TWI401333B - Sputtering apparatus and sputtering method - Google Patents

Description

Sputtering device and sputtering method

The present invention relates to a sputtering apparatus and a sputtering method.

At the time of film formation, magnetron sputtering is often used in terms of the film forming speed and the like. The magnetron sputtering method is a magnet assembly composed of a plurality of magnetic poles that are alternately transformed by polarity after the target, and the magnet assembly is used to form a magnetic flux in front of the target to capture electrons, thereby improving the front of the target. The electron density increases the probability of collision of such electrons with the gas introduced into the vacuum processing chamber, increasing the plasma density and sputtering.

However, in recent years, as the size of the substrate has increased, the magnetron sputtering apparatus has also become large. As such a device, a sputtering apparatus capable of forming a large-area substrate by arranging a plurality of targets in parallel is known (for example, Patent Document 1).

In this sputtering apparatus, since the constituent members for capturing the anode or the shield of the secondary electrons flying from the target are provided between the targets, it is impossible to set the targets close to each other. The interval between the targets is widened. Between these targets, since the sputtered particles are not released, the film forming speed on the surface of the substrate and the opposing portion of the target becomes extremely slow, and the film thickness is uniform in the surface. Sex is bad.

In order to solve such a problem, a sputtering apparatus as shown in Fig. 1 is considered. The sputtering apparatus 1 is provided with a plurality of targets 12a to 12d which are arranged side by side at a predetermined interval in the vacuum processing chamber 11, and are connected. Two AC power supplies E of the adjacent targets (12a and 12b, 12c and 12d). In the sputtering apparatus 1, since one of the targets connected to one AC power source is used as a cathode and the other is used as an anode and is alternately sputtered, it is not necessary to provide an anode or the like between the targets. Components, and the target can be placed close to the configuration.

[Patent Document 1] Japanese Patent Publication No. 2002-508447 (for example, the description of the patent application).

However, if the targets are placed close to each other, since the electrons emitted from the upper space 212 of the adjacent target end portion flow into the anode, the plasma P does not occur, and the end portion of the target is not splashed. Plating, remaining as a non-erodible area. At this time, even if the magnetic flux is moved in parallel to the non-eroded area, the target end portion cannot be eroded, so that the target can not be comprehensively eroded, and the utilization efficiency of the target is deteriorated. Further, since the non-erosion area remains, it may cause abnormal discharge or particles in the sputtering.

Further, since the plasma P is generated between adjacent targets connected to one AC power source, a space 122 having a lower plasma density than other spaces is generated. At this time, when the reaction gas is introduced into the sputtering apparatus and reactive sputtering is performed, the reaction cannot be promoted in the portion where the plasma density is low, and the film quality in the surface of the substrate S cannot be made uniform.

Accordingly, the problem of the present invention is to solve the above problems of the prior art, and to provide a non-eroded area on the target, and A sputtering device capable of forming a film of uniform film quality during sputtering.

The sputtering apparatus of the present invention includes: at least four or more targets that are arranged side by side at a specific interval in the vacuum processing chamber; and a negative potential is applied to two of the targets arranged side by side. And an alternating current power source having a positive potential or a ground potential, wherein each of the alternating current power sources is connected to two targets that are not adjacent to each other.

By connecting each AC power source to two targets that are not adjacent to each other, the distance between the anode and the cathode can be widened, and electrons do not flow into the anode. By this, the plasma will be generated in front of the target and can cover the full erosion of the target.

Further, by connecting two targets having one or more targets interposed therebetween, the plasmas are repeatedly generated and a space having a low plasma density is not generated, so that the plasma density in front of the substrate is slightly uniform. When reactive sputtering is performed, a film having a uniform film quality can be formed.

The sputtering apparatus according to the present invention includes: a magnet assembly including a plurality of magnets disposed behind each target so as to form a magnetic flux in front of each target; and a magnetic flux relative to the target It is desirable to drive the magnet assembly in a parallel manner. By moving the magnet assembly in parallel to the left and right, the target can be completely uniformly eroded.

Further, if the magnet assembly is placed behind each target, it is also conceivable that the magnets interfere with each other to cause a collapse of the magnetic field balance. In this case, the magnetic flux formed by each magnet assembly is provided. It is desirable that the density is formed into a uniform magnetic flux density correcting means.

