JPH06220633A - Deposited thin film forming device - Google Patents

Abstract

PURPOSE:To widen the forming range of a uniform film thickness in a thin film forming device. CONSTITUTION:In a deposited thin film forming device where a heated substrate is disposed in an active gas atmosphere, and a beam-like material to be deposited is jetted from the target irradiated with an excimer laser, and the thin film of a superconductive metallic compds., etc., is formed on the substrate, the targets 11A-11C consisting of the same material as a target supporting member 12 are holded respectively to the target supporting member so that each vertical line on the surface of the targets 11A-11C at the central position of an electromagnetic wave beam may be passed the different positions on the surface of the substrate, and a target holder 12 is rotated through a controlling means, the targets 11A-11C are controlled to move in turn to the irradiation position of the electromagnetic wave beam so that the beam of the material to be deposited may be faced to the wide range on the substrate and an uniform thin film may be formed in a wide range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor deposition thin film production apparatus, and more particularly to a vapor deposition thin film production apparatus employing a vapor deposition method generally known as a laser vapor deposition method.

[0002]

2. Description of the Related Art Superconducting metal compound thin films having a superconducting transition temperature (Tc) of 80 K or higher are known. The raw material of such a thin film is, for example, a rare earth element such as yttrium, an alkaline earth metal such as barium, and an oxide of Cu that is a transition metal, and these are formed into a thin film material through sintering or the like. Thin film manufacturing methods include reactive vapor deposition and reactive M
BE method and reactive sputtering method are known.
In these methods, conventionally, a method of forming a desired superconducting phase by performing heat treatment after depositing a thin film has been adopted, but a good film shape has not been obtained.

For this reason, recently, by sufficiently supplying an oxidizing source and heating the substrate when forming a thin film,
A method of forming a desired superconducting phase without performing heat treatment after forming a thin film has been adopted. In the case of adopting such a method, the laser vapor deposition method, which allows the atmosphere around the substrate to be relatively freely selected, is theoretically advantageous, and in particular, research has been advanced in recent years. This advantage is applicable not only to the formation of the superconducting oxide thin film, but also to the metal element and the low boiling point element (N,
P, O, S, Se, Te, F, Cl, Br, I, etc.) is also useful for forming thin films of ceramics, chalcogenides, and other oxides. Being tried. According to the laser deposition method,
In particular, under a condition called laser ablation, by irradiating the target with a laser pulse having a large energy density, it is possible to form a thin film having an extremely close composition to the target composition.

The conventional laser vapor deposition method is disclosed in, for example, Japanese Patent Laid-Open No.
-17685, "Applied Physics Letters" (
Volume 51 No. 11 pages 861-863). With reference to FIG. 8, a conventional vapor deposition thin film production apparatus adopting a laser vapor deposition method will be described by taking the method for producing a metal oxide superconducting material layer described in the above publication as an example.

In FIG. 8, in a vacuum chamber 21, substrates 23 and 2 supported by substrate holders 22 and 22 ', respectively.
One of 3'and the target 25 held by the target holder 24 are arranged to face each other with an extremely short distance of about 20 to 45 mm, and the target 25 is located outside the vacuum chamber 21. A laser beam 26 forming an ultraviolet ray is emitted from an excimer laser irradiating device (not shown) to the surface from an angle of about 45 degrees.
The surface of the target 25 is heated by this laser beam 26, and the particles on the surface are ejected as a beam 27 by evaporation (ablation), and are deposited on the surface of the substrate 23 arranged facing the target 25.

The target 25 is a target holder 24.
It is considered that the target surface becomes uniform by being rotated through the rotation of No. 1 and that the laser irradiation position is changed so that the evaporation from the surface of the target 25 also becomes uniform if necessary. Oxygen gas is supplied into the vacuum chamber 21 to form an oxide, and the substrates 23 and 23 'are heated to a temperature of, for example, several hundreds of degrees to accelerate oxidation.

[0007]

[Problems to be Solved by the Invention]

In the above vapor deposition thin film forming apparatus, it is desired to form a thin film having a uniform film thickness in the widest possible range. However, since the distance between the target and the substrate is extremely short as described above. However, there is a problem that the forming range of the thin film is extremely narrow. Therefore, the laser deposition method
Though considered to be an advantageous method in principle, in reality,
It is hard to say that it is still in practical use.

