Substrate processing method and substrate processing apparatus

Abstract

To remove a reaction product, which is generated during etching of a molybdenum film on a surface of a substrate, while suppressing reduction of productivity.SOLUTION: The present invention relates to a substrate processing method for successively processing a plurality of substrates on a substrate basis. The substrate includes a molybdenum film on a surface. The substrate processing method includes the steps of: (A) carrying the substrate into a processing container and mounting the substrate on a mounting table; (B) etching the molybdenum film by making a first process gas containing fluorine into plasma after the step (A); (C) etching the molybdenum film by making a second process gas containing chlorine into plasma after the step (B); and (D) cleaning the inside of the processing container by generating the plasma of the first process gas inside of the processing container between the step (A) and the step (B). The step (D) is continued until a light emission intensity of plasma light of a predetermined wavelength is not changed any more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. [Background technology]

[0002] The method for cleaning an etching apparatus disclosed in Patent Document 1 involves replacing the sample with a dummy substrate after each etching of a sample having a metal film. In this method, deposits of carbon-based substances are removed by a plasma treatment using oxygen and carbon tetrafluoride in the first step, and residues and metal films that could not be removed in the first step are removed by a plasma treatment using boron trichloride and chlorine in the second step, thereby cleaning the inside of the vacuum chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-237432 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure removes reaction products generated during etching of a molybdenum film on a substrate surface while suppressing deterioration in productivity. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate processing method for sequentially processing a plurality of substrates, each substrate having a molybdenum film on its surface, the method comprising: (A) a step of loading the substrate into a processing vessel and placing the substrate on a mounting table; (B) after the step (A), a step of generating a first processing gas containing fluorine into plasma to etch the molybdenum film; (C) after the step (B), a step of generating a second processing gas containing chlorine into plasma to etch the molybdenum film; and (D) between the steps (A) and (B), generating plasma of the first processing gas inside the processing vessel; During etching of the molybdenum filmInside the processing vessel Molybdenum chloride formed in and a step of cleaning the surface of the substrate, wherein the step (D) comprises: The point at which the change in emission intensity per unit time of the fluorine emission line spectrum falls below the threshold value It will continue until [Effects of the Invention]

[0006] According to the present disclosure, reaction products generated during etching of a molybdenum film on a substrate surface can be removed while suppressing deterioration in productivity. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a longitudinal sectional view showing an outline of the configuration of a plasma processing apparatus as a substrate processing apparatus according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view showing a substrate to be processed in the plasma processing apparatus of FIG. 1. [Figure 3] 2 is a flowchart illustrating an example of substrate processing using the plasma processing apparatus of FIG. [Figure 4] 1A and 1B are diagrams illustrating a state of a substrate during substrate processing. [Figure 5] 1A and 1B are diagrams illustrating a state of a substrate during substrate processing. [Figure 6] FIG. 10 is a diagram showing the change over time in the emission intensity of a specific plasma light detected by an emission monitor when etching a molybdenum film with plasma of a first processing gas in step S3 of a comparative example. [Figure 7] FIG. 10 is a diagram showing the time change in the emission intensity of a specific plasma light detected by an emission monitor during cleaning with plasma of a first processing gas in step S2 of the embodiment and etching of a molybdenum film with the same plasma in step S3, which is performed consecutively to step S2. [Figure 8] FIG. 10 is a diagram showing the change over time in the emission intensity of a specific plasma light detected by an emission monitor when etching a molybdenum film with plasma of the second process gas in step S4 of the comparative example. [Figure 9] 9 is a diagram showing the time change in the emission intensity of a specific plasma light detected in the example in the same manner as in FIG. 8. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacture of flat panel displays (FPDs) such as liquid crystal displays (LCDs), a molybdenum (Mo) film formed on the surface of a substrate such as a glass substrate may be etched using plasma. The etching of the Mo film is performed while the substrate is placed on a stage in a processing chamber of a substrate processing apparatus.

[0009] However, when a Mo film is etched, reaction products are generated. If these reaction products remain in the processing vessel after etching of the Mo film on one substrate, and then etching is performed on the next substrate, problems such as defects on the substrate may occur. For this reason, cleaning is performed to remove the reaction products from the processing vessel.

