Film formation method

Abstract

To provide a film formation method that can stably form a yttrium oxide film having conductivity to a substrate with an arc ion plating PVD method.SOLUTION: This film formation method comprises: disposing, in a chamber, a target comprising yttrium and a substrate that is an object on which a film is to be formed; introducing at least oxygen into the chamber; applying a prescribed bias voltage to the substrate; evaporating the surface of the target in oxygen to form a yttrium oxide film on the substrate; and setting the oxygen partial pressure in the chamber during the evaporation so as to be a pressure of less than 0.4 Pa, and setting an O / Y ratio, which is the ratio of oxygen to yttrium in the yttrium oxide film on the substrate, so as to be 1.5 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for forming a coating having excellent plasma resistance on the surface of a substrate. [Background technology]

[0002] Conventionally, there has been a demand for materials with excellent plasma resistance for components used in environments exposed to plasma, such as semiconductor manufacturing equipment. In Patent Document 1, in order to obtain such materials, yttrium oxide (Y 2 O 3 A technique for forming a Y 2 O 3 film is disclosed. 2 O 3 By plasma spraying using powder as a raw material, a film of yttrium oxide is formed on the surface of components where damage by plasma is a problem.

[0003] Meanwhile, in recent years, the formation of an yttrium oxide film on a substrate by a vacuum deposition method (PVD: Physical Vapor Deposition) has been considered. In this type of PVD method, a film is formed on a substrate using ionized materials, making it possible to form a dense coating compared to thermal spraying methods, which may have defects in the film. It is generally known that in the PVD method, a certain percentage of the evaporated atoms are ionized and become ions. Therefore, by applying a voltage (bias) to the substrate on which the film is to be formed and changing the incident ion energy, it is possible to control the density of the film and the film properties (crystal structure and mechanical properties).

[0004] Among the PVD methods, the AIP (arc ion plating) method is a film formation method based on the evaporation and ionization of a cathode material by vacuum arc discharge under conditions of a large current (tens to hundreds of A) and low voltage. In this case, when forming a film of an insulating material such as an oxide, it is necessary to perform reactive film formation in an atmosphere containing oxygen using a metal target. In this case, since the discharge surface of the cathode is oxidized, if there is an area on the cathode surface where arc discharge does not occur, oxides will accumulate in that area, and the area will expand, making it difficult to maintain the discharge. In order to solve this problem, Patent Document 2 discloses that stable discharge can be achieved by using an evaporation source having a weak magnetic field of 3 to 50 gauss. Patent Document 3 discloses that this method is used to apply a bipolar pulse to form an oxide under conditions in pure oxygen. The same document also discloses that a film is formed by superimposing a high-current pulse arc on a direct current to form an oxide containing Zr, Cr, Mo, and Al, Si, Fe, Co, Ni, and Y. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-164354 A [Patent Document 2] Patent No. 5306198 [Patent Document 3] Patent No. 5877147 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have used the method disclosed in Patent Document 2 to obtain Y 2 O 3However, it was found that there was a problem that an oxide formed on the target surface during long-term discharge, and discharge eventually became impossible. In addition, the power supply system of the high-current pulse arc described in Patent Document 3 is complicated and expensive compared to a normal DC power supply, so there is a problem that it is difficult to apply industrially.

[0007] An object of the present invention is to provide a film formation method capable of stably maintaining discharge during film formation when stably forming an electrically conductive yttrium oxide film on a substrate using an arc ion plating method. [Means for solving the problem]

[0008] In order to achieve the above object, the inventors of the present application have conducted extensive experiments to form a conductive yttrium oxide film, and as a result have discovered a new film formation method.

[0009] The film formation method according to the present invention is a film formation method for forming an yttrium oxide film on a substrate, which is an object of the film formation, by an arc ion plating method, and includes the steps of: placing a target made of yttrium and the substrate in a chamber; introducing at least oxygen into the chamber; applying a predetermined bias voltage to the substrate; evaporating the surface of the target in oxygen to form an yttrium oxide film on the substrate; and setting the oxygen partial pressure in the chamber during the evaporation to a pressure less than 0.4 Pa such that the O / Y ratio, which is the ratio of oxygen to yttrium in the yttrium oxide film on the substrate, is 1.5 or less.