As a method for solving the above problems, it has been attempted to form a film over a wide range by rotating the substrate on its own axis. In this case, however, there is a limit to increase the area, and in addition, the substrate It is difficult to adopt the method of rotating while heating because the equipment becomes complicated and the cost increases. Alternatively, if an attempt is made to obtain a uniform film over a wide range by widening the distance between the target and the substrate, the compound composition will change before the target evaporates and reaches the substrate surface. However, there arises a problem that a desired composition cannot be obtained in the formed thin film.

The present invention has improved the vapor deposition thin film production apparatus adopting the above-mentioned conventional laser vapor deposition method, thereby suppressing the increase in cost as low as possible and depositing a thin film having a uniform thickness over a wide range. An object is to provide a possible improved thin film deposition apparatus.

[0011]

In order to achieve the above object, a vapor deposition thin film production apparatus of the present invention comprises a substrate supporting member for supporting a substrate and a target supporting member for holding a target facing the substrate. In the vapor deposition thin film production apparatus for depositing a thin film on the substrate, the target supporting member, comprising: a member, an irradiating unit for irradiating the surface of the target with an electromagnetic wave beam having an extremely short pulse, and a control unit. Is capable of holding a plurality of the targets, the control means controls at least the target support member so that each of the held targets are sequentially irradiated to the electromagnetic beam, the target support member, Perpendicular lines on the surface of the target at the center positions of the electromagnetic waves irradiated to the respective targets are different from each other on the surface of the substrate. It characterized in that for holding the respective target to pass through the location.

The inventor of the present invention has created the present invention by paying attention to the fact that, in the laser vapor deposition method, beam-like vaporized substances having a narrow divergence angle are emitted substantially perpendicularly to the surface of the target. That is, the beam from the target is emitted in a direction substantially perpendicular to the surface of the target, and by changing the surface direction of the target, the emission direction of the beam is such that its angle changes according to the degree of angular change of the surface direction of the target. is there.

In order to obtain the angle change in the surface direction of the target, a plurality of targets having the same composition are prepared, and the targets are held so that the perpendicular directions of the surfaces of the targets face different positions on the substrate. Each target is sequentially irradiated with the electromagnetic wave of. In this case, the target support member is rotated, or the target support member is periodically swung to sequentially select each target. Further, a configuration in which only one target is used and the direction of the surface thereof is gently changed along the circumferential direction, for example, can be considered to be included in one of the configurations including a plurality of targets of the present invention. .

According to the present invention, in order to obtain a uniform film thickness in a wide range, it is necessary to know the range of uniform film thickness formed by each target for each type of target. As an example, for a certain type of target, the center of the irradiation position of the electromagnetic wave beam on the target surface is the apex, and the apex angle is bisected by the vertical line on the target surface at the apex, and the base is on the substrate surface. Considering the isosceles triangle in (1), the range of the base of the isosceles triangle whose apex angle is 12 degrees is the range in which the variation in film thickness is within ± 10%.
Based on this, the range of uniform film thickness obtained by the distribution sum of a plurality of targets can be predicted. To be precise, the center of the film thickness distribution is slightly deviated to the side where the laser is irradiated, and the laser has an elliptical shape that is narrow in the vertical direction and wide in the horizontal direction both before and after focusing. Since it has a property, it is necessary to consider that the film thickness distribution has an elliptical shape.

In order to obtain a uniform film thickness, it is possible to perform feedback control such as detecting the formed film thickness and shortening the irradiation time at a target that faces a specific direction. When a film thickness meter is used for this purpose, a film thickness meter is installed corresponding to each target, or the calibration constant of the film thickness is changed for each target. Alternatively, it is also possible to employ a method of detecting the generation rate of the evaporation material near the target by an evaporation rate detector.

The range of the apex angle within which the variation of the film thickness obtained by one target falls within a certain range is the pressure of the atmospheric gas around the substrate, the energy density obtained on the target by one pulse, the type of the target, and It has also been found that there are some differences depending on the manufacturing method and the like. Therefore, according to the present invention, when a plurality of targets is provided and a configuration in which the surface normal direction is selected for each of the plurality of targets is adopted, it is preferable that the target is actually used in advance for each type of target and each ambient condition. By measuring the obtained film thickness distribution, the angular difference between the respective targets in the apparatus of the present invention is selected.

As the light source from the irradiation unit of the present invention, ultraviolet light absorbed by many substances is preferable, and in this case, YA combined with an excimer laser or a non-linear optical element.
A G laser or the like is used. In order to irradiate only a specific target among the plurality of targets, the target holder can be rotated in synchronization with the laser pulse. For example, the laser pulse is irradiated only when a specific target is located within the irradiation range by computer control.

