Substrate processing method

Abstract

This invention provides a substrate processing method that enables stable reduction properties. [Solution] The substrate processing method includes raising the temperature of the substrate in a housing section 11 provided by the substrate processing apparatus 10, supplying a gas that does not contain oxidizing gas to the housing section 11 to increase the pressure inside the housing section 11 to remove adsorbed gas from the surface of the heated substrate S, and supplying an active species generated from a reducing gas to the housing section 11 to reduce the surface of the substrate S from which the adsorbed gas has been removed. The substrate processing method further includes supplying an active species generated from oxygen gas and a noble gas to the housing section 11 before raising the temperature of the substrate S to a temperature at which the surface is reduced inside the housing section 11 containing the substrate S, thereby oxidizing a portion of the inner surface of at least one of the plasma generation chamber 21 and housing section 11 provided by the substrate processing apparatus 10 that is composed of aluminum oxide or silicon oxide.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method.

Background Art

[0002] As a method for reducing an oxide layer formed on the surface of a metal layer, a method using plasma of hydrogen gas is known. In this method, the oxide layer is reduced by the reaction of oxygen contained in the oxide layer with hydrogen ions or hydrogen radicals contained in the plasma (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described substrate surface processing method, it is required to stabilize the reducibility from the viewpoint of improving mass productivity.

Means for Solving the Problems

[0005] A substrate processing method for solving the above problems includes: raising the temperature of a substrate in a housing provided by a substrate processing apparatus; supplying a gas that does not contain oxidizing gas to the housing to increase the pressure inside the housing to remove adsorbed gas from the surface of the heated substrate; and supplying an active species generated from a reducing gas to the housing to reduce the surface of the substrate from which the adsorbed gas has been removed. The substrate processing method further includes supplying an active species generated from oxygen gas and a noble gas to the housing before raising the temperature of the substrate to the temperature at which the surface is reduced inside the housing containing the substrate to oxidize a portion of the inner surface of at least one of the plasma generation chamber and the housing provided by the substrate processing apparatus that is composed of aluminum oxide or silicon oxide.

[0006] According to the above configuration, by oxidizing the parts of the plasma generation chamber and the housing that are made of aluminum oxide or silicon oxide, it is possible to suppress the deactivation of the reducing active species generated in the plasma generation chamber. This makes it possible to stabilize the reducing properties of the active species generated from the reducing gas, thereby improving mass productivity in substrate processing.

[0007] In the above substrate processing method, before removing the adsorbed gas from the heated surface of the substrate by increasing the pressure inside the housing, the portion of the inner surface composed of aluminum oxide or silicon oxide may be oxidized.

[0008] According to the above configuration, the inner surface is oxidized before the adsorbed gas is removed, so the active species containing the oxidation source are supplied to the containment section at a lower substrate temperature. This suppresses the progression of oxidation on the substrate surface when oxidizing the ceramic surface.

[0009] In the above substrate processing method, the surface of the substrate is the surface of a metal layer, and the surface of the metal layer may be oxidized. According to the above configuration, the surface of the oxidized metal layer can be reduced by the reducing active species contained in the plasma generated from the reducing gas.

[0010] In the substrate processing method described above, the reducing gas may include hydrogen gas. According to the above configuration, the surface of the substrate can be reduced by hydrogen radicals contained in the plasma generated from hydrogen gas.

[0011] In the substrate processing method described above, the flow rate of the oxygen gas may be 1 sccm or more and 10 sccm or less.

[0012] With the above configuration, a flow rate of 1 sccm or more of oxygen gas makes it possible to increase the certainty of oxidizing the inner surface. A flow rate of 10 sccm or less of oxygen gas makes it less likely for oxidation sources to remain in the containment during subsequent processing after the oxidation of the inner surface. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a diagram showing the structure of a substrate processing apparatus. [Figure 2] Figure 2 is a timing chart illustrating the substrate processing method. [Figure 3] Figure 3 is a diagram illustrating the operation of the substrate processing method. [Figure 4] Figure 4 is a diagram illustrating the operation of the substrate processing method. [Figure 5] Figure 5 is a graph showing the relationship between the standard value and standard deviation of relative reflectance and the number of substrates in the test example. [Figure 6] Figure 6 is a graph showing the relationship between the number of particles and the number of substrates in the test example. [Modes for carrying out the invention]

[0014] An embodiment of the substrate processing method will be described with reference to Figures 1 to 6. [Substrate Processing Apparatus] The substrate processing apparatus will be described with reference to FIG. 1.

