JP2000144386A - Formation of thin film by laser vapor deposition and laser vapor deposition device used in this formation of thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a thin film by a laser vapor deposition method capable of preventing the reevaporation of a thin film deposited on the surface of a substrate and the damage to the inside face of an airtight chamber and capable of forming a thin film low in granular deposit density, and to provide a laser vapor deposition device used in this thin film forming method. SOLUTION: As to the thin film forming method and laser vapor deposition device, a vapor depositing material evaporated from a target 2 in an airtight chamber 4 irradiated with a laser beam 3 is deposited on the surface of a substrate 1, a shielding board 16 for checking the passage of the laser beam 3 is interposed on the space between the substrate 1 or the airtight chamber 4 and the target 2, and while the application of the laser beam 3 reflected by the target 2 to the surface of the substrate 1 or the inside face of the chamber 4 is checked by the shielding board 16, the vapor depositing material is deposited on the surface of the substrate 1.

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 thin film by a laser vapor deposition method capable of forming a thin film having a low granular deposit density, and a laser vapor deposition apparatus used in the method.

[0002]

2. Description of the Related Art Conventionally, in a laser vapor deposition method, a target is irradiated with a laser beam having a large energy density under reduced pressure, and a vaporized substance evaporated from the target irradiated with the laser beam is deposited on the surface of a substrate. Is done. In general, a laser vapor deposition apparatus used in a thin film forming method by a laser vapor deposition method has a configuration as shown in FIG. 3, and this laser vapor deposition apparatus can be evacuated to a high vacuum and has an atmospheric gas. The substrate 1 and the target 2 are arranged in parallel in an airtight chamber 4 in which
The laser light 3 emitted from the laser oscillation means 7 provided outside the airtight chamber 4 is collected by the condenser lens 8 and the reflection mirror 1.
5 is introduced into the hermetic chamber 4 via optical means such as 5 and the laser beam 3 is irradiated from above the target 2 obliquely. In the drawings, reference numeral 5 denotes a substrate holder, 6 denotes a target holder, 9 denotes a vacuum pump, 10
Is an atmosphere gas introduction pipe, and 11 is a laser light introduction window.

Further, the laser vapor deposition apparatus is not limited to the configuration shown in FIG. 3, but a laser vapor deposition apparatus as shown in FIG. 4 is also used. That is, in this laser vapor deposition apparatus, the target holder 6 holding the target 2 is disposed obliquely upward to intersect with the optical axis of the laser light 3 entering through the laser light introduction window 11. While being rotated by the target driving means 12, it is moved along the surface direction of the substrate 1, that is, in the direction coinciding with the optical axis of the laser light 3. The condensing lens 8 at this time is to be moved back and forth and right and left by the condensing lens driving means 14 so that the diameter of the laser light 3 condensed on the target 2 does not change.

In the laser deposition method, a number of parameters such as a pressure at the time of film formation, a substrate temperature, an atmosphere, and an energy density of a laser beam can be independently selected, and the composition of a thin film deposited on the surface of the substrate can be selected. There are advantages such as easy control and high film formation speed. Further, since the laser vapor deposition method does not require any electromagnetic field, even if charged particles are contained in a deposition material to be a thin film, it is not affected by the charged particles. Therefore, it can be said that this laser vapor deposition method is suitable for forming a high-quality thin film.In addition to employing the laser vapor deposition method having many advantages, it can be applied to oxide superconducting thin films and photoelectric devices having excellent characteristics. Fabrication of applicable semiconductor thin films has been studied.

[0005]

However, when the above-mentioned conventional thin film forming method and laser vapor deposition apparatus are adopted, the following inconveniences have occurred.
That is, a laser vapor deposition apparatus having the configuration shown in FIG.
In the thin film forming method using this, the laser light 3 applied to the target 2 to evaporate the deposition material is reflected by the target 2, and the reflected laser light 3 is directed to the inner surface of the hermetic chamber 4. As a result, the inner surface of the hermetic chamber 4 is damaged. Reference numeral 18 in FIG. 3 indicates a portion where the inner surface of the airtight chamber 4 is damaged.