Further, the sputtering method according to the present invention is characterized in that the substrate is moved to a position facing at least four or more targets which are arranged at a predetermined interval in the vacuum processing chamber, and are arranged side by side. The two targets that are not adjacent to each other in the target alternately apply a negative potential and a positive potential or a ground potential, and plasma is generated on the target to form a film on the substrate.

According to the sputtering apparatus of the present invention, it is possible to obtain an excellent effect that the film quality of the formed film is uniform even when the non-erosion region remains on the target. .

Referring to Fig. 2, the sputtering apparatus 2 of the present invention is a blade type, and includes a load lock processing chamber 20 that transports a substrate from a wafer shutter (not shown) in the atmosphere, and stores it. The vacuum processing chamber 21 that performs sputtering and the transfer processing chamber 22 that is disposed between the load lock processing chamber 20 and the vacuum processing chamber 21 are provided. The load lock processing chamber 20, the transfer processing chamber 22, and the vacuum processing chamber 21 are connected via separate valves. Although not shown in the figure, the load lock processing chamber 20, the vacuum processing chamber 21, and the transfer processing chamber 22 are connected to a vacuum pump and a vacuum gauge for monitoring the degree of vacuum.

In the load lock processing chamber 20, a transfer arm that transports the substrate holder on which the substrate S is mounted is provided. By this transfer arm, from the outside (wafer In the gate, the substrate S mounted on the substrate holder is housed in the load lock processing chamber 20.

A transfer robot (not shown) is provided in the transfer processing chamber 22, and after the load lock chamber 20 is evacuated to a specific degree of vacuum, the partition valve is opened, and the substrate S is transferred to the vacuum to the same degree of vacuum. The processing chamber 22 is transferred. Then, the partition valve between the transfer processing chamber 22 and the vacuum processing chamber 21 is opened, and the substrate S is transferred to the vacuum processing chamber 21 by the transfer robot.

In the vacuum processing chamber 21, a gas introduction means 23 (refer to Fig. 3) is provided. The gas introduction means 23 is connected to the gas sources 233a, 233b via gas introduction pipes 232 provided between the mass flow controllers 231a, 231b, respectively. The gas sources 233a and 233b are sealed with a sputtering gas such as argon gas or a reaction gas such as H ₂ O, O ₂ or N _{2 ,} and these gases can be fixed by the quality controllers 231a and 231b. The flow rate is introduced into the vacuum processing chamber 21.

The target assembly 24 is disposed at a position facing the substrate S that is carried into the vacuum processing chamber 21 . The target assembly 24 has six targets 241a to 241f formed in a substantially rectangular shape. The target assembly bodies 241a to 241f are ITO, Al alloy, Mo, or the like which are manufactured by a known method in accordance with the composition of the film formed on the substrate, and are bonded to the back sheet for cooling. (not shown).

Further, the targets 241a to 241f are arranged side by side with a space D1 so as to be positioned on the same plane parallel to the substrate S. The interval D1 is set such that the space between the sides of the targets 241a to 241f does not occur. A plasma is generated to cause the sides of the targets 241a to 241f to be sputtered. This distance is 1~10mm, and the ideal system is 2~3mm. By arranging the targets 241a to 241f in close proximity, the sputtered particles reach the entire surface of the substrate disposed at a position opposed to the targets 241a to 241f, and the film thickness distribution can be made uniform.

On the back surfaces of the targets 241a to 241f, electrodes 242a to 242f and an insulating plate 243 are sequentially mounted, and these are attached to specific positions of the target assembly 24, respectively. The electrodes 242a to 242f are respectively connected to three AC power sources E1 to E3 disposed outside the vacuum processing chamber 21.

The AC power supplies E1 to E3 are connected such that voltages are alternately applied to two targets that are not adjacent to each other. For example, one of the terminals of the AC power source E1 is connected to the electrode 242a behind the target 241a, and the other terminal is connected to the electrode 242d behind the target 241d. In addition, the voltage applied by the AC power source may be either a sine wave or a rectangular wave.