[0010] One cleaning method involves replacing the substrate in the processing vessel with a dummy substrate after etching is completed and placing it on a mounting table. In this state, plasma of a cleaning gas is generated to remove reaction products from the processing vessel. There is also a cleaning method that does not use a dummy substrate. In this method, after the etched substrate is removed from the processing vessel and before the next substrate is loaded, plasma of a cleaning gas is generated to remove reaction products from the processing vessel.

[0011] However, in the method using a dummy substrate, productivity is reduced due to the time required to replace the normal product substrate with the dummy substrate. Furthermore, in the method not using a dummy substrate, the substrate mounting surface of the mounting table is exposed to plasma, so the plasma intensity cannot be increased, and therefore it takes time to remove the reaction products from the processing chamber. Therefore, even the method not using a dummy substrate has room for improvement in terms of productivity.

[0012] Therefore, the technology according to the present disclosure removes the reaction products generated during etching of the molybdenum film on the substrate surface while suppressing deterioration of productivity.

[0013] Hereinafter, a substrate processing method and a substrate processing apparatus according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] <Plasma processing device 1> Fig. 1 is a longitudinal sectional view showing the outline of the configuration of a plasma processing apparatus as a substrate processing apparatus according to this embodiment, Fig. 2 is a sectional view showing a substrate to be processed by the plasma processing apparatus of Fig. 1.

[0015] The plasma processing apparatus 1 shown in Fig. 1 is a single-wafer processing apparatus that sequentially processes a plurality of substrates one by one. The substrate to be processed by the plasma processing apparatus 1 is a glass substrate G (hereinafter referred to as "substrate G") that is rectangular in plan view. A molybdenum (Mo) film F1 is formed on the surface of the substrate G as shown in Fig. 2. The plasma processing apparatus 1 processes the substrate G with plasma of the processing gas to etch the Mo film F1.

[0016] In this embodiment, the Mo film F1 is formed on a gate insulating (GI) film F2 and is etched by the plasma processing apparatus 1 so as to function as a gate electrode. The GI film F2 is, for example, a silicon-based insulating film. A photoresist (PR) film F3 is formed on the Mo film F1 as an etching mask. The thickness of the Mo film F1 is, for example, 200 nm to 300 nm.

[0017] As shown in FIG. 1, the plasma processing apparatus 1 includes a container body 10 having a rectangular cylindrical shape with a bottom. The container body 10 is made of a conductive material, such as aluminum, and is electrically grounded. An opening is formed on the top surface of the container body 10. This opening is airtightly sealed by a rectangular metal window 20 provided insulated from the container body 10. Specifically, the opening is airtightly sealed by the metal window 20 and a metal frame 14 (described later). The space surrounded by the container body 10 and the metal window 20 forms a processing space K1 in which a substrate G to be processed in the plasma processing is located during plasma processing. The space above the metal window 20 forms an antenna chamber K2 in which a high-frequency antenna (plasma antenna) 80 (described later) is disposed. A loading / unloading port 11 for loading / unloading the substrate G into / out of the processing space K1 and a gate valve 12 for opening / closing the loading / unloading port 11 are provided on the sidewall of the container body 10.

[0018] A mounting table 30 is provided at the lower side of the processing space K1 so as to face the metal window 20. The mounting table 30 has a mounting body 31, the upper surface of which serves as a substrate mounting surface on which a substrate G is placed, and the mounting body 31 is installed on the bottom surface of the container body 10 via legs 32.

[0019] The table main body 31 is provided with a base 31a made of a conductive material, for example, aluminum, and an electrostatic chuck 31b that holds the substrate G by electrostatic attraction. A high-frequency power supply 41 is connected to the base 31a via a matching box 40. The high-frequency power supply 41 supplies high-frequency bias power, for example, high-frequency power having a frequency of 3.2 MHz, to the base 31a. This allows ions in the plasma generated in the processing space K1 to be attracted to the substrate G.

