the gas supply amount, growth temperature,
By controlling the film formation processing time, it is possible to easily perform the growth of each monomolecular layer accompanied by the self-stopping mechanism under a wide range of film formation conditions. It is preferable to supply each gas in the direction perpendicular to the substrate. As a result, efficient convection can be generated over the entire surface of the base material, and a thin film of excellent quality can be manufactured. It is preferable that the substrate for epitaxial growth has the same crystal structure as the target thin film material and a lattice constant close to it, but a buffer layer for relaxing the degree of lattice mismatch is formed on the substrate before film formation. By providing it, an epitaxial thin film having good crystallinity can be manufactured. The base material moves in the source gas and purge gas supply section while being heated and kept at a constant temperature. In each case, the substrate is held in each gas supply unit for a certain period of time as film formation processing time.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. For example, the movement of the base material may be continuous movement in one direction including the rotation direction in addition to the reciprocating movement as in the embodiment. Although nitrogen gas was used as the carrier gas and the purge gas, an inert gas such as argon or helium can also be used.

[0016]

The EXAMPLES apparatus shown in Embodiment 1 FIGS. 1 and 2, as raw materials ZnC1 ₂ and oxygen gas, to produce a ZnO thin film on a sapphire (0001) substrate 10 of 10 mm × 10 mm. In FIG. 1, the film formation reaction section 1 of the present apparatus is composed of a horizontal quartz reaction tube, and the growth temperature is maintained by an electric furnace 2 surrounding the film formation reaction section. Here, the film formation reaction section is mainly composed of two regions, a first atomic layer forming unit 3 (a region of the first source gas atmosphere) and a second atomic layer forming unit 4 (a region of the second source gas atmosphere). Between the two areas, the purge gas supply unit 5 (the area of the purge gas atmosphere)
Exists and separates each area. As shown in FIG. 2, the shape of the base material support base was such that the outer peripheral portion of the base material support base was projected from the upper surface of the base material to a length t = 1 mm. When gas is supplied to the base material in this state, convection 21 occurs on the base material, so that a convection region 22 is formed on the base material.

[0017] one consisting ZnC1 ₂ of the raw material is placed on the raw material boat 6 in the raw material supply unit, held in a predetermined material temperature (673 K) by the electric heater, it is gasified. The ZnC1 ₂ gas is blown onto the base material from the first raw material gas supply port A (first raw material gas supply means) using nitrogen gas as a carrier gas to form a Zn atomic layer in the first atomic layer forming portion. This is the first step. As a second step, nitrogen gas is blown from the purge gas supply port C (purification means for purging gas supply) to the base material that has moved to the purge gas supply unit, thereby removing the Zn raw material excessively deposited from one atomic layer.
Next, as a third step, another source of oxygen gas and nitrogen gas is supplied from the source gas supply port B (second source gas supply means) to the base material that has moved to the second atomic layer forming portion. Form an oxygen (O) atomic layer. At this time, the nitrogen gas serves as a diluent gas for adjusting the oxygen concentration, and the nitrogen gas in this case may not be used depending on the film forming conditions. Finally, as the fourth step, nitrogen gas is blown to the base material that has moved to the purge gas supply unit again to remove the 0 raw material that has accumulated in excess of one atomic layer. By performing the steps from the first step to the fourth step, one molecular layer of ZnO is formed and
Cycle. The movement of the base material to each step is performed by controlling the movement of the base material support base 11. Example 1
Table 1 shows the film forming conditions in. The gas supply nozzle used had a diameter of 6 mm or 8 mm.

[0018]

[Table 1]

The raw material gas and the purge gas are always supplied, and the exhaust gas is discharged from the exhaust port. Further, the total pressure in the device is kept at atmospheric pressure. FIG. 3 shows the X-ray diffraction result of the thin film produced by 200 cycles. Only the diffraction peak of the hexagonal ZnO (0002) plane was observed near 344 degrees, which indicated that the ZnO thin film was epitaxially grown on the sapphire (0001) substrate. FIG. 4 shows the relationship between the number of cycles and the film thickness of the ZnO thin film produced. It was found that the film thickness increased in proportion to the number of cycles. At this time, the growth film thickness per cycle was 0.256 nm from the inclination of the graph. Here, the lattice constant of hexagonal ZnO is
c = 0.520661 nm, and the grown film thickness per cycle was almost in agreement with the value of 1/2 of the lattice constant c (c / 2 = 0.26). Therefore,
A ZnO thin film is formed for each molecular layer under the control of a self-stopping mechanism.

Example 2 A ZnO thin film was produced by changing the growth temperature using the apparatus shown in FIGS. Table 2 shows film forming conditions. Figure
Figure 5 shows the relationship between the growth temperature and the growth film thickness for each cycle.
It can be seen that the ZnO thin film grows in each molecular layer by the self-terminating mechanism in the growth temperature range of 723K to 823K.

[0021]

[Table 2]

Reference Example 1 A ZnO thin film was prepared by changing the length t in which the outer peripheral portion of the base material support was projected from the top surface of the base material as compared with Example 1. The film forming conditions were the same as in Table 1. Table 3 shows the result of the area ratio of the thin film growth region to the upper surface of the base material of the thin film prepared in Comparative Example and the growth state of the thin film.