Further, in the laser vapor deposition apparatus having the structure shown in FIG. 4 and the thin film forming method using the same, the laser beam 3 irradiated to the target 2
The reflected laser light 3
Is irradiated toward the surface of the substrate 1, so that the thin film deposited on the surface of the substrate 1 is re-evaporated by the laser beam 3. Reference numeral 17 in FIG. 4 indicates a portion where the thin film is re-evaporated by the laser beam 3.

In the laser deposition method, several μm
Granular deposits (droplets) having a size on the order of m are generated, and these particulate deposits are included in the thin film formed on the surface of the substrate 1, resulting in a decrease in the quality of the thin film. Sometimes. Then, in order to suppress the generation of such granular deposits, it is preferable that the surface of the target 2 be processed smoothly until it becomes a mirror-like surface. When the surface of the target 2 is mirror-finished, the above-mentioned inconveniences have become more prominent.

The present invention has been made in view of these inconveniences, and prevents the thin film deposited on the surface of the substrate from being re-evaporated and from damaging the inner surface of the hermetic chamber. It is an object of the present invention to provide a method of forming a thin film by a laser vapor deposition method that can prevent the formation of a thin film having a low granular deposit density, and a laser vapor deposition apparatus used in the thin film forming method.

[0009]

According to a first aspect of the present invention, there is provided a thin film forming method for depositing a vapor deposition material evaporated from a target in an airtight chamber irradiated with a laser beam on a surface of a substrate. A shield plate is provided between the substrate or the hermetic chamber and the target to block the passage of laser light, and the laser light reflected by the target is applied to the surface of the substrate or the inner surface of the hermetic chamber. The deposition material is deposited on the surface of the substrate while blocking with a shielding plate. A thin film forming method according to a second aspect of the present invention is the method according to the first aspect, wherein the shielding plate is moved in conjunction with the target. The thin film forming method according to claim 3 of the present invention is claim 1
Alternatively, the method according to claim 2, wherein the shielding plate is rotated.

According to a fourth aspect of the present invention, there is provided a laser vapor deposition apparatus comprising: a hermetic chamber in which a target and a substrate are disposed; and a laser oscillating means provided outside the hermetic chamber to emit laser light. A shielding plate for blocking the passage of laser light is interposed between the substrate or the airtight chamber and the target, and the laser light reflected by the target is applied to the surface of the substrate or the inner surface of the airtight chamber. Irradiating with a shielding plate. A laser vapor deposition apparatus according to claim 5 of the present invention is as described in claim 4,
The shielding plate is configured to move in conjunction with the target.

According to a sixth aspect of the present invention, there is provided a laser vapor deposition apparatus according to the fourth or fifth aspect, wherein the shielding plate is configured to rotate.
The laser vapor deposition apparatus according to claim 7 of the present invention is as described in any one of claims 4 to 6, wherein the material for forming the shielding plate has a laser ablation threshold energy higher than that of the material for forming the target. It is characterized by the following. An eighth aspect of the present invention is directed to the laser vapor deposition apparatus according to any one of the fourth to seventh aspects, wherein the target-side surface of the shielding plate has an uneven surface.

In the method for forming a thin film according to the first aspect and the laser vapor deposition apparatus according to the fourth aspect, the laser light reflected by the target may be applied to the surface of the substrate or the inner surface of the airtight chamber. , The substrate or the airtight chamber and the target are blocked by a shielding plate interposed between the target and the airtight chamber. Therefore, the surface of the target is processed smoothly until it becomes mirror-like, and even if the laser light is reflected on the surface of the target, the thin film deposited on the surface of the substrate is re-evaporated, It would not be possible for the inner surface to be damaged.