[0015] As shown in FIG. 1, the substrate processing apparatus 10 includes a housing portion 11, a plasma supply portion 12, and a gas supply portion 13. The housing portion 11 houses the substrate S to be processed. The gas supply portion 13 supplies a plasma generation gas to the plasma supply portion 12. The plasma generation gas is a reducing gas and a mixed gas of oxygen (O2) gas and a rare gas. The reducing gas may be a gas containing hydrogen (H) atoms. The gas containing hydrogen atoms may be, for example, any one of silane (SiH4) gas, phosphine (PH3) gas, ammonia (NH3) gas, and hydrogen (H2) gas. The reducing gas may contain a rare gas. The rare gas may be at least one of argon (Ar) gas and helium (He) gas. The rare gas may be only Ar gas, only He gas, or both Ar gas and He gas.

[0016] The rare gas constituting the mixed gas may be, for example, at least one of argon gas and helium gas. The rare gas may be only argon gas, only helium gas, or both argon gas and helium gas.

[0017] The gas supply portion 13 includes, for example, a mass flow controller for the reducing gas, a mass flow controller for the oxygen gas, and a mass flow controller for the rare gas. Each mass flow controller is connected to a cylinder of each gas located outside the substrate processing apparatus 10.

[0018] The plasma supply portion 12 includes a plasma generation chamber 21, a plasma source 22, and a high-frequency power supply 23. The plasma generation chamber 21 is connected to the housing portion 11. The gas supply portion 13 is connected to a gas supply port 21A formed in the plasma generation chamber 21.

[0019] The plasma source 22 is disposed around the plasma generation chamber 21. A high-frequency power supply 23 for supplying high-frequency power to the plasma source 22 is connected to the plasma source 22. The plasma source 22 may be an inductively coupled plasma source or a magnetron-type plasma source as long as it can generate plasma from the mixed gas.

[0020] The plasma supply unit 12 generates plasma from the plasma generation gas by supplying high-frequency power from the high-frequency power supply 23 to the plasma source 22 in a state where the plasma generation gas is supplied to the plasma generation chamber 21. Then, the plasma supply unit 12 supplies the plasma from the plasma generation chamber 21 to the storage unit 11.

[0021] The plasma generated from the reducing gas contains active species generated from a gas containing hydrogen atoms. The gas containing hydrogen atoms may be, for example, hydrogen gas as described above. The active species are, for example, hydrogen ions and hydrogen radicals having reducing properties.

[0022] The storage unit 11 includes a plasma supply port connected to the plasma generation chamber 21. Inside the storage unit 11, a diffusion unit 14 is disposed at a position facing the plasma supply port. The active species generated in the plasma generation chamber 21 and supplied to the storage unit 11 diffuse in the radial direction of the plasma supply port in the storage unit 11 by colliding with the diffusion unit 14.

[0023] Inside the storage unit 11, a support unit 15 for supporting the substrate S is disposed. The support unit 15 may be, for example, a stage on which the substrate S is placed or a clamp that grips the periphery of the substrate S. The support unit 15 has a heating unit (not shown) for heating the substrate S. The heating unit may be, for example, a resistance heating device or the like. The substrate S is supplied with active species generated from the plasma generation gas. The surface of the substrate S includes a surface to be reduced by the active species generated from the reducing gas. The surface of the substrate S may be the surface of a metal layer. The surface of the metal layer is oxidized.

[0024] That is, the surface of the metal layer may be composed of a metal oxide. The substrate S includes, for example, a silicon layer and a metal layer. The metal layer is laminated on the silicon layer, thereby forming the surface of the substrate S. The metal layer may be composed of, for example, copper. The surface of the metal layer may be composed of, for example, copper oxide.

