JP2021005628A - Surface treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a treatment time in a surface treatment apparatus for surface treatment of an object to be treated using an atmospheric pressure thermal plasma jet. SOLUTION: A surface treatment apparatus includes a support base 10 for supporting an object to be processed 50, a plasma source 20 for irradiating the object to be processed 50 with a plasma jet 30 generated by DC arc discharge, and two atoms on the plasma source 20. A gas supply mechanism that supplies a plasma generating gas containing a molecular gas, and a magnetic field application mechanism that applies a magnetic field to the plasma jet 30 irradiated from the plasma source 20 to scan the plasma jet 30 with respect to the object to be processed 50. 29 and is provided. The separation distance between the plasma jet injection port 21a of the plasma source 20 and the object to be processed 50 at the time of surface treatment of the object to be processed 50 is 20 mm or more. [Selection diagram] Fig. 1

Description

The present invention relates to a surface treatment apparatus that performs surface treatment of an object to be treated by using an atmospheric pressure thermal plasma jet.

It is known that crystallization occurs by irradiating an amorphous silicon (a—Si) film formed on a quartz substrate with an atmospheric plasma jet (TPJ).

In the conventional TPJ irradiation system, a surface treatment such as annealing is performed while linearly scanning the TPJ on the object to be processed by using an XY stage that supports the object to be processed such as an a-Si film (for example, patent). Reference 1).

Japanese Unexamined Patent Publication No. 2013-197140

However, the method of linearly scanning the TPJ has a problem that the time required to process the entire surface of the object to be processed becomes long.

In view of the above, it is an object of the present invention to shorten the treatment time in the surface treatment apparatus using TPJ.

In order to achieve the above object, the surface treatment apparatus according to the present invention is a surface treatment apparatus that performs surface treatment of an object to be processed by using an atmospheric pressure thermal plasma jet, and includes a support base for supporting the object to be processed. , To the plasma source that irradiates the object to be treated with the plasma jet generated by DC arc discharge, the gas supply mechanism that supplies the plasma generation gas containing diatomic molecule gas to the plasma source, and the plasma jet that is irradiated from the plasma source. On the other hand, it is equipped with a magnetic field application mechanism that applies a magnetic field to scan the plasma jet against the object to be processed, and the separation distance between the plasma jet injection port of the plasma source and the object to be processed during surface treatment of the object to be processed is , 20 mm or more.

According to the surface treatment apparatus according to the present invention, a plasma generating gas containing a diatomic molecular gas is introduced into the plasma source in a state where the separation distance between the plasma jet injection port of the plasma source and the object to be processed is set to 20 mm or more. The length of the plasma jet is extended to several tens of mm or more, and the plasma jet is scanned against the object to be processed by the magnetic field application mechanism. Therefore, the processing range can be greatly expanded by one scanning of the plasma jet, so that the processing time can be shortened.

In the surface treatment apparatus according to the present invention, the separation distance may be 50 mm or more. By doing so, the processing range in one scanning of the plasma jet is further expanded, so that the processing time can be further shortened. In this case, if the separation distance is 100 mm or more, the processing range in one scanning of the plasma jet is further expanded, so that the processing time can be further shortened.

In the surface treatment apparatus according to the present invention, the magnetic field application mechanism may be arranged between the plasma source and the support base. In this way, the plasma jet can be easily magnetically deflected.

In the surface treatment apparatus according to the present invention, the magnetic field application mechanism may be arranged in the vicinity of the plasma jet injection port inside the plasma source. In this way, the plasma jet can be magnetically deflected even when the separation distance between the plasma jet injection port and the object to be processed is relatively small.

In the surface treatment apparatus according to the present invention, the support base may be movable in a direction perpendicular to the direction from the plasma source to the support base. In this way, the processing time can be further shortened by combining the scanning of the plasma jet by the magnetic field deflection and the scanning of the plasma jet by the movement of the support base. In this case, when the plasma jet emitted from the plasma source is scanned in the direction perpendicular to the moving direction of the support base, both scans can be combined most efficiently, and the processing time can be further shortened. ..