[0010] According to this method, the amount of oxygen in the yttrium oxide film can be changed by controlling the oxygen partial pressure in the chamber during film formation, thereby lowering the electrical resistance of the film and obtaining a conductive yttrium oxide film. In particular, since the oxygen partial pressure is set to less than 0.4 Pa, oxides are unlikely to form on the target surface, and it is possible to prevent the discharge voltage from increasing, making it difficult to sustain the discharge.

[0011] The above method may further comprise setting an oxygen partial pressure in the chamber during the evaporation so that the O / Y ratio is less than 1.4.

[0012] According to this method, the electrical resistance of the film can be further reduced, and a conductive yttrium oxide film can be stably obtained.

[0013] The above method may further comprise setting an oxygen partial pressure in the chamber so that the electrical resistance of the yttrium oxide film is 10,000Ω or less.

[0014] According to this method, by controlling the oxygen partial pressure during film formation to change the amount of oxygen in the film, it is possible to stably obtain a conductive yttrium oxide film having an electrical resistance of 10,000 Ω or less.

[0015] The above method may further comprise setting the oxygen partial pressure so that a discharge voltage during film formation is 20 V or less.

[0016] According to this method, the increase in the rate of increase in the discharge voltage caused by an increase in the discharge voltage can be suppressed by controlling the oxygen partial pressure, and a stable discharge can be maintained during film formation.

[0017] The above method may further include the oxygen partial pressure being 0.17 Pa or higher.

[0018] According to this method, it is possible to prevent the roughness of the formed film from increasing in accordance with a decrease in the oxygen partial pressure.

[0019] The above method may further comprise introducing argon into the chamber in addition to oxygen.

[0020] According to this method, it is possible to lower the discharge voltage during film formation, and to stabilize the discharge during film formation.

[0021] The above method may further comprise applying a pulse voltage to the substrate as the bias voltage.

[0022] According to this method, even if the resistance of the film formed on the substrate is relatively high, it is possible to suppress charge-up, which is the accumulation of electric charges due to incident ions. Effect of the Invention

[0023] According to the present invention, it is possible to provide a film formation method that can stably maintain discharge during film formation when stably forming a conductive yttrium oxide film on a substrate using an arc ion plating method. [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing a schematic configuration of a film formation apparatus for performing a film formation method according to an embodiment of the present invention. [Diagram 2] 4 is a graph showing the relationship between the O / Y ratio, which is the ratio of oxygen to yttrium in the yttrium oxide film on the substrate, and the electrical resistance of the yttrium oxide film in an example of the present invention. [Diagram 3] 4 is a graph showing the relationship between oxygen flow rate and oxygen partial pressure in an embodiment of the present invention. [Figure 4] 4 is a graph showing the relationship between oxygen partial pressure and discharge voltage in an embodiment of the present invention. [Diagram 5] 4 is a graph showing the relationship between oxygen partial pressure and discharge voltage in an embodiment of the present invention. [Figure 6] 4 is a graph showing the surface roughness of yttrium oxide films formed by changing the oxygen partial pressure in an embodiment of the present invention. [Figure 7] 4 is a graph showing a change in oxygen partial pressure during long-term discharge in an embodiment of the present invention. [Figure 8] 4 is a graph showing a change in discharge voltage during long-term discharge in an embodiment of the present invention. [Figure 9]4 is a graph showing the O / Y ratio of an yttrium oxide film formed by changing the oxygen partial pressure in an example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a schematic diagram showing a schematic configuration of a film formation apparatus 10 for performing a film formation method according to one embodiment of the present invention. The film formation method according to the embodiment of the present invention is a method for forming a coating having excellent plasma resistance on the surface of a substrate.