[0025] The housing section 11 includes an exhaust port 11A formed in the wall opposite to the plasma supply port. An exhaust unit 16 is connected to the exhaust port 11A. The exhaust unit 16 includes, for example, a pressure regulating valve and various pumps to adjust the pressure inside the housing section 11, reducing the pressure inside the housing section 11 to a predetermined pressure.

[0026] In the substrate processing apparatus 10, at least one of the inner surfaces of the plasma generation chamber 21 and the housing section 11 includes a portion made of aluminum oxide or silicon oxide. In the substrate processing apparatus 10, only the inner surface of the plasma generation chamber 21 may include a portion made of aluminum oxide or silicon oxide, or only the inner surface of the housing section 11 may include a portion made of aluminum oxide or silicon oxide. Alternatively, both the inner surface of the plasma generation chamber 21 and the inner surface of the plasma generation chamber 21 may include a portion made of aluminum oxide or silicon oxide.

[0027] Among the members constituting the inner surface of the plasma generation chamber 21, for example, the cylindrical member constituting the inner surface of the plasma generation chamber 21 may be made of aluminum oxide or silicon oxide. Among the members constituting the inner surface of the housing 11, for example, the support portion 15, the platen ring surrounding the support portion 15, and at least one of the anti-adhesion plate may be made of aluminum oxide or silicon oxide.

[0028] Each component may be composed entirely of aluminum oxide or silicon oxide, or only the surface of each component that constitutes the plasma generation chamber 21 or the inner surface of the housing 11 may be composed of aluminum oxide or silicon oxide.

[0029] The inner surface of the plasma generation chamber 21 may include only a portion made of aluminum oxide, or only a portion made of silicon oxide, or both a portion made of aluminum oxide and a portion made of silicon oxide. The inner surface of the housing 11 may include only a portion made of aluminum oxide, or only a portion made of silicon oxide, or both a portion made of aluminum oxide and a portion made of silicon oxide.

[0030] Furthermore, the diffusion section 14 located within the space defined by the containment section 11 may also be made of aluminum oxide or silicon oxide. Alternatively, only the surface of the diffusion section 14 may be made of aluminum oxide or silicon oxide.

[0031] The substrate processing apparatus 10 includes a control unit 30. The control unit 30 controls the driving of the plasma supply unit 12 and the gas supply unit 13. The control unit 30 controls the driving of the plasma supply unit 12 by, for example, controlling the driving of the high-frequency power supply 23. For example, the control unit 30 controls the timing of supplying high-frequency power from the high-frequency power supply 23 to the plasma source 22, and the magnitude of the power supplied by the high-frequency power supply 23.

[0032] The control unit 30 includes electronic circuits such as a CPU and an MPU. The control unit 30 includes storage such as an SSD or an HDD. The control unit 30 includes memory such as ROM, RAM, or registered memory. The control unit 30 may also include integrated circuits such as an ASIC or an FPGA. All processing to be performed by the control unit 30 may be performed by the software provided by the control unit 30, or by a combination of the integrated circuits and software provided by the control unit 30.

[0033] The control unit 30 is equipped with a substrate processing program for executing a substrate processing method. By executing the substrate processing program, the control unit 30 causes the substrate processing apparatus 10 to perform tasks such as supplying various gases and generating plasma.

[0034] [Substrate Processing Method] The substrate processing method will be explained with reference to Figure 2. The substrate processing method includes raising the temperature of the substrate S, removing adsorbed gases, reducing the surface of the substrate S, and oxidizing the portion of the inner surface composed of aluminum oxide or silicon oxide.

[0035] To raise the temperature of the substrate S, the substrate S is heated within the housing section 11. To remove the adsorbed gas, a gas that does not contain oxidizing gas is supplied to the housing section 11, thereby increasing the pressure inside the housing section 11 and removing the adsorbed gas from the surface of the heated substrate S. To reduce the surface of the substrate S, plasma generated from the reducing gas is supplied to the housing section 11, thereby reducing the surface of the substrate S from which the adsorbed gas has been removed.