In the surface treatment apparatus according to the present invention, the plasma jet injection port may have a shape extended along the direction in which the plasma jet irradiated from the plasma source is scanned. By doing so, even when the maximum scanning angle of the plasma jet is large, it is possible to prevent the magnetic field-deflected plasma jet from interfering with the periphery of the plasma jet injection port.

In the surface treatment apparatus according to the present invention, the plasma-producing gas may be argon or nitrogen. In this way, the length of the plasma jet can be extended longer. In this case, the argon flow rate is 0.4 L / min or more and 0.5 L / min or less, the nitrogen flow rate is 0.65 L / min or more and 0.95 L / min or less, or the argon flow rate is 0.9 L / min or more 1 It may be .5 L / min or less and the nitrogen flow rate may be 0.3 L / min or more and 0.5 L / min or less. In this way, the length of the plasma jet can be increased to 100 mm or more.

According to the present invention, the processing time can be shortened in a surface treatment apparatus that performs surface treatment of an object to be treated by using an atmospheric pressure thermal plasma jet.

FIG. 1 is a configuration diagram of a surface treatment apparatus according to an embodiment. FIG. 2 is an enlarged view showing the vicinity of the plasma jet injection port of the surface treatment apparatus shown in FIG. FIG. 3 is a diagram showing an example of arrangement of the magnetic field application mechanism in the surface treatment apparatus shown in FIG. FIG. 4 is a diagram showing the effect of introducing argon gas and nitrogen gas into the plasma source of the surface treatment apparatus shown in FIG. FIG. 5 is a diagram showing the effect of introducing argon gas and nitrogen gas into the plasma source of the surface treatment apparatus shown in FIG. FIG. 6 is a diagram showing the effect of introducing argon gas and nitrogen gas into the plasma source of the surface treatment apparatus shown in FIG. FIG. 7 is a diagram showing a range processed by a single scan of the plasma jet by the surface treatment apparatus according to the comparative example. FIG. 8 is a diagram showing a range processed by a single scan of the plasma jet by the surface treatment apparatus according to the embodiment. FIG. 9 is a diagram showing the combined effect of plasma jet scanning due to magnetic field deflection and support base movement in the surface treatment apparatus according to the embodiment.

Hereinafter, the surface treatment apparatus according to the embodiment, specifically, the surface treatment apparatus for performing the surface treatment of the object to be treated by using the atmospheric pressure thermal plasma jet will be described with reference to the drawings.

In addition to annealing (heat treatment), foreign matter removal, film formation, oxidation, and the like are assumed as the surface treatment by the surface treatment apparatus according to the present embodiment. When film formation or oxidation is performed, the film formation species or oxidation species may be added to the plasma jet.

FIG. 1 is a configuration diagram of the surface treatment apparatus according to the embodiment, and FIG. 2 is an enlarged view showing the vicinity of the plasma jet injection port of the surface treatment apparatus shown in FIG.

The surface treatment apparatus shown in FIG. 1 mainly includes a support base 10 that supports the object to be processed 50, a plasma source 20 that irradiates the object to be processed 50 with a plasma jet 30 generated by a DC arc discharge, and a plasma source 20. It includes a gas supply mechanism for supplying a plasma generating gas containing a diatomic molecule gas, and a magnetic field application mechanism 29 for applying a magnetic field to the plasma jet 30 to scan the plasma jet 30 with respect to the object to be processed 50. In the present embodiment, the plasma source 20 is arranged above the support base 10, and the magnetic field application mechanism 29 is arranged between the plasma source 20 and the support base 10.

As the support base 10, for example, an XY stage may be used. In this case, the support base 10 can move in a direction (horizontal direction in the present embodiment) perpendicular to the direction from the plasma source 20 toward the support base 10 (vertical direction in the present embodiment). FIG. 1 shows, for example, how the support base 10 moves to the right.

The plasma source 20 mainly includes an anode 21 and a cathode 22 for generating an arc discharge, and a power supply 23 for applying a DC voltage between the anode 21 and the cathode 22.

The anode 21 has a substantially cylindrical shape provided with an internal space 28, and has a plasma jet injection port 21a leading to the internal space 28 on the support base 10 side. The anode 21 may be made of, for example, a metal containing copper (Cu) having a high thermal conductivity as a main component.

