JP7534722B2 - Ion beam irradiation device and ion beam irradiation method - Google Patents

Description

The present invention relates to an ion beam irradiation device and an ion beam irradiation method that are used in the display manufacturing process and irradiate an ion beam onto an object to be irradiated that forms a display.

In recent years, research and development has been progressing on using oxide semiconductors as the semiconductor material that forms the thin-film transistors (TFTs) that make up flat panel displays. In particular, displays that use an In-Ga-Zn-O oxide semiconductor called IGZO are already being mass-produced and are being used in commercially available smartphones, tablet devices, and other devices.

Patent Document 1 describes a resistance-reducing process for a semiconductor film formed on a substrate from an oxide semiconductor material, and cites a plasma process using argon or hydrogen as an example of the resistance-reducing process. The inventors also proposed ion implantation as an alternative resistance-reducing process to plasma treatment, and confirmed that the resistance value of the oxide semiconductor film is reduced by implanting ions such as argon or boron into the oxide semiconductor film. It would be beneficial to have an apparatus and method that can further reduce the resistance value of the oxide semiconductor film compared to these processes.

In recent years, thin, bendable flexible displays have been proposed. One example of a flexible display is a foldable display known as a foldable display. Other proposals include a rollable display, which allows the display to be bent and stored in a manner that allows it to be rolled up inside the housing of a terminal. By adopting such flexible displays, it is possible to enlarge the display screen of a terminal without compromising portability or storability.

Substrates that make up flexible displays and on which TFTs are formed include thin glass and plastic films such as polyimide. When a plastic film is used for the substrate, the heat resistance temperature of the substrate is lower than when thin glass is used. Therefore, when a plastic film is used for the substrate, each process of manufacturing the display needs to be carried out at a lower temperature than when a glass substrate is used.

Patent Publication 2018-170319

The present invention aims to provide an ion beam irradiation device and an ion beam irradiation method that can reduce the resistance of an oxide semiconductor film that forms a TFT of a display.

The ion beam irradiation apparatus of the present invention comprises:
An ion beam irradiation device used in a manufacturing process of a display panel, which irradiates an irradiation target having an oxide semiconductor film with an ion beam containing predetermined ions,
A heating device for heating the irradiation object is provided,
The heating device is configured such that after the irradiation object is heated by the heating device, at least some of the ions can penetrate the oxide semiconductor film into the oxide semiconductor film.

According to this configuration, the oxide semiconductor film heated by the heating device is irradiated with an ion beam. The inventors confirmed that the resistance value of the oxide semiconductor film is reduced when the object to be irradiated is irradiated with an ion beam after heating, compared to when the object to be irradiated is irradiated with an ion beam at room temperature. The reason for the reduction in the resistance value has not been clearly elucidated, but the inventors believe that it is due to one or more of the following factors (a) to (c):
(a) When an oxide semiconductor film is irradiated with an ion beam while the temperature is elevated, metal elements in the oxide semiconductor film are bonded to each other, thereby generating carriers. Alternatively, bonds between metal elements in the oxide semiconductor film that have been cut by ion beam irradiation are rebonded by temperature elevation, thereby suppressing an increase in carrier scattering (a decrease in carriers and a decrease in orderliness).
(b) Irradiating the heated oxide semiconductor film with an ion beam improves the order of molecules in the oxide semiconductor film, thereby increasing carrier mobility. Alternatively, irradiating the oxide semiconductor film with an ion beam suppresses a decrease in the order of molecules in the oxide semiconductor film, thereby suppressing a decrease in carrier mobility.
(c) By increasing the temperature of the oxide semiconductor film, the breaking of bonds between metal elements and oxygen in the oxide semiconductor film due to ion beam irradiation was suppressed, an increase in carrier scattering was suppressed, and a decrease in carrier mobility was suppressed.
In the ion beam irradiation device of the present invention, the phrase "after the heating device heats the irradiation target, the ion beam is irradiated so that at least a part of the ions can reach the inside of the oxide semiconductor film" refers to a concept including irradiating the irradiation target with the ion beam so that at least a part of the ions can reach the inside of the oxide semiconductor film while the heating device heats the irradiation target. The ion beam irradiation device of the present invention may be any device that irradiates an ion beam onto an oxide semiconductor film that has been heated from room temperature or a predetermined temperature by a heating device.
In the ion implantation apparatus of the present invention, an ion beam is irradiated onto an object to be irradiated such that at least some of the ions can penetrate the oxide semiconductor film. Therefore, more bonds between atoms constituting the oxide semiconductor film are broken, and more carriers are generated, compared to a case where all of the irradiated ions are retained within the oxide semiconductor film.

The ion beam irradiation device of the present invention may also be configured such that the ions are boron ions, neon ions, or argon ions.

The ion beam irradiation device of the present invention may also be configured such that the irradiation object is formed from a predetermined base material and has a base material layer that gives flexibility to the display panel, and the heating device heats the irradiation object at a temperature equal to or lower than the heat resistance temperature of the base material.

The ion beam irradiation device of the present invention may also be configured such that the heating device includes a lamp that irradiates the irradiation object with light to heat the irradiation object.