[0026] 1 shows an example of a film forming apparatus for carrying out the film forming method according to the embodiment of the present invention, and the film forming apparatus for carrying out the film forming method is not limited to the one shown in Fig. 1. This film forming apparatus 1 is an apparatus that uses a physical vapor deposition method (PVD method) to form a film on the surface of a workpiece W (substrate) placed in a vacuum chamber 2. This film forming apparatus 1 includes an AIP apparatus that forms a film using an arc ion plating method, a sputtering apparatus that forms a film using a sputtering method, and the like.

[0027] The film forming apparatus 10 is an arc ion plating apparatus and includes a vacuum chamber 12, a rotary table 14, a plurality of substrate holders 16, a bias power supply 18, a target 20 as an evaporation source, an arc power supply 22, a heater 24, an argon tank 30, an oxygen tank 32, a vacuum pump P, and a controller 50.

[0028] The vacuum chamber 12 accommodates a turntable 14 and a plurality of substrate holders 16 arranged on the turntable 14. The interior of the vacuum chamber 12 (i.e., the space accommodating the turntable 14 and the plurality of substrate holders 16) is maintained in a vacuum or near vacuum state by a vacuum pump P during various processes including the film formation process. The vacuum chamber 12 is provided with a gas inlet 12A and an exhaust outlet 12B.

[0029] The turntable 14 has a disk shape including a center line extending in the vertical direction of Fig. 1. The turntable 14 is disposed in the vacuum chamber 12. In the film formation process, the turntable 14 rotates around its center line while supporting a plurality of substrate holders 16. The turntable 14 may further include a rotation platform on which each of the substrate holders 16 is individually disposed so that each of the substrate holders 16 can rotate on its own axis. The number of substrate holders 16 is not limited to two as shown in Fig. 1.

[0030] Each of the multiple substrate holders 16 supports a workpiece W on which a film is to be formed. In this embodiment, the workpiece W is disposed on the outer circumferential surface of the substrate holder 16. Note that only some of the workpieces W are illustrated in FIG.

[0031] In this embodiment, the workpiece W is made of A6061 alloy (Al alloy) and is a square plate piece of 20 mm×20 mm. However, the material and shape of the workpiece W are not limited to this.

[0032] Each of the substrate holders 16 is made of a conductive material, such as stainless steel.

[0033] The plurality of substrate holders 16 are disposed at equal intervals in the circumferential direction of the rotary table 14. In this state, the center line of each of the plurality of substrate holders 16 is parallel to the center line of the rotary table 14.

[0034] The bias power supply 18 applies a negative bias voltage to each of the substrate holders 16 via the rotary table 14. In this embodiment, the bias power supply 18 applies a negative bias voltage intermittently to each of the substrate holders 16. That is, the bias power supply 18 is a pulse power supply. When the resistance of the film formed on the workpiece W is relatively high, applying a DC bias as the bias voltage may cause a problem of charge accumulation (charge-up) due to the incident ions. On the other hand, by applying a pulse voltage as the bias voltage as in this embodiment, the problem can be suppressed even when the resistance of the film formed on the workpiece W is relatively high. More specifically, the charge-up problem can be suppressed by switching the bias between the negative side and 0V or the positive side as the pulse voltage on the order of μS or mS.

[0035] In addition, when the bias power supply 18 is not applying a negative bias voltage in the film forming process, no bias is applied. Alternatively, the bias power supply 18 can alternately apply a negative bias voltage and a positive bias voltage to each of the multiple substrate holders 16. The absolute value of the negative bias voltage is greater than the absolute value of the positive bias voltage.

[0036] If a negative bias voltage and a positive bias voltage are applied alternately, the bias power supply 18 may be, for example, an alternating current power supply (AC power supply) or a high frequency power supply (RF power supply).

[0037] The target 20 is a disk-shaped member made of yttrium. As an example, the target 20 is a disk having a diameter of 100 mm.

[0038] Arc power supply 22 is a DC power supply that functions as a discharge power supply that generates a vacuum arc discharge in target 20 placed in vacuum chamber 2. At this time, target 20 functions as a cathode in the discharge. Meanwhile, as shown in Fig. 1, vacuum chamber 12 functions as an anode in the discharge. Target 20 receives the discharge generated by arc power supply 22 and releases ions of evaporated yttrium from its surface. Incidentally, arc power supply 22 and target 20 constitute an arc evaporation source.

