JP7587937B2 - Conductive film forming method and film forming apparatus - Google Patents

Description

The present invention relates to a method for forming a conductive film and a film forming apparatus.

A technique is known for coating the inner surface of a recess formed in a film formation target with a metal film. In this technique, a metal film is formed on the film formation target and an overhanging portion of the metal film formed on the film formation target is etched alternately. This prevents the opening of the recess from being blocked by the overhanging portion of the metal film, and coats the inner surface of the recess with the metal film (see, for example, Patent Document 1).

JP 2008-283144 A

The recess covered with the metal film that functions as wiring is formed by the bottom surface of the recess, the inner side surface of the recess, and the top surface surrounding the opening of the recess. In recent years, in response to the requirements of devices manufactured using such film-forming targets, there has been a new demand for the formation of a conductive film that has a uniform thickness on the bottom surface and the inner side surface, while the top surface is sufficiently thicker than the bottom surface and the inner side surface.

The present invention aims to provide a method for forming a conductive film and a film forming apparatus that can ensure the thickness of the conductive film formed on the top surface surrounding the opening of the recess on which the film is to be formed, while suppressing variations in the thickness of the portions formed on the bottom surface and inner surface that define the recess.

The method for forming a conductive film to solve the above problem includes a first step including the start of forming a conductive film, and a second step that is performed after the first step and includes the end of forming the conductive film. The first step includes forming the conductive film by sputter deposition on a film formation target that has a film formation surface with a plurality of recesses and moves relative to a target, and etching the conductive film formed on the film formation target. The second step includes forming the conductive film by sputter deposition on the film formation target, and etching the conductive film by making the etching amount per unit time smaller than that of the first step.

The film forming apparatus for solving the above problem includes a film forming unit that forms a conductive film by sputtering on a film forming target having a film forming surface with a plurality of recesses, an etching unit that etches the conductive film formed on the film forming target, a transport unit that moves the film forming target relative to the target, and a control unit that controls the driving of the film forming unit, the etching unit, and the transport unit. The control unit controls the driving of the film forming unit, the etching unit, and the transport unit to execute a first step including the start of the formation of the conductive film, and a second step that is performed after the first step and includes the end of the formation of the conductive film. The first step includes forming the conductive film by sputtering on the film forming target that moves relative to the target, and etching the conductive film formed on the film forming target. The second step includes forming the conductive film by sputtering on the film forming target, and etching the conductive film by making the etching amount per unit time smaller than that of the first step.

When sputtering is performed on a film formation surface having a recess, the sputtered particles are more likely to reach the top surface surrounding the opening of the recess, and less likely to reach the bottom surface of the recess and the inner surface of the recess in that order. Therefore, when a conductive film is formed only by sputtering, the film thickness on the surface that defines the recess increases. In this respect, according to the above configuration, since the conductive film formed on the film formation target in the first step is etched, conductive particles are released from the corners covering the vicinity of the opening of the recess and the part formed on the bottom surface of the conductive film, and the conductive particles can be attached to the inner surface of the recess. As a result, it is possible to thicken the part of the conductive film located on the inner surface of the recess. In addition, since the second step is performed by sputtering with a smaller amount of etching than the first step, it is possible to preferentially allow the sputtered particles to reach the top surface surrounding the opening of the recess and the bottom surface. As a result, it is possible to increase the thickness of the conductive film at the top surface surrounding the opening of the recess, while minimizing the variation in thickness between the bottom surface and the inner side surface that define the recess.

In the above-mentioned conductive film forming method, the first step may include alternately forming the conductive film and etching the conductive film. With this configuration, it is possible to suppress the variation in film thickness on the surface defining the recess, compared to a case where the conductive film is formed and the conductive film is etched only once.

In the above-mentioned conductive film forming method, alternately forming the conductive film and etching the conductive film in the first step may include alternately etching the conductive film with a first etching amount per unit time and etching the conductive film with a second etching amount per unit time that is greater than the first etching amount.

According to the above configuration, in the first step, it is possible to alternate between a step in which the sputtered particles are prioritized to adhere to the top surface surrounding the opening of the recess and the bottom surface defining the recess, and a step in which the conductive particles emitted from the conductive film are prioritized to adhere to the inner surface defining the recess. This makes it possible to further reduce the variation in thickness on the surface defining the recess.

In the above-mentioned conductive film forming method, the sputter deposition includes emitting sputter particles according to the cosine law, the etching of the conductive film in the first step and the etching of the conductive film in the second step include etching the conductive film by irradiating an ion beam, and the etching of the conductive film in the second step may include irradiating the ion beam onto the film-forming target at an angle of incidence smaller than the angle of incidence in the first step.

According to the above configuration, in the second step, among the sputter particles emitted from the target by the sputter deposition, the sputter particles that are incident on the deposition target from an oblique direction are preferentially etched. Therefore, it is possible to increase the thickness of the conductive film at the portion formed on the top surface while suppressing the increase in the thickness variation between the inner surface and the bottom surface of the conductive film.

In the above-mentioned conductive film forming method, etching the conductive film in the first step may include irradiating the ion beam from a first ion source, and etching the conductive film in the second step may include irradiating the ion beam using a second ion source that irradiates the ion beam at an incidence angle smaller than the incidence angle of the first ion source.

The above configuration has two ion sources that irradiate ion beams at different angles of incidence, making it possible to simplify each ion source and reduce the processing load of the ion source compared to a system having only one ion source.

In the above-mentioned conductive film forming method, etching the conductive film in the first step may include irradiating the ion beam from an ion source, and etching the conductive film in the second step may include irradiating the ion beam at an incidence angle smaller than the incidence angle of the ion beam irradiated in the first step using the same ion source as in the first step.

With the above configuration, etching in the first step and etching in the second step can be performed using the same ion source, so the film formation device can be simplified compared to when two ion sources are used.