A plasma-generating gas containing a diatomic molecule gas is introduced into the internal space 28 through a gas introduction pipe 28a penetrating the outer wall of the anode 21. In this embodiment, for example, argon gas and nitrogen gas are used as the plasma generating gas. The gas introduction pipe 28a is connected to a gas supply mechanism (not shown) such as a gas cylinder that supplies diatomic molecule gas.

The cathode 22 is inserted and held in the conductor 24 arranged above the plasma jet injection port 21a. The lower end of the cathode 22 is exposed from the conductor 24 to the internal space 28 and has a sharp shape toward the plasma jet injection port 21a. The cathode 22 may be composed of, for example, tungsten to which a small amount of lanthanum oxide is added. The conductor 24 may be made of, for example, copper.

An insulator 25 is arranged between the anode 21 and the conductor 24. The insulator 25 may be made of, for example, alumina, ceramics, or the like.

A hollow portion 26 into which water for cooling the cathode 22 is introduced is formed around the cathode 22 in the conductor 24, and water for cooling the anode 21 is introduced around the plasma jet injection port 21a in the anode 21. The hollow portion 27 to be formed is formed. Water is supplied to the hollow portion 26 through the water supply pipe 26a penetrating the outer wall portion of the conductor 24, and water is drained through the drain pipe 26b penetrating the outer wall portion of the conductor 24. Water is supplied to the hollow portion 27 through the water supply pipe 27a penetrating the outer wall portion of the anode 21, and water is drained through the drain pipe 27b penetrating the outer wall portion of the anode 21.

The distance between the electrodes (distance between the anode 21 and the cathode 22) ES shown in FIG. 2 can be appropriately set according to the surface treatment content, but may be set to, for example, 2.0 mm. Similarly, the diameter φ of the plasma jet injection port 21a shown in FIG. 2 can be appropriately set according to the surface treatment content, but may be set to 2.0 mm, for example. The shape of the plasma jet injection port 21a can be appropriately set according to the surface treatment content, the scanning method of the plasma jet 30, and the like, and may be circular or any other shape.

It is presumed that the plasma jet 30 to which the magnetic field is applied from the magnetic field application mechanism 29 is magnetically deflected by the Lorentz force. Therefore, for example, the magnetic field application mechanism 29 is arranged so that the magnetic field is generated in a direction perpendicular to both the traveling direction of the plasma jet 30 (vertically downward in FIG. 1) and the direction in which the plasma jet 30 is desired to be scanned. You may.

For example, as shown in FIG. 3, four electromagnets 29a, 29b, 29c, and 29d may be arranged below the anode 21 so as to surround the plasma jet injection port 21a as the magnetic field application mechanism 29. Specifically, in FIG. 3, the electromagnets 29a and 29b are arranged so as to sandwich the upper end of the plasma jet injection port 21a from the left and right, and the electromagnets 29c and 29d sandwich the lower end of the plasma jet injection port 21a from the left and right. Be placed. In this arrangement, the electromagnets 29a and 29c are set to the first polarity and the electromagnets 29b and 29d are set to the second polarity (opposite polarity of the first polarity) by using a control device (not shown), and the first polarity and the second polarity are set respectively. By appropriately reversing the polarity, the magnetic field B can be generated in the left-right direction of FIG. As a result, the plasma jet 30 can be scanned in the vertical direction of FIG. Here, as shown in FIG. 3, the plasma jet injection port 21a may have a shape extended along the direction in which the plasma jet is scanned.

As a current source (not shown) that supplies a current to each of the coils of the electromagnets 29a, 29b, 29c, and 29d, for example, one that generates alternating current with a frequency of 0 to 200 Hz in the range of ± 2A may be used. Further, an arbitrary voltage signal may be amplified by using a function generator and applied to the coils of the electromagnets 29a, 29b, 29c and 29d.