[0039] The heater 24 is provided in the vacuum chamber 12 and generates heat when supplied with current from a heater power supply (not shown). As a result, the environment in the vacuum chamber 12 and the workpiece W are heated.

[0040] The argon tank 30 contains argon therein and supplies argon gas to the vacuum chamber 12. Similarly, the oxygen tank 32 contains oxygen therein and supplies oxygen to the vacuum chamber 12. The amount of gas supplied from these tanks is controlled by adjusting the opening of a regulator (not shown) in response to a command from the controller 50. In another embodiment, the amount of gas supplied may be manually adjusted by an operator.

[0041] The vacuum pump P puts the internal space of the vacuum chamber 12 into a vacuum state (evacuation) through the exhaust port 12B.

[0042] In addition to the regulators mentioned above, controller 50 controls vacuum pump P, bias power supply 18, arc power supply 22, and various voltages or currents of heater 24, as well as controls the rotation of turntable 14, etc. EXAMPLES

[0043] Next, examples of the film forming method according to the present embodiment will be described. In the following description, oxygen may be represented as O and yttrium as Y. The present invention is not limited to the scope of the following examples.

[0044] <Example 1> A description will be given of Example 1 below. In carrying out the film forming method, as shown in Fig. 1, a target 20 and a workpiece W are attached in a film forming apparatus 10, and a vacuum chamber 12 is evacuated by a vacuum pump P to create a vacuum state.

[0045] Next, after preheating inside the vacuum chamber 12 by the heater 24, argon gas is introduced from the argon tank 30 into the vacuum chamber 12 through the gas inlet 12A, and as a pretreatment, the surface of the workpiece W is bombarded with argon gas ions. Here, bombardment means that heavy inert gas ions such as argon ions are generated by plasma discharge, and these ions are irradiated onto the workpiece W to heat the surface of the workpiece W, and this heating cleans the surface.

[0046] After the above bombardment, pure oxygen gas is introduced at a flow rate of about 240 sccm so that the pressure in the chamber becomes about 1 Pa. In another embodiment, instead of pure oxygen gas, Ar-O 2 A mixed gas (for example, Ar 450 sccm, oxygen 50 to 75 sccm) may be introduced so that the pressure inside the chamber becomes about 2 Pa. Note that, in order to maintain a stable discharge, it is desirable to set the total pressure inside the chamber in the range of 0.6 Pa to 4 Pa.

[0047] Next, the target 20 is discharged in the vacuum chamber 12 while functioning as a cathode, and an yttrium oxide film is formed on the workpiece W. At this time, the temperature of the workpiece W during film formation is around 300°C (200°C to 400°C), the arc current is in the range of 100A to 150A, and the voltage applied to the workpiece W is a unipolar pulse with a frequency of 200kHz, DUTY 56% or 300kHz, DUTY 60%, and the average voltage is changed between 10 and 50V. The thickness of the yttrium oxide film formed on the workpiece W is about 5 to 100μm. As mentioned above, as an example, A6061Al (20mm x 20mm square piece shape) is used for the workpiece W. The amount of oxygen in the formed yttrium oxide film is controlled by changing the pressure of oxygen flowing into the chamber, that is, the oxygen partial pressure (oxygen flow rate).

[0048] Next, a method for evaluating the yttrium oxide film formed on the workpiece W will be described together with its indices.

[0049] (1) O / Y ratio (ratio of oxygen to yttrium in the yttrium oxide film on the workpiece W) The formed test piece (workpiece W) was cut along the film thickness direction and embedded in a resin for evaluation. The cross section was polished and then O and Y were measured at 10 points in the film from the cross-sectional direction using EDX (Energy Dispersive X-ray Spectroscopy), and the O / Y ratio was calculated from the average value.