FIG. 1 is a diagram showing the configuration of a film forming apparatus according to a first embodiment. FIG. 4 is a schematic diagram for explaining an example of the operation of the film forming apparatus. 11A and 11B are schematic diagrams for explaining another example of the operation of the film forming apparatus. 3A to 3C are schematic views for explaining a method for forming a conductive film in the first embodiment. FIG. 4 is a schematic diagram showing a distribution curve of sputtered particles emitted from a target. 3A to 3C are schematic diagrams illustrating a method for forming a conductive film in the embodiment. 3A to 3C are schematic diagrams illustrating a method for forming a conductive film in the embodiment. 1 is a SEM image of a cross-sectional structure of a test piece of Example 1. 1 is an SEM image of a cross-sectional structure of a test piece of Comparative Example 1. 13 is an SEM image of a cross-sectional structure of a test piece of Comparative Example 2. 5A to 5C are schematic views for explaining a method of forming a conductive film in the second embodiment. FIG. 11 is a diagram showing the configuration of a film formation chamber according to a second embodiment. FIG. 2 is a diagram showing the configuration of a film formation chamber in the embodiment.

[First embodiment]
A conductive film forming method and a film forming apparatus according to a first embodiment will be described with reference to Figures 1 to 10. The film forming apparatus, the conductive film forming method, and examples will be described in this order below.

[Film forming equipment]
The film forming apparatus will be described with reference to Figures 1 to 3. Figure 1 shows a schematic side view of the film forming apparatus.

As shown in FIG. 1, the film forming apparatus 10 includes a film forming chamber 11 and a loading/unloading chamber 12. A gate valve 13 is located between the film forming chamber 11 and the loading/unloading chamber 12. An exhaust unit 14 is connected to the film forming chamber 11 and the loading/unloading chamber 12.

The deposition chamber 11 includes a cathode 15, an ion source 16, a transport unit 17, a gas supply unit 18, and a target power supply 19. The cathode 15 includes a target 15T. The target 15T is formed of a predetermined metal. The target 15T may be formed of a single metal or an alloy. The material for forming the target 15T may be at least one selected from the group consisting of, for example, Cu, Al, Ti, Ta, W, Mn, Zr, Hf, V, Ag, Pd, Pt, Au, Mg, Co, and Ni.

Target 15T has a shape that extends along the depth direction in FIG. 1. The surface to be sputtered of target 15T is exposed in the space defined by film formation chamber 11. The surface to be sputtered faces transport unit 17. Therefore, when film formation target S is being transported by transport unit 17, the surface to be sputtered faces film formation target S.

The ion source 16 has an irradiation port for irradiating an ion beam. The irradiation port is exposed in the space partitioned by the film formation chamber 11. The irradiation port has a shape extending along the depth direction in FIG. 1. The irradiation port faces the transport unit 17. Therefore, when the film formation target S is transported by the transport unit 17, the irradiation port faces the film formation target S. The ion source 16 generates an ion beam from a predetermined gas. The gas used to generate the ion beam may be, for example, a rare gas. The rare gas may be, for example, Ar. The ion source 16 is an example of an etching unit that etches a conductive film formed on the film formation target S. The ion source 16 etches the conductive film by irradiating the conductive film with an ion beam.

The transport unit 17 moves the film-forming target S relative to the target 15T. In this embodiment, the transport unit 17 moves the film-forming target S relative to the target 15T, whose position is fixed in the film-forming chamber 11. The transport unit 17 has a shape that extends along the transport direction of the film-forming target S.

The transport unit 17 transports the film-forming target S along the transport direction so that the film-forming target S faces the sputtered surface of the target 15T and the irradiation port of the ion source 16. The transport unit 17 alternates between a first transport and a second transport when transporting the film-forming target S. The first transport is a transport of the film-forming target S from the load/unload chamber 12 toward the film-forming chamber 11. In contrast, the second transport is a transport of the film-forming target S along the direction from the film-forming chamber 11 toward the load/unload chamber 12.

The gas supply unit 18 supplies a predetermined sputtering gas into the space defined by the deposition chamber 11. The gas supply unit 18, together with the exhaust unit 14, maintains the space defined by the deposition chamber 11 at a predetermined pressure by supplying the sputtering gas at a predetermined flow rate. The sputtering gas may be, for example, a rare gas. The rare gas may be, for example, Ar.

The target power supply 19 is connected to the cathode 15. The target power supply 19 applies a voltage to the target 15T. The target power supply 19 may be a DC power supply or an AC power supply.

In the film forming apparatus 10 of this embodiment, the film forming unit includes a cathode 15, a target power supply 19, and a gas supply unit 18. The film forming unit forms a conductive film on the film forming target S by sputtering film formation using a target 15T.

The film formation target S has, for example, a rectangular shape. In the film formation target S, the length of one side is, for example, 1500 mm or more and 2200 mm or less. The film formation target S may be, for example, a glass substrate. The film formation target S has a film formation surface on which a conductive film is formed. The film formation surface has a plurality of recesses. For example, the film formation surface has a plurality of grooves extending in a direction perpendicular to the extension direction of the target 15T, and the plurality of grooves are arranged at intervals in the extension direction of the target 15T. Also, for example, the film formation surface has a plurality of grooves extending in the extension direction of the target 15T, and the plurality of grooves are arranged at intervals in the direction perpendicular to the extension direction of the target 15T.

The loading/unloading chamber 12 loads the film-forming target S before film formation into the film-forming chamber 11, and loads the film-forming target S after film formation out of the film-forming chamber 11. When loading the film-forming target S before film formation into the film-forming chamber 11, the film-forming target S before film formation is first loaded into the loading/unloading chamber 12 exposed to the atmosphere. Next, the space defined by the loading/unloading chamber 12 is exhausted by the exhaust unit 14, thereby reducing the pressure to the same level as that of the film-forming chamber 11. After that, the gate valve 13 is opened, so that the space defined by the loading/unloading chamber 12 is connected to the space defined by the film-forming chamber 11. Then, the loading/unloading chamber 12 loads the film-forming target S before film formation into the film-forming chamber 11.