[0036] In oxidizing the portion of the inner surface composed of aluminum oxide or silicon oxide, plasma generated from oxygen gas and a noble gas is supplied to the housing 11 before the substrate S is heated to the temperature at which the surface is reduced within the housing 11 containing the substrate S. This oxidizes the portion of the inner surface composed of aluminum oxide or silicon oxide, at least one of the inner surfaces of the plasma generation chamber 21 and the housing 11. The substrate processing method will be described below with reference to the drawings.

[0037] In the substrate processing method of this embodiment described below, the reducing gas includes hydrogen gas and helium gas, the noble gas supplied to the plasma generation chamber 21 along with oxygen gas is argon gas, and the gas that does not contain an oxidizing gas consists of hydrogen gas and helium gas. The oxidizing gas is a gas containing oxygen. The gas containing oxygen may be, for example, oxygen gas, ozone (O3) gas, nitric oxide (NO) gas, or nitrogen dioxide (NO2) gas. In the substrate processing method of this embodiment, the surface of the substrate S is the surface of a metal layer, and the surface of the metal layer is oxidized. In the substrate processing method of this embodiment, the inner surface of the plasma generation chamber 21 of the substrate processing apparatus 10 is made of aluminum oxide, and a part of the inner surface of the housing section 11 is made of aluminum oxide.

[0038] Figure 2 is a timing chart showing the driving modes of the gas supply unit 13, the high-frequency power supply 23 (RF), and the heating unit (HT). In addition to the driving modes of each unit, Figure 2 also shows an example of the behavior of the temperature T of the substrate S and an example of the behavior of the pressure P inside the housing unit 11. In Figure 2, Ar, O2, H2, and He each indicate the timing when the supply of each gas is started (ON) and the timing when the supply of each gas is stopped (OFF).

[0039] As shown in Figure 2, in the substrate processing method, first, at timing t0, the substrate S is placed on the support part 15. This initiates heating of the substrate S. Next, at timing t1, the gas supply unit 13 begins supplying argon gas to the plasma generation chamber 21, thereby increasing the pressure inside the containment unit 11 to pressure PB. After the pressure inside the containment unit 11 has increased, at timing t2, the high-frequency power supply 23 begins supplying high-frequency power to the plasma source 22. As a result, plasma is generated from the argon gas in the plasma generation chamber 21, and the plasma is supplied from the plasma generation chamber 21 to the containment unit 11. Subsequently, at timing t3, the gas supply unit 13 begins supplying oxygen gas to the plasma generation chamber 21.

[0040] As a result, plasma generated from oxygen gas and argon gas is supplied to the containment section 11, and oxidation sources contained in the plasma collide with the materials constituting the inner surface of the plasma generation chamber 21 and the materials constituting the inner surface of the containment section 11. Consequently, the inner surfaces of the plasma generation chamber 21 and the containment section 11 are oxidized. The period from timing t1 to timing t4 corresponds to the oxidation process.

[0041] In the oxidation process, the flow rate of oxygen gas may be, for example, 1 sccm or more and 10 sccm or less, and the flow rate of argon gas may be, for example, 100 sccm or more and 300 sccm or less. The high-frequency power may be, for example, 1000 W or more and 2000 W or less. The pressure P inside the containment section 11 may be, for example, 0.1 Pa or more and 5 Pa or less. By having an oxygen gas flow rate of 1 sccm or more, it is possible to increase the certainty of oxidation of the inner surface. By having an oxygen gas flow rate of 10 sccm or less, the oxidation source is less likely to remain inside the containment section 11 in processes after the oxidation process.

[0042] Next, at timing t4, the gas supply unit 13 stops supplying argon gas and oxygen gas, and the high-frequency power supply 23 stops supplying high-frequency power. Also at timing t4, the gas supply unit 13 starts supplying hydrogen gas and helium gas. As a result, the pressure inside the containment unit 11 is further increased to pressure PC. Subsequently, at timing t5, the gas supply unit 13 stops supplying helium gas while maintaining the supply of hydrogen gas. Then, at timing t6, the gas supply unit 13 stops supplying hydrogen gas.