[0050] (2) Electrical resistance of yttrium oxide film Electrodes were placed in contact with the back and front of the workpiece W (substrate), and a voltage (3.5 to 350 mV, depending on the resistance value) was applied between the two electrodes, and the electrical resistance of the film was calculated from the current value that flowed at that time. A milliohm high tester (HIOKI3540) was used for the measurement.

[0051] FIG. 2 shows the electrical resistance of yttrium oxide films with different O / Y ratios. As described above, the O / Y ratio is controlled by changing the oxygen partial pressure (oxygen flow rate) in the chamber. As shown in FIG. 2, when the O / Y ratio of the yttrium oxide film is less than 1.4, the electrical resistance of the film drops sharply, and it was confirmed that the film has electrical conductivity. It is more preferable to set the O / Y ratio to 1.35 or less. In this case, the electrical resistance of the yttrium oxide film can be stably maintained at 10,000Ω or less. In this measurement, since the upper limit of the resistance value measured by the measuring device is 30,000Ω, all the measurement points of 30,000Ω in FIG. 2 show that the electrical resistance is higher than that.

[0052] In addition, when a film is formed using oxygen alone and the oxygen flow rate is low, the pressure in the chamber is low, the discharge voltage increases, and the discharge tends to become unstable. Therefore, Ar gas is further introduced into the chamber to form an Ar-O 2 It is more desirable to form the film in an atmosphere. For example, when only 50 sccm of oxygen is introduced into the chamber and discharge is performed, the pressure in the chamber is 1×10 -2 In contrast, when 450 sccm of Ar gas and 50 sccm of oxygen gas were introduced and the chamber pressure was set to 2.5 Pa, the discharge voltage was low at around 17 V and a stable discharge could be maintained. It is more preferable to introduce Ar so that the chamber pressure during discharge is 1 Pa or higher.

[0053] In the present invention, the yttrium oxide film is a film containing Y 2 O 3 and Y are mixed together, and Y 2 O 3 By changing the ratio of Y to O, the ratio of Y to O in the film changes. 2 O 3 The film in which Y and O are mixed is collectively called an "yttrium oxide film." In this case, the ratio of Y to O is an atomic ratio. As an example, the thickness of the yttrium oxide film on the workpiece W is 50 μm or more.

[0054] <Example 2> Next, Example 2 will be described. In Example 2, a target 20 (diameter 100 mm) made of metal Y was attached to the arc evaporation source of an arc ion plating device (FIG. 1) connected to an arc power source 22 made of a DC power source, and after evacuation and preheating, argon gas was introduced into the vacuum chamber 2 at 150 sccm or 450 sccm. At this time, the pressure (total pressure) in the vacuum chamber 2 was introduced to be about 1 to 2 Pa. Then, pure oxygen gas was introduced at a constant value (for example, 45 sccm), and the arc evaporation source was discharged for 5 minutes with a current of 100 A or more and 150 A or less, and the transition of the discharge voltage at that time was measured. Then, the amount of oxygen in the vacuum chamber 2 was increased, and the process of discharging for another 5 minutes was repeated, and the experiment was performed until the oxygen flow rate at which the discharge voltage suddenly increased.

[0055] Fig. 3 is a graph showing the relationship between the flow rate of oxygen introduced into the vacuum chamber 2 and the oxygen partial pressure in Example 2. The oxygen partial pressure was calculated by multiplying the total pressure in the vacuum chamber 2 measured with a diaphragm pressure gauge (MKS) by the oxygen flow rate and then dividing the result by the total gas flow rate (argon + oxygen). As shown in Fig. 3, it can be seen that the oxygen partial pressure changes almost linearly with respect to the oxygen flow rate.

[0056] Figures 4 and 5 are graphs showing the relationship between oxygen partial pressure and discharge voltage in Example 2. Figure 4 shows the results when the arc current was 100 A, and Figure 5 shows the results when the arc current was 150 A. Both Figures 4 and 5 show experiments with two levels of argon gas introduction (150 sccm or 450 sccm).