[0020] An exhaust port 13 is formed in the bottom wall of the vessel body 10, and an exhaust unit 50 having a pressure control valve, a vacuum pump, etc. (not shown) is connected to this exhaust port 13. The processing space K1 can be depressurized by this exhaust unit 50 and maintained at a predetermined pressure during cleaning processing, etching processing, etc. The exhaust unit 50 may be provided for each of the multiple exhaust ports 13, or may be provided commonly to the multiple exhaust ports 13.

[0021] A metal frame 14, which is a rectangular frame made of a metal material such as aluminum, is provided on the upper surface of the side wall of the vessel body 10. The vessel body 10, the metal frame 14, and the metal window 20 constitute a processing vessel C that is configured to be depressurizable and that accommodates the mounting table 30.

[0022] The metal window 20 is formed, for example, in a rectangular shape when viewed from above. The metal window 20 also functions as a shower head that supplies processing gas to the processing space K1. For example, the metal window 20 is formed with a number of gas discharge holes 21 that discharge processing gas downward and a diffusion chamber 22 that diffuses the processing gas, and the gas discharge holes 21 and the diffusion chamber 22 are in communication with each other.

[0023] The diffusion chamber 22 is connected to a gas supply source 61 via a gas supply pipe 60. A gas supply mechanism 62 is connected to the gas supply pipe 60. The gas supply mechanism 62 includes a flow rate control valve (not shown), an on-off valve (not shown), etc., and supplies the process gas etc. from the gas supply source 61 to the diffusion chamber 22. The metal window 20 is electrically insulated from the metal frame 14 by an insulating member 23 .

[0024] Furthermore, a top plate portion 70 is disposed above the metal window 20. The top plate portion 70 is supported by a side wall portion 71 provided on the metal frame 14.

[0025] The space surrounded by the metal window 20, the side wall portion 71, and the top plate portion 70 constitutes an antenna chamber K2, and a high frequency antenna 80 is disposed inside the antenna chamber K2 so as to face the metal window 20.

[0026] The high frequency antenna 80 is spaced apart from the metal window 20 via a spacer (not shown) made of, for example, an insulating material. A high-frequency power supply 43 serving as plasma generating means is connected to the high-frequency antenna 80 via a matching box 42. High-frequency power of, for example, 13.56 MHz is supplied to the high-frequency antenna 80 from the high-frequency power supply 43 via the matching box 42. As a result, an induction electric field is formed inside the processing space K1 via the metal window 20, and the processing gas discharged from the gas discharge holes 21 is converted into plasma by the induction electric field.

[0027] Furthermore, in the plasma processing apparatus 1, a window 15 is provided on the side wall of the vessel body 10. An emission monitor 90 is connected to the plasma processing apparatus 1 so that plasma light inside the processing vessel C enters the emission monitor 90 as a detector through the window 15. The emission monitor 90 detects the emission intensity of light of a specific wavelength of the plasma light. The detection result by the emission monitor 90 is output to a control unit U, which will be described later.

[0028] The plasma processing apparatus 1 is further provided with a control unit U. The control unit U is, for example, a computer equipped with a processor such as a CPU, a memory, and the like, and has a program storage unit (not shown). The program storage unit stores a program for controlling the substrate processing by the plasma processing apparatus 1, which will be described later. The above-mentioned program may be recorded on a computer-readable storage medium and installed into the control unit U from the storage medium. The above-mentioned storage medium may be temporary or non-temporary. Some or all of the program may be realized by dedicated hardware (circuit board). The control unit U also controls a transfer mechanism 100 that transfers the substrate G into and out of the processing chamber C.

[0029] <Substrate processing> Next, a description will be given of substrate processing by the plasma processing apparatus 1. Fig. 3 is a flowchart for explaining an example of substrate processing by the plasma processing apparatus 1. Figs. 4 and 5 are views showing the state of the substrate G during substrate processing.