In the method for forming a thin film according to the second aspect and the laser vapor deposition apparatus according to the fifth aspect, since the shielding plate moves in conjunction with the target, the shielding plate is shielded from the laser light reflected on the surface of the target. The relative positional relationship with the plate is maintained, and even when the target is moved to form a thin film over the entire surface of the substrate, the thin film is re-evaporated or the inner surface of the hermetic chamber is damaged. Will not occur. In the thin film forming method according to the third aspect and the laser vapor deposition apparatus according to the sixth aspect, since the shielding plate is rotating, the laser light reflected on the surface of the target is located at one position on the surface of the shielding plate. As a result,
The advantage that the shielding plate can be used for a long period is ensured.

In the laser vapor deposition apparatus according to claim 7, since the material for forming the shielding plate has a laser ablation threshold energy higher than the material for forming the target,
It is possible to prevent impurities generated from the shielding plate from being mixed into the thin film formed on the surface of the substrate. In the laser vapor deposition apparatus according to claim 8, the target side surface of the shielding plate has an uneven surface, and the laser light reflected on the surface of the target and irradiated on the shielding plate is scattered by the uneven surface. Therefore, it is possible to prevent an inconvenience such that the laser beam leaks out of the hermetic chamber through the incident path while maintaining the high intensity.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is an explanatory view showing a simplified structure of a laser vapor deposition apparatus according to a first embodiment. This laser vapor deposition apparatus is different from the conventional one shown in FIG. Similarly, a substrate 1 on which a thin film is to be formed is horizontally disposed in a hermetic chamber 4 into which an atmospheric gas can be introduced while being evacuated to a high vacuum, and a target 2 is provided on the surface of the substrate 1 It has a configuration arranged so as to have an obliquely upward surface state that intersects with the optical axis of the laser light 3. And
The laser vapor deposition apparatus has a laser oscillation means 7 from which laser light 3 is emitted. Note that an excimer laser or an Nd: YAG laser is desirable as the laser oscillation means 7. In the present embodiment, the fourth harmonic (wavelength 266n) of the Nd: YAG laser is used.
m) is used as the laser light 3.

The hermetic chamber 4 is provided with a laser light introduction window 11, and the laser light is emitted from a laser oscillation means 7 provided outside the hermetic chamber 4 at an external position close to the laser light introduction window 11. A condensing lens 8 for condensing the laser light 3 and guiding the laser light 3 into the airtight chamber 4 is provided. The inside of the airtight chamber 4 contains the substrate 1.
A substrate holder 5 for holding the target, a target holder 6 for holding the target 2, and a vacuum pump 9 are provided, and one end of an atmosphere gas introduction pipe 10 for introducing an atmosphere gas is opened. The pressure and atmosphere in the airtight chamber 4 can be arbitrarily changed.

The substrate 1 mounted on the substrate holder 5 is positioned on a plane parallel to the optical axis of the laser beam 3, and its surface is formed by a built-in motor (not shown) within a film forming surface. In addition to being rotatable in the same direction as the rotation axis, that is, being movable along the vertical direction, the distance between the target 2 and the target 2 is adjusted. It will be adjusted to get closer. The substrate holder 5 has a heater (not shown) for heating the substrate 1.
Is built-in.

On the other hand, the target 2 mounted on the target holder 6 is also rotatable in its surface by a built-in motor (not shown),
The laser light 3 entering from 1 is arranged on the optical axis of the incident laser light 3 so that the laser light 3 directly hits the surface of the target 2. Therefore, the laser light 3 emitted from the laser oscillation means 7 is guided by the condenser lens 8, passes through the laser light introduction window 11, and
The light is focused on the surface of the target 2 placed in the airtight chamber 4.

Further, a target driving device 12 for moving the target holder 6 together with the target 2 along the direction coincident with the optical axis of the laser beam 3 is attached to the airtight chamber 4. When the target 2 moves on the optical axis of the laser beam 3, the diameter of the laser beam 3 condensed on the surface of the target 2 changes. 13 is connected to the condenser lens 8, and depending on the lens driving device 13, the condenser lens 8
Are driven along a direction coinciding with the optical axis and a vertical direction. Reference numeral 14 in FIG. 1 indicates a control device, that is, a control device for linking the condenser lens driving device 12 and the target driving device 13,
This control device 14 only needs to operate simply by keeping the distance between the target 2 and the condenser lens 8 at the same distance, but if a more accurate control is required, the microcomputer is used. Will be used.