In contrast, when the film-forming target S after film formation is transported out, the gate valve 13 is opened, and the space defined by the load/unload chamber 12 is connected to the space defined by the film-forming chamber 11. Next, the load/unload chamber 12 transports the film-forming target S after film formation out of the film-forming chamber 11. Then, after the gate valve 13 is closed, the load/unload chamber 12 is exposed to the atmosphere. Then, the film-forming target S after film formation is transported out of the load/unload chamber 12.

The film forming apparatus 10 is equipped with a control unit 10C. The control unit 10C controls the operation of the film forming unit, the ion source 16, and the transport unit 17. In addition to the film forming unit, the ion source 16, and the transport unit 17, the control unit 10C also controls the operation of the gate valve 13 and the exhaust unit 14.

As shown in FIG. 2, the control unit 10C, for example, while the transport unit 17 is performing the first transport, drives the film formation unit to form a conductive film on the film formation surface of the film formation target S. At this time, the control unit 10C causes the gas supply unit 18 to supply sputtering gas at a predetermined flow rate, and causes the target power supply 19 to apply a predetermined voltage to the target 15T. This generates plasma in the vicinity of the target 15T, and the target 15T is sputtered. This causes sputter particles SP to be emitted from the target 15T.

As shown in FIG. 3, the control unit 10C, for example, while the transport unit 17 is performing the second transport, drives the ion source 16 to etch the conductive film formed on the film formation target S. At this time, the control unit 10C drives the ion source 16 to cause the ion source 16 to irradiate the ion beam IB from the irradiation port.

The control unit 10C may drive the film forming unit to form a conductive film while the transport unit 17 is performing the second transport. The control unit 10C may drive the ion source 16 to etch the conductive film while the transport unit 17 is performing the first transport.

[Method of forming conductive film]
A method for forming a conductive film will be described with reference to Fig. 4 to Fig. 6. Fig. 4, Fig. 6, and Fig. 7 shown below show a cross-sectional structure of the film-forming target S along a plane perpendicular to the plane on which the film-forming target S extends and perpendicular to the direction in which the recess SH of the film-forming target S extends.

The method for forming a conductive film includes a first step including the start of the formation of the conductive film, and a second step that is performed after the first step and includes the end of the formation of the conductive film. The first step includes forming a conductive film by sputtering on a film-forming target S that moves relative to the target, and etching the conductive film formed on the film-forming target S. The second step includes forming a conductive film by sputtering on the film-forming target S, and etching the conductive film by reducing the amount of etching per unit time compared to the first step. The method for forming a conductive film will be described in detail below with reference to the drawings.

In this embodiment, the first step alternates between forming a conductive film and etching the conductive film. In the first step, a set of forming a conductive film and etching the conductive film is repeated multiple times. In the first step, a conductive film is formed on the film-forming target S during the first transport of the film-forming target S, and the conductive film is etched during the second transport of the film-forming target S.

FIG. 4 diagrammatically illustrates sputtered particles SP flying toward the film-forming target S in the first transport, and a conductive film formed by the accumulation of the sputtered particles SP.
As shown in Fig. 4, the film-forming target S has a plurality of recesses SH. Each recess SH is formed by a top surface ST, a bottom surface SHb, and an inner side surface SHs. During the first transfer, the target 15T is sputtered, causing a plurality of sputter particles SP to fly toward the film-forming target S. As a result, a conductive film CF is formed on the film-forming target S, covering the bottom surface SHb, the inner side surface SHs, and the top surface ST of the film-forming target S. The top surface ST is a surface that surrounds the opening SHa of the recess SH in the film-forming target S.

FIG. 5 is a distribution diagram of emission frequency showing, in a polar coordinate system, the emission angle distribution of sputtered particles SP emitted from erosion points on the sputtered surface of the metal target 15T.
As shown in Fig. 5, the radius vector, which is the distance between a specific point on the polar coordinates and the erosion point 15TE of the sputtered surface 15Ta, is the emission frequency F. Also, the deviation angle, which is the angle formed by the straight line connecting the specific point on the polar coordinates and the erosion point 15TE and the sputtered surface 15Ta, is the emission angle θ. The emission angle distribution shown in Fig. 5 can be obtained from the actual measurement value of the film thickness distribution on the film formation target S. The emission angle distribution can be obtained, for example, from the distribution of the film thickness on each of the film formation targets S arranged at different TS distances.

As shown in Figure 5, in the distribution curve DC showing the distribution of the emission frequency of sputtered particles SP, the emission angle θ with the highest emission frequency F is 90°, and the relationship between the emission frequency F and the emission angle θ is given by the general cosine law, that is, F = cosn(90-θ) (n is an integer of 1 or more).

Therefore, as shown in FIG. 4, in a cross section along a plane perpendicular to the plane on which the film-forming target S extends and perpendicular to the direction in which the recess SH of the film-forming target S extends, the conductive film CF has the following shape. That is, the portion of the conductive film CF located on the top surface ST has a predetermined thickness. In addition, the opening SHa of each recess SH is reached not only by sputter particles SP flying in a direction perpendicular to the plane on which the film-forming target S extends, but also by sputter particles SP flying in a direction intersecting the plane at a predetermined angle. Therefore, the sputter particles SP are deposited on the top surface ST so as to extend into the area defined by the opening SHa.

In contrast, on the bottom surface SHb of the surfaces defining the recess SH, the sputtered particles SP are deposited so as to have a convex shape facing away from the bottom surface SHb. On the other hand, almost no sputtered particles SP reach the inner side surface SHs. Therefore, at the time when the first transport is completed, there is a variation in thickness in the portion of the conductive film CF formed on the surface defining the recess SH.

Figure 6 shows a schematic diagram of the particles of the ion beam IB flying toward the film-forming target S during the second transport, and the shape of the conductive film CF obtained by etching using the ion beam IB.

As shown in FIG. 6, the ion beam IB travels along the direction in which the ion source 16's irradiation port and the transport unit 17 face each other, and therefore the multiple particles IP contained in the ion beam IB also travel along the direction in which the irradiation port and the transport unit 17 face each other. Therefore, each particle IP is incident on the film-forming target S from a direction that is approximately perpendicular to the plane on which the film-forming target S spreads. As a result, some of the particles IP collide with the portion of the conductive film CF that is formed on the bottom surface SHb of the recess SH. In addition, another portion of the particles IP collide with the portion of the conductive film CF that is located on the top surface ST. In contrast, the particles IP hardly collide with the portion of the conductive film CF that is located on the inner side surface SHs of the recess SH.