[0030] (Step S1) First, as shown in FIG. 3, under the control of the control unit U, the substrate G is carried into the processing chamber C and placed on the mounting table 30. Specifically, the control unit U controls the gate valve 12 so that the loading / unloading port 11 on the sidewall of the vessel body 10 is opened. The control unit U also controls the transfer mechanism 100 and the like so that the substrate G is transferred from a transfer chamber (not shown) under a vacuum atmosphere adjacent to the processing vessel C into the processing space K1 through the loading / unloading port 11 and placed on the upper surface of the mounting table 30, i.e., the substrate mounting surface. Note that in FIG. 1, the transfer mechanism 100 is shown separated from the transfer chamber for ease of explanation, but in an actual apparatus, the transfer mechanism 100 is disposed inside the transfer chamber adjacent to the processing vessel C and is configured to be able to transfer the substrate G between the transfer chamber and the processing vessel C. Thereafter, the control unit U controls the gate valve 12 to close the loading / unloading port 11. Then, the control unit U controls the exhaust unit 50 to exhaust the processing space K1 to a predetermined pressure.

[0031] (Step S2) Subsequently, under the control of the control unit U, plasma of the same first processing gas containing fluorine is generated inside the processing vessel C to clean the inside of the processing vessel C before etching the Mo film F1 with plasma of the same first processing gas in step S3 described below. Specifically, the control unit U controls the gas supply mechanism 62 and other components so that a mixed gas of sulfur hexafluoride (SF6) gas and oxygen (O2) gas is supplied as a first process gas to the processing space K1 through the metal window 20. The control unit U also controls the high-frequency power supply 43 and other components so that the SF6 gas and O2 gas are converted into plasma. As a result, the inside of the processing container C is cleaned with the plasma of the SF6 gas and O2 gas.

[0032] During this cleaning, the emission intensity of the plasma is detected by the emission monitor 90, and the detection result is output to the control unit U. This cleaning is continued until the emission intensity of the plasma light of the predetermined wavelength no longer changes. Specifically, it is as follows:

[0033] That is, during cleaning, the emission intensity of plasma light of the wavelength of the fluorine emission line spectrum peaks once, then gradually decreases as cleaning progresses, i.e., as the amount of foreign matter in the processing vessel C decreases, and becomes constant when the amount of foreign matter in the processing vessel C is nearly gone (see FIG. 7 described below). Therefore, during cleaning, the control unit U controls the emission monitor 90 so that the emission monitor 90 receives plasma light of the wavelength of the fluorine emission line spectrum, measures its intensity, and outputs the measurement result. The control unit U then determines whether the decrease in the emission intensity of the fluorine emission line spectrum per unit time has fallen from a state exceeding a threshold to a state below the threshold, and controls cleaning to continue until it is determined that the decrease is below the threshold.

[0034] (Step S3) Next, under the control of the control unit U, the first processing gas containing fluorine is turned into plasma to etch the Mo film F1. Specifically, similar to step S2, a mixed gas of SF6 gas and O2 gas is supplied as a first process gas to the processing space K1 through the metal window 20, and the control unit U controls the gas supply mechanism 62, the high-frequency power supply 43, etc. so that the SF6 gas and the O2 gas are plasmatized. As a result, the Mo film F1 on the substrate G is etched. Specifically, as shown in FIG. 4, the portion of the Mo film F1 on the substrate G that is not masked by the PR film F3 (hereinafter referred to as the unmasked portion) is etched.

[0035] In step S3, the etching of the Mo film F1 using plasma of a first process gas containing fluorine (specifically, plasma of SF6 gas and O2 gas) has a high etching rate and a high selectivity to the PR film, but a low selectivity to the GI film F2. Therefore, the etching in step S3 is performed so as not to expose the GI film F2. Specifically, the etching in step S3 is performed until the thickness of the unmasked portion of the Mo film F1 is 30 to 50 nm.

[0036] Furthermore, the etching in step S3 is performed continuously from the cleaning in step S2, that is, the supply of high frequency power for generating plasma is not stopped between the etching in step S3 and the cleaning in step S2.

