Plasma processing method and plasma processing apparatus

Abstract

Provided are a plasma processing method and a plasma processing apparatus capable of improving the reduction rate of an oxide film and suppressing damage to a substrate. The disclosed plasma processing method includes: a disposing step of disposing a substrate including a metal and an oxide film formed on the metal on a surface thereof in a plasma processing chamber; and a first step for reducing the oxide film by introducing a first gas into the plasma processing chamber and generating a first plasma. The oxide film is a film formed by oxidizing the surface of the metal. The first gas contains water vapor and argon. In the first gas, the ratio (Va / Vw) of the volume (Va) of the argon to the volume (Vw) of the water vapor is within the range of 0.01-1.50.

Description

Technical Field

[0001] The present disclosure relates to a plasma processing method and a plasma processing apparatus. Background Art

[0002] Circuit elements mounted on circuit boards or the like are usually provided with electrodes for electrically connecting the elements to each other. On the surface of the electrodes, an oxide film of the metal contained in the electrodes is formed. Such a surface oxide film is known to reduce the connection strength of the joint formed at the electrode. In the past, a technique for removing the surface oxide film has been proposed.

[0003] In claim 1 of Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-262378), it is described as follows: "A plasma treatment method for removing an oxide film on a surface of an object having an electrode made of copper or a copper alloy by plasma treatment, the plasma treatment method comprising: a step of plasma-treating the object using a plasma generating gas containing a reducing gas, and a step of cooling the object to room temperature in a reducing gas environment after the plasma treatment."

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-262378 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Regarding the removal of the oxide film, it is required to increase the reduction rate of the oxide film. On the other hand, during the reduction of the oxide film, it is necessary to suppress damage to the substrate other than the oxide film. One of the purposes of the present disclosure is to provide a plasma processing method and a plasma processing device that have a high reduction rate of the oxide film and can suppress damage to the substrate.

[0009] Means for solving problems

[0010] One aspect of the present disclosure relates to a plasma processing method, comprising:

[0011] a placement step of placing a substrate including a metal on a surface and an oxide film formed on the metal in a plasma processing chamber; and

[0012] In a first step, a first gas is introduced into the plasma processing chamber to generate a first plasma to reduce the oxide film.

[0013] The oxide film is a film formed by oxidation of the surface of the metal.

[0014] The first gas contains water vapor and argon,

[0015] In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.50.

[0016] Another aspect of the present disclosure relates to a plasma processing apparatus for processing a substrate including a metal and an oxide film formed on the metal on a surface thereof, the plasma processing apparatus comprising:

[0017] a chamber having a plasma processing chamber for performing plasma processing on the substrate;

[0018] a gas supply device that controls the gas supplied from the gas supply source and supplies the gas as a process gas to the plasma processing chamber; and

[0019] electrodes and a power supply to generate plasma in the plasma processing chamber,

[0020] The oxide film is a film formed by oxidation of the surface of the metal.

[0021] The plasma processing apparatus performs a first step of plasma processing the substrate using a first plasma in the plasma processing chamber.

[0022] In the first step, a first gas is supplied to the plasma processing chamber as the process gas.

[0023] The first gas contains water vapor and argon,

[0024] In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.50.

[0025] Effects of the Invention

[0026] According to the present disclosure, it is possible to perform plasma processing in which the reduction rate of an oxide film is high and damage to a substrate is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The structure of the plasma processing apparatus according to Embodiment 1 is schematically shown.

[0028] Figure 2 It is a graph showing the results of evaluations performed in Examples.

[0029] Figure 3 This is a graph showing an example of the emission spectrum of plasma measured in Examples.

[0030] Figure 4 This is a graph showing another example of the emission spectrum of plasma measured in Examples.

[0031] Figure 5 This is a graph showing another example of the emission spectrum of plasma measured in Examples. DETAILED DESCRIPTION

[0032] Hereinafter, the embodiments of the present disclosure will be described with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but other numerical values ​​and other materials may also be applied as long as the invention to which the present disclosure relates can be implemented. In this specification, a description such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be replaced by "numerical value A or more and numerical value B or less". In the following description, when the lower limit and upper limit of numerical values ​​related to specific physical properties, conditions, etc. are exemplified, as long as the lower limit does not become above the upper limit, any one of the exemplified lower limits and any one of the exemplified upper limits can be arbitrarily combined. In the following description, when examples of constituent elements and examples of methods are listed, as long as there is no special description, only one of the listed examples may be used, or a plurality of the listed examples may be used in combination.