Conductive particles CP are emitted from the conductive film CF at the portion where the particle IP collides. The conductive particles CP emitted from the portion of the conductive film CF formed on the bottom surface SHb fly toward the inner side surface SHs and adhere to the portion of the conductive film CF formed on the inner side surface SHs. When viewed from a viewpoint facing the opening SHa, the conductive particles CP emitted from the portion of the conductive film CF that protrudes toward the area defined by the opening SHa also fly toward the inner side surface SHs and adhere to the portion of the conductive film CF formed on the inner side surface SHs. As a result, the thickness of the conductive film CF becomes thinner at the portion where the conductive particles CP are emitted, while the thickness of the conductive film CF becomes thicker at the portion where the conductive particles CP adhere.

In the first process, film formation in the first transport and etching in the second transport are alternately performed, so that it is possible to suppress the variation in film thickness on the bottom surface SHb and the inner side surface SHs of the recess SH, compared to the case where the formation of the conductive film CF and the etching of the conductive film CF are each performed only once. Each time the film formation in the first transport and the etching in the second transport are performed, the position on the inner side surface SHs of the recess SH where the conductive particles CP emitted from the conductive film CF adhere changes. In detail, the thickness of the conductive film CF increases each time the film formation in the first transport is performed, so that the distance between the position where the conductive particles CP emitted from the conductive film CF adhere and the bottom surface SHb increases each time the etching in the second transport is performed. Therefore, it is possible to suppress the variation in film thickness on the inner side surface SHs of the recess SH.

As described above, when forming the conductive film CF and etching the conductive film CF are performed alternately in the first step, etching the conductive film CF with a first etching amount per unit time and etching the conductive film CF with a second etching amount per unit time may be performed alternately. The second etching amount is greater than the first etching amount.

For example, the conductive film CF may be etched with a first etching amount in the first second transport, and the conductive film CF may be etched with a second etching amount in the second second transport. Then, in the third and subsequent second transports, etching of the conductive film CF with the first etching amount and etching of the conductive film CF with the second etching amount may be repeated alternately in this order. Also, for example, the conductive film CF may be etched with a second etching amount in the first second transport, and the conductive film CF may be etched with the first etching amount in the second second transport. Then, in the third and subsequent second transports, etching of the conductive film CF with the second etching amount and etching of the conductive film CF with the first etching amount may be repeated alternately in this order.

The amount of etching by the ion beam IB is adjusted by the flow rate of the gas supplied to the ion source 16 and the pressure in the space defined by the deposition chamber 11. For example, the amount of etching tends to increase as the flow rate of the gas supplied to the ion source 16 increases. Also, the amount of etching tends to increase as the pressure in the space defined by the deposition chamber 11 decreases.

In the first step, it is possible to alternate between a step in which the adhesion of sputtered particles SP to the top surface ST and bottom surface SHb is prioritized and a step in which the adhesion of conductive particles CP emitted from the conductive film CF to the inner side surface SHs is prioritized. This makes it possible to further reduce thickness variations on the bottom surface SHb and inner side surface SHs.

In the film formation in the first transfer, as described above, the sputter particles SP are likely to reach the top surface ST and the bottom surface SHb. However, the number of sputter particles SP that can reach the bottom surface SHb is smaller than the number of sputter particles SP that can reach the top surface ST. Therefore, the film thickness at the top surface ST surrounding the opening SHa is thicker than the film thickness at the bottom surface SHb. As a result, when viewed from a viewpoint opposite to the plane on which the film formation target S spreads, if the etching amount is determined by prioritizing etching of the portion of the conductive film CF that protrudes into the area defined by the opening SHa, the portion of the conductive film CF formed on the bottom surface SHb is excessively etched. On the other hand, if the etching amount is determined to prevent excessive etching of the portion of the conductive film CF formed on the bottom surface SHb, the etching of the portion of the conductive film CF that protrudes into the area defined by the opening SHa is insufficient.

Therefore, by alternately performing etching with the first etching amount and etching with the second etching amount, excessive or insufficient etching is prevented in the etching of the portion of the conductive film CF that protrudes into the area defined by the opening SHa and in the etching of the portion formed on the bottom surface SHb.

Figure 7 shows a schematic diagram of the sputtered particles SP flying toward the film-forming target S in the second process, and the shape of the conductive film CF formed on the film-forming target S. Note that Figure 7 also shows a schematic diagram of the shape of the conductive film CF at the point when the first process is completed and the second process is started.

As shown in FIG. 7, in the second process, a conductive film CF is formed on the film formation target S with a reduced amount of etching compared to the first process. In this embodiment, the conductive film CF is not etched in the second process, so that the amount of etching is reduced compared to the first process. Therefore, in both the first and second transports described above, the conductive film CF is formed by sputter deposition using the target 15T.

At the time the second process is started, from the viewpoint of suppressing the variation in thickness of the portion of the conductive film CF formed on the inner side surface SHs of the recess SH, the portion formed on the bottom surface SHb of the recess SH has a variation in thickness. That is, in a cross section perpendicular to the plane on which the film-forming target S extends and perpendicular to the direction in which the recess SH extends, the portion of the conductive film CF formed on the bottom surface SHb has a concave shape facing in the direction approaching the bottom surface SHb.

As described above, the sputtered particles SP are emitted from the sputtered surface 15Ta of the target 15T according to the cosine law, so that the sputtered particles SP are deposited on the bottom surface SHb in a manner that suppresses the variation in film thickness. As a result, by performing the second process, it is possible to suppress the variation in film thickness between the film thickness on the inner side surface SHs of the recess SH and the film thickness on the bottom surface SHb of the recess SH.