By connecting the AC power sources E1 to E3 in this manner, if one of the targets (241a, 241b, and 241c) applies a negative voltage from the AC power sources E1 to E3, the targets 241a, 241b, and 241c are provided. As the function of the cathode, the other targets 241d, 241e, and 241f provide functions as an anode. Then, plasma is formed in front of the cathode targets 241a, 241b, and 241c, and the targets 241a, 241b, and 241c are sputtered. In response to the frequency of the AC power source, the targets 241a to 241f are alternately applied with a voltage and are respectively sputtered, and the sputtered particles reach the entire surface of the substrate S, and the film thickness is uniformly formed.

The target assembly 24 is disposed at each target 241a. Six magnet assemblies 244 after ~241f. Each of the magnet assemblies 244 is formed in the same structure, and has a support portion 245 that is disposed in parallel with the targets 241a to 241f, and is disposed along the longitudinal direction of the target so as to be alternately changed in polarity on the support portion 245. There is a rod-shaped central magnet 246. And a peripheral magnet 247 composed of a plurality of magnets disposed to surround the periphery of the central magnet 246. Each of the magnets is designed such that the volume of the central magnet is converted into the same magnetization and the sum of the volume of the peripheral magnet 247 converted to the same magnetization. Thereby, a tunnel-shaped magnetic flux that forms a balanced closed path in front of the targets 241a to 241f captures electrons ionized in front of the target and secondary electrons generated by sputtering, thereby improving the target as a cathode. The density of the plasma formed in front of it.

However, since the magnet assemblies 244 are also close to each other, the magnetic fields interfere with each other, and there is a magnetic field corresponding to the magnet assembly 244 located behind the targets 241a, 241f at both ends, and a target corresponding to the position at the center. The balance of the magnetic field of the magnet assembly 244 after the 241c and 241d collapses. At this time, the film thickness distribution in the plane of the substrate S cannot be made slightly uniform. At this time, in order to correct the balance of the magnetic field, the auxiliary magnet 248 is provided in the target assembly 24. The auxiliary magnet 248 has the same polarity as the peripheral magnet 247 of the adjacent magnet assembly 244. The spacing between the auxiliary magnet 248 and the peripheral magnet 247 is the same as the interval D2 of each of the magnet assemblies 244. By providing the auxiliary magnet 248 under the prevention plate 249 disposed on the outer side of the targets 241a and 241f at both ends as described above, the magnetic field balance can be improved.

By the magnet assembly 244, in front of the targets 241a to 241f Since the tunnel-shaped magnetic flux is formed, the density of the plasma located in front of the central magnet 246 and the peripheral magnet 247 is low. Thus, the positions of the targets 241a to 241f, which have a lower plasma density, are located above the central magnet 246, and remain as non-erosion portions. Here, it is necessary to change the position of the tunnel-shaped magnetic flux, and uniformly etch the targets 241a to 241f to improve the use efficiency.

In order to change the position of the tunnel-shaped magnetic flux, the magnet assembly 244 and the auxiliary magnet 248 are disposed at specific positions on the drive shaft 250, and the drive shaft 250 is used as a driving means to enable the position of each of the magnet assemblies 244 to be left and right. In the parallel movement mode, the ball screw 251 is provided as a driving means, and is not limited to a mechanical driving means such as a ball screw 251, but an air cylinder may be used, but when the ball screw is used, the magnet can be more accurately controlled. The position of the assembly 244. The moving distance of the magnet assembly 244 is not particularly limited as long as the targets 241a to 241f can be uniformly eroded. For example, the magnet assemblies 244 can be moved in parallel at intervals of points A to B, respectively. Further, the magnet assembly 244 is not only moved in the left-right direction but also moved in parallel in the longitudinal direction. By causing the magnet assembly 244 to move in two dimensions in parallel, the targets 241a to 241f can be more uniformly eroded.

The movement of the magnet assembly 244 may be either during film formation or after film formation. However, in order to suppress the occurrence of abnormal discharge accompanying the movement of the magnetic flux during film formation, it is preferable to move after film formation.

In the case of moving in the film formation, the ball screw 251 is driven during sputtering so that the targets 241a to 241f are uniformly eroded from the point A to the point B, and are preferably 2.5 mm/sec or more. For 4~ At a cycle of 15 mm/sec, the magnet assembly 244, that is, the magnetic flux is moved in parallel.