[0057] As shown in Figures 4 and 5, the discharge voltage increases with the oxygen partial pressure, and it can be seen that the increase in discharge voltage with respect to the increase in oxygen partial pressure becomes rapid between 0.3 and 0.4 Pa. From the viewpoint of discharge voltage, this phenomenon indicates that a discharge voltage of 20 V or less is desirable in the system used in this experiment. From this, it was discovered that in order to maintain a stable discharge during film formation, it is necessary to control the oxygen partial pressure in the vacuum chamber 2 to less than 0.4 Pa at most.

[0058] <Example 3> Next, Example 3 will be described. In Example 3, a target 20 (diameter 100 mm) made of metal Y was attached to the arc evaporation source of an arc ion plating device (FIG. 1) connected to an arc power source 22 made of a DC power source, and after evacuation and preheating, argon gas was introduced into the vacuum chamber 2 at 150 sccm. At this time, the pressure (total pressure) in the vacuum chamber 2 was introduced to be about 2 Pa. Then, pure oxygen gas was introduced, the arc evaporation source was discharged with a current of 125 A, and an yttrium oxide film was formed on a Si substrate (workpiece W) with a target thickness of 3 μm. Note that a pulse bias (voltage -10 V, frequency 200 kHz, pulse width 2.8 μS) was applied during film formation. The surface roughness (Ra) of the formed film was measured with a stylus-type surface roughness meter (Tokyo Seimitsu SURFCOM TOUCH550).

[0059] FIG. 6 is a graph showing the surface roughness of the yttrium oxide film formed by changing the oxygen partial pressure in Example 3. As shown in FIG. 6, the surface roughness increases with a decrease in the oxygen partial pressure, and since a large surface roughness requires polishing or the like in practical use, it is desirable that the surface roughness be kept below 0.4 μm. For this reason, it is desirable to set the lower limit of the oxygen partial pressure (x)=0.17 Pa obtained by substituting Ra(y)=0.4 into the regression equation (y=-1.7628x+0.6961) based on the results of FIG. 6. In this way, it is desirable to set the oxygen partial pressure during film formation to 0.17 Pa or more.

[0060] <Example 4> Next, Example 4 will be described. In Example 4, a target 20 (diameter 100 mm) made of metal Y was attached to the arc evaporation source of an arc ion plating device (FIG. 1) connected to an arc power supply 22 made of a DC power supply, and after evacuation and preheating, argon gas was introduced into the vacuum chamber 2 at 450 sccm. At this time, the gas was introduced so that the pressure (total pressure) in the vacuum chamber 2 was about 2 Pa. Thereafter, pure oxygen gas was introduced at 50 sccm, and the arc evaporation source was discharged at a current of 100 A for 400 minutes, and the transition of the oxygen partial pressure and discharge voltage in the vacuum chamber 2 was measured.

[0061] Fig. 7 is a graph showing the change in oxygen partial pressure during long-term discharge in Example 4. Fig. 8 is a graph showing the change in discharge voltage during long-term discharge in Example 4.

[0062] 7 and 8, it can be seen that the discharge voltage was stabilized (20 V or less) and long-term discharge became possible by controlling the oxygen partial pressure in the vacuum chamber 2 to less than 0.4 Pa. Note that the above-mentioned Examples 2 and 4 are intended to evaluate the discharge characteristics, and no film was actually formed.

[0063] As described above, when the discharge current (arc current) is in the range of 100 A or more and 150 A or less, and the amount of argon gas introduced is in the range of 150 sccm or more and 450 sccm or less, by adjusting the oxygen partial pressure in the vacuum chamber 2 to a range of less than 0.4 Pa, it is possible to maintain a stable discharge.