[0033] (Plasma treatment method)

[0034] Hereinafter, the plasma processing method according to the present embodiment may be referred to as a “processing method (M)”. The processing method (M) includes a placement step and a first step. These steps will be described below.

[0035] (Configuration process)

[0036] The placement step is a step of placing a substrate including a metal and an oxide film formed on the metal on its surface in a plasma processing chamber. The oxide film is a film formed by oxidation of the surface of the metal. At least a portion of the oxide film (surface oxide film) present on the surface of the metal is exposed. In the treatment method (M), at least a portion of the exposed oxide film is reduced by the first step.

[0037] There is no particular limitation on the metal whose surface is oxidized, as long as it is a metal that requires the surface oxide film to be reduced. Examples of metals whose surfaces are oxidized include electrodes and wiring of components. The metal whose surface is oxidized may be copper, a copper alloy or silver, or copper or silver. Examples of components include LED components, MOSFET components, and various other components.

[0038] The electrodes (pads, etc.) of components (LED components, etc.) are sometimes connected to wiring (circuit wiring, lead frames, etc.) by wire bonding, etc. If an oxide film is formed on the surface of the electrode or wiring, poor connection is likely to occur. Therefore, it is important to reduce (or remove) the surface oxide film. Furthermore, by reducing the surface oxide film, the wettability of the sealing resin can be improved, and the reliability of the sealing achieved by the sealing resin can be improved. On the substrate, at least one component can be configured, and multiple components can also be configured.

[0039] (1st step)

[0040] The first step is a step of reducing the oxide film by introducing a first gas (process gas) into a plasma processing chamber and generating a first plasma. The first gas contains water vapor and argon (argon gas). In the first gas, the ratio Va / Vw of the volume Va of argon to the volume Vw of water vapor is in the range of 0.01 to 1.50. In the first step, water vapor is used as a process gas, thereby generating hydrogen radicals in the first plasma. In the first step, the substrate is exposed to the first plasma, so that at least a portion of the exposed oxide film is reduced by the generated hydrogen radicals.

[0041] As shown in the embodiment, by setting the ratio Va / Vw to a range of 0.01 to 1.50, the reduction rate Rr of the oxide film can be increased while the etching rate Re of the metal is reduced. That is, by setting the ratio Va / Vw to a range of 0.01 to 1.50, it is possible to take into account both the high reduction rate Rr of the oxide film and the low etching rate Re of the metal. Thus, the ratio of the reduction rate Rr to the etching rate Re (selectivity Rr / Re) can be increased. By increasing the selectivity Rr / Re, it is possible to suppress damage to the metal and reduce the oxide film in a short time. In addition, the reduction rate of the oxide film is the thickness of the oxide film reduced per unit time.

[0042] The first gas may be composed of only water vapor and argon. The first gas may also contain other gases besides water vapor and argon. In a preferred example, the first gas does not contain oxygen.

[0043] The first step is performed before a step in which disadvantages are caused by the presence of an oxide film. For example, the first step may be performed before the step of connecting the electrodes and wirings described above.

[0044] The first plasma can be generated by supplying high-frequency power to an electrode (plasma generation electrode) while the first gas is introduced into the plasma processing chamber. The high-frequency power may be 20 W or more or 150 W or more, and may be 1000 W or less or 450 W or less. The frequency of the high-frequency power (high-frequency voltage) may also be in the range of 3 MHz to 30 MHz (e.g., 13.56 MHz). The pressure in the plasma processing chamber when the first plasma is generated may also be 1 Pa or more or 5 Pa or more, and may be 132 Pa or less or 30 Pa or less.

[0045] The ratio Va / Vw can be controlled by controlling the flow rates of water vapor and argon (argon gas) supplied to the plasma processing chamber. Water vapor and argon can be supplied to the plasma processing chamber separately or in a mixed state. By supplying water vapor and argon to the plasma processing chamber in a mixed state, more uniform processing can be performed.

[0046] The electrode to which the voltage for plasma generation is applied may be provided as the substrate stage on which the substrate is arranged, or the electrode may be arranged inside the substrate stage. Alternatively, the electrode to which the voltage for plasma generation is applied may be arranged at a position other than the substrate stage.