Furthermore, in the laser vapor deposition apparatus according to the present embodiment, the substrate 1 held by the substrate holder 5
A shielding plate 16 for blocking the passage of the laser light 3 is provided at an arbitrary position between the target 2 and the target 2 held by the target holder 6. That is, the shielding plate 16 prevents the laser beam 3 reflected by the target 2 from being irradiated toward the surface of the substrate 1, and is positioned and supported by the target holder 6 holding the target 2. I have.
Therefore, when the target 2, that is, the target holder 6 is moved by the target driving device 12, the shielding plate 16 supported by the target holder 6 also moves, and the laser beam reflected on the surface of the target 2 is moved. The relative positional relationship between 3 and shielding plate 16 will be maintained.

Although not shown, the shielding plate 16 may be configured to be movable in the vertical direction, that is, in the direction toward and away from the target 2, and is supported by the target holder 6. Shield plate 16
It is a matter of course that the shield plate 16 may be rotated after a motor is provided for rotating the shield plate 16. When the shielding plate 16 is configured to rotate, the laser light 3 reflected on the surface of the target 2 is used.
Is prevented from being concentrated on one location on the target side surface of the shielding plate 16, so that the advantage that the life of the shielding plate 16 is prolonged is secured.

In this case, the material of the shielding plate 16 may be any material as long as it has a laser ablation threshold energy higher than that of the material of the target 2. In the case of Si), the shielding plate 16 is made of stainless steel. Note that the shielding plate 16 in the case of the target 2 made of Si may be made using the same Si. And shielding plate 1
If the laser ablation threshold energy of 6 is higher than that of the target 2, even if impurities are generated as the laser light 3 reflected by the target 2 is irradiated on the shielding plate 16, the impurity is generated. No impurities will be mixed into the thin film. Further, the target side surface of the shielding plate 16 may be formed as a fine uneven surface. With such a configuration, the laser light 3 is scattered on the uneven surface, so that the laser light 3 having high intensity remains. Does not leak back to the outside of the airtight chamber 4 through the incident path.

Next, a method of forming a thin film by a laser vapor deposition method using the laser vapor deposition apparatus according to the first embodiment will be described. When forming a thin film by laser deposition,
The distance between the substrate 1 and the target 2 is adjusted to be appropriate by moving the substrate holder 5 up and down in advance, and the laser light 3 emitted from the laser oscillating means 7 is condensed by the condenser lens 8 into the airtight chamber 4. Then, the light is focused on the surface of the target 2. Then, a vapor deposition material is generated from the target 2 on which the laser beam 3 is focused, and the generated vapor deposition material is deposited on the surface of the substrate 1 to form a thin film. At this time, since the shielding plate 16 for blocking the passage of the laser light 3 is interposed between the substrate 1 and the target 2, the laser light 3 reflected by the target 2 is directed to the surface of the substrate 1. Irradiation is prevented by the shielding plate 16.

At this time, the substrate 1 and the target 2 are rotated to obtain a thin film of uniform film quality, while the target holder 6 and the shielding plate 16 are rotated by the Are moved along a direction coinciding with the optical axis, that is, the horizontal direction, and a thin film over the entire surface of the substrate 1 is to be formed. The condenser lens 8 is also driven by the condenser lens driving device 13 in conjunction with the target 2, and the diameter of the laser beam 3 on the surface of the target 2 is kept constant irrespective of the movement of the target 2. As a result, the incident energy density of the laser beam 3 is always constant, so that the plume generated from the target 2 is stable.