On the other hand, a portion of the conductive film CF is formed on the top surface ST so as to suppress protrusion into the area defined by the opening SHa when viewed from a viewpoint opposite the plane on which the film-forming target S extends. Therefore, even if the conductive film CF is formed without performing etching in the second process, it is possible to further deposit sputtered particles SP on the top surface ST while suppressing protrusion into the area defined by the opening SHa, compared to the case where the first process is not performed.

When sputtering is performed on a deposition surface having a recess SH, the sputtered particles are more likely to reach the top surface ST of the deposition target S, and are less likely to reach the bottom surface SHb of the recess SH, and the inner side surface SHs of the recess, in that order. Therefore, when a conductive film CF is formed only by sputtering, there is a large variation in film thickness on the surface that defines the recess SH.

In this respect, according to this embodiment, the conductive film CF formed on the film formation target S is etched in the first step, so that conductive particles CP are released from the corners of the conductive film CF that cover the vicinity of the opening SHa of the recess SH and from the portion formed on the bottom surface SHb, and this makes it possible to attach the conductive particles CP to the inner side surface SHs of the recess. As a result, it is possible to increase the thickness of the portion of the conductive film CF that is located on the inner side surface SHs of the recess SH.

In addition, in the second process, the amount of etching is smaller than in the first process, and sputtering deposition is performed, so that the sputtered particles SP can preferentially reach the top surface ST and bottom surface SHb surrounding the opening SHa of the recess SH. As a result, it is possible to increase the thickness of the conductive film CF at the top surface ST surrounding the opening SHa of the recess SH, while suppressing the variation in thickness between the bottom surface SHb and the inner side surface SHs that define the recess SH.

[Example]
An example and a comparative example will be described with reference to FIGS.
[Example 1]
A glass substrate having a plurality of recesses on its film-forming surface was prepared as a film-forming target. In the film-forming surface, recesses having a depth of 650 nm and a width of 500 nm were formed at a pitch of 1 μm in a cross section perpendicular to the plane on which the film-forming target spreads and perpendicular to the extending direction of the recesses. The film-forming target was transported in a state in which the extending direction of the recesses of the film-forming target was perpendicular to the transporting direction of the film-forming target. Then, while the film-forming target was being transported, the first and second steps were performed under the following conditions to form a conductive film such that the thickness of the portion of the conductive film formed on the top surface surrounding the opening of the recesses was 600 nm or more.

In the first process, film formation was performed during the first transport, and etching was performed during the second transport. In contrast, in the second process, film formation was performed during both the first and second transports. In addition, in the second transport, transports in which etching was performed with the first etching amount and transports in which etching was performed with the second etching amount were alternated.

[First step]
[Film formation conditions]
Target: NiCu target Power supply: 5.8 kW
・Deposition pressure 0.45 Pa
Sputtering gas: Ar gas Gas flow rate: 150 sccm
・Transport speed: 857 mm/min. ・Transportation count: 4 times

[Etching conditions]
Supply gas: Ar gas Applied voltage: 2500V
Chamber pressure: 0.06 Pa (first etching amount)
Gas flow rate: 20 sccm (first etching amount)
Chamber pressure: 0.04 Pa (second etching amount)
Gas flow rate: 25 sccm (second etching amount)
・Transport speed: 100 mm/min ・Transportation frequency: 4 times

[Second step]
Target: NiCu target Power supply: 5.8 kW
・Pressure inside chamber: 0.45 Pa
Sputtering gas: Ar gas Gas flow rate: 150 sccm
・Transport speed: 857 mm/min ・Transportation count: 3 times

[Comparative Example 1]
A film formation target was prepared that was the same as the film formation target of Example 1. Then, a conductive film was formed on the film formation surface of the film formation target by performing film formation in the first transfer and etching in the second transfer eight times each under the following conditions. In the second transfer, as in Example 1, a transfer in which etching was performed with the first etching amount and a transfer in which etching was performed with the second etching amount were alternately performed.

[Film formation conditions]
Target: NiCu target Power supply: 5.8 kW
・Deposition pressure 0.45 Pa
Sputtering gas: Ar gas Gas flow rate: 150 sccm
・Transport speed: 857 mm/min ・Transportation count: 8 times

[Etching conditions]
Supply gas: Ar gas Applied voltage: 2500V
Chamber pressure: 0.06 Pa (first etching amount)
Gas flow rate: 20 sccm (first etching amount)
Chamber pressure: 0.04 Pa (second etching amount)
Gas flow rate: 25 sccm (second etching amount)
・Transport speed: 100 mm/min ・Transportation count: 8 times

[Comparative Example 2]
A film-forming target was prepared that was the same as the film-forming target in Example 1. A conductive film was formed on the film-forming surface of the film-forming target by performing sputtering film formation under the following conditions in both the first transfer and the second transfer.

[Film formation conditions]
Target: NiCu target Power supply: 5.8 kW
・Deposition pressure 0.45 Pa
Sputtering gas: Ar gas Gas flow rate: 150 sccm
・Transport speed: 857 mm/min ・Transportation count: 6 times

[Observation results]
The results of observing the conductive films formed by the methods of Example 1, Comparative Example 1, and Comparative Example 2 are shown in Fig. 8 to Fig. 10. Fig. 8 is an SEM image of the conductive film formed by the method of Example 1, Fig. 9 is an SEM image of the conductive film formed by the method of Comparative Example 1, and Fig. 10 is an SEM image of the conductive film formed by the method of Comparative Example 2.

In the conductive film shown in FIG. 8, it was found that the thickness TT at the top surface was 635 nm, the thickness TS at the inside surface was 108 nm, and the thickness TB at the bottom surface was 121 nm. It was also found that the distance G between the portions having the thickness TT was 100 nm. Thus, in the conductive film formed by the method of Example 1, it was found that the thickness TS at the inside surface and the thickness TB at the bottom surface were almost the same, and that the thickness TT at the top surface was 600 nm or more. Furthermore, it was found that the distance G between the portions having the thickness TT at the top surface was also sufficiently maintained.