The ion beam irradiation device of the present invention may also be configured such that the heating device has a plurality of lamp units in which a plurality of the lamps are arranged at predetermined positions.

With this configuration, even if the size of the object to be irradiated changes, the heating device can be configured by changing the arrangement of the lamp units or the number of lamp units used.

The ion beam irradiation device of the present invention may also be configured such that the heating device includes a resistance heating section that heats the irradiation object by resistance heating.

With this configuration, the object to be irradiated can be heated by resistance heating, so the object to be irradiated can be heated more uniformly compared to, for example, a case where the heating device is configured with a lamp heater.

The ion beam irradiation method in this embodiment includes the steps of:
An ion beam irradiation method used in a manufacturing process of a display panel, in which an irradiation target having an oxide semiconductor film is irradiated with an ion beam containing predetermined ions, the method comprising the steps of:
A first step of heating the irradiation object;
The method includes a second step, which is performed after the first step, of irradiating the oxide semiconductor film with the ion beam so that at least a part of the ions can reach inside the oxide semiconductor film.

According to this method, an oxide semiconductor film heated from room temperature or a predetermined temperature is irradiated with an ion beam. The inventors confirmed that the resistance value of the oxide semiconductor film is reduced when the object to be irradiated is heated and irradiated with an ion beam, compared with the case where the object to be irradiated is irradiated with an ion beam at room temperature.
In the ion beam irradiation method of the present invention, the "second step of irradiating the oxide semiconductor film with the ion beam after the first step so that at least some of the ions can reach the inside of the oxide semiconductor film" includes irradiating the oxide semiconductor film with the ion beam while heating the object to be irradiated so that at least some of the ions can reach the inside of the oxide semiconductor film. The ion beam irradiation method of the present invention may be any method in which an ion beam is irradiated to an oxide semiconductor film that has been heated from room temperature or a predetermined temperature by a heating device.
In the ion implantation method of the present invention, an ion beam is irradiated onto an object to be irradiated such that at least some of the ions can penetrate the oxide semiconductor film. Therefore, more bonds between atoms constituting the oxide semiconductor film are broken, and more carriers are generated, compared to a case where all of the irradiated ions are retained within the oxide semiconductor film.

In addition, in the ion beam irradiation method of the present invention, the ions may be boron ions, neon ions, or argon ions.

The object may be formed from a specific base material and have a base material layer that provides flexibility to the display panel, and in the first step, the object to be irradiated may be heated at a temperature equal to or lower than the heat resistance temperature of the base material.

The present invention makes it possible to reduce the resistance of the oxide semiconductor film that forms the TFT of a display.

FIG. 1 is a schematic diagram showing a first ion beam irradiation device in a first embodiment of the present invention. FIG. 2 is a schematic view partially illustrating the inside of a processing chamber in the first embodiment. FIG. 2 is a side view showing the holding device according to the first embodiment. FIG. 4 is a front view showing a modified example of the heating device in the first embodiment. FIG. 13 is a schematic diagram showing a second ion beam irradiation device according to a second embodiment of the present invention. FIG. 2 is a cross-sectional view showing an irradiation object in the first and second embodiments. 11 is a cross-sectional view showing a modified example of an irradiation object in the first and second embodiments. FIG. 3 is a flowchart illustrating an ion beam irradiation method according to the present invention. 13 is a graph showing the results of measuring the sheet resistance after performing room temperature implantation, room temperature implantation followed by 300° C. annealing, and high temperature implantation at 300° C. using various ion species in an IGZO film. 13 is a graph showing the results of measuring sheet resistance versus ion energy when a 50 nm thick IGZO film was implanted with boron ions (B ⁺ ) at room temperature, annealed at 300° C. after room temperature implantation, and implanted at a high temperature of 300° C. 13 is a graph showing the results of measuring sheet resistance versus ion energy when boron ions (B ⁺ ) are implanted into a 25 nm-thick IGZO film at room temperature and at a high temperature of 300° C.; 13 is a table showing the results of measuring the film density of an IGZO film, and the film density of an IGZO film after a heat treatment, boron ion implantation, a heat treatment after boron ion implantation, and a high-temperature boron ion implantation of the IGZO film.

A first ion beam irradiation apparatus 10A according to a first embodiment of the present invention will be described.
The first ion beam irradiation device 10A shown in FIG. 1 is used in a process for manufacturing a display panel such as a liquid crystal display or an organic EL display, and is an apparatus for irradiating an object T corresponding to the irradiation object of the present invention with an ion beam IB. The first ion beam irradiation device 10A is particularly an apparatus for irradiating an object T having an oxide semiconductor film 102 shown in FIG. 6 with an ion beam IB. The first ion beam irradiation device 10A is not limited to an apparatus capable of irradiating an ion beam IB only to an object T having an oxide semiconductor film. For example, the first ion beam irradiation device 10A may also be used when irradiating an object on which a low-temperature polysilicon film is formed with an ion beam IB. In other words, the first ion beam irradiation device 10A may be any apparatus that has a function of irradiating an object T having an oxide semiconductor film with an ion beam IB.