[0043] From timing t4 to timing t6, the inside of the containment section 11 is pressurized by the helium and hydrogen gases supplied into the containment section 11, and the supply of hydrogen gas is maintained even after the supply of helium gas is stopped. This removes the adsorbed gases adsorbed on the substrate S. Adsorbed gases include, for example, oxygen gas, water, and organic impurities. The period from timing t4 to timing t6 corresponds to the degassing process.

[0044] In the degassing process, the flow rate of hydrogen gas may be, for example, 1500 sccm to 2000 sccm, and the flow rate of helium gas may be, for example, 1800 sccm to 2500 sccm. The pressure P inside the containment section 11 may be, for example, 500 Pa to 1000 Pa.

[0045] Thus, in this embodiment, before removing the adsorbed gas from the heated surface of the substrate S by increasing the pressure inside the housing 11, the portion of the inner surface composed of aluminum oxide or silicon oxide is oxidized.

[0046] Furthermore, between timing t5 and timing t6, the temperature T of the substrate S is heated from the temperature TA at which heating began at timing t0 to the temperature TB at which the surface of the substrate S is reduced. The temperature T of the substrate S only needs to be raised to temperature TB before the process of reducing the surface of the substrate S is performed. Therefore, the temperature T of the substrate S only needs to be raised to temperature TB between timing t4 and timing t7, which will be explained below.

[0047] Next, from timing t6 to timing t7, the exhaust unit 16 exhausts the contents of the housing unit 11. The exhaust unit 16 continues to exhaust the contents of the housing unit 11 after the substrate S is placed in the support unit 15. Between timing t6 and timing t7, the gas supply unit 13 does not supply gas to the housing unit 11, so the contents of the housing unit 11 are exhausted, and the pressure inside the housing unit 11 is reduced to pressure PA. The pressure P in the housing unit 11 after the pressure reduction may be higher than pressure PA.

[0048] Then, at timing t7, the gas supply unit 13 starts supplying argon gas, thereby increasing the pressure inside the containment unit 11 to pressure PB. Subsequently, at timing t8, the high-frequency power supply 23 starts supplying high-frequency power to the plasma source 22. Next, at timing t9, the gas supply unit 13 starts supplying hydrogen gas to the plasma generation chamber 21. As a result, reducing active species are supplied to the surface of the substrate S placed inside the containment unit 11, and consequently, the surface of the metal layer of the substrate S is reduced. Next, at timing t10, the gas supply unit 13 stops supplying hydrogen gas, and the high-frequency power supply 23 stops supplying high-frequency power. The period from timing t7 to timing t10 ​​corresponds to the reduction process.

[0049] In the reduction process, the flow rate of hydrogen gas may be, for example, 100 sccm or more and 300 sccm or less, and the flow rate of argon gas may be, for example, 100 sccm or more and 300 sccm or less. The high-frequency power may be, for example, 1000 W or more and 4000 W or less. The pressure inside the housing 11 may be, for example, 1.0 Pa or more and 100 Pa or less. The temperature T of the substrate S may be, for example, 150°C or more and 350°C or less.

[0050] From timing t10 ​​to timing t11, the gas supply unit 13 maintains the supply of argon gas. This removes the hydrogen gas supplied into the containment unit 11 up to timing t10 ​​from the containment unit 11.

[0051] The processing from timing t0 to timing t11 is performed in a single board processing cycle. The number of boards S processed at one time may be one or two or more.

[0052] [Effect] The operation of the substrate processing method will be explained with reference to Figures 3 and 4. Below, the operation of the substrate processing method will be explained when the inner surface of the plasma generation chamber 21 is made of aluminum oxide.

[0053] As shown in Figure 3, the plasma generation chamber 21 comprises a surface layer 21S that constitutes the inner surface of the plasma generation chamber 21, and a main body 21B having the surface layer 21S. The surface layer 21S is made of aluminum oxide. The surface layer 21S is an oxide film formed by the anodizing of the aluminum main body 21B.

[0054] In the plasma generation chamber 21, plasma is generated from a mixed gas composed of hydrogen gas and argon gas, causing oxygen ions in the surface layer 21S to react with hydrogen ions in the plasma. This extracts oxygen ions from the aluminum oxide, resulting in the formation of a reduced region in the surface layer 21S. The reduced region is a region composed of aluminum oxide in which the proportion of oxygen ions is lower than the stoichiometric ratio and the proportion of aluminum ions is higher.