In the plasma source 20, when a DC voltage is applied between the anode 21 and the cathode 22 from the power supply 23 and the plasma generating gas containing the binary molecular gas is supplied from the gas introduction tube 28a to the internal space 28, the DC arc discharge. Generates a plasma jet 30. The generated plasma jet 30 is irradiated to the object to be processed 50 from the plasma jet injection port 21a. Further, in the present embodiment, when the plasma jet 30 is irradiated to the object to be processed 50 from the plasma jet injection port 21a, the plasma jet 30 is scanned by moving the support base 10 and the plasma jet 30 is operated by the magnetic field application mechanism 29. Scanning is performed. FIG. 1 shows a case where the object to be processed 50 is, for example, a silicon film 52 (a-Si film 52a) formed on a quartz substrate 51. The crystalline silicon (c—Si) film 52b is formed by irradiating the a—Si film 52a with the plasma jet 30.

Hereinafter, the effect of introducing a plasma generating gas containing a diatomic molecule gas, specifically, argon gas and nitrogen gas, into the plasma source 20 will be described with reference to FIGS. 4 to 6.

FIG. 4 shows the power density profile of the plasma jet 30 when the distances (hereinafter, referred to as separation distances d) between the plasma source 20 (specifically, the plasma jet injection port 21a) and the object to be processed 50 are 30 mm and 50 mm, respectively. Shown. The power density profile is two-dimensionally represented with the position directly below the plasma jet injection port 21a on the object to be processed 50 as the center (0 mm). In FIG. 4, the profile (embodiment) shown by the solid line is obtained by introducing argon gas and nitrogen gas into the plasma source 20, and the plasma generation conditions are that the argon gas flow rate is 1.3 L / min and nitrogen gas. The flow rate is 0.4 L / min and the input power is 2.3 kW. On the other hand, in FIG. 4, the profile shown by the broken line (comparative example) was obtained by introducing only argon gas into the plasma source 20, and the plasma generation conditions were that the argon gas flow rate was 7.7 L / min and the input power. Is 1.9 kW.

When the plasma generating gas does not contain a diatomic molecule gas such as nitrogen, the power density of the plasma jet begins to decrease when the separation distance d exceeds several mm, and as shown in FIG. 4, the separation distance d is 30 mm. In the above, it is greatly reduced as compared with the plasma jet 30 of the present embodiment using the diatomic molecule gas. On the other hand, as shown in FIG. 4, the plasma jet 30 of the present embodiment maintains a power density of 715 W / cm ² when the separation distance d is 30 mm and 445 W / cm ² when the separation distance d is 50 mm.

In FIG. 5, the wafer temperature (unit: ° C.) was measured with respect to a 4-inch silicon wafer having a thickness of 525 μm, which is the object to be processed 50, with a separation distance d of 180 mm and changing the flow rates of argon gas and nitrogen gas. The result. Here, the plasma generation conditions are that the distance between the electrodes (distance between the anode 21 and the cathode 22) ES is 3.0 mm, the diameter φ of the plasma jet injection port 21a is 3.0 mm, and the discharge current amount is 140 A.

As shown in FIG. 5, when the argon gas flow rate is 0.4 L / min or more and 0.5 L / min or less and the nitrogen gas flow rate is 0.65 L / min or more and 0.95 L / min or less, and the argon gas flow rate is When the flow rate of nitrogen gas is 0.3 L / min or more and 0.5 L / min or less at 0.9 L / min or more and 1.5 L / min or less, a wafer temperature of 600 ° C. or higher is obtained.

FIG. 6 is a result of measuring the length (unit: mm) of the plasma jet 30 extending from the plasma jet injection port 21a while changing the flow rates of the argon gas and the nitrogen gas under the same plasma generation conditions as in FIG. As shown in FIG. 6, the length of the plasma jet 30 exceeds approximately 100 mm in a wide flow rate range including the flow rate range of the argon gas and the nitrogen gas obtained in FIG. 5 with a wafer temperature of 600 ° C. or higher. ..

In the surface treatment apparatus of the present embodiment shown in FIG. 1, the separation distance d between the plasma jet injection port 21a and the object to be treated 50 at the time of surface treatment of the object to be treated 50 is set to 10 mm or more, preferably 20 mm or more. To. Here, if the thickness of the object to be processed 50 is as thin as a semiconductor wafer or the like, the separation distance d is substantially equal to the distance between the plasma jet injection port 21a and the support base 10.