[0047] The first step may be performed under the condition that a deliberate self-bias voltage is generated between the substrate stage that functions as an electrode and the first plasma. Alternatively, the first step may be performed under the condition that a deliberate self-bias voltage is not generated between the substrate stage and the first plasma. The self-bias voltage may also be generated using a power supply for generating a self-bias voltage. For example, a high-frequency power supply for generating a self-bias voltage may also be connected to the substrate stage that functions as an electrode.

[0048] The time for performing the first step may be selected in consideration of the reduction rate of the oxide film, the thickness of the surface oxide film to be reduced, etc. The first step is preferably performed for a time period sufficient for all the surface oxide films to be reduced to be reduced.

[0049] The ratio Va / Vw is preferably in the range of 0.01 to 1.00, or in the range of 0.50 to 1.00. Within these ranges, both a high reduction rate Rr of the oxide film and a particularly high selectivity Rr / Re can be achieved.

[0050] The first step may also be performed when the temperature of the substrate is below 60°C (for example, below 50°C). By performing the first step when the temperature of the substrate is below 60°C, re-oxidation of the metal can be suppressed. The temperature of the substrate may also be controlled by the time of generating the first plasma, the gas for cooling, and the like. For example, when the substrate temperature rises and approaches 60°C during the period of processing using the first plasma, the processing based on the first plasma may be stopped, and a cooling gas may be introduced into the plasma processing chamber during the stop period to cool the substrate. Moreover, the processing based on the first plasma may be performed again after the substrate temperature drops. Examples of cooling gas include nitrogen and rare gases (for example, argon and helium). Alternatively, the substrate temperature may be controlled to be below 60°C by cooling the substrate stage on which the substrate is arranged. In this case, a substrate stage having a flow path through which a coolant flows may also be used. There is no particular limitation on the lower limit of the substrate temperature during the first step, and it may be above 0°C.

[0051] (Step 2)

[0052] The processing method (M) may also include a second step after the first step, in which a second gas (process gas) containing nitrogen atoms is introduced into the interior of the plasma processing chamber to generate a second plasma, and the substrate is exposed to the second plasma. Through the second step, the surface of the metal whose oxide film is reduced can be inhibited from being oxidized again. The second gas may contain nitrogen gas or may be nitrogen gas. Alternatively, the second gas may be at least one gas selected from the group consisting of nitrogen gas and ammonia gas.

[0053] The second plasma may be generated under the conditions exemplified for the first plasma except that the process gas is different. The time for performing the second step is not particularly limited. The time for performing the second step may be within a range of 1 second to 120 seconds.

[0054] In the processing method (M), when the substrate that has undergone the first step is taken out of the plasma processing chamber, the reduced pressure state in the plasma processing chamber may be released by introducing an inert gas into the plasma processing chamber. Examples of the inert gas include nitrogen and rare gases (such as argon and helium). By using an inert gas as a gas for releasing the reduced pressure state in the plasma processing chamber, it is possible to suppress the re-oxidation of the surface of the metal whose oxide film has been reduced.

[0055] (Plasma treatment device)

[0056] Hereinafter, the plasma processing apparatus according to the present embodiment is sometimes referred to as a "processing apparatus (A)". The processing method (M) described above can be easily performed using the processing apparatus (A). However, the processing method (M) can also be performed using an apparatus other than the processing apparatus (A). The matters described for the processing method (M) can be applied to the processing apparatus (A), and therefore repeated descriptions are omitted. The matters described for the processing apparatus (A) can also be applied to the processing method (M).

[0057] The processing device (A) is a plasma processing device for processing a substrate including a metal whose surface is oxidized. The processing device (A) includes: a chamber having a plasma processing chamber for plasma processing a substrate; a gas supply device for controlling a gas supplied from a gas supply source and supplying the gas as a process gas to the plasma processing chamber; and an electrode and a power supply for generating plasma in the plasma processing chamber. In the processing device (A), a first step of plasma processing a substrate using a first plasma is performed in the plasma processing chamber. In the first step, the first gas is supplied to the plasma processing chamber as a process gas. The first gas contains water vapor and argon. In the first gas, a ratio Va / Vw of a volume Va of argon to a volume Vw of water vapor is in a range of 0.01 to 1.50.

[0058] The first step performed in the processing device (A) corresponds to the first step performed in the processing method (M). In the processing device (A), the first step is performed using a first gas having a ratio Va / Vw in the range of 0.01 to 1.50. Therefore, according to the processing device (A), the same effect as that obtained by the processing method (M) can be obtained.