In the case of the movement after the film formation, the film formation is stopped, the power supply E1 to E3 is stopped, and the discharge is stopped once, and the substrate S as the next film formation target is placed on the target targets 241a to 241f. At the position, the ball screw 251 is driven to move the magnetic flux from point A to point B, respectively, and hold it. In this case, the magnet assembly 244 may be moved in parallel at least until the next film formation starts. Then, after the film formation of the substrate S to be conveyed is completed, the magnetic fluxes are again moved in parallel in the same order. By repeating this operation in this order, the targets 241a to 241f can be uniformly etched while sequentially forming a film on the substrate.

In the present embodiment, the balance of the magnetic field can be corrected via the auxiliary magnet 248. However, the present invention is not limited thereto as long as it can correct the balance of the magnetic field. For example, the magnetic field may be corrected by merely increasing the width of the peripheral magnet or changing the peripheral magnet 247 to a material that increases the density of the magnetic flux generated by the magnet.

In the present embodiment, the sputtering apparatus 2 is a vane type apparatus, but may be an inline type.

In the present embodiment, the case where the number of the targets to be arranged in parallel is six is described. However, the number of the targets is not limited thereto, and may be appropriately selected depending on the size of the substrate or the like. However, the number of targets must be four or more. This is because when there are less than four pieces, it is impossible to connect the targets that are not adjacent to each other. Moreover, since the AC power supplies E1 to E3 are connected to two targets, the number of targets must be an even number. whether In any case, the method of connecting the respective AC power sources is not particularly limited as long as it connects two targets that are not adjacent to each other.

Fig. 4 is a view showing an example of connection between a target and an AC power source when the number of targets is changed. In addition, in FIG. 4, the same component as FIG. 3 is attached with the same code|symbol.

When the number of the targets 241 is a multiple of 4, for example, when the number of targets is 4, as shown in FIG. 4(a), if two targets 241 are arranged side by side with one target 241 interposed therebetween, When the AC power source E is connected, all the targets 241 can be connected without being adjacent to each other. In this case, if the target is connected by two pieces as shown in FIG. 3, it is necessary to connect the targets adjacent to each other, and the effect of the present invention cannot be obtained.

In the case where 10 targets 241 are arranged side by side, as shown in FIG. 4(b), each of the targets at both ends may be connected, and the remaining targets are respectively separated by one target and two 2 The ground is connected to the power source E.

On the other hand, as shown in FIG. 4(c), the targets at both ends may be connected by one target, and the remaining targets may be separated from the power source E by two targets. connection. Even if 10 targets are placed side by side, by connecting targets that are not adjacent to each other, the plasma will be generated in front of the target and can cover the overall erosion of the target.

Hereinafter, a method of forming a film on the surface of the substrate S using the sputtering apparatus of the present invention will be described.

First, the substrate S is transferred from the wafer gate to the position facing the targets 241a to 241f arranged side by side via the load lock processing chamber 20 and the transfer processing chamber 22, and the inside of the vacuum processing chamber 21 is evacuated by means of vacuum evacuation. Vacuum exhaust. Next, a sputtering gas such as Ar is introduced into the vacuum processing chamber 21 via the gas introduction means 23, and a specific film formation gas atmosphere is formed in the vacuum processing chamber 21. In addition, at the time of reactive sputtering, a gas selected from at least one of H ₂ O gas, O ₂ gas, and N ₂ gas is introduced as a reaction gas while introducing a sputtering gas. Then, while maintaining the film formation environment, positive or negative voltages are applied to the targets 241a to 241f by the AC power sources E1 to E3 at several kHz to several hundreds of kHz. When an electric field is formed on the target as a cathode and plasma is generated in front of the target, the target is sputtered and the sputtered particles are released. By performing this action interactively in response to the frequency of the AC power source, each target is uniformly sputtered. Then, the AC power is stopped and the film formation is completed.

Further, the ball screw 251 may be driven to drive the magnet assembly 244 during film formation, or the AC power source E1 to E3 may be stopped after the film formation is terminated, and the discharge may be stopped for a while, and then the next film formation target is used. When the substrate S is transported to the position facing the targets 241a to 241f, the ball screw 251 is driven to move the magnet assembly 244 in parallel, that is, the magnetic flux is moved in parallel and held.