At this time, the separation distance between the substrate 1 and the target 2 does not change even if the target 2 moves horizontally, and is constant. Therefore, the distance between the target 2 and the substrate 1 is sufficient. Can be formed, and the distance between the substrate 1 and the plume is stable. Therefore, substrate 1
A thin film having a large area and a uniform film quality is formed on the surface. Further, in the first embodiment, the laser light 3 reflected by the target 2 is applied to the surface of the substrate 1, but is blocked by the shielding plate 16 interposed between the substrate 1 and the target 2. Therefore, the surface of the target 2 is processed smoothly until it becomes mirror-like, and even if the laser light 3 is reflected on the surface of the target 2,
It does not occur that the thin film deposited on the surface of the substrate 1 is re-evaporated.

(Example) By using the laser vapor deposition apparatus according to the first embodiment to form a microcrystalline Si thin film, the following results were obtained. That is, first, in this case, the diameter is about 20 mm and the thickness is about 10 mm.
A mirror-shaped target 2 is prepared by treating a 1-mm disc-shaped Si single crystal with hydrofluoric acid for 1 minute, and a quartz substrate having a diameter of 10 cm and a thickness of 0.7 mm is used as the substrate 1. . The angle between the incident laser beam 3 and the normal to the surface of the target 2 is set to 45 °, and the shielding plate 16 made of stainless steel is simply fixed to the target holder 6. It has become.

After such preparation, the surface temperature of the substrate 1 is set to room temperature, and the distance between the substrate 1 and the optical axis of the laser beam 3 is set to 1
0 mm, the energy of the laser beam 3 is 180 mJ /
Pulse, laser pulse rate 10Hz, target 2
Under the condition that the rotation speed of the laser beam is 20 rpm and the moving speed of the target 2 and the condensing lens 8 in the direction coinciding with the optical axis of the laser 3 is 50 mm / min, laser deposition is performed for 4 minutes while the substrate 1 is fixed. did. According to the result, the thin film formed on the surface of the substrate 1 shows no trace of re-evaporation due to the irradiation of the laser beam 3 reflected by the target 2, and the thin film It was confirmed that the sediment density was sufficiently low at about 10 ⁴ cm ^-2 .

Second Embodiment FIG. 2 is an explanatory view showing a simplified configuration of a laser vapor deposition apparatus according to a second embodiment. In this case, the basic configuration of the laser vapor deposition apparatus is different from that of the first embodiment. Therefore, the same reference numerals are given to the corresponding devices, parts, and members in FIG. 2 which are the same as those in FIG. 1, and the detailed description thereof will be omitted.

In the laser vapor deposition apparatus according to the second embodiment, the substrate 1 and the target 2 are arranged in a hermetic chamber 4 in parallel with each other as in the conventional embodiment shown in FIG. Laser light 3 emitted from the installed laser oscillation means 7 is introduced into the hermetic chamber 4 via optical means such as a condenser lens 8 and a reflection mirror 15 and then obliquely from above the target 2. It has a configuration to be irradiated. At this time, a shielding plate 16 for intercepting the passage of the laser light 3 is interposed between the target 2 and the airtight chamber 4, and the laser light 3 reflected by the target 2 passes through the airtight chamber 4. Irradiation to the inner surface is to be prevented by the shielding plate 16.

Therefore, when the laser vapor deposition apparatus according to the second embodiment is used in the method of forming a thin film by the laser vapor deposition method, a thin film is formed on the surface of the substrate 1 through the same process as in the first embodiment. Will be. However, at this time, a shielding plate 1 is provided between the target 2 and the airtight chamber 4.
6 is interposed, and the passage of the laser light 3 reflected by the target 2 and applied to the inner surface of the hermetic chamber 4 is blocked by the shielding plate 16, so that the surface of the target 2 becomes mirror-like. Even if the laser beam 3 is reflected on the surface of the target 2, the inner surface of the hermetic chamber 4 cannot be damaged.