Further, when the surface of the target is scooped through the laser irradiation to change its surface shape,
The perpendicular direction of the surface may change or the vapor deposition rate may change in the portion, and in such a case, a desired film thickness distribution cannot be obtained. To avoid this, irradiate the laser for an extremely short time without changing the surface shape of the target, or move the target position or the laser irradiation direction so that the laser irradiates the entire target surface uniformly. Therefore, it is preferable to frequently change the laser irradiation position on the target.

[0019]

The target supporting member is prepared by preparing a plurality of targets having the same composition by the structure in which the targets are held so that the perpendiculars on the surfaces of the respective targets at the center positions of the electromagnetic waves pass through different positions on the substrate surface. By irradiating each target with electromagnetic waves in sequence, the evaporated material of the target is ejected uniformly over a wide range and is deposited on the substrate, so that a thin film having a uniform film thickness and composition over a wide range. Are formed on the substrate.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vapor deposition thin film forming apparatus according to the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic plan view of a vapor deposition thin film production apparatus according to an embodiment of the present invention. In the figure, a laser beam 2 forming an ultraviolet ray from an excimer laser 1
Enters the vacuum chamber 5 through the nitrogen-purged optical box 3. The optical box 3 is provided with a condenser lens 4, and the laser beam 2 is arranged so as to be focused in front of the surface of the target 11 via the condenser lens 4. As the condenser lens 4, artificial quartz or the like is selected.

The vacuum chamber 5 is evacuated to a vacuum of, for example, about 10 ^-6 torr, and when vapor deposition is subsequently performed to form an oxide, the oxygen gas forming the active gas is discharged from the gas supply pipe 6. Supplied. As a material for the laser beam introduction window 7 of the vacuum chamber 5, artificial quartz single crystal, MgF ₂ single crystal, sapphire, or the like having a thickness that can withstand a pressure difference of 1 atm is adopted.

The target holder 12, which is a target support member, has a disk shape and is rotatable about its rotation axis 13. The target holder may be rotated instead of rotating. The target holder 12 holds three targets 11A to 11C, which will be described later, and any one of them is sequentially and selectively irradiated to the laser 2. A substrate 14 is arranged at a position facing a target irradiated by the laser 2, the substrate 14 is heated to, for example, about 750 ° C., and is supported by a substrate holder 15 which is a substrate supporting member. The opposing distance between the substrate 14 and the target is, for example, 60 mm.

The excimer laser 2 to be irradiated is a pulsed laser having a pulse width of usually about 10 to 30 nS, and the targets 11A to 11C are irradiated to the laser 2 by local heating for a short time with this extremely short pulse width. Evaporate is ejected from its surface while being sprayed. Evaporated substances from each target flow as a beam 16 toward the facing substrate 14 and are deposited on the surface of the substrate 14.

2A and 2B are explanatory views showing the details of the arrangement of the targets on the target holder shown in FIG. 1. FIG. 2A is a view of the target holder as seen from the front, and FIG. 2B is its BB arrow. It is a perspective view. As shown in FIGS. 11A and 11B, three small disc-shaped targets, that is, targets 11A to 11C are arranged in the disc-shaped target holder 12, and the targets 11A and 11C are arranged.
Each C is supported by being inclined with respect to the target holder 12 via a spacer (not shown). Perpendicular lines on the surface of each target point in the direction indicated by the arrow at the center of each target in FIG. 7A, and are outside the target holder 12 in the radial direction in the target 11A and in the target holder 12 in the target 11C. For example, they are tilted inwardly in the radial direction by, for example, 20 degrees, and in the target 11B, they face the direction perpendicular to the surface of the target holder 12. The tilt angles of the target holders 11A and 11C are the same.

FIG. 3 is a plan view for explaining how the substrate is irradiated by the arrangement of the targets.
(C) shows that the targets 11A to 11C are irradiated with the laser, respectively. Through the movement by the target holder 12, the target 1
When 1A is at the irradiation position, the beam 16A is directed from the center on the substrate to the left side in the drawing as shown in FIG.
When 1B is in the irradiation position, the beam 16B moves toward the center of the drawing, and when the target 11C is in the irradiation position as shown in FIG. 7C, the beam 16C moves to the right in the drawing. I'm heading.

By arranging and tilting the targets, the target holder 12 is rotated in a fixed direction in synchronism with the pulse of the laser, or is simply rotated periodically so that each target is sequentially arranged at the laser irradiation position. Thus, each target is sequentially irradiated with the laser. In FIG. 1, the substrate surface is the XZ plane, the X axis is in the plane of the drawing, the Z axis is the direction perpendicular to the drawing, and the rotation axis 13 of the target holder 12 is at the position Z = 0. Think In this case, as described above, the three targets 11A-1
By arranging the perpendicular direction of the surface of 1C in the radial direction of the target holder, the film thickness distribution is averaged in the X-axis direction.