[0055] The more times plasma is generated from the mixed gas in the plasma generation chamber 21, the larger the reduced region becomes in the surface layer 21S. Hydrogen radicals, which are active species contained in the plasma, are more easily deactivated when they come into contact with aluminum than when they come into contact with aluminum oxide. As a result, hydrogen radicals are more likely to recombine, and the number of hydrogen radicals supplied to the containment section 11 decreases.

[0056] Furthermore, the reduced region is more prone to sputtered particle emission when argon ions collide with it compared to the unreduced region. As a result, aluminum-containing particles are more easily supplied to the containment section 11 as particles.

[0057] In contrast, as shown in Figure 4, when plasma is generated in the plasma generation chamber 21 from a mixed gas composed of oxygen and argon, the reduced region of the surface layer 21S is re-oxidized by the oxidation source in the plasma. Furthermore, the supply of the oxidation source to the surface layer 21S also oxidizes the reducing active species adsorbed on the surface layer 21S. This suppresses the oxidation of the surface layer 21S.

[0058] Thus, in the surface layer 21S, the reduced region does not expand, making it difficult for hydrogen radicals contained in the plasma to be deactivated. As a result, the recombination of hydrogen radicals is suppressed, and the number of hydrogen radicals supplied to the containment section 11 increases.

[0059] Furthermore, as mentioned above, in the unreduced region, sputtered particles are less likely to be emitted when argon ions collide, compared to the reduced region. As a result, aluminum-containing particles are less likely to be supplied to the containment section 11 as particles.

[0060] By oxidizing the inner surface of the plasma generation chamber 21, it is possible to suppress the deactivation of hydrogen radicals generated in the plasma generation chamber 21. This makes it possible to stabilize the reducing properties of the plasma generated from the reducing gas, thereby increasing the mass productivity in the processing of the substrate S. Furthermore, by oxidizing the inner surface of the plasma generation chamber 21, the emission of sputtered particles from the inner surface of the plasma generation chamber 21 is suppressed. This suppresses the adhesion of particles to the substrate S placed in the containment section 11. As a result, it is possible to increase the mass productivity in the processing of the substrate S.

[0061] Furthermore, since the oxidation process is performed before the degassing process, plasma containing the oxidation source is supplied into the containment section 11 while the substrate S is at a lower temperature. This suppresses the progression of oxidation on the surface of the substrate S during the oxidation process. In addition, since gas that does not contain oxidizing gas is supplied to the containment section 11 during the degassing process, the oxidation source supplied into the containment section 11 during the oxidation process is less likely to remain in the containment section 11 during the reduction process.

[0062] [Example Test] A test example of the substrate processing method will be explained with reference to Figures 5 and 6. [Test Example 1] A substrate processing apparatus 10 was prepared, in which the inner surface of the plasma generation chamber 21 was made of aluminum oxide, and a portion of the inner surface of the housing section 11 was also made of aluminum oxide. Using the substrate processing apparatus 10, when processing one substrate S, the oxidation process, degassing process, and reduction process were performed in order. The conditions for each process were set as follows. Furthermore, 2000 substrates S were processed one by one under the same conditions. As the substrate S, a substrate comprising a disc-shaped silicon substrate and a copper layer formed on the silicon substrate was prepared.

[0063] (oxidation process) • Step 1: 2 seconds High-frequency power 0W / Argon gas 200 sccm / Oxygen gas 0 sccm • Step 2: 1 second High-frequency power 1400W / Argon gas 200 sccm / Oxygen gas 0 sccm • Step 3: 4 seconds High-frequency power 1800W / Argon gas 200 sccm / Oxygen gas 6 sccm / 1.0 Pa (Degassing process) • Step 1: 7 seconds High-frequency power 0W / Hydrogen gas 1800 sccm / Helium gas 2200 sccm / 800 Pa • Step 2: 7 seconds High-frequency power 0W / Hydrogen gas 1800 sccm / 900 Pa (Reduction process) • Step 1: 2 seconds High-frequency power 0W / Argon gas 200 sccm / Hydrogen gas 0 sccm / 2.0 Pa • Step 2: 1 second High-frequency power 1400W / Argon gas 200 sccm / Hydrogen gas 0 sccm / 2.0 Pa • Step 3: 2 seconds High-frequency power 4300W / Argon gas 200 sccm / Hydrogen gas 200 sccm / 3.0 Pa • Step 4: 7 seconds High-frequency power 4300W / Argon gas 200 sccm / Hydrogen gas 200 sccm / 3.0 Pa