[0031]

As described above, according to the first aspect of the present invention,
According to the method for forming a thin film according to the above, and the laser deposition apparatus according to the fourth aspect of the present invention, the laser light reflected by the target is irradiated on the surface of the substrate or the inner surface of the airtight chamber, It is blocked by a shielding plate interposed between the airtight chamber and the target. Therefore, the surface of the target is processed smoothly until it becomes mirror-like, and even if the laser light is reflected on the surface of the target, the reflected laser light is applied to the surface of the substrate. As a result, the thin film deposited on the surface of the substrate cannot be re-evaporated or the inner surface of the hermetic chamber cannot be damaged.

A thin film forming method according to claim 2 of the present invention,
And according to the laser vapor deposition apparatus according to claim 5 of the present invention, since the shielding plate moves in conjunction with the target,
The relative positional relationship between the laser beam reflected on the surface of the target and the shielding plate is maintained, and even when the thin film is formed over the entire surface of the substrate while moving the target, the thin film is re-formed. This has the effect that no evaporation or damage to the inner surface of the airtight chamber takes place. According to the method for forming a thin film according to the third aspect of the present invention and the laser deposition apparatus according to the sixth aspect of the present invention, since the shielding plate is rotating, the laser light reflected on the surface of the target is shielded. As a result that irradiation is not concentrated on one place on the surface of the plate, an effect is obtained that the shielding plate can be used for a long time.

According to the laser vapor deposition apparatus of the present invention, since the material for forming the shielding plate has a laser ablation threshold energy higher than that of the material for forming the target, the shielding material is formed in the thin film formed on the surface of the substrate. The effect is obtained that the impurities generated from the plate can be prevented from being mixed. According to the laser vapor deposition apparatus of claim 8 of the present invention, the target side surface of the shielding plate has an uneven surface, and the laser beam reflected on the surface of the target and irradiated on the shielding plate is irradiated with the uneven surface. Therefore, it is possible to prevent an inconvenience such that the laser light leaks up the incident path and leaks out of the hermetic chamber while maintaining the high intensity.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a simplified configuration of a laser deposition apparatus according to a first embodiment.

FIG. 2 is an explanatory diagram showing a simplified configuration of a laser vapor deposition apparatus according to a second embodiment.

FIG. 3 is an explanatory view schematically showing an example of a laser vapor deposition apparatus according to a conventional mode.

FIG. 4 is an explanatory view schematically showing another example of a laser vapor deposition apparatus according to a conventional mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Target 3 Laser beam 4 Airtight chamber 16 Shield plate

Claims (8)

[Claims] 1. A method for forming a thin film on a surface of a substrate, the method comprising: depositing, on a surface of a substrate, a vapor deposition material evaporated from a target in a hermetically sealed chamber irradiated with laser light. A shielding plate that prevents passage is interposed, and a deposition material is deposited on the surface of the substrate while blocking the laser light reflected by the target from irradiating the surface of the substrate or the inner surface of the airtight chamber with the shielding plate. A method for forming a thin film by a laser vapor deposition method, characterized by depositing. 2. The thin film forming method according to claim 1, wherein the shielding plate is moved in conjunction with a target. 3. The method for forming a thin film according to claim 1, wherein the shielding plate is rotated. 4. A laser vapor deposition apparatus comprising: a hermetic chamber in which a target and a substrate are arranged; and a laser oscillating means installed outside the hermetic chamber to emit laser light. A shielding plate that blocks the passage of laser light is interposed between the airtight chamber and the target, and shields the laser light reflected by the target from irradiating the surface of the substrate or the inner surface of the airtight chamber. A laser vapor deposition apparatus used in the thin film forming method, wherein the laser vapor deposition apparatus is configured to prevent the laser deposition. 5. The laser vapor deposition apparatus according to claim 4, wherein the shielding plate is configured to move in conjunction with the target. 6. The laser vapor deposition apparatus according to claim 4, wherein the shielding plate is configured to rotate. 7. The laser vapor deposition apparatus according to claim 4, wherein a material for forming the shielding plate has a laser ablation threshold energy higher than a material for forming the target. Laser deposition equipment. 8. The laser vapor deposition apparatus according to claim 4, wherein the target side surface of the shielding plate has an uneven surface.