[0064] <Example 5> Next, a fifth embodiment will be described. In the fifth embodiment, a target 20 (diameter 100 mm) made of metal Y was attached to the arc evaporation source of an arc ion plating device (FIG. 1) connected to an arc power supply 22 made of a DC power supply, and after evacuation and preheating, bombardment was performed with argon gas ions. After this gas bombardment, pure oxygen gas was introduced into the vacuum chamber 2 at about 1 Pa and a flow rate of about 240 sccm, or a mixed gas of argon and pure oxygen (Ar 450 sccm, oxygen 50 to 75 sccm) so that the total pressure was about 2 Pa. Then, a discharge was performed using the target 20 of metal Y as a cathode to form an yttrium oxide film on the workpiece W. The temperature of the workpiece W during film formation was about 300°C, the arc current was between 100 and 150 A, and the voltage applied to the workpiece W was a unipolar pulse with a frequency of 200 kHz, DUTY 56% or 300 kHz, DUTY 60%, and the average voltage was changed between 10 and 50 V. The thickness of the formed film is about 5 to 100 μm. A6061Al (20×20 square) was used as the substrate of the workpiece W. The amount of oxygen in the yttrium oxide film was controlled by changing the oxygen partial pressure (oxygen flow rate) in the vacuum chamber 2.

[0065] Fig. 9 is a graph showing the O / Y ratio of the yttrium oxide film formed by changing the oxygen partial pressure in Example 5. The method of calculating the O / Y ratio is the same as the method described above. As shown in Fig. 9, it can be confirmed that the O / Y ratio of the yttrium oxide film formed in the range of the oxygen partial pressure less than 0.4 Pa is 1.5 or less (1.51 or less).

[0066] The above is a detailed description of the embodiments of the present invention. The yttrium oxide film obtained by the film forming method according to the present invention can be widely applied to members exposed to plasma, such as semiconductor manufacturing equipment. In particular, by forming the yttrium oxide film by the arc ion plating method, it is possible to form a film that is denser and more plasma-resistant than when the film is formed by the thermal spraying method.

[0067] The film formation method according to the present invention is a film formation method for forming an yttrium oxide film on a substrate, which is the object of the film formation, by an arc ion plating method, and includes the steps of placing a target 20 made of yttrium and a workpiece W (substrate) in a vacuum chamber 2, introducing at least oxygen into the vacuum chamber 2, applying a predetermined bias voltage to the workpiece W, evaporating the surface of the target 20 in the oxygen to form an yttrium oxide film on the workpiece W, and setting the oxygen partial pressure in the vacuum chamber 2 during the evaporation to a pressure less than 0.4 Pa such that the O / Y ratio, which is the ratio of oxygen to yttrium in the yttrium oxide film on the workpiece W, is 1.5 or less.

[0068] According to this film formation method, the amount of oxygen in the yttrium oxide film is changed by controlling the oxygen partial pressure in the vacuum chamber 2 during film formation, thereby lowering the electrical resistance of the film and obtaining a conductive yttrium oxide film. In particular, since the oxygen partial pressure is set to less than 0.4 Pa, oxides are unlikely to form on the surface of the target 20, and it is possible to prevent an increase in discharge voltage that makes it difficult to sustain discharge.

[0069] In the above method, it is preferable to further include setting the oxygen partial pressure in the vacuum chamber 2 during the evaporation so that the O / Y ratio is less than 1.4. According to this method, the electrical resistance of the film can be further reduced, and a conductive yttrium oxide film can be stably obtained.

[0070] In the above method, it is preferable to further include setting the oxygen partial pressure in the vacuum chamber 2 so that the electrical resistance of the yttrium oxide film is 10,000Ω or less. According to this method, by controlling the oxygen partial pressure during film formation to change the amount of oxygen in the film, it is possible to stably obtain a conductive yttrium oxide film having an electrical resistance of 10,000Ω or less.

[0071] In the above method, it is preferable to further include setting the oxygen partial pressure so that the discharge voltage during film formation is not more than 20 V. According to this method, the oxygen partial pressure can be used to suppress an increase in the rate of increase in the discharge voltage caused by an increase in the discharge voltage, thereby making it possible to stably maintain the discharge during film formation.

[0072] In the above method, it is preferable that the oxygen partial pressure is equal to or higher than 0.17 Pa. According to this method, it is possible to prevent the roughness of the formed film from increasing in accordance with a decrease in the oxygen partial pressure.