[0059] The gas supply source supplies water vapor and argon gas. The water vapor supply source is not particularly limited, and a known water vapor supply source may be used. For example, a gasification device that vaporizes water may be used as the water vapor supply source. As the argon gas supply source, an argon gas cylinder or the like may be used.

[0060] The gas supply device controls the flow rate of the gas supplied from the gas supply source and supplies it to the plasma processing chamber. For the gas supply device, a mass flow controller or the like can be used. The volume ratio of the gases constituting the process gas (the first gas and the second gas) can be regarded as the same as the flow ratio of the gas supplied to the plasma processing chamber.

[0061] The electrodes and power supply for generating plasma are not particularly limited, and electrodes and power supplies used in known plasma processing apparatuses may be used.

[0062] The processing apparatus may also include other equipment in addition to the above-mentioned equipment as needed. Examples of other equipment include a decompression device (such as a vacuum pump) for decompressing the interior of the plasma processing chamber, a pressure gauge for monitoring the pressure in the plasma processing chamber, a thermometer for monitoring the temperature of the substrate (or the temperature of the substrate stage), and a control device. For these equipment, the same equipment as that used in a known plasma processing apparatus can be used.

[0063] The control device includes a storage device storing a program for executing a given process, and controls a given device based on the program. The control device is connected to a measuring device (a pressure gauge, a thermometer, etc.) and performs control corresponding to the output of the measuring device. In the above-mentioned first process, the control device controls the given device (a gas supply device, a power supply, etc.) so that the first plasma is generated when the first gas is introduced into the plasma processing chamber. For example, the control device controls the gas supply device so that the ratio Va / Vw of the volume Va of argon to the volume Vw of water vapor in the first gas is in the range of 0.01 to 1.50.

[0064] In the processing apparatus (A), the ratio Va / Vw is preferably in the range of 0.50 to 1.00. In the processing apparatus (A), the first step may be performed when the temperature of the substrate is below 60°C. In the processing apparatus (A), a second step of processing the substrate using a second plasma in a plasma processing chamber may be performed after the first step. In this case, in the second step, a second gas containing nitrogen atoms may be supplied to the plasma processing chamber as a process gas. The second step performed in the processing apparatus (A) corresponds to the second step performed in the processing method (M). When performing the second step, the control device controls a given device (gas supply device, power supply, etc.) so that a second plasma is generated when the second gas is introduced into the plasma processing chamber.

[0065] From another perspective, the present disclosure discloses a method (PM) for manufacturing a component mounting substrate. The manufacturing method (PM) includes a step (i) of processing a substrate including at least one component having at least one electrode and wiring by a processing method (M). The manufacturing method (PM) may also include, after step (i), a step (ii) of connecting the at least one electrode and the wiring by wire bonding. The manufacturing method (PM) may also include, after step (ii), a step (iii) of sealing the substrate after step (ii) with a sealing resin. There is no particular limitation on the sealing resin, and a known sealing resin (silicone resin, epoxy resin, etc.) may also be used. At least one component may also include a semiconductor light emitting element (light emitting diode, etc.). The component mounting substrate may also be a light emitting device including a light emitting diode.

[0066] Hereinafter, an example of the present embodiment will be described in detail with reference to the accompanying drawings. For the processes and components of the example described below, the above-mentioned processes and components can be applied. In addition, the processes and components of the example described below can be changed based on the above-mentioned description. In addition, the matters described below can also be applied to the above-mentioned embodiment. In addition, in the processes and components described below, processes and components that are not necessary for the processing method (M) and the processing device (A) involved in the present disclosure can also be omitted.

[0067] (Implementation method 1)

[0068] In Embodiment 1, an example of a processing device (A) and a processing method (M) is described. Figure 1 Schematically shows the structure of the plasma processing apparatus 100 according to the first embodiment.

[0069] The plasma processing apparatus 100 includes a chamber 110, a gas supply device 120, an electrode 130, a power supply 140, a decompression device 150, and a control device 200. The interior of the chamber 110 is a plasma processing chamber 111. A substrate 10 having a surface including a metal and an oxide film formed on the metal is disposed in the plasma processing chamber 111. The plasma processing chamber 111 is decompressed by the decompression device 150.

[0070] The gas supply device (gas flow control device) 120 includes a plurality of mass flow controllers for controlling the flow rate of the gas supplied from the gas supply source 20. The gas supply source 20 includes a plurality of gas supply sources corresponding to the gas supplied. At least a portion of the gas supply source 20 (for example, a gas bottle) may be included in the plasma processing apparatus 100 or may not be included in the plasma processing apparatus 100.