[0037] The etching time in step S3 is set, for example, based on the end of the cleaning in step S2 (i.e., the point at which the change per unit time in the emission intensity of the fluorine emission line spectrum becomes equal to or less than a threshold). That is, the etching in step S3 is continued, for example, until a predetermined time has elapsed from the end of the cleaning in step S2 (i.e., the point at which the emission intensity of the plasma light of a predetermined wavelength no longer changes). The predetermined time is set so that the GI film F2 is not exposed by the etching in step S3, as described above, and is, for example, several tens of seconds. The etching in step S3 and the cleaning in step S2 are basically the same in terms of process conditions such as the flow rate of the first process gas containing fluorine (specifically, SF6 gas and O2 gas), the pressure inside the process vessel C, and the high-frequency power supplied by the high-frequency power supply 43. The period before the end of cleaning, which is determined by the light emission from the plasma, is determined as step S2, and the period thereafter as step S3. However, the process conditions for step S3 and step S2 may be different as necessary.

[0038] When the etching in step S3 is completed, the supply of high-frequency power for generating plasma of SF6 gas and O2 gas is stopped, and the control unit U controls the gas supply mechanism 62, the high-frequency power supply 43, the exhaust unit 50, etc. so that the supply of SF6 gas and O2 gas is stopped and the SF6 gas and O2 gas in the processing vessel C are exhausted.

[0039] Note that etching of the Mo film F1 also progresses somewhat in step S2, and cleaning of the inside of the processing vessel C also progresses somewhat in step S3. Therefore, the two steps, step S2 and step S3, can be regarded as a single step below. That is, etching of the Mo film F1 using plasma of a first processing gas containing fluorine (specifically, plasma of SF gas and O gas) and cleaning of the inside of the processing vessel C can be regarded as a single step that continues until the emission intensity of plasma light of a predetermined wavelength stops changing.

[0040] (Step S4) Subsequently, under the control of the control unit U, the second processing gas containing chlorine is turned into plasma to further etch the Mo film F1. Specifically, the control unit U controls the gas supply mechanism 62 and other components so that a mixed gas of chlorine (Cl) gas and O gas is supplied as a second process gas to the processing space K1 through the metal window 20. The control unit U also controls the high-frequency power supply 43 and other components so that the Cl and O gases are converted into plasma. This etches the Mo film F1 on the substrate G. Specifically, as shown in FIG. 5, etching is performed so that the portions of the Mo film F1 that were thinned in step S3 are removed, i.e., so that the GI film F2 is exposed in the unmasked portions.

[0041] The etching of the Mo film F1 using the plasma of the second process gas containing chlorine (specifically, the plasma of Cl gas and O gas) in step S4 has a low etching rate but a high selectivity to the GI film F2, so that the unmasked portion of the GI film F2 can be exposed from the Mo film F1 without changing its thickness.

[0042] During the etching in step S4, the emission intensity of the plasma is detected by the emission monitor 90, and the detection result is output to the control unit U. Then, the etching in step S4 is continued until the emission intensity of the plasma light of the predetermined wavelength no longer changes. Specifically, it is as follows:

[0043] That is, as etching of the Mo film F1 using the plasma of Cl gas and O gas progresses, the emission intensity of the plasma light of the oxygen emission line spectrum wavelength gradually increases and becomes constant near the point where the entire desired portion of the GI film F2 is exposed (see FIG. 9, described later). Therefore, during etching, the control unit U controls the emission monitor 90 so that the emission monitor 90 receives the plasma light of the oxygen emission line spectrum wavelength, measures its intensity, and outputs the measurement result. The control unit U then determines whether the increase per unit time in the emission intensity of the oxygen emission line spectrum has dropped from above a threshold to below the threshold, and controls the etching to continue until it is determined that the increase is below the threshold.

[0044] When the etching in step S4 is completed, the supply of high-frequency power for generating plasma of Cl gas and O gas is stopped, and the supply of Cl gas and O gas is stopped. The control unit U controls the gas supply mechanism 62, the high-frequency power supply 43, the exhaust unit 50, etc. so that the Cl gas and O gas inside the processing vessel C are exhausted.