FIG. 4 is an explanatory view showing the state of film formation on the substrate 14 irradiated with each target according to FIG. 3 at the above coordinates. A front view of the substrate 14 is shown in the center of the drawing and a central portion of the substrate is shown on the lower side. A graph showing the film thickness distribution in the X-axis direction and a graph showing the film thickness distribution in the Z-axis direction in the central portion of the substrate are shown on the right side in correspondence with each other. A shaded figure 17 shown in the front view shows a set of positions where the film thickness is formed to be a predetermined value or more, and reference numerals 17A, 17B,
17C are mainly targets 11A, 11B and 11 respectively.
The collective portion formed corresponding to C is indicated by an arrow.
As shown in the figure, the gathering portions 17A to 17C corresponding to the respective targets are substantially elliptical having a major axis in the Z-axis direction and a minor axis in the X-axis direction. In particular, the film thickness is averaged in the portion where the beams emitted from the respective targets overlap each other, and the range of the uniform film thickness portion is increased as compared with the conventional case.

In order to expand the uniform range of the film thickness, the film thickness distribution obtained by carrying out the same vapor deposition step while holding the three targets in the same manner and different from the embodiment in the same plane direction 5 showing the same as FIG.
It will be apparent from a comparison between FIG. 4 and the film thickness distribution obtained in the above example.

In order to verify the uniformity of the film thickness, the following experiments were actually conducted and confirmed. First, as a comparative example, 99.9% pure Y ₂ O ₃ , BaCO ₃ , and CuO.
The powders were mixed at a molar ratio of 1: 2: 3, pressed at room temperature under a pressure of 1 ton and pressed in air at 950 ° C. for 1 hour.
Sintering was carried out for 0 hours to prepare a Y ₂ Ba ₂ CuO ₇ sintered body target. The upper and lower surfaces of this sintered target are parallel to each other. One of the obtained targets is vertically fixed on the target holder, and the target is separated by a separation distance 6c.
The substrates were arranged facing each other at the position m. After heating the substrate to 750 ° C or higher and temporarily setting the vacuum chamber to 4 × 10 ^-6 torr or less,
Oxygen was introduced to 80 mtorr. In this state, the laser irradiation part was operated under an output of 250 mJ per pulse and a pulse repetition frequency of 10 Hz. In the case of this example, the energy density per unit area of each pulse of the laser irradiated on the target was about 2.3 J / cm ² due to the above-mentioned configuration. The vapor deposition time was 30 minutes. The film distribution obtained in this comparative example is elliptical, and the range in which the film thickness is 7,000 Å ± 10% is:
The width of the incident laser beam is 25, which corresponds to the vertical direction.
mm, the width of the incident laser beam was wide and the range was surrounded by an ellipse of about 15 mm corresponding to the horizontal direction.

Two targets manufactured in the same manner as the target of the comparative example were prepared, one of them was placed at the same position on the target holder as the previous comparative example, and the other was in contact with it, and the same centered on the rotation center of the target holder. Placed on the circumference of. The other target was attached by tilting 20 degrees toward the center of rotation by a spacer having an angle of about 20 degrees. As a result, the vertical line on the surface of each target is 2c in the radial and horizontal directions of the substrate on the substrate surface.
It will face m away. The vapor deposition was carried out in the same manner as in the comparative example above, except that the irradiated target was alternately changed at 1-minute intervals through the rotation of the target holder.

In the obtained film thickness distribution, the range of ± 10% with respect to the target value of 4000 angstroms is the range of 25 mm in the vertical direction and 30 mm in the horizontal direction. In comparison with the above, the horizontal range having a uniform film thickness was approximately doubled.

FIG. 6A is a plan view of a target arrangement in another embodiment of the vapor deposition thin film forming apparatus of the present invention.
In this embodiment, the target holder 12 'in FIG.
Shows the case where the rotation axis of is in the direction perpendicular to the drawing. The position of the target 11B shows the target position where laser irradiation is actually performed. By rotating or rotating the target holder 12 ′, any of the targets 11A to 11C is arranged at this irradiation position at a predetermined cycle or in synchronization with the pulsed laser, and the target material is evaporated by the laser irradiation. Also in this figure, the perpendicular directions of the surfaces of the target 11A and the target 11C are inclined with respect to the target holder 12 in the horizontal direction and the mutually opposite directions via the spacer, respectively. As shown in b), by irradiating the surfaces of the substrate 14 with the beams 16A to 16C in different directions, it is possible to form a thin film having a film thickness distribution similar to that shown in FIG.