[0071] exist Figure 1 In the example shown, the gas supply source 20 includes a water vapor supply source 21, an argon gas supply source 22, and a nitrogen gas supply source 23, and the gas supply device 120 includes corresponding mass flow controllers 121 to 123. The gases whose flow rates are controlled by the gas supply device 120 are mixed in the gas flow path 125 and introduced into the plasma processing chamber 111. When the second step is not performed, the nitrogen gas supply source 23 and the mass flow controller 123 are not required.

[0072] Figure 1The plasma processing apparatus 100 of the example shown includes a lower electrode 131 and an upper electrode 132 as an electrode 130. The lower electrode 131 is connected to a power supply 140 as a high frequency power supply. The upper electrode 132 is connected to the ground. The lower electrode 131 also functions as a substrate stage for arranging the substrate 10. A matching circuit or the like may be connected between the electrode 130 and the power supply 140 as required.

[0073] Plasma is generated by applying a high frequency voltage to the lower electrode 131 while a process gas is introduced into the plasma processing chamber 111. According to this structure, the above-mentioned self-bias voltage can be generated. In addition, the structure of the electrode and the power supply is not limited to Figure 1 For example, a high frequency power source for generating plasma may be connected to the upper electrode 132. Alternatively, a high frequency power source for generating plasma may be connected to the upper electrode 132, and a power source for generating a self-bias may be connected to the lower electrode 131.

[0074] The control device 200 is connected to predetermined devices to control these devices. The above-mentioned steps are performed by the control device 200. Hereinafter, an example of performing the first step using the plasma processing apparatus 100 will be described.

[0075] First, the substrate 10 is placed in the plasma processing chamber 111. Specifically, the substrate 10 is placed on the lower electrode 131 as a substrate stage. Next, the gas supply device 120 is controlled to introduce the above-mentioned first gas into the plasma processing chamber 111. Next, a high-frequency voltage is applied to the lower electrode 131 to generate a first plasma in the plasma processing chamber 111. The substrate 10 is exposed to the first plasma, whereby the metal oxide film of the substrate 10 is reduced. The first step is performed in this way.

[0076] When the second step is performed, after the first step, the gas supply device 120 is controlled to introduce the second gas into the plasma processing chamber 111. Then, a high frequency voltage is applied to the lower electrode 131 to generate a second plasma in the plasma processing chamber 111. The substrate 10 is exposed to the second plasma, and thus the substrate 10 is processed.

[0077] After the above-mentioned processing is performed, the chamber 110 is opened and the substrate 10 is taken out. When the pressure in the plasma processing chamber 111 is returned to the atmospheric pressure, the decompression state in the plasma processing chamber may be released by introducing an inert gas into the plasma processing chamber as described above.

[0078] (Note)

[0079] Based on the description of the above embodiments, the following techniques are disclosed.

[0080] (Technique 1)

[0081] A plasma treatment method, comprising:

[0082] a placement step of placing a substrate including a metal on a surface and an oxide film formed on the metal in a plasma processing chamber; and

[0083] In a first step, a first gas is introduced into the plasma processing chamber to generate a first plasma to reduce the oxide film.

[0084] The oxide film is a film formed by oxidation of the surface of the metal.

[0085] The first gas contains water vapor and argon,

[0086] In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.50.

[0087] (Technique 2)

[0088] The plasma processing method according to technique 1, wherein:

[0089] The ratio Va / Vw is in the range of 0.50 to 1.00.

[0090] (Technique 3)

[0091] The plasma treatment method according to technique 1 or 2, wherein:

[0092] The first step is performed in a state where the temperature of the substrate is 60° C. or lower.

[0093] (Technique 4)

[0094] The plasma processing method according to any one of techniques 1 to 3, wherein:

[0095] After the first step, the method further includes a second step of introducing a second gas containing nitrogen atoms into the plasma processing chamber to generate a second plasma, and exposing the substrate to the second plasma.

[0096] (Technique 5)

[0097] A plasma processing device is used to process a substrate including a metal and an oxide film formed on the metal on the surface, the plasma processing device comprising:

[0098] a chamber having a plasma processing chamber for performing plasma processing on the substrate;

[0099] a gas supply device that controls the gas supplied from the gas supply source and supplies the gas as a process gas to the plasma processing chamber; and

[0100] electrodes and a power supply to generate plasma in the plasma processing chamber,

[0101] The oxide film is a film formed by oxidation of the surface of the metal.