[0064] [Test Example 2] In this experiment, each substrate S was treated in the same manner as in Test Example 1, except that the oxidation process was omitted and 825 substrates S were treated.

[0065] [Evaluation Method] [Reduction performance] First, the reflectance of the silicon substrate to light with a wavelength of 480 nm was measured. Next, the reflectance of the copper layer, which was sputter-deposited onto the silicon substrate, to light with a wavelength of 480 nm was measured before processing by the substrate processing method. Subsequently, the reflectance of the copper layer to light with a wavelength of 480 nm was measured after processing by the substrate processing method. For the copper layers before and after processing, the relative reflectance, which is the reflectance of the copper layer relative to the reflectance of the silicon substrate, was calculated. Furthermore, for each substrate S, a normalized standard value was calculated by dividing the relative reflectance of the copper layer after processing by the relative reflectance of the copper layer before processing.

[0066] For each substrate S, the relative reflectance was calculated at five locations along the diameter of the substrate S. Specifically, the relative reflectance was calculated at the center of the substrate S, the first outer edge of the substrate S, the second outer edge of the substrate S, the midpoint of the line segment connecting the center and the first outer edge, and the midpoint of the line segment connecting the center and the second outer edge. Then, for each substrate S, the standard deviation of the relative reflectance was calculated using the processed relative reflectances at these five locations.

[0067] [Number of particles] An electron microscope was used to observe the surface of each substrate treated in Test Examples 1 and 2, thereby measuring the number of aluminum-containing particles attached to the surface. In this process, particles with a diameter of 19 nm or larger were counted as aluminum particles. In Test Example 2, the number of aluminum particles was measured only on the first 670 of the 825 substrates S.

[0068] [Evaluation Results] The evaluation results for the reduction performance of the substrate processing method are shown in Figure 5. The evaluation results for the number of aluminum particles are shown in Figure 6.

[0069] As shown in Figure 5, in Test Example 1, the standard value was found to be approximately 1 regardless of the number of substrates S that were processed. In other words, according to Test Example 1, even after going through a substrate processing method that includes an oxidation step, the surface of the copper layer can be reduced by a reduction step to have the same reflectivity as before processing.

[0070] Furthermore, in Test Example 1, it was observed that the standard deviation of the relative reflectance after processing was almost 0%, regardless of the number of substrates S processed. In contrast, in Test Example 2, it was observed that the standard deviation of the relative reflectance after processing increased as the number of substrates S processed increased. Moreover, in Test Example 2, it was observed that the standard deviation of the relative reflectance after processing was larger than in Test Example 1, regardless of the number of substrates S processed.

[0071] Thus, according to Test Example 1, it can be said that variations in the degree of reduction within the surface of the substrate S can be suppressed. In other words, according to Test Example 1, it is possible to reduce the entire surface of the substrate S to a similar degree.

[0072] As shown in Figure 6, in Test Example 1, regardless of the number of substrates S processed, the number of aluminum particles attached to the substrate S was almost zero, and at most one. In contrast, in Test Example 2, it was observed that the number of aluminum particles attached to the substrate S increased as the number of substrates S processed increased. Furthermore, in Test Example 2, it was observed that the number of aluminum particles was two or less when the number of substrates S processed was 200 or less. On the other hand, when the number of substrates S processed was 360, the number of aluminum particles was 11, and when the number of substrates S processed was 670, the number of aluminum particles was 22.