According to the present embodiment described above, the plasma source 20 has a diatomic molecule in a state where the separation distance d between the plasma jet injection port 21a of the plasma source 20 and the object to be processed 50 is set to 10 mm or more, preferably 20 mm or more. The length of the plasma jet 30 is extended to several tens of mm or more by introducing a plasma generating gas containing a gas, and the plasma jet 30 is scanned against the object to be processed 50 by the magnetic field application mechanism 29. Therefore, the processing range of the plasma jet 30 in one scan is greatly expanded, so that the processing time can be shortened.

FIG. 7 shows, as a comparative example, a state in which the plasma jet 30 is scanned at a maximum scanning angle of 45 ° with a separation distance d of 4 mm. In the case shown in FIG. 7, the range processed by one scan of the plasma jet 30 is 8 mm.

FIG. 8 shows a state in which the plasma jet 30 is scanned at a maximum scanning angle of 45 ° with a separation distance d of 20 mm in the present embodiment. In the case shown in FIG. 8, the range processed by one scan of the plasma jet 30 is 40 mm, which is much larger than that of the comparative example. Therefore, in the present embodiment, by setting the separation distance d more preferably 50 mm or more, further preferably 100 mm or more, the range processed by one scanning of the plasma jet 30 is further expanded, and thus the processing time. Can be further shortened.

Further, according to the present embodiment, since the magnetic field application mechanism 29 is arranged between the plasma source 20 and the support base 10, the plasma jet 30 can be easily magnetically deflected.

Further, according to the present embodiment, since the support base 10 can move in a direction perpendicular to the direction from the plasma source 20 toward the support base 10, scanning of the plasma jet 30 by magnetic field deflection and scanning of the support base 10 and the support base 10 are performed. The processing time can be further shortened in combination with the scanning of the plasma jet 30 by movement. In this case, when the plasma jet 30 irradiated from the plasma source 20 is scanned in a direction perpendicular to the moving direction of the support base 10, as shown in FIG. 9, both scans are combined most efficiently. The processing time can be further shortened. Note that FIG. 9 shows a processing range when scanning the plasma jet 30 shown in FIGS. 7 (Comparative Example) and 8 (Embodiment) while moving the object to be processed 50 together with the support base 10. There is.

Further, according to the present embodiment, the plasma jet injection port 21a has a shape (see FIG. 3) extended along the scanning direction of the plasma jet 30 irradiated from the plasma source 20, so that the maximum of the plasma jet 30 is reached. Even when the scanning angle is large, it is possible to prevent the magnetic field-deflected plasma jet 30 from interfering with the periphery of the plasma jet injection port 21a.

Further, according to the present embodiment, since the plasma generating gas introduced into the plasma source 20 is argon and nitrogen, the length of the plasma jet 30 can be extended longer.

Although not shown in the present embodiment, the top of the plasma source 20 may be attached to the gantry via an actuator. In this way, the plasma source 20 can be moved up and down by the actuator.

Further, in the present embodiment, the XY stage is used as the support base 10, but instead of or in addition to this, the support base 10 may be configured to be rotatable. In this way, when the object to be processed 50 is, for example, a disk-shaped semiconductor wafer or the like, the plasma jet 30 is scanned by magnetic field deflection in the radial direction of the object to be processed 50 while rotating the object to be processed 50. The entire surface of the object to be processed 50 can be processed. Alternatively, the support base 10 may be fixed if the scanning range of the plasma jet 30 due to magnetic field deflection can be secured sufficiently large. Alternatively, the support base 10 may be fixed and the plasma source 20 may be configured to be movable.

Further, in the present embodiment, the magnetic field application mechanism 29 is arranged between the plasma source 20 and the support base 10, but instead, the magnetic field application mechanism 29 is installed in the plasma jet injection port 21a inside the plasma source 20. It may be placed in the vicinity of. In this way, the plasma jet 30 can be magnetically deflected even when the separation distance d between the plasma jet injection port 21a and the object to be processed 50 is relatively small.