[0023]

[Table 3]

When t.ltoreq.0 as shown in FIG. 6, there is no convection and the reaction of the gas supplied onto the substrate is not sufficiently carried out. As a result, the growth area of the thin film was small, atomic layer deposition was insufficient, and the crystallinity of the thin film tended to decrease. On the other hand, when 0 <t, the growth area of the thin film was increased and the quality of the thin film was also improved. On the other hand, when t was further increased, the gas exchange on the substrate could not be performed smoothly, so the atomic layer deposition became insufficient, the surface roughness of the thin film increased, and the crystallinity decreased. From these results, in order to perform uniform atomic layer deposition on the base material, the length t at which the outer peripheral portion of the base material support protrudes from the top surface of the base material.
Was found to be optimal within the range of 0 <t ≦ 0.5l.

[0025]

According to the present invention, it is possible to provide a method for producing a high-quality thin film by an atomic layer deposition method under atmospheric pressure without using expensive equipment such as vacuum equipment and valves and complicated steps. That is, according to the present invention, it is possible to perform atomic layer level thin film formation controlled by the self-stopping mechanism by a simple and inexpensive device having neither an expensive vacuum device nor a gas supply valve. Further, since gas switching is not required, the process can be simplified and the production efficiency is high. further,
Since the raw material gas is not mixed on the base material, a good quality thin film can be produced.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for producing a thin film according to the present invention.

FIG. 2 is an enlarged view of a main part of a substrate supporting portion of a thin film manufacturing apparatus according to the present invention.

FIG. 3 is a graph showing typical X-ray diffraction results of the ZnO thin film produced in Example 1.

FIG. 4 is a graph showing the relationship between the number of cycles and the film thickness of the ZnO thin film produced in Example 1.

FIG. 5 shows the relationship between the growth temperature of the ZnO thin film prepared in Example 2 and the growth film thickness of each cycle.

FIG. 6 is an enlarged view of a main part of a substrate supporting portion used in a reference example.

[Explanation of symbols]

1: Film formation reaction part 2: Electric furnace 3: First atomic layer formation part (first source gas atmosphere region) 4: Second atomic layer formation part (second source gas atmosphere region) 5: Purge gas supply part ( Purge gas atmosphere area) 6: Raw material boat 7: Exhaust port 10: Substrate 11: Substrate support 21: Convection of gas 22: Convection area on the substrate A: First raw material gas supply port (first raw material gas supply) Means) B: Second raw material gas supply b (second raw material gas supply means) C: Purge gas supply b (purification means) l: Base material supporting portion length t: Outer peripheral portion of base material supporting base protrudes from base material upper surface Length

Continued front page    F-term (reference) 4K029 BA18 BA49 CA02 DA06 DB05                       EA04 JA00                 4K030 AA03 AA14 BA21 BA47 EA03                       FA10 GA04 KA02                 5F045 AA15 AB22 AC03 AC11 AF09                       BB14 BB17 EC01 EE01 EF15                       EM01

Claims (10)

[Claims] 1. A method of manufacturing a thin film by an atomic layer deposition method under atmospheric pressure, comprising a region consisting of a first source gas atmosphere, a region consisting of a second source gas atmosphere, and dividing the two regions. A step of forming a purge gas atmosphere region in the film formation reaction section, and moving the base material to each area in the film formation reaction section while separating the purge gas atmosphere area on the base material. And a step of producing a thin film by alternately supplying gas. 2. The method for producing a thin film according to claim 1, wherein in the step of producing the thin film, a region where the supplied gas convects is formed on the substrate. 3. The thin film according to claim 2, wherein the source gas and the purge gas are supplied in a direction substantially perpendicular to the surface of the base material so that the supplied gas convects on the base material. Production method. 4. The method for producing a thin film according to claim 1, wherein in the step of producing the thin film, the base material is moved stepwise within each of the regions. 5. The method for producing a thin film according to claim 1, further comprising a step of providing a buffer layer on the base material before the step of producing the thin film. 6. An apparatus for producing a thin film using an atomic layer deposition method under atmospheric pressure, comprising a base material support base and a base material moving means for moving the base material support base in a film forming reaction section. Between the gas supply means for supplying the source gas containing the vaporized metal halide to the film formation reaction section, the gas supply means for supplying the source gas containing oxygen to the film formation reaction section, and the two gas supply means An apparatus for producing a thin film, comprising: a purifying unit that is provided and that supplies a purge gas to a film forming reaction unit. 7. The base material support base has a shape in which a supplied gas is convected on the base material.
The thin film manufacturing apparatus described. 8. The base material support base has a shape in which an outer peripheral portion of the base material support base is projected from an upper surface of the base material so that the supplied gas is convected on the base material. 6. The thin film manufacturing apparatus according to 6. 9. The gas supply unit and the purifying unit supply the source gas and the purge gas in a substantially vertical direction with respect to the base material so that the supplied gas is convected on the base material. The thin film manufacturing apparatus according to any one of claims 6 to 8. 10. A thin film manufactured by the manufacturing method according to claim 1.