As shown in FIG. 6, the object T in this embodiment is a rectangular glass substrate 101 on which a TFT is formed. An oxide semiconductor film 102 is formed on the substrate 101, and the oxide semiconductor film 102 is covered with an insulating film 103. A gate 104 made of metal is formed on the insulating film 103. In FIG. 6, in order to facilitate understanding of the present invention, only the configuration related to the gist of the present invention is shown in a simplified form. The oxide semiconductor film 102 does not need to be formed directly on the surface of the substrate 101, and may be formed, for example, on an insulating film (not shown) formed on the substrate 101. In this embodiment, the oxide semiconductor film 102 is IGZO (indium gallium zinc oxide: InGaZnO), but is not limited thereto. For example, the oxide semiconductor film 102 may be indium zinc oxide (ITZO), zinc oxide (ZnO), indium gallium oxide (IGO), indium tin oxide (ITO), or indium oxide (InO).

As shown in FIG. 1, the first ion beam irradiation device 10A includes an ion source unit 11, an ion beam transport unit 12, and a processing unit 13. The ion source unit 11 includes a plasma generation chamber 11a that generates plasma from raw materials supplied from the outside, and an extraction electrode 11b for extracting ions contained in the plasma generated in the plasma generation chamber 11a as an ion beam IB. The ion source unit 11 also includes an acceleration electrode 11c for accelerating the ions extracted from the plasma generation chamber 11a.

The ion beam transport unit 12 includes a vacuum vessel 12a through which the ion beam IB passes and a mass analyzer 12b, and transports the ion beam IB from the ion source unit 11 into the processing chamber 14 of the processing unit 13. While passing through the inside of the vacuum vessel 12a, the ion beam IB is mass-separated by the mass analyzer 12b, and the ion beam IB consisting of the desired ions is introduced into the processing chamber 14. The ion beam IB introduced into the processing chamber 14 is irradiated onto the object T, so that the object T is subjected to an ion beam irradiation process. The ion source unit 11 and the ion beam transport unit 12 in this embodiment adopt a configuration that is widely known in ion beam irradiation devices used in display manufacturing processes.

The processing unit 13 has a processing chamber 14 in which an ion beam irradiation process is performed on the target object T, a transfer chamber 15 that communicates with the processing chamber 14, and a load lock chamber 16 adjacent to the transfer chamber 15. The processing unit 13 also has a transfer section 17 that transfers the target object T between the processing unit 13 and the load lock chamber 16. In this embodiment, the transfer section 17 is configured as a room having a specific partitioned internal space, but it may also be an area outside the load lock chamber 16 that is placed under atmospheric pressure.

The transfer chamber 15 and the load lock chamber 16 constitute a transfer path L1, which is a path along which the object T is transferred from the transfer section 17 into the processing chamber 14 and the processed object T is transferred from the processing chamber 14 to the transfer section 17. The first ion beam irradiation device 10A has two transfer paths L1, one of which is referred to as a first transfer path L1a and the other as a second transfer path L1b. The object T is transferred along the transfer path L1 by multiple transfer robots (not shown).

The first ion beam irradiation device 10A has two transfer paths L1, i.e., the first transfer path L1a and the second transfer path L1b, and is equipped with two transfer chambers 15 and two load lock chambers 16. In this embodiment, one of the two transfer chambers 15 is referred to as the first transfer chamber 15a, and the other is referred to as the second transfer chamber 15b. In addition, one of the two load lock chambers 16 is referred to as the first load lock chamber 16a, and the other is referred to as the second load lock chamber 16b. In addition, the transfer section 17 corresponding to the first load lock chamber 16a is particularly referred to as the first transfer section 17a, and the transfer section 17 corresponding to the second load lock chamber 16b is particularly referred to as the second transfer section 17b. Note that the first transfer section 17a and the second transfer section 17b do not need to be separate independent rooms or areas. For example, the target T may be transported from the same location to each of the first load lock chamber 16a and the second load lock chamber 16b.

In the first ion beam irradiation device 10A, the first transfer chamber 15a and the first load lock chamber 16a form the first transfer path L1a, and the second transfer chamber 15b and the second load lock chamber 16b form the second transfer path L1b.

A first gate valve 19a is disposed between the first load lock chamber 16a and the first transfer section 17a to isolate the interior of the first load lock chamber 16a from the first transfer section 17a. A second gate valve 19b is disposed between the first load lock chamber 16a and the first transfer chamber 15a to isolate the internal spaces of the two chambers. Similarly, a third gate valve 19c is disposed between the second load lock chamber 16b and the second transfer section 17b, and a fourth gate valve 19d is disposed between the second load lock chamber 16b and the second transfer chamber 15b.

The object T to be transported along the first transport path L1a is first transported from the first transfer section 17a into the first load lock chamber 16a with the first gate valve 19a open and the second gate valve 19b closed. Then, after the first gate valve 19a is closed, the first load lock chamber 16a is evacuated by an exhaust pump (not shown), and then the second gate valve 19b is opened. Then, the object T is transported from the first load lock chamber 16a through the first transport chamber 15a into the processing chamber 14, where a predetermined ion beam irradiation process is performed. The processed object T is transported from the processing chamber 14 through the first transport chamber 15a again into the first load lock chamber 16a. Then, the second gate valve 19b is closed, and a predetermined gas or air is introduced into the first load lock chamber 16a, thereby returning the inside of the first load lock chamber 16a to atmospheric pressure. The first gate valve 19a is then opened, and the target object T is transported to the first delivery section 17a.