[0102] The plasma processing apparatus performs a first step of plasma processing the substrate using a first plasma in the plasma processing chamber.

[0103] In the first step, a first gas is supplied to the plasma processing chamber as the process gas.

[0104] The first gas contains water vapor and argon,

[0105] In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.50.

[0106] (Technique 6)

[0107] The plasma processing device according to technique 5, wherein:

[0108] The ratio Va / Vw is in the range of 0.50 to 1.00.

[0109] (Technique 7)

[0110] The plasma processing device according to technology 5 or 6, wherein:

[0111] The first step is performed in a state where the temperature of the substrate is 60° C. or lower.

[0112] (Technique 8)

[0113] The plasma processing apparatus according to any one of Techniques 5 to 7, wherein:

[0114] After the first step, a second step of processing the substrate using a second plasma in the plasma processing chamber is performed.

[0115] In the second step, a second gas containing nitrogen atoms is supplied to the plasma processing chamber as the process gas.

[0116] [Example]

[0117] The processing method and processing apparatus of the present disclosure are described in more detail by using an embodiment. In this embodiment, the effect of changing the process gas in plasma processing is evaluated. Figure 1 The same device as shown.

[0118] As the process gas, water vapor or a mixed gas of water vapor and argon gas was used. Furthermore, the reduction rate Rr of the oxide film and the etching rate Re of the metal (copper) were evaluated when the ratio Va / Vw of the volume Va of argon gas to the volume Vw of water vapor was changed. A high-frequency power of 13.56 MHz (600 W) was applied to the lower electrode, and the flow rate of argon gas was changed relative to the flow rate of water vapor.

[0119] The reduction rate Rr of the oxide film is obtained by the following steps. First, prepare multiple substrates (for example, glass substrates) on which an oxide film with a film thickness of X (for example, a CuO film with a film thickness of X) is formed. Next, the surface of the substrate is exposed to plasma, and XPS (X-ray photoelectron spectroscopy) is used to measure the depth distribution of the composition of the substrate surface after plasma treatment. Then, for multiple substrates with different plasma treatment times, the depth distribution of the composition of the substrate surface is measured and compared, thereby deriving the time T1 required for the entire oxide film to be reduced to a metal film (for example, a Cu film), and the film thickness Y of the metal film when the entire oxide film with a film thickness of X is reduced to a metal film. The reduction rate Rr is the thickness of the oxide film reduced per unit time, and is calculated by the formula Rr=X / T1.

[0120] In addition, the etching rate Re of the metal film is calculated by the following steps. First, a substrate on which an oxide film (e.g., CuO) with a film thickness of X is formed is prepared. Next, the surface of the substrate is exposed to plasma, the oxide film is reduced and changed into a metal film, and the overall time T3 until the metal film disappears is further measured. Here, through the above-mentioned experiment conducted to calculate the reduction rate Rr of the oxide film, the time T1 required for the oxide film (film thickness X) to be reduced and the film thickness Y of the metal film at this time are known. The time T2 required for the metal film with a film thickness Y to disappear is calculated by the formula T2=T3-T1. The etching rate Re is calculated by the formula Re=Y / T2.

[0121] The composition of the process gas and the evaluation results are shown in Table 1. The Ar flow rate (argon flow rate) in Table 1 is a relative value when the water vapor flow rate is set to 100. In Table 1, the ratio of the argon flow rate to the water vapor flow rate is regarded as the ratio Va / Vw. The reduction rate Rr in Table 1 represents the thickness of the oxide film reduced per 1 minute of plasma treatment.

[0122]

Table 1

[0123]

[0124] exist Figure 2 The results of Table 1 above are shown in FIG. Figure 2 As is clear, by setting the ratio Va / Vw to a range of 0.01 to 1.50, it is possible to take into account both the high reduction rate Rr of the oxide film and the low etching rate Re of the metal. Furthermore, by setting the ratio Va / Vw to a range of 0.01 to 1.00 or a range of 0.50 to 1.00, it is possible to take into account both the high reduction rate Rr of the oxide film and the particularly high selectivity Rr / Re. For example, by setting the ratio Va / Vw to a range of 0.01 to 1.00, it is possible to achieve an etching rate Re of more than 0.1 nm / min and a selectivity Rr / Re of more than 107. In addition, according to Table 1 and Figure 2 It is believed that by setting the ratio Va / Vw to a range of 0.01 to 1.50, an etching rate Re of 0.1 nm / min or more and a selectivity Rr / Re of 80 or more can be achieved. By increasing the selectivity Rr / Re, damage to metals (electrodes, etc.) can be reduced and the oxide film can be reduced in a short time.