In the conductive film shown in FIG. 9, it was found that the thickness TT at the top surface was 648 nm, the thickness TS at the inner surface was 119 nm, and the thickness TB at the bottom surface was 89 nm. It was also found that the distance G between the portions having the thickness TT was 58 nm. Thus, in the conductive film formed by the method of Comparative Example 1, the thickness TB at the bottom surface was thinner than the thickness TS at the inner surface, and the thickness variation between the inner surface and the bottom surface was greater than that of the conductive film formed by the method of Example 1. It was also found that the portion of the conductive film formed on the bottom surface had a concave shape toward the bottom surface. Furthermore, it was found that the distance G between the portions having the thickness TT was not sufficiently maintained in the conductive film formed by the method of Comparative Example 1.

In the conductive film shown in FIG. 10, it was found that the thickness TT at the top surface was 597 nm, the thickness TS at the inner surface was 92 nm, and the thickness TB at the bottom surface was 185 nm. It was also found that the distance G between the portions having the thickness TT was 129 nm. Thus, in the conductive film formed by the method of Comparative Example 2, it was found that the thickness TB at the bottom surface was almost twice the thickness TS at the inner surface, and there was a large variation in thickness between the inner surface and the bottom surface. It was also found that the portion of the conductive film formed on the bottom surface had a convex shape facing away from the bottom surface. On the other hand, it was found that the thickness TT at the top surface was less than 600 nm. It was found that the distance between the portions having the thickness TT was sufficiently maintained.

Thus, it was found that the method of Example 1 achieved the target thickness TT at the top surface and reduced the thickness variation between the inner surface and the bottom surface. It was also found that the flatness of the conductive film at the bottom surface was improved and that the distance G between the portions having the thickness TT was adequately maintained.

As described above, according to the first embodiment of the conductive film forming method and the film forming apparatus, the following effects can be obtained.
(1) It is possible to increase the thickness of the portion of the conductive film CF formed on the top surface ST surrounding the opening SHa of the recess SH while suppressing the variation in thickness between the inner side surface SHs and the bottom surface SHb that define the recess SH.

(2) Compared to the case where the conductive film CF is formed and the conductive film CF is etched only once, it is possible to reduce the variation in thickness between the inner side surface SHs and the bottom surface SHb that define the recess SH.

(3) In the first step, it is possible to alternate between a step in which the sputtered particles SP are preferentially attached to the top surface ST surrounding the opening SHa of the recess SH and the bottom surface SHb defining the recess SH, and a step in which the conductive particles CP emitted from the conductive film CF are preferentially attached to the inner side surface SHs defining the recess SH. This makes it possible to further reduce the variation in thickness between the inner side surface SHs and the bottom surface SHb.

[Second embodiment]
A conductive film forming method and a film forming apparatus according to the second embodiment will be described with reference to Fig. 11 to Fig. 13. The second embodiment is different from the first embodiment in that the conductive film is etched in the second step. Therefore, the following will describe these differences in detail. The conductive film forming method and the film forming apparatus will be described in order below.

[Method of forming conductive film]
The conductive film forming method will be described with reference to Fig. 11. As described above, the conductive film forming method in this embodiment differs from the conductive film forming method in the first embodiment only in the second step, and therefore the second step will be described in detail below while the description of the first step will be omitted.

That is, the second step of this embodiment includes etching of the conductive film CF in addition to the sputter deposition in the second step of the first embodiment. In the second step of this embodiment, similar to the first step, sputter deposition is performed in the first transport, and etching is performed in the second transport. Of these, the sputter deposition performed in the first transport is common to the sputter deposition performed in the second step of the first embodiment, so the etching performed in the second step will be described in detail below.

Figure 11 shows a schematic diagram of the sputtered particles SP flying toward the film-forming target S in the second process, the particles IP of the ion beam IB flying toward the film-forming target S, and the shape of the conductive film CF.

As shown in FIG. 11, the etching of the conductive film CF in the second process is similar to the etching of the conductive film CF in the first process, in that the conductive film CF is etched by irradiating the ion beam IB. As described above, in the second transport of the second process, the ion beam IB is irradiated toward the film-forming target S, so that the particles IP contained in the ion beam IB reach the film-forming target S. At this time, the ion beam IB is irradiated to the film-forming target S at an angle of incidence smaller than the angle of incidence in the first process.

The angle formed by the plane on which the film-forming target S spreads and the direction of irradiation of the ion beam IB is the angle of incidence of the ion beam IB. As described above, in the first step, the ion beam IB is irradiated along the direction in which the irradiation port of the ion source 16 and the transport unit 17 face each other, so the angle of incidence of the ion beam IB in the first step is approximately 90°. In contrast, in the second step, the ion beam IB is irradiated to the film-forming target S at an angle of incidence smaller than 90°.

Therefore, in the second step, among the sputter particles SP emitted from the target 15T by the sputter deposition, the sputter particles SP that are incident on the deposition target S from an oblique direction are preferentially etched. This makes it possible to increase the thickness of the portion of the conductive film CF that is formed on the top surface ST of the deposition target S while suppressing the large variation in thickness of the portion of the conductive film CF that is formed on the inner side surface SHs that defines the recess SH.

As described above, the sputtered particles SP emitted from the target 15T are emitted from the erosion point 15TE of the sputtered surface 15Ta according to the cosine law, so the sputtered particles SP include sputtered particles SP that travel straight toward the film-forming target S and sputtered particles SP that are incident on the film-forming target S from an oblique direction. In the second step, the ion beam IB irradiated from the ion source 16 is incident on the film-forming target S at an incident angle smaller than 90°, so that the particles IP of the ion beam IB collide with the part of the conductive film CF formed on the film-forming target S that is formed by the deposition of the sputtered particles SP that are incident from an oblique direction with respect to the plane on which the film-forming target S spreads. As a result, the conductive particles CP are emitted from the part of the conductive film CF that is formed by the deposition of the sputtered particles SP that are incident from an oblique direction with respect to the plane on which the film-forming target S spreads.

As a result, the thickness of the portion formed on the plane including the opening SHa of the recess SH and the portion formed on the bottom surface SHb is maintained, and the portion that protrudes into the area defined by the opening SHa when viewed from a viewpoint facing the film-forming target S is etched by the particles IP of the ion beam IB.