Further, in the present embodiment, the magnetic field application mechanism 29 is arranged so that the magnetic field is generated in the direction perpendicular to both the traveling direction of the plasma jet 30 and the direction in which the plasma jet 30 is desired to be scanned. As long as it can be deflected, the arrangement of the magnetic field application mechanism 29 is not particularly limited. Further, in the example shown in FIG. 3, four electromagnets 29a to 29d are arranged as the magnetic field application mechanism 29, but the number of magnets constituting the magnetic field application mechanism 29 is not particularly limited. Further, as the magnetic field application mechanism 29, for example, a permanent magnet having a moving mechanism may be used instead of the electromagnet.

Further, in the present embodiment, argon gas and nitrogen gas are used as the plasma generating gas, but other gases having a relatively high ionization voltage, such as helium gas, neon gas, and krypton gas, are used instead of the argon gas. Alternatively, instead of the nitrogen gas, another molecular gas such as chlorine gas, hydrogen gas, oxygen gas, carbon dioxide gas and the like may be used.

Further, the surface treatment apparatus of the present embodiment is configured as shown in FIG. 1, but the configuration of the surface treatment apparatus is particularly limited as long as the surface treatment of the object to be treated can be performed using the atmospheric pressure thermal plasma jet. Not done. For example, in the surface treatment apparatus of the present embodiment, the plasma source 20 is arranged above the support base 10, but instead, the plasma source 20 and the support base 10 may be arranged side by side in the horizontal direction.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention. That is, the description of the above-described embodiment is essentially merely an example, and is not intended to limit the present invention, its application, or its use.

10 Support stand 20 Plasma source 21 Plasma source 21a Plasma jet injection port 22 Cathode 23 Power supply 24 Conductor 25 Insulator 26, 27 Hollow part 26a, 27a Water supply pipe 26b, 27b Drainage pipe 28 Internal space 28a Gas introduction pipe 29 Magnetic field application mechanism 29a, 29b, 29c, 29d Electromagnet 30 Plasma jet 50 Processed object 51 Quartz substrate 52 Silicon film 52a a-Si film 52b c-Si film

Claims (11)

A surface treatment device that performs surface treatment of an object to be treated using an atmospheric pressure thermal plasma jet.
A support base that supports the object to be processed and
A plasma source that irradiates the object to be processed with a plasma jet generated by DC arc discharge,
A gas supply mechanism that supplies a plasma-generating gas containing a diatomic molecule gas to the plasma source,
A magnetic field application mechanism for applying a magnetic field to a plasma jet irradiated from the plasma source and scanning the plasma jet with respect to the object to be processed is provided.
A surface treatment apparatus in which the separation distance between the plasma jet injection port of the plasma source and the object to be treated at the time of surface treatment of the object to be treated is 20 mm or more. The surface treatment apparatus according to claim 1, wherein the separation distance is 50 mm or more. The surface treatment apparatus according to claim 2, wherein the separation distance is 100 mm or more. The surface treatment apparatus according to any one of claims 1 to 3, wherein the magnetic field application mechanism is arranged between the plasma source and the support. The surface treatment apparatus according to any one of claims 1 to 3, wherein the magnetic field application mechanism is arranged in the vicinity of the plasma jet injection port inside the plasma source. The surface treatment apparatus according to any one of claims 1 to 5, wherein the support base can move in a direction perpendicular to the direction from the plasma source to the support base. The surface treatment apparatus according to claim 6, wherein the plasma jet irradiated from the plasma source is scanned in a direction perpendicular to the moving direction of the support base. The surface treatment apparatus according to any one of claims 1 to 7, wherein the plasma jet injection port has a shape extended along a direction in which a plasma jet irradiated from the plasma source is scanned. The surface treatment apparatus according to any one of claims 1 to 8, wherein the plasma-producing gas is argon and nitrogen. The surface treatment apparatus according to claim 9, wherein the flow rate of argon is 0.4 L / min or more and 0.5 L / min or less, and the flow rate of nitrogen is 0.65 L / min or more and 0.95 L / min or less. The surface treatment apparatus according to claim 9, wherein the flow rate of argon is 0.9 L / min or more and 1.5 L / min or less, and the flow rate of nitrogen is 0.3 L / min or more and 0.5 L / min or less.

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