Similarly, the object T to be transported along the second transport path L1b is first transported from the second transfer section 17b into the first load lock chamber 16a with the third gate valve 19c open and the fourth gate valve 19d closed. Then, after the third gate valve 19c is closed, the second load lock chamber 16b is evacuated by an exhaust pump (not shown), and then the fourth gate valve 19d is opened. Then, the object T is transported from the second load lock chamber 16b through the second transport chamber 15b into the processing chamber 14, where a predetermined ion beam irradiation process is performed. The object T that has been subjected to the process is transported from the processing chamber 14 through the second transport chamber 15b again into the second load lock chamber 16b. Then, the fourth gate valve 19d is closed, and a predetermined gas or air is introduced into the second load lock chamber 16b, thereby returning the second load lock chamber 16b to atmospheric pressure. The third gate valve 19c is then opened, and the target object T is transported to the second delivery section 17b.

Inside the processing chamber 14, a holding device 20 for holding the object T and a heating device 30 for heating the object T are arranged. The first ion beam irradiation device 10A is equipped with two holding devices 20. In this embodiment, one of the holding devices 20 for holding the object T brought into the processing chamber 14 along the first transport path L1a is referred to as the first holding device 20a, and the object T held by the first holding device 20a is referred to as the first object T1. Similarly, the other holding device 20 for holding the object T brought into the processing chamber 14 along the second transport path L1b is referred to as the second holding device 20b, and the object T held by the second holding device 20b is referred to as the second object T2.

The first ion beam irradiation device 10A is equipped with two heating devices 30, the heating device 30 that heats the first object T1 is referred to as the first heating device 30a, and the heating device 30 that heats the second object T2 is referred to as the second heating device 30b. As shown in Figures 1 and 2, the first heating device 30a and the second heating device 30b are both installed on the inner wall of the processing chamber 14.

As shown by the dashed line in FIG. 1, the holding device 20 is configured to move linearly along a predetermined transfer path 22 in the processing chamber 14 while holding the object T. More specifically, the holding device 20 is a device that transfers the holder 21 shown in FIG. 2 along the transfer path 22 while holding the object T. In other words, the object T moves linearly along the transfer path 22 while being held by the holder 21 of the holding device 20.

The first ion beam irradiation device 10A is configured so that the target object T crosses the ion beam IB while moving linearly along the transfer path 22. In other words, the target object T is subjected to an ion beam irradiation process as the target object T crosses the ion beam IB. Note that the first ion beam irradiation device 10A may be configured to move the target object T back and forth along the transfer path 22 once or multiple times, so that the target object T crosses the ion beam IB multiple times.

The first ion beam irradiation device 10A has two holding devices 20 and thus has two transfer paths 22. Of the two transfer paths 22, the transfer path 22 corresponding to the first holding device 20a is referred to as the first transfer path 22a, and the transfer path 22 corresponding to the first holding device 20a is referred to as the second transfer path 22b. The first holding device 20a moves the first object T1 back and forth between a first start point Pa and a first end point Qa shown in FIG. 1. The second holding device 20b moves the second object T2 back and forth between a second start point Pb and a second end point Qb shown in FIG. 1.

As shown in FIG. 2, the holding device 20 has a comb-shaped holding body 21 that holds the placed object T, and the holding body 21 is configured to be able to rotate around a predetermined rotation axis A. As shown in FIG. 3, the object T brought into the processing chamber 14 is placed on the holding body 21 in a lying state and is held by the holding body 21 by a clamp (not shown). The holding body 21 then rotates around the rotation axis A so as to rise up. This rotation causes the object T to rise up, and the object T faces the heating device 30, as shown by the dashed line in FIG. 3. The heating device 30 then operates to heat the object T for a predetermined period of time, and immediately thereafter the holding body 21 begins to move along the transport path 22. As the holder 21 moves along the transfer path 22, the target object T moves from the first starting point Pa to the first ending point Qa, or from the second starting point Pb to the second ending point Qb, during which the target object T crosses the ion beam IB and is irradiated with the ion beam IB.

After the ion beam irradiation process is performed on the target object T in the processing chamber 14, the holder 21 rotates again around the rotation axis A, so that the target object T is laid down again, and is transported to the outside along the transport path L1 by a transport robot (not shown).

More specifically, the first object T1, which is carried into the processing chamber 14 and held by the first holding device 20a, faces the first heating device 30a at the first starting point Pa, and is heated by the first heating device 30a at the first starting point Pa. The first object T1 heated by the first heating device 30a is transported by the first holding device 20a from the first starting point Pa to the first end point Qa, during which the first object T1 is irradiated with the ion beam IB. After that, the first object T1 returns to the first starting point Pa again, and is then carried out of the processing chamber 14. Similarly, the second object T2, which is carried into the processing chamber 14 and held by the second holding device 20b, faces the second heating device 30b at the second starting point Pb, and is heated by the second heating device 30b at the second starting point Pb. The second object T2 heated by the second heating device 30b is transported by the second holding device 20b from the second starting point Pb to the second end point Qb, during which the second object T2 is irradiated with the ion beam IB. After that, the second object T2 returns to the second starting point Pb again, and is then transported out of the processing chamber 14.