[Example 1]

In Example 1, a sputtering apparatus as shown in Figs. 2 and 3 was used to form a film, and the number of generations of the arc discharge in the film formation was investigated.

A target made of In ₂ O ₃ -10 Wt% SnO ₂ (ITO) having a width of 200 mm, a length of 1700 mm, and a thickness of 10 mm was provided in parallel with the substrate at a position 150 mm from the substrate. The target interval is 2 mm. After the respective targets, a magnet assembly having a width of 170 mm, a length of 1570 mm, and a thickness of 40 mm was provided at a distance of 47 mm from each target, and the driving distance via the ball screw 251 was 50 mm. As the substrate S, a glass substrate having a width of 1000 mm and a length of 1200 mm and a thickness of 0.7 mm was prepared.

After the substrate was transferred, vacuum evacuation was performed, and then argon gas as a sputtering gas was introduced through a gas introduction means at 240 sccm to form a film formation environment of 0.67 Pa. Further, as a reaction gas, H ₂ O gas was introduced at _2.0 sccm and O ₂ gas at 1.5 sccm. Each AC power supply E has a frequency of 25 kHz, and the power is gradually increased by 5 kW from 0 kw each time (each input time is 120 seconds). Finally, after the power is raised to 15 kW and input for 120 seconds, the AC power supply is temporarily stopped. The magnet assembly is moved when one substrate is used. In this way, the film is sequentially formed, and the voltage value and the current value are monitored, and the number of occurrences of abnormal discharge (arc discharge) in one minute is counted. When the target is taken out from the sputtering apparatus to visually confirm the surface thereof, each target system is completely eroded.

[Comparative Example 1]

In Comparative Example 1, a device in which two targets adjacent to each other of six targets arranged in parallel are connected to an AC power source, and the voltage and current values are monitored and counted while forming a film under the same conditions. The number of abnormal discharges produced.

The result is shown in Figure 5. In Fig. 5, the integrated power is displayed on the horizontal axis (kWh), and the vertical axis shows the number of times of abnormal discharge (times/minute). Yubi In the first example, as the integrated power increases, the number of abnormal discharges also increases. On the other hand, in the first embodiment, as the integrated electric power increases, the number of abnormal discharges does not increase.

[Example 2]

In Example 2, the in-plane uniformity of the film quality was evaluated when reactive sputtering was performed using the sputtering apparatus shown in FIGS. 2 and 3.

The evaluation of the in-plane uniformity of the film quality was carried out by changing the flow rate ratio of the reaction gas at the time of film formation, and investigating the ratio of the flow rate at which the impedance ratio was the most decreased at each point on the film, and proceeding with the difference in the flow rate ratio.

Using the same material as the sputtering apparatus used in Example 1, the flow rate of the reaction gas was changed as in Example 1 to form a plurality of films. As a reaction gas, H ₂ O gas was changed at 2.0 sccm, O ₂ gas was 0.0 to 4.0 sccm, and was introduced at a scale of 0.5 sccm. Each of the AC power supplies E has a frequency of 25 kHz, and the power is gradually increased from 0 kw, and finally increased until 15 kW, and the AC power supply is stopped after 25 seconds of input, and the film formation is completed. The film thickness of each film obtained was 1000 Å. Then, each substrate was transferred to an annealing furnace and atmospherically annealed at 200 degrees for 60 minutes. The resistivity was measured for the point X on the formed film corresponding to the upper portion of the target 241c, and the point Y corresponding to the upper portion between the targets 241b and 241c.

[Comparative Example 2]

The same conditions as in the second embodiment were carried out using a device in which two targets adjacent to each other among six targets arranged side by side were connected to an AC power source. Film formation and annealing are performed to form a film on the substrate S, respectively. The resistivity was also measured at each of the points X and Y for each of the formed films.

Fig. 6 shows the flow rate (sccm) of the O ₂ gas on the horizontal axis and the resistivity (μ Ω cm) of each point on the vertical axis.