[0125] In the above experiment, the emission spectrum of the plasma was measured when the ratio Va / Vw was changed. In addition, in the above experiment, the emission spectrum of the plasma was measured when the process gas was changed to a mixed gas of water vapor and oxygen. At this time, the flow rate of water vapor and the flow rate of oxygen were set to 10 mL / min respectively. Figure 3 to Figure 5 The measured emission spectrum is shown in FIG. Figure 3 to Figure 5 The vertical axis represents the luminous intensity.

[0126] Figure 3 The emission spectrum in the case where the ratio Va / Vw=0 (comparative example) is shown. Figure 4 The emission spectrum when the ratio Va / Vw=1.00 is shown. Figure 5 The emission spectra when a mixed gas of water vapor and oxygen is used as the process gas are shown. In each figure, the emission intensity of the peak value (near 656 nm) of the Hα line of hydrogen is shown by numerical values.

[0127] As per Figure 3 as well as Figure 4 As can be seen from the comparison, the intensity of the emission spectrum Hα of hydrogen atoms is increased by using a mixed gas of water vapor and argon as the process gas. Therefore, it can be considered that the number of hydrogen radicals increases by using a mixed gas of water vapor and argon as the process gas. Figure 4 and Figure 5As is clear from the comparison of , when oxygen is added to water vapor, the intensity of Hα decreases. Therefore, it is considered that the addition of oxygen to water vapor reduces the number of hydrogen radicals.

[0128] Industrial Applicability

[0129] The present disclosure can be applied to a plasma processing method and a plasma processing apparatus.

[0130] Description of Reference Numerals

[0131] 10: Substrate

[0132] 20: Gas supply source

[0133] 100: Plasma treatment device

[0134] 110: Chamber

[0135] 111: Plasma treatment chamber

[0136] 120: Gas supply device

[0137] 130: Electrode

[0138] 140: Power supply.

Claims

1. A plasma treatment method, comprising: a placement step of placing a substrate having a surface including a metal and an oxide film formed on the metal in a plasma processing chamber; and In a first step, a first gas is introduced into the plasma processing chamber to generate a first plasma to reduce the oxide film. The oxide film is a film formed by oxidation of the surface of the metal. The first gas contains water vapor and argon, In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.

50.

2. The plasma processing method according to claim 1, wherein: The ratio Va / Vw is in the range of 0.50 to 1.

00.

3. The plasma processing method according to claim 1 or 2, wherein: The first step is performed in a state where the temperature of the substrate is 60° C. or lower.

4. The plasma processing method according to claim 1 or 2, wherein: After the first step, the method further includes a second step of introducing a second gas containing nitrogen atoms into the plasma processing chamber to generate a second plasma, and exposing the substrate to the second plasma.

5. A plasma processing device for processing a substrate having a metal and an oxide film formed on the metal on the surface, the plasma processing device comprising: a chamber having a plasma processing chamber for performing plasma processing on the substrate; a gas supply device for controlling the gas supplied from the gas supply source and supplying the gas as a process gas to the plasma processing chamber; and electrodes and a power supply to generate plasma in the plasma processing chamber, The oxide film is a film formed by oxidation of the surface of the metal. The plasma processing apparatus performs a first step of plasma processing the substrate using a first plasma in the plasma processing chamber. In the first step, a first gas is supplied to the plasma processing chamber as the process gas. The first gas contains water vapor and argon, In the first gas, a ratio Va / Vw of a volume Va of the argon to a volume Vw of the water vapor is in a range of 0.01 to 1.

50.

6. The plasma processing apparatus according to claim 5, wherein: The ratio Va / Vw is in the range of 0.50 to 1.

00.

7. The plasma processing apparatus according to claim 5 or 6, wherein: The first step is performed in a state where the temperature of the substrate is 60° C. or lower.

8. The plasma processing apparatus according to claim 5 or 6, wherein: After the first step, a second step of processing the substrate using a second plasma is performed in the plasma processing chamber. In the second step, a second gas containing nitrogen atoms is supplied to the plasma processing chamber as the process gas.

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