[0045] (Step S5) Then, under the control of the control unit U, the substrate G is unloaded from the processing vessel C. Specifically, the control unit U controls the gate valve 12 so that the loading / unloading port 11 on the sidewall of the container body 10 is opened. The control unit U also controls the transfer mechanism 100 and the like so that the substrate G placed on the mounting table 30 is unloaded from the processing container C through the loading / unloading port 11. Thereafter, the control unit U controls the gate valve 12 so that the loading / unloading port 11 is closed.

[0046] This completes the series of substrate processing steps, and steps S1 to S5 are performed in sequence for the next substrate G. In other words, in this embodiment, when a plurality of substrates G are processed consecutively in the plasma processing apparatus 1, steps S1 to S5 are performed in sequence for each substrate G.

[0047] <Action and effect> In this embodiment, as described above, the etching in step S4 uses plasma of the second process gas containing chlorine (specifically, plasma of Cl gas and O gas). Etching of the Mo film F1 using this plasma has a high selectivity to the GI film F2, but generates a reaction product called molybdenum chloride (MoCl), which has a low vapor pressure. Because of its low vapor pressure, this reaction product easily adheres to the inner wall of the process vessel C. Even if the inner wall surface of the process vessel C is heated to a high temperature to prevent adhesion, it is not possible to completely prevent adhesion due to factors such as the pressure inside the process vessel C.

[0048] In this embodiment, as described above, the reaction products inside the processing vessel C are removed, i.e., cleaned, but dummy substrates are not used for this cleaning. Therefore, there is no need to replace the dummy substrates with product substrates, and the reaction products can be removed while suppressing a decrease in productivity.

[0049] Furthermore, in this embodiment, cleaning is performed with the substrate G placed on the substrate mounting surface of the mounting table 30, and the substrate mounting surface of the mounting table 30 is not exposed to plasma, so the plasma intensity can be increased, unlike when the substrate mounting surface of the mounting table 30 is exposed to plasma. From this perspective, this embodiment also makes it possible to remove the reaction products while suppressing a decrease in productivity.

[0050] Furthermore, in this embodiment, the etching in step S3 is performed immediately after the cleaning in step S2. Therefore, compared to a configuration in which another step is inserted between the cleaning in step S2 and the etching in step S3, the time required for substrate processing in this embodiment is shorter, and the Mo film F1 can be etched while removing the reaction products with high productivity.

[0051] Furthermore, in this embodiment, as described above, steps S1 to S5 are performed in order for each substrate G. Specifically, in this embodiment, for each substrate G, before etching the Mo film F1 in step S3, reaction products inside the processing vessel C are removed, i.e., cleaned, in step S2. Therefore, when processing multiple substrates G, it is possible to prevent the reaction products generated in step S4 from accumulating inside the processing vessel C. In this embodiment, the cleaning of the inside of the processing vessel C in step S2 is continued until the emission intensity of the plasma light of the predetermined wavelength no longer changes. Therefore, the cleaning can sufficiently reduce the amount of reaction products inside the processing vessel C, and can further prevent the reaction products from adversely affecting the substrate G.

[0052] Here, we will explain a method (hereinafter referred to as the comparative method) that, unlike this embodiment, omits cleaning the inside of the processing vessel C in step S2, performs etching of the Mo film F1 for a predetermined time in step S3, and then performs etching of the Mo film F1 in step S4. When substrates G are continuously processed using this comparative method, reaction products accumulate inside the processing vessel C. As the reaction products accumulate, in step S3, the proportion of the plasma of the first processing gas that is used to react with the reaction products rather than to etch the Mo film F1 increases. As a result, with the comparative method, the unmasked portion of the Mo film F1 after etching in step S3 becomes thicker with each processing of a substrate.

[0053] The unmasked portion of the Mo film F1 after etching in step S3 must have a desired thickness for the following reasons. That is, the etching of the Mo film F1 in step S4 using plasma of the second process gas containing chlorine, which is performed following step S3, has a low selectivity to the PR film F3. Therefore, if it takes time to completely etch the unmasked portion of the Mo film F1 thickly, the mask is excessively worn and the line width of the mask becomes narrower, which results in a narrow line width of the Mo film F1 after etching in step S4. Therefore, in the comparative method, the line width of the Mo film F1 after etching in step S4 becomes thinner with each processing of a substrate.