In the first ion beam irradiation device 10A, the ion beam IB is irradiated immediately after the heating device 30 heats the target T, but it is sufficient that the ion beam IB can be irradiated to the target T that is at room temperature or in a state where the temperature is raised from a predetermined temperature. For example, the first ion beam irradiation device 10A may have the heating device 30 disposed in the transfer chamber 15 or the load lock chamber 16. The first ion beam irradiation device 10A may also have a configuration for preliminarily heating the target T by a device other than the heating device 30 disposed in the transfer chamber 15 or the load lock chamber 16, etc.

The heating device 30 of this embodiment heats the object T before the object T is irradiated with the ion beam IB, and is a lamp heater composed of a halogen lamp that emits infrared rays. More specifically, as shown in FIG. 2, the heating device 30 includes a plurality of lamp units 32 in which a plurality of lamps 31 are arranged at predetermined positions, and a control unit 33 that controls each lamp unit 32. In this embodiment, each lamp unit 32 has a total of 12 lamps 31 arranged, three in the vertical direction and four in the horizontal direction. In addition, the heating device 30 of this embodiment has a configuration in which two lamp units 32 are arranged vertically and two in the horizontal direction, with the longitudinal direction of the housing of the lamp unit 32 facing horizontally.

The control unit 33 controls each lamp unit 32, and may not only control the on/off of the lamps 31 but also change the output of the lamps 31. The control unit 33 may also control the lamp units 32 based on the results of measurements of the surface temperature of the object T, etc.

The number or arrangement of the lamp units 32 used may be changed depending on the size of the object T. FIG. 4 shows a modified version of the heating device 30, in which the heating device 30 is configured with two lamp units 32 arranged vertically and four lamp units 32 arranged horizontally, with the longitudinal direction of the housing oriented vertically. In this way, by changing the arrangement or number of the lamp units 32, a heating device 30 can be easily manufactured according to the size of the object T.

The heating device 30 is not limited to the form shown in this embodiment. The first ion beam irradiation device 10A may irradiate the ion beam IB to the object T so that at least some of the ions can reach the inside of the oxide semiconductor film 102 while the heating device 30 heats the object T. In other words, the first ion beam irradiation device 10A may be capable of irradiating the ion beam to the oxide semiconductor film 102 in a state in which the temperature is raised from room temperature or a predetermined temperature by the heating device 30. For example, the heating device 30 may be configured so that the holding device 20 has a function of heating the object T.

Next, an ion beam irradiation method using the first ion beam irradiation apparatus 10A of the first embodiment will be described.
The ion beam irradiation method in this embodiment irradiates the oxide semiconductor film 102 of the target T shown in Fig. 6 with the ion beam IB so that at least some of the ions contained in the ion beam IB reach the oxide semiconductor film 102. The inventors have discovered that the resistance value of the oxide semiconductor film 102 is reduced by irradiating the heated oxide semiconductor film 102 with the ion beam IB. Although the reason why the sheet resistance is reduced has not been clearly elucidated, the inventors believe that it is due to one or more of the following factors (a) to (c).
(a) When an oxide semiconductor film is irradiated with an ion beam while the temperature is elevated, metal elements in the oxide semiconductor film are bonded to each other, thereby generating carriers. Alternatively, bonds between metal elements in the oxide semiconductor film that have been cut by ion beam irradiation are rebonded by temperature elevation, thereby suppressing an increase in carrier scattering (a decrease in carriers and a decrease in orderliness).
(b) Irradiating the heated oxide semiconductor film with an ion beam improves the order of molecules in the oxide semiconductor film, thereby increasing carrier mobility. Alternatively, irradiating the oxide semiconductor film with an ion beam suppresses a decrease in the order of molecules in the oxide semiconductor film, thereby suppressing a decrease in carrier mobility.
(c) By increasing the temperature of the oxide semiconductor film, the breaking of bonds between metal elements and oxygen in the oxide semiconductor film due to ion beam irradiation was suppressed, an increase in carrier scattering was suppressed, and a decrease in carrier mobility was suppressed.

The inventors performed a process of ion implantation of each ion species at room temperature (hereinafter, room temperature implantation) for various positive ions of H ⁺ , He ⁺ , B ⁺ , C ⁺ , N ⁺ , O ⁺ , F ⁺ , Ne ⁺ , PHx ⁺ , and Ar ⁺ into an IGZO film formed on the surface of the object T under the same conditions, a process of annealing the object T to 300 ° C after the room temperature implantation (hereinafter, room temperature implantation followed by heating at 300 ° C), and a process of ion implantation of each ion species in a state where the object T is heated to 300 ° C (hereinafter, 300 ° C high temperature implantation), and measured the sheet resistance of the IGZO film after each process. In addition, for comparison, the sheet resistance value of the IGZO film at room temperature and the sheet resistance value of the IGZO film after the annealing process at 300 ° C were measured. FIG. 9 is a graph showing the results.