In the second process, similar to the first process, sputter deposition in the first transport and etching in the second transport are alternately repeated, so that each time a pair of the first transport and the second transport is repeated, the thickness of the portion of the conductive film CF formed on the top surface ST and the portion formed on the bottom surface SHb increases.

[Film forming equipment]
The film forming apparatus will be described with reference to Figures 12 and 13. The film forming apparatus of this embodiment is different from the film forming apparatus of the first embodiment only in the structure of the ion source provided in the film forming chamber, so the description of the other structures in the film forming apparatus will be omitted. Figure 12, which will be referred to below, shows the structure of a first example in the film forming apparatus of this embodiment, while Figure 13 shows the structure of a second example in the film forming apparatus of this embodiment.

As shown in FIG. 12, the film formation chamber 11 includes a first inclined ion source 21 and a second inclined ion source 22 in addition to the above-mentioned ion source 16. Each of the first inclined ion source 21 and the second inclined ion source 22 irradiates an ion beam IB that is incident on the film formation target S at an incidence angle smaller than the incidence angle of the ion source 16. When viewed from a viewpoint facing the side of the film formation apparatus, the direction of the ion beam IB irradiated by the first inclined ion source 21 and the direction of the ion beam IB irradiated by the second inclined ion source 22 have an axisymmetric relationship with the direction of the ion beam IB irradiated by the ion source 16 as the axis of symmetry.

In the deposition chamber 11, the conductive film CF is etched using the ion source 16 in the second transfer of the first step, while the conductive film CF is etched using the first inclined ion source 21 and the second inclined ion source 22 in the second transfer of the second step. As a result, the part of the conductive film CF formed on the deposition target S, which is formed by the deposition of sputtered particles SP incident from an oblique direction from the sputtered surface 15Ta toward the deposition target S, is etched by the particles IP of the ion beam IB. As a result, it is possible to increase the thickness of the part of the conductive film CF formed on the top surface ST and the part formed on the bottom surface SHb while suppressing the growth of a part of the conductive film CF so as to protrude into the area defined by the opening SHa of the recess SH when viewed from a viewpoint opposite to the direction in which the deposition target S spreads.

By using the first example of the film forming apparatus of this embodiment, when etching the conductive film CF in the second step, the ion beam IB can be irradiated using the tilted ion sources 21 and 22 that irradiate the ion beam IB at an angle of incidence smaller than the angle of incidence of the ion source 16. Note that the ion source 16 is an example of a first ion source, and the tilted ion sources 21 and 22 are an example of a second ion source.

In this way, since the film forming apparatus is equipped with ion sources 16, 21, and 22 that irradiate the ion beam IB at different angles of incidence, it is possible to simplify each of the ion sources 16, 21, and 22 and reduce the processing load of the ion sources 16, 21, and 22 compared to a case in which only one ion source is provided.

13, the deposition chamber 11 is provided with one ion source 23. The ion source 23 of this embodiment is different from the ion source 16 of the first embodiment described above in that the direction of irradiation of the ion beam IB irradiated by the ion source 23 can be changed. The ion source 23 can irradiate the ion beam IB along the direction in which the irradiation port of the ion source 23 and the transport unit 17 face each other, that is, along a direction perpendicular to the plane on which the deposition target S spreads. In addition, the ion source 23 can irradiate the ion beam IB along a first inclined direction intersecting with the transport direction when viewed from a viewpoint facing the side of the deposition chamber 11. Furthermore, the ion source 23 can irradiate the ion beam IB along a second inclined direction intersecting with the transport direction when viewed from a viewpoint facing the side of the deposition chamber 11. The first inclined direction has an axisymmetric relationship with the second inclined direction with respect to the direction in which the irradiation port of the ion source 23 and the transport unit 17 face each other.

In the second transport of the first step, the deposition chamber 11 irradiates the ion beam IB along a direction perpendicular to the plane on which the deposition target S spreads. In contrast, in the second transport of the second step, the deposition chamber 11 can alternate between, for example, a second transport in which the deposition target S is transported while irradiating the ion beam IB along a first tilt direction, and a second transport in which the deposition target S is transported while irradiating the ion beam IB along a second tilt direction.

By using the second example of the film forming apparatus of this embodiment, when etching the conductive film CF in the second process, the same ion source 23 as in the first process can be used, and the ion beam IB can be irradiated at an angle of incidence smaller than the angle of incidence of the ion beam IB irradiated in the first process.

In this way, since etching in the first step and etching in the second step can be performed using the same ion source 23, it is possible to simplify the film formation apparatus compared to the case where two ion sources are used.

As described above, according to the second embodiment of the conductive film forming method and the film forming apparatus, the following effects can be obtained.
(4) It is possible to increase the thickness of the portion of the conductive film CF formed on the top surface ST while suppressing large variations in the thickness of the portion of the conductive film CF formed on the inner side SHs that defines the recess SH.

(5) It is possible to simplify each of the ion sources 16, 21, and 22, and reduce the processing load of the ion sources 16, 21, and 22.
(6) Since the same ion source 23 can be used for both the first and second etching steps, the film forming apparatus can be simplified compared to the case where two ion sources are used.

It should be noted that each of the above-described embodiments can be modified and implemented as follows.
[First step]
In the first step, the amount of etching in the second transfer may be the same for all the second transfers. Even in this case, the effect equivalent to the above-mentioned (2) can be obtained by alternately repeating the film formation in the first transfer and the etching in the second transfer.

- In the first step, the deposition of the conductive film CF and the etching of the conductive film CF may be performed simultaneously. For example, the deposition of the conductive film CF and the etching of the conductive film CF may be performed in both the first transport and the second transport. Even in this case, if the etching amount per unit time of the conductive film CF is made smaller in the second step than in the first step, an effect similar to that of (1) described above can be obtained.

[Second step]
In the second step of the second embodiment, the deposition of the conductive film CF and the etching of the conductive film CF may be performed simultaneously. For example, the deposition of the conductive film CF and the etching of the conductive film CF may be performed in both the first transport and the second transport. Even in this case, if the etching amount per unit time of the conductive film CF is set smaller in the second step than in the first step, the effect equivalent to that of (1) described above can be obtained.