[0054] In contrast, in this embodiment, cleaning of the interior of the processing vessel C in step S2 is continued until the emission intensity of the plasma light of the predetermined wavelength stops changing, and the amount of reaction products inside the processing vessel C is sufficiently reduced for each substrate G. Then, in this embodiment, etching of the Mo film F1 in step S3 is performed until a predetermined time has elapsed from the end of the cleaning in step S2 (i.e., the point at which the emission intensity of the plasma light of the predetermined wavelength stops changing). Therefore, in this embodiment, the unmasked portion of the Mo film F1 after etching in step S3 has a constant desired thickness. Therefore, according to this embodiment, when substrates G are processed repeatedly, the Mo film F1 after etching in step S4 can be formed into a desired shape (specifically, a desired line width) for each substrate G. [Example]

[0055] In the comparative example, a plurality of substrates G were processed successively using the above-mentioned comparative method. On the other hand, in the example, five substrates G were processed consecutively by the method according to this embodiment. In the comparative example and the example, SF6 gas and O2 gas were used as the first processing gas, and Cl2 gas and O2 gas were used as the second processing gas. In the comparative example, etching of the Mo film F1 in step S3 was carried out for about 40 seconds, whereas in the example, etching of the Mo film in step S3 was carried out until about 40 seconds had elapsed since the change per unit time in the emission intensity of the plasma light at the wavelength (704 nm) of the fluorine emission spectrum became equal to or less than the threshold value, as described above.

[0056] Fig. 6 shows the time variation of the emission intensity of specific plasma light detected by the optical emission monitor 90 during etching of the Mo film F1 with a plasma of SF6 gas and O2 gas in step S3 of the comparative example. Fig. 7 shows the time variation of the emission intensity of specific plasma light detected by the optical emission monitor 90 during cleaning with a plasma of SF6 gas and O2 gas in step S2 of the example and etching of the Mo film F1 with the same plasma in step S3, which is performed consecutively to step S2. In Fig. 6, the horizontal axis indicates the elapsed time from the start of step S3, i.e., the start of plasma generation of SF6 gas and O2 gas. In Fig. 7, the horizontal axis indicates the elapsed time from the start of step S2, i.e., the start of plasma generation of SF6 gas and O2 gas. In Figs. 6 and 7, the vertical axis indicates the emission intensity of plasma light corresponding to the wavelength (704 nm) of the fluorine emission line spectrum.

[0057] 6, in the comparative example, the peak of the emission intensity of the plasma light corresponding to the wavelength (704 nm) of the fluorine emission line spectrum occurred later with each processing of the substrate G. This indicates that reaction products were accumulating in the processing vessel C with each processing of the substrate G.

[0058] 7, in the example, the position of the peak of the emission intensity of the plasma light corresponding to the wavelength (704 nm) of the fluorine emission line spectrum did not change even when the substrate G was repeatedly processed. This indicates that the accumulation of reaction products in the processing vessel C was suppressed.

[0059] Fig. 8 is a diagram showing the change over time in the emission intensity of specific plasma light detected by an optical emission monitor 90 during etching of the Mo film F1 with a plasma of Cl2 gas and O2 gas in step S4 of a comparative example. Fig. 9 is a diagram showing the change over time in the emission intensity of specific plasma light detected in an example in the same manner as Fig. 8. In Figs. 8 and 9, the horizontal axis represents the elapsed time from the start of step S4, i.e., the start of plasma generation of Cl2 gas and O2 gas, and the vertical axis represents the emission intensity of plasma light corresponding to the wavelength (777 nm) of the oxygen emission line spectrum.

[0060] As shown in Figure 8, in the comparative example, with each processing of substrate G, the timing (see the two-dot chain line) at which the increase per unit time in the emission intensity of plasma light at the wavelength (777 nm) of the oxygen emission line spectrum falls below the threshold value, as described above, was delayed. Specifically, for the fourth substrate G, the timing was delayed by approximately 14 seconds compared to the first substrate G. This indicates that with each processing of substrate G, the time required to completely etch the unmasked portions of the Mo film F1 in step S4 increases. If the time required to completely etch the unmasked portions of the Mo film F1 increases, the line width of the masked portions of the Mo film F1 after etching in step S4 becomes narrower.