The objects T used in the measurements were all glass substrates each having an IGZO film formed thereon to a thickness of 50 nm, and in each treatment, various ions were implanted into the IGZO film under the same conditions of 1×10 ¹⁵ ions/cm ² .

9, it was confirmed that for all ion species measured, the sheet resistance value was reduced by high-temperature implantation at 300° C. compared with room-temperature implantation and room-temperature implantation followed by heat treatment at 300° C. In particular, when boron ions (B ⁺ ), neon ions, and argon ions (Ar ⁺ ) were implanted, the resistance value after high-temperature implantation at 300° C. was 1×10 ⁴ Ω/sq. or less, and the sheet resistance value was significantly reduced compared with room-temperature implantation followed by heat treatment at 300° C.

In other words, it was confirmed that by using an ion beam IB containing either boron ions (B ⁺ ), neon ions, or argon ions (Ar ⁺ ), the resistance value of the IGZO film can be reduced sufficiently for practical use, even when the target object T is heated to a relatively low temperature of 300°C.

The inventors also used boron ions (B ⁺ ) to implant an IGZO film having a thickness of 50 nm at room temperature, heat treatment at 300° C. after implantation at room temperature, and high-temperature implantation at 300° C. while changing the ion energy, and then measured the sheet resistance of each IGZO film. FIG. 10 is a graph showing the results.

In Figure 10, in the case of room temperature implantation followed by 300°C heat treatment, the sheet resistance value is reduced in the 10-20 keV ion energy region compared to room temperature implantation, but is increased in the 30-80 keV region compared to room temperature implantation. This is thought to be because in the 10-20 keV region, room temperature implantation first creates oxygen vacancies in the IGZO film, generating electrons, and then during the subsequent heat treatment, the oxygen vacancies are repaired and at the same time, boron and oxygen in the IGZO film combine to generate additional new oxygen vacancies.

In contrast, in the 30-80 keV region, many boron ions penetrate the IGZO film during boron ion implantation, and it is believed that this is because the oxygen vacancies are repaired without creating any additional oxygen vacancies during the subsequent heat treatment.

On the other hand, when high-temperature implantation at 300°C is performed, the sheet resistance is reduced in all regions from 20 to 80 keV compared to room temperature implantation and room temperature implantation followed by heating at 300°C. This is because oxygen vacancies are generated and carriers are generated by implanting boron ions into the object T, which has been heated to 300°C in advance. At the same time, the dangling bonds in the IGZO film that were cut by the implantation of boron ions are immediately restored to bonds, which is presumably why the sheet resistance is lower than in the case of room temperature implantation.

In this way, it was confirmed that regardless of the energy of the boron ions implanted, by performing high-temperature implantation at 300°C, the sheet resistance of the IGZO film can be further reduced compared to room temperature implantation and room temperature implantation followed by heat treatment at 300°C.

The inventors further performed similar measurements by changing the thickness of the IGZO film. In detail, using boron ions (B ⁺ ), the ion energy was changed and room temperature implantation and high temperature implantation at 300° C. were performed on an IGZO film having a thickness of 25 nm, and the sheet resistance value of each IGZO film was measured after performing each of these implantations. FIG. 11 is a graph showing the results.

As can be seen from FIG. 11, it was confirmed that even when a 25 nm thick IGZO film is used, the sheet resistance of the IGZO film can be reduced by performing high-temperature implantation at 300° C., regardless of the energy of the implanted ions, compared to room temperature implantation. In other words, even when the IGZO film is thin, the sheet resistance of the IGZO film can be reduced by performing high-temperature implantation at 300° C.

Furthermore, it was confirmed that the sheet resistance value of the IGZO film could be reduced to less than 1×10 ⁴ Ω/sq. regardless of whether the IGZO film had a thickness of 50 nm or 25 nm, regardless of the ion energy.

As can be seen from Figures 9 to 11, when it is desired to process an object T on which an IGZO film is formed at 300°C or less, the resistance value of the IGZO film can be reduced more by ion implantation in a state where the object T is heated to 300°C than by performing room temperature implantation on the object T and then annealing at 300°C.

Furthermore, by implanting boron ions (B ⁺ ), neon ions, and argon ions (Ar ⁺ ) into the target T heated to 300° C., the sheet resistance of the IGZO film can be reduced to less than 1×10 ⁴ Ω/sq. In particular, since the sheet resistance of an IGZO film having a thickness of 25 nm can be reduced to less than 1×10 ⁴ Ω/sq., the IGZO film can also be applied to devices requiring thinner semiconductor films.

The inventors further measured the film density of an amorphous IGZO (a-IGZO) film that was not implanted with ions, a heat-treated a-IGZO film, an a-IGZO film implanted with boron ions (B ⁺ ) at room temperature, an a-IGZO film implanted with boron ions (B ⁺ ) and then heat-treated, and an a-IGZO film implanted at high temperature, by XRR (X-ray reflectivity) analysis. Figure 12 is a table showing the results.