In the vapor deposition thin film production apparatus of the present invention, since it is not necessary to rotate the substrate during heating, it is possible to form a uniform film thickness in a wide range despite the simple structure. However, also in the vapor deposition thin film production apparatus of the present invention, conventionally used substrate rotation can be adopted in addition to the above configuration. In this case, in order to obtain a uniform film thickness in the widest possible range, two targets are used, the perpendicular direction of the target surface is shifted in the radial direction of the substrate for vapor deposition, and the rotation of the substrate is also adopted. To do.

FIG. 7 is a plan view of the substrate for explaining the film shape obtained by using the rotation of the substrate together. In this substrate, the perpendicular directions on the surface of the targets are arranged so as to be perpendicular to each other so that the film formation by the two targets is performed in the range shown by the diagonal lines in the drawing. Through this target arrangement, as shown in the figure, a substantially uniform thin film is formed from the center of the substrate to the vicinity of the periphery of the substrate. Therefore, by rotating this substrate around the center sequentially or at high speed, It is possible to form a uniform thin film on almost the entire surface of the substrate.

By using the vapor deposition thin film forming apparatus of the present invention, YB
a ₂ Cu ₃ O ₇ and a thin film having the same type of crystal structure, and Bi ₂ Sr ₂ Ca _(n-1) Cu _(n) O _{(2n + 4 + d)} (n = 1, 2,
3), thin films of (Ln, M) ₂ CuO ₄ (Ln = rare earth metal, M = earth metal, etc.) were prepared, and a wide uniform film thickness range could be obtained. Even if a part of the metal element or the like is substituted from the above compound, the vapor deposition conditions do not change so much. Therefore, a thin film of a similar compound other than the above can be prepared by this apparatus. Further, it can be widely used for forming thin films of ceramics or the like having different structures.

It should be noted that each of the embodiments described above is merely an example, and is not intended to limit the scope of the present invention. Therefore, configurations in which well-known changes and modifications are made from the above embodiment are also included in the scope of the present invention.

[0037]

As described above, according to the vapor deposition thin film forming apparatus of the present invention, the vapor deposition thin film having a uniform thickness can be formed in a wide range despite the simple structure. Has a remarkable effect of expanding.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a vapor deposition thin film production apparatus according to an embodiment of the present invention.

2A and 2B are respectively a front view of the arrangement of targets on a target holder in FIG. 1 and a BB arrow view thereof.

3 (a) to 3 (c) are explanatory views of the action of the target inclination in the embodiment of FIG. 1, respectively.

4 is an explanatory view of a film thickness distribution of a thin film formed by the embodiment of FIG.

FIG. 5 is an explanatory diagram of a film thickness distribution of a thin film formed by a conventional device.

6A is a plan view of a target arrangement in the second embodiment, and FIG. 6B is an explanatory view of a beam direction.

FIG. 7 is a front view of a substrate for explaining the shape of a thin film when the substrate is also rotated.

FIG. 8 is a schematic plan view of a conventional vapor deposition thin film manufacturing apparatus.

[Explanation of symbols]

 1: Laser irradiation part 2: Laser 3: Optical box 5: Vacuum chamber 11A-11C: Target 12: Target holder 14: Substrate 16A-16C: Evaporated beam

Claims (3)

[Claims] 1. A substrate support member for supporting a substrate,
A target support member for holding the target facing the substrate, an irradiation unit for irradiating the surface of the target with an electromagnetic wave beam having an extremely short pulse, and a control unit are provided, and a thin film is formed on the substrate. In the vapor deposition thin film production apparatus for depositing, the target support member can hold a plurality of the targets, and the control means at least the targets so that the held targets are sequentially irradiated to the electromagnetic wave beam. The target support member controls the support member, and the target support member is configured such that the normals on the surface of the target at the center positions of the electromagnetic waves irradiated to the targets pass through different positions on the surface of the substrate, respectively. An apparatus for producing a vapor-deposited thin film, which holds a target. 2. The vapor deposition thin film production apparatus according to claim 1, wherein the target support member rotates the target in synchronization with a pulse of the electromagnetic wave beam. 3. The target material is mainly composed of (a) at least one rare earth metal element or Bi, (b) at least one alkaline earth metal, and (c) at least one transition metal element. 3. The vapor deposition thin film production apparatus according to claim 1 or 2, wherein the crystal structure is a compound similar to perovskite and composed of an oxide as a component.