[Deposition chamber]
In the first example of the film formation apparatus of the second embodiment, the film formation chamber 11 may include only one of the first inclined ion source 21 and the second inclined ion source 22. Even in this case, by providing the ion beam IB irradiated by the first inclined ion source 21 or the second inclined ion source 22, it is possible to obtain the effects equivalent to the above-mentioned (4) and (5) to some extent.

- In a second example of the film forming apparatus of the second embodiment, the ion source 23 may be capable of irradiating the ion beam IB along only one of the first tilt direction and the second tilt direction, in addition to the direction perpendicular to the plane on which the film forming target S extends. Even in this case, since the ion source 23 can irradiate the ion beam IB along either the first tilt direction or the second tilt direction, it is possible to obtain effects equivalent to the above-mentioned (4) and (6) to a certain extent.

[Transport section]
The transport unit 17 may transport the target 15T and the ion sources 16, 21, 22, and 23 instead of the film-forming target S. In this case, the film-forming chamber 11 may be provided with a support unit that supports the film-forming target S. The transport unit may change the positions of the target 15T and the ion sources 16, 21, 22, and 23 with respect to the film-forming target S, the position of which is fixed in the film-forming chamber 11. Even in this case, if the conductive film CF is etched in the second step by reducing the etching amount per unit time compared to the first step, an effect equivalent to the above-mentioned (1) can be obtained.

REFERENCE SIGNS LIST 10... Film forming apparatus 10C... Control unit 11... Film forming chamber 15... Cathode 15T... Target 16... Ion source 17... Transport unit 21... First inclined ion source 22... Second inclined ion source CF... Conductive film IB... Ion beam S... Film forming target SH... Recess SHa... Opening SHb... Bottom surface SHs... Inner surface ST... Top surface

Claims (7)

A first step including initiating the formation of a conductive film;
a second step that is performed after the first step and includes completing the formation of the conductive film;
the first step includes forming the conductive film by sputtering on a film-forming target that has a film-forming surface having a plurality of recesses and moves relatively to a target, and etching the conductive film formed on the film-forming target;
the second step includes forming the conductive film on the film formation target by the sputtering film formation, and etching the conductive film with an etching amount per unit time that is greater than 0 and smaller than that of the first step;
The conductive film forming method, wherein the first step includes alternately forming the conductive film and etching the conductive film. The step of alternately forming the conductive film and etching the conductive film in the first step includes:
2. The method for forming a conductive film according to claim 1, comprising alternately etching the conductive film at a first etching amount per unit time and etching the conductive film at a second etching amount per unit time that is greater than the first etching amount. A first step including initiating the formation of a conductive film;
a second step that is performed after the first step and includes completing the formation of the conductive film;
the first step includes forming the conductive film by sputtering on a film-forming target that has a film-forming surface having a plurality of recesses and moves relatively to a target, and etching the conductive film formed on the film-forming target;
the second step includes forming the conductive film on the film formation target by the sputtering film formation, and etching the conductive film with an etching amount per unit time that is greater than 0 and smaller than that of the first step;
The sputter deposition includes emitting sputter particles according to a cosine law;
the etching of the conductive film in the first step and the etching of the conductive film in the second step include etching the conductive film by irradiation of an ion beam;
The conductive film forming method, wherein etching the conductive film in the second step includes irradiating the film-forming target with the ion beam at an incident angle smaller than an incident angle in the first step. The etching of the conductive film in the first step includes irradiating the conductive film with the ion beam from a first ion source,
4. The method for forming a conductive film according to claim 3, wherein etching the conductive film in the second step includes irradiating the ion beam using a second ion source that irradiates the ion beam at an incident angle smaller than an incident angle of the first ion source. the etching of the conductive film in the first step includes irradiating the conductive film with the ion beam from an ion source;
4. The method for forming a conductive film according to claim 3, wherein etching the conductive film in the second step includes irradiating the ion beam at an incidence angle smaller than the incidence angle of the ion beam irradiated in the first step using the same ion source as in the first step. a film formation unit that forms a conductive film by sputtering using a target on a film formation target having a film formation surface with a plurality of recesses;
an etching unit that etches the conductive film formed on the film formation target;
a transport unit that moves the film-forming target relative to the target;
a control unit that controls driving of the film forming unit, the etching unit, and the transport unit,
the control unit controls driving of the film forming unit, the etching unit, and the transport unit to execute a first process including a start of formation of the conductive film, and a second process that is performed after the first process and includes an end of formation of the conductive film;
the first step includes forming the conductive film by the sputtering deposition on the film-forming target that moves relatively to the target, and etching the conductive film formed on the film-forming target;
the second step includes forming the conductive film on the film formation target by the sputtering film formation, and etching the conductive film with an etching amount per unit time that is greater than 0 and smaller than that of the first step;
The film forming apparatus, wherein the first step includes alternately forming the conductive film and etching the conductive film. a film formation unit that forms a conductive film by sputtering using a target on a film formation target having a film formation surface with a plurality of recesses;
an etching unit that etches the conductive film formed on the film formation target;
a transport unit that moves the film-forming target relative to the target;
a control unit that controls driving of the film forming unit, the etching unit, and the transport unit,
the control unit controls driving of the film forming unit, the etching unit, and the transport unit to execute a first process including a start of formation of the conductive film, and a second process that is performed after the first process and includes an end of formation of the conductive film;
the first step includes forming the conductive film by the sputtering deposition on the film-forming target that moves relatively to the target, and etching the conductive film formed on the film-forming target;
the second step includes forming the conductive film on the film formation target by the sputtering film formation, and etching the conductive film with an etching amount per unit time that is greater than 0 and smaller than that of the first step;
The sputter deposition includes emitting sputter particles according to a cosine law;
the etching of the conductive film in the first step and the etching of the conductive film in the second step include etching the conductive film by irradiation of an ion beam;
The film formation apparatus, wherein the etching of the conductive film in the second step includes irradiating the film formation target with the ion beam at an incident angle smaller than an incident angle in the first step.