12, the film density of the a-IGZO film heat-treated after implanting boron ions (B ⁺ ) is almost the same as that of the a-IGZO film implanted with boron ions (B ⁺ ) at room temperature. In contrast, the film density of the a-IGZO film implanted at high temperature is increased by 0.08 g/cm ³ compared to the a-IGZO film heat-treated after implanting boron ions (B ⁺ ).

The film density of the a-IGZO film that was heat-treated after implanting boron ions (B ⁺ ) is smaller than that of the unimplanted film. This is because the ion implantation causes oxygen loss in the crystals of the IGZO film, increasing the number of dangling bonds of metal atoms. In this case, the mobility of free electrons in the crystals decreases.

In contrast, in a-IGZO films implanted at high temperature, the film density remains almost unchanged compared to room temperature implantation. When implanted at high temperature, the bonds and film density increase, and the electron mobility increases, compared to when heat treatment is performed after ion implantation. Therefore, high temperature injection into IGZO films can be applied to devices that require high responsiveness.

In the ion beam irradiation method according to the present embodiment, it is considered that one of the factors that reduces the resistance value of the oxide semiconductor film 102 is that oxygen or metal defects occur inside the oxide semiconductor film 102 due to irradiation of the oxide semiconductor film 102 with the ion beam IB. In other words, in the ion beam irradiation method according to the present embodiment, it is not necessary to irradiate the ion beam IB so that the ions contained in the ion beam IB remain within the oxide semiconductor film 102. The beam energy may be set so that at least some of the ions contained in the ion beam IB can penetrate the oxide semiconductor film 102, thereby causing more defects in the oxide semiconductor film 102.

First, plasma containing, for example, argon ions is generated in the plasma generation chamber 11a. Then, the ions contained in the plasma generated in the plasma generation chamber 11a are extracted as an ion beam, and the ion beam IB is mass-separated by passing it through the ion beam transport unit 12, and the ion beam IB consisting of argon ions is guided into the processing chamber 14.

On the other hand, as shown in FIG. 8, a first step S1 is performed in which the object T, which is the object to be irradiated, is heated. More specifically, in the first step S1, the object T transported into the processing chamber 14 along the transport path L1 is heated by the heating device 30 while being held by the holding device 20. The temperature of the oxide semiconductor film 102 increases as the object T is heated. After that, the object T is transported along the transfer path 22, and a second step S2 is performed in which the object T is irradiated with the ion beam IB.

The first ion beam irradiation device 10A is configured to hold the second object T2 in the second holding device 20b and wait while the first object T1 is irradiated with the ion beam IB. This allows the second object T2 to be heated and the second object T2 to be irradiated with the ion beam immediately after the first object T1 is irradiated with the ion beam. The first ion beam irradiation device 10A is also configured to hold the first object T1 in the first holding device 20a and wait while the second object T2 is irradiated with the ion beam IB. This allows the first object T1 to be heated and the first object T1 to be irradiated with the ion beam immediately after the second object T2 is irradiated with the ion beam. In other words, the first ion beam irradiation device 10A is provided with a plurality of transport paths L1, thereby improving the throughput of the process of ion beam irradiation of the object T.

In the second step S2, it is necessary to make the argon ions contained in the ion beam IB reach the inside of the oxide semiconductor film 102. Therefore, it is necessary to appropriately set the beam energy of the ion beam IB, but the optimal beam energy of this ion beam IB varies depending on the material and film thickness of the oxide semiconductor that constitutes the oxide semiconductor film 102, the presence or absence of an insulating film 103 that covers the oxide semiconductor film 102, the thickness dimension of the insulating film 103, etc.

Also, as shown in FIG. 7, the object T may have a structure in which a release layer 105 and a base material layer 106 are disposed between the substrate 101 and the oxide semiconductor film 102. In this modification, the base material layer 106 is made of, for example, polyimide, and the base material layer 106 provides flexibility to the display panel formed from the object T.

When the base layer 106 is peeled off from the glass substrate 101 via the peeling layer 105, it functions as a flexible substrate layer that gives flexibility to the display. In other words, when a flexible display is created from the object T, the flexible display can be folded or bent by having the base layer 106.

In this case, the control unit 33 of the heating device 30 of the first ion beam irradiation device 10A controls the heating device 30 so that the temperature to which the target object T is heated does not exceed the heat resistance temperature of the base material, such as polyimide, that forms the base material layer 106.

The ion beam irradiation method of this embodiment can reduce the resistance value of the oxide semiconductor film 102. Therefore, the thickness dimension of the display panel formed from the object T can be reduced, which contributes to making the display panel thinner. In addition, the ion beam irradiation device and ion beam irradiation method of the present invention are particularly useful in display devices that employ a folding, folding, or rolling-up storage method, such as so-called foldable displays or rollable displays.

Next, a second ion beam irradiation device 10B in a second embodiment of the present invention will be described. However, components having the same functions as the first ion beam irradiation device 10A in the first embodiment are given the same reference numerals as in the first embodiment, and their description will be omitted. In addition, the second ion beam irradiation device 10B uses the same ion source unit 11 and ion beam transport unit 12 as the first ion beam irradiation device 10A, and these components are omitted in FIG. 5.