Fig. 6(a) shows the measurement results of Comparative Example 1. The resistivity value of the point X shown by the solid line is the lowest when the flow rate of the O ₂ gas is 0.5 sccm, and becomes 255 μ Ω cm. The point Y shown by the broken line is the lowest resistivity when the flow rate of the O ₂ gas is _2.0 sccm, and becomes 253 μ Ω cm. The difference in the flow rate of the O ₂ gas having the lowest resistivity at the point X and the point Y was 1.5 sccm which was extremely different. It was found that in Comparative Example 2, the film quality in the surface of the substrate was uneven.

On the other hand, in the second embodiment shown in FIG. 6(b), the resistivity value of the point X shown by the solid line is the lowest 250 μ Ω cm when the flow rate of the O ₂ gas is 1.0 sccm. At the point Y shown by the broken line, the resistivity becomes the lowest 248 μ Ω cm when the flow rate of the O ₂ gas becomes 1.5 sccm. In the second embodiment, the difference in the flow rate of the O ₂ gas having the lowest resistivity at the point X and the point Y is 0.5 sccm, which is one-half or less of the previous device, and the film surface in the reactive sputtering can be known. Internal uniformity is improved.

[Industrial use possibility]

The sputtering apparatus of the present invention improves the film quality uniformity of the formed film by improving the connection method of the alternating current power source without leaving a non-erosion area on the target. Therefore, the present invention can be utilized in the manufacture of large screens. The field of flat panel displays.

241a~241f‧‧‧ Target

242a~242f‧‧‧electrode

244‧‧‧Magnetic assembly

250‧‧‧ drive shaft

251‧‧‧Rolling screw

E1~E3‧‧‧AC power supply

S‧‧‧Substrate

[Fig. 1] Schematic diagram of the previous device

[Fig. 2] A schematic configuration diagram of a sputtering apparatus of the present invention

[Fig. 3] A schematic configuration diagram of a vacuum processing chamber in a sputtering apparatus of the present invention

[Fig. 4] A diagram showing another connection example of an AC power supply

[Fig. 5] A graph showing the number of occurrences of abnormal discharge with respect to integrated power

[Fig. 6] (a) is a graph showing the relationship between the flow rate of O ₂ gas and the resistivity when a film is formed using a conventional apparatus. (b) A graph showing the relationship between the flow rate of O ₂ gas and the resistivity when film formation is performed using the sputtering apparatus of the present invention.

21‧‧‧vacuum processing room

23‧‧‧ gas introduction means

24‧‧‧Target assembly

231a, 231b‧‧‧ mass flow controller

232‧‧‧ gas introduction tube

233a, 233b‧‧‧ gas source

241a~f‧‧‧ Target

242a~f‧‧‧Power supply

243‧‧‧Insulation board

244‧‧‧Magnetic assembly

245‧‧‧Support Department

246‧‧‧Central Magnet

247‧‧‧Surround magnet

248‧‧‧Auxiliary magnet

249‧‧‧Anti-board

250‧‧‧ drive shaft

251‧‧‧Rolling screw

E1~3‧‧‧Power supply

S‧‧‧Substrate

Claims (4)

A sputtering apparatus comprising: at least four or more targets arranged side by side at a specific interval in a vacuum processing chamber; and a negative potential applied to two of the targets arranged side by side And an alternating current power source having a positive potential or a ground potential, wherein each of the alternating current power sources is connected to two targets that are not adjacent to each other. The sputtering device according to claim 1, wherein the sputtering device further includes: a plurality of magnets disposed behind each of the targets in such a manner that a magnetic flux is formed in front of each of the targets The magnet assembly formed by the magnet assembly and the driving means for driving the magnet assemblies in such a manner that the magnetic flux moves in parallel with respect to the target. The sputtering apparatus according to claim 1 or 2, further comprising: when each of the magnet assemblies is disposed after each of the targets, each of the magnets is passed through each of the magnets A magnetic flux density correcting means for uniformizing the density of the magnetic flux formed by the assembly. A sputtering method, comprising: moving a substrate to a position facing at least four or more targets arranged in parallel in a vacuum processing chamber at a specific interval; and for side by side The two targets of the plurality of targets that are not adjacent to each other are alternately applied with a negative potential and a positive potential or a ground potential, and a plasma is generated on the target to form a film on the substrate.