[0061] On the other hand, as shown in Figure 9, in the example, the above timing (see the two-dot chain line) hardly changed even when the substrate G was repeatedly processed. Specifically, the above timing for the second substrate G was delayed by about 4 seconds compared to the first substrate G, but the above timing for the third and subsequent substrates G was almost the same as that for the second substrate G. This indicates that even when the substrate G was repeatedly processed, the time required to completely etch the unmasked portion of the Mo film F1 in step S4 hardly changed. Therefore, in the example, for each substrate G, the masked portion of the Mo film F1 after etching in step S4 could be made to have the desired line width.

[0062] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0063] For example, although the plasma processing apparatus according to the present embodiment has been described above as an inductively coupled plasma apparatus having a metal window, it may also be an inductively coupled plasma apparatus having a dielectric window instead of a metal window. In this case, the processing gas may be supplied from the sidewall, or a beam supporting the dielectric window from below may be configured as a shower head, and the processing gas may be supplied from the beam. Furthermore, the technology according to the present disclosure is not limited to inductively coupled plasma apparatuses, but may also be applied to other types of plasma apparatuses, such as capacitively coupled plasma apparatuses and microwave plasma apparatuses. [Explanation of symbols]

[0064] 1. Plasma processing equipment 30 Mounting table C. Processing vessel F1 Molybdenum film G Glass substrate U control section

Claims

1. A substrate processing method for sequentially processing a plurality of substrates, the method comprising: the substrate has a molybdenum film on its surface; (A) carrying the substrate into a processing chamber and placing the substrate on a placement table; (B) after the step (A), a step of generating plasma from a first process gas containing fluorine to etch the molybdenum film; (C) after the step (B), a step of generating a second processing gas containing chlorine into plasma and etching the molybdenum film; (D) between the step (A) and the step (B), generating plasma of the first process gas inside the processing vessel and cleaning molybdenum chloride generated inside the processing vessel during etching of the molybdenum film, The substrate processing method, wherein the step (D) is continued until a change in the emission intensity per unit time of the fluorine emission line spectrum becomes equal to or less than a threshold value.

2. The substrate processing method according to claim 1 , wherein the step (D) and the step (B) are carried out consecutively.

3. 3. The substrate processing method according to claim 1, wherein the first processing gas contains sulfur hexafluoride gas, and the second processing gas contains chlorine gas.

4. 4. The substrate processing method according to claim 1, wherein in the step (D), the substrate is exposed to plasma of the first processing gas.

5. A substrate processing apparatus that sequentially processes a plurality of substrates, a mounting table on which the substrate having a molybdenum film on its surface is placed; a processing vessel configured to be decompressible and accommodating the stage therein; a control unit, The control unit (A) carrying the substrate into the processing chamber and placing it on the stage; (B) after the step (A), a step of generating plasma from a first process gas containing fluorine to etch the molybdenum film formed on the surface of the substrate; (C) after the step (B), a step of generating a second processing gas containing chlorine into plasma and etching the molybdenum film; (D) between the step (A) and the step (B), a step of generating plasma of the first processing gas inside the processing vessel and cleaning molybdenum chloride generated inside the processing vessel during etching of the molybdenum film is performed; and The substrate processing apparatus controls the step (D) so as to continue until the amount of change per unit time in the emission intensity of the fluorine emission line spectrum becomes equal to or less than a threshold value.

6. The substrate processing apparatus according to claim 5 , wherein the control unit controls the process (D) and the process (B) to be performed consecutively.

7. 7. The substrate processing apparatus according to claim 5, wherein the first process gas contains sulfur hexafluoride gas, and the second process gas contains chlorine gas.

8. 8. The substrate processing apparatus according to claim 5, wherein in the step (D), the substrate is exposed to plasma of the first processing gas.

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