The second ion beam irradiation device 10B includes a heating chamber 40 and a resistance heating device 41 disposed in the heating chamber 40. The resistance heating device 41 heats the object T by resistance heating. The resistance heating device 41 has an internal heating element (not shown) that generates heat when electricity is applied, and heats the object T placed on the resistance heating unit 41a by generating heat from the heating element. That is, in the second ion beam irradiation device 10B, the object T is heated via the resistance heating unit 41a that generates heat by resistance heating. In the second ion beam irradiation device 10B, the object T can be heated in contact with the resistance heating unit 41a, and compared to the heating device 30, which is a lamp heater, the object T can be heated more uniformly, and the in-plane uniformity of the temperature of the object T can be improved.

As shown in FIG. 5, the second ion beam irradiation device 10B has one transfer chamber 15 connected to the processing chamber 14. In addition, two load lock chambers 16, 16 and a heating chamber 40 are connected to the transfer chamber 15.

In the second ion beam irradiation device 10B, the object T is transported along the third transport path L2a and the fourth transport path L2b shown in FIG. 5. In both the third transport path L2a and the fourth transport path L2b, the object T transported into the load lock chamber 16 is first transported into the heating chamber 40 via the transport chamber 15. The object T transported into the heating chamber 40 is placed on the resistance heating unit 41a and heated by the resistance heating device 41. The object T is then transported into the processing chamber 14 and irradiated with the ion beam IB. The object T is then transported again to the delivery unit 17 via the transport chamber 15 and the load lock chamber 16.

In the second ion beam irradiation device 10B, while one object T is being heated, another object T is being heated in the heating chamber 40. For example, as shown in FIG. 5, while the third object T3, which has been brought into the processing chamber 14 via the third transport path L2a, is being irradiated with the ion beam IB, the fourth object T4, which has been brought into the heating chamber 40 via the fourth transport path L2b, is being heated. When the third object T3 is irradiated with the ion beam IB and taken out of the processing chamber 14, the fourth object T4 is brought into the processing chamber 14, and the fourth object T4 is irradiated with the ion beam IB. During this time, the object T is again brought into the heating chamber 40 via the third transport path L2a and heated.

In other words, the second ion beam irradiation device 10B of the second embodiment can improve the throughput of the ion beam irradiation process on one object T by heating another object T while irradiating the other object T with the ion beam IB. Furthermore, in the second ion beam irradiation device 10B and the ion beam irradiation method using the second ion beam irradiation device 10B, the resistance value of the oxide semiconductor film 102 is reduced by irradiating the heated object T with the ion beam IB.

The present invention is not limited to the above-described embodiment and modified examples, and it goes without saying that various modifications are possible without departing from the spirit of the invention.

IB Ion beam T Target object 10A, 10B Ion beam irradiation device 11 Ion source unit 12 Ion beam transport unit 13 Processing unit 14 Processing chamber 20 Holding device 30 Heating device 31 Lamp 32 Lamp unit 40 Heating chamber 41 Resistance heating device 101 Substrate 102 Oxide semiconductor film 106 Base material layer

Claims (7)

An ion beam irradiation device used in a manufacturing process of a display panel, which irradiates an irradiation target having an oxide semiconductor film with an ion beam containing predetermined ions,
A heating device for heating the irradiation object is provided,
After the heating device heats the irradiation object, the ion beam is irradiated so that at least a part of the ions can penetrate the oxide semiconductor film ;
The ion beam irradiation device, wherein the ions are any one of H ⁺ , He ⁺ , B ⁺ , C ⁺ , N ⁺ , F ⁺ , Ne ⁺ , PHx ⁺ , and Ar ⁺ . the irradiation target is formed of a predetermined base material and has a base material layer that imparts flexibility to the display panel;
2. The ion beam irradiation device according to claim 1 , wherein the heating device heats the irradiation object to a temperature equal to or lower than the heat-resistant temperature of the base material. The ion beam irradiation device according to claim 1, wherein the heating device includes a lamp that irradiates the irradiation object with light to heat the irradiation object. 4. The ion beam irradiation device according to claim 3 , wherein the heating device has a plurality of lamp units in which a plurality of the lamps are arranged at predetermined positions. The ion beam irradiation device according to claim 1 , wherein the heating device comprises a resistance heating portion that heats the irradiation object by resistance heating. An ion beam irradiation method used in a manufacturing process of a display panel, in which an ion beam containing predetermined ions is irradiated onto an irradiation target having an oxide semiconductor film, the method comprising the steps of:
A first step of heating the irradiation object;
a second step of irradiating the oxide semiconductor film with the ion beam so that at least some of the ions penetrate the oxide semiconductor film into the oxide semiconductor film after the first step;
Including,
The ion beam irradiation method, wherein the ions are any one of H ⁺ , He ⁺ , B ⁺ , C ⁺ , N ⁺ , F ⁺ , Ne ⁺ , PHx ⁺ , and Ar ⁺ . the irradiation target is formed of a predetermined base material and has a base material layer that imparts flexibility to the display panel;
The ion beam irradiation method according to claim 6 , wherein in the first step, the irradiation object is heated to a temperature equal to or lower than the heat-resistant temperature of the base material.