[0073] In the above method, it is preferable to further include introducing argon in addition to oxygen into the vacuum chamber 2. According to this method, it is possible to lower the discharge voltage during film formation, and to stabilize the discharge during film formation.

[0074] In the above method, it is preferable to further include applying a pulse voltage as the bias voltage to the workpiece W. According to this method, even if the resistance of the coating formed on the workpiece W is relatively high, it is possible to suppress charge-up, in which electric charges are accumulated due to incident ions.

[0075] In addition, it is desirable to obtain a film with high electrical resistance, with an O / Y ratio of 1.4 to 1.5, as the yttrium oxide film. In this case, as described above, by setting the oxygen partial pressure in the vacuum chamber 2 to a pressure of less than 0.4 Pa and such that the O / Y of the yttrium oxide film is 1.5 or less, excellent discharge stability can be obtained.

[0076] Furthermore, if the oxygen flow rate (oxygen partial pressure) is high during film formation, oxides are formed on the surface of the metal target 20, causing the discharge voltage to rise and making it difficult to sustain the discharge. As in the previous embodiment, the rate at which the discharge voltage increases tends to increase as the discharge voltage increases, so it is desirable to adjust the oxygen flow rate (oxygen partial pressure) so that the discharge voltage is 20 V or less, more preferably 18 V or less. Furthermore, since the roughness of the film formed increases with a decrease in the oxygen partial pressure in the vacuum chamber 2, it is preferable that the oxygen partial pressure be 0.17 Pa or more.

[0077] However, these are merely examples, and the present invention is not to be interpreted in any way as being limited by the description of the above-mentioned embodiment. In the present invention, the substrate is not limited to one made of an insulating material, and may be made of a conductive material. In the present invention, the manner in which the negative bias voltage and the positive bias voltage are alternately applied is not limited to the pulse-like form described in the above-mentioned embodiment, and may be, for example, a sinusoidal form. In addition, if the arc current is too small, the discharge is not stable, and if it is too large, the target may be heated, so that it is desirable to set the arc current in the range of 50 A or more and 200 A or less for a target with a diameter of about 100 mm. [Explanation of symbols]

[0078] 10 Film deposition equipment 12 Vacuum chamber 14 Rotating Table 16 Substrate holder 18 Bias power supply 20 Target 22 Arc Power Supply 24 Heater 30 Argon Tank 32 Oxygen Tank 50 Controller W Work W (base material)

Claims

1. A method for forming a yttrium oxide film on a substrate by an arc ion plating method, comprising the steps of: placing a target made of yttrium and the substrate in a chamber; introducing at least oxygen into the chamber; applying a predetermined bias voltage to the substrate; evaporating a surface of the target in oxygen to form a yttrium oxide film on the substrate; setting an oxygen partial pressure in the chamber during the evaporation to a pressure less than 0.4 Pa such that an O / Y ratio, which is a ratio of oxygen to yttrium in the yttrium oxide film on the substrate, is 1.5 or less; The film forming method comprises:

2. 2. The method for forming an yttrium oxide film according to claim 1, The film forming method further comprises setting an oxygen partial pressure in the chamber during the evaporation so that the O / Y ratio is less than 1.

4.

3. 3. The method for forming an yttrium oxide film according to claim 2, The film forming method further comprises setting an oxygen partial pressure in the chamber so that the electrical resistance of the yttrium oxide film is 10,000 Ω or less.

4. 2. The method for forming an yttrium oxide film according to claim 1, The film forming method further comprises setting the oxygen partial pressure so that a discharge voltage during film formation is 20 V or less.

5. 2. The method for forming an yttrium oxide film according to claim 1, The film forming method further comprises: the oxygen partial pressure being 0.17 Pa or more.

6. A method for forming an yttrium oxide film according to any one of claims 1 to 5, The method further comprises introducing argon into the chamber in addition to oxygen.

7. A method for forming an yttrium oxide film according to any one of claims 1 to 5, The film forming method further comprises applying a pulse voltage to the substrate as the bias voltage.

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