[0073] As described above, according to one embodiment of the substrate processing method, the following effects can be obtained. (1) By oxidizing the inner surface of the plasma generation chamber 21 and the inner surface of the housing 11, it is possible to suppress the deactivation of hydrogen radicals generated in the plasma generation chamber 21. This makes it possible to stabilize the reducing properties of the plasma generated from the reducing gas, thereby improving the mass productivity in processing the substrate S.

[0074] (2) By oxidizing the inner surface of the plasma generation chamber 21, the emission of sputtered particles from the inner surface of the plasma generation chamber 21 is suppressed. This suppresses the adhesion of particles to the substrate S placed in the containment section 11. As a result, it is possible to improve the mass productivity in processing the substrate S.

[0075] (3) Since the oxidation process is performed before the degassing process, the plasma containing the oxidation source is supplied into the housing 11 at a lower temperature of the substrate S, so that oxidation on the surface of the substrate S is suppressed during the oxidation process.

[0076] (4) If the substrate S has a metal layer and the oxidized surface of the metal layer is the surface of the substrate S, the surface of the oxidized metal layer can be reduced by the reducing active species contained in the plasma generated from the reducing gas.

[0077] (5) If the reducing gas contains hydrogen gas, the surface of the substrate S can be reduced by hydrogen radicals contained in the plasma generated from the hydrogen gas.

[0078] (6) When the oxygen gas flow rate is 1 sccm or more, it is possible to increase the certainty of oxidation of the inner surface. When the oxygen gas flow rate is 10 sccm or less, the oxidation source is less likely to remain in the containment section 11 in processes after the oxidation process.

[0079] The above-described embodiment can be implemented with the following modifications. [Oxidation process] An oxidation step may be performed between the degassing step and the reduction step. Even in this case, since the oxidation step is performed before the reduction step, it is possible to re-oxidize the inner surface of the containment section 11 and the inner surface of the plasma generation chamber 21 before the reduction step. Therefore, it is possible to obtain the effects similar to those described in (1) and (2) above. The oxidation process may be performed at a predetermined frequency. For example, the oxidation process may be performed before the reduction process each time the degassing and reduction processes are carried out for a predetermined number of substrates S, for example, 25 substrates. Even in this case, since the oxidation process is performed before the reduction process, it is possible to re-oxidize the inner surface of the housing section 11 and the inner surface of the plasma generation chamber 21 before the reduction process. Therefore, it is possible to obtain the effects similar to those described in (1) and (2) above.

[0080] [substrate] The metal layer of the substrate S may be composed of a metal other than copper. The surface of the substrate S is not limited to the surface of the metal layer. The surface of the substrate S may be an inorganic material such as an inorganic nitride or inorganic sulfide, or an organic polymer layer, etc. [Explanation of Symbols]

[0081] 10... Circuit board processing equipment 11...Detention Unit 12…Plasma supply unit 13…Gas Supply Department 21…Plasma generation room 22…Plasma source 23…High frequency power supply S... Circuit board

Claims

1. To raise the temperature of a substrate within the housing section of a substrate processing device. By supplying a gas that does not contain oxidizing gas to the containment section and increasing the pressure inside the containment section, adsorbed gas is removed from the heated surface of the substrate. By supplying the active species generated from the reducing gas to the aforementioned containment section, the surface of the substrate from which the adsorbed gas has been removed is reduced. Includes, The apparatus further includes supplying an active species generated from oxygen gas and a noble gas to the housing containing the substrate before raising the substrate temperature to a temperature at which the surface is reduced, thereby oxidizing a portion of the inner surface of at least one of the plasma generation chamber and the housing of the substrate processing apparatus that is composed of aluminum oxide or silicon oxide. Substrate processing method.

2. Before removing the adsorbed gas from the heated surface of the substrate by increasing the pressure inside the housing, the portion of the inner surface composed of aluminum oxide or silicon oxide is oxidized. The substrate processing method according to claim 1.

3. The surface of the substrate is the surface of the metal layer, The surface of the metal layer is oxidized. The substrate processing method according to claim 1 or 2.

4. The reducing gas includes hydrogen gas. The substrate processing method according to claim 1 or 2.

5. The flow rate of the oxygen gas is 1 sccm or more and 10 sccm or less. The substrate processing method according to claim 1 or 2.

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