Plasma treatment method

Abstract

A plasma processing method for plasma etching a metal film formed below a metal wiring pattern using the metal wiring pattern according to one embodiment of the present invention includes: a first step (S31) for forming a protective film on the metal wiring pattern by plasma generated using a first gas; a second step (S32) for etching the metal film by plasma generated using a second gas after the first step; a third step (S33) for etching the metal film after the second step by plasma generated using a third gas such that the etching shape of the metal film becomes a vertical shape after the second step; and a fourth step (S35) for removing the protective film formed on the metal wiring pattern by plasma generated using a fourth gas. The second step (S32) and the third step (S33) are repeated until the etching depth of the metal film reaches a predetermined depth.

Description

Technical Field

[0001] The present invention relates to a plasma processing method.

Background Art

[0002] With the miniaturization and three-dimensionalization of semiconductor device structures, the application of alternative metals to replace copper as wiring metals has been under consideration. Specifically, ruthenium that can be pattern-processed by plasma etching can be mentioned. Ruthenium wiring has a laminated structure, and it is necessary to appropriately perform plasma etching through a mask and process it into a pattern. The ruthenium pattern can be produced by irradiating a plasma generated from a mixed gas containing oxygen gas and halogen gas onto the surface of ruthenium that has been previously mask-treated and etching it in the vertical direction. However, with an increase in the number of wiring layers and miniaturization of the wiring width, the wiring processing of ruthenium becomes complicated, and the number of processes is expected to increase.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

[0005] Generally, wiring in devices using ruthenium has a stacked structure. In this specification, the stacked wiring is simplified to two layers, referred to as the upper ruthenium layer and the lower ruthenium layer. A method is being considered to optimize the processing process by treating the upper ruthenium layer as a mask immediately after processing the upper ruthenium layer and etching the lower ruthenium layer vertically.

[0006] For example, Non-Patent Document 1 proposes a process for insulating adjacent elements by vertically etching the ruthenium located at the bottom that is exposed to the plasma interface, relative to a pre-etched ruthenium pattern at the top and ruthenium embedded at the bottom through an insulating layer (Figure 1). In Figure 1, 10 represents the mask, 11 the ruthenium pattern at the top, 12 the insulating layer, 13 the ruthenium layer at the bottom, 14 the underlayer, and 15 the ions in the plasma, and shows cross-sectional views of the wiring before and after plasma processing.

[0007] Furthermore, Patent Document 1 discloses a process for vertically etching a metal located at the bottom embedded in a dielectric along a pattern structure of a metal located at the top (Figure 2). In Figure 2, 21 is the mask, 22 is the ruthenium pattern located at the top, 23 is the insulating layer, 24 is the underlayer, and 25 is the ruthenium layer located at the bottom, and cross-sectional views of the wiring before and after plasma treatment are shown.

[0008] However, in the etching process of the ruthenium layers 13 and 25 located at the bottom, as illustrated in Figures 1 and 2, plasma is also irradiated onto the ruthenium patterns 11 and 22 located at the top, as shown in Figures 3 and 4, resulting in side etching. Furthermore, the etching residue in the pattern grooves of the ruthenium layers 13 and 25 located at the bottom, as well as the effects of the tapered shape, reduce the electrical conductivity of the ruthenium layers 13 and 25 located at the bottom. In Figure 3, 16 and in Figure 4, 26, show the residue generated in the pattern grooves of the ruthenium layers 13 and 25 located at the bottom.

[0009] The present invention provides a technique that suppresses side etching of the ruthenium located at the top, removes residue from the ruthenium layer at the bottom, and enhances the verticality of the pattern, while enabling vertical processing of the ruthenium layer at the bottom. Other problems and novel features are described herein and in the accompanying drawings. [Means for solving the problem]

[0010] A plasma treatment method for plasma etching a metal film deposited beneath a metal wiring pattern, according to one embodiment of the present invention, comprises: a first step of forming a protective film on the metal wiring pattern with plasma generated using a first gas; a second step of etching the metal film with plasma generated using a second gas after the first step; a third step of etching the metal film after the second step with plasma generated using a third gas so that the etching shape of the metal film becomes vertical; and a fourth step of removing the protective film formed on the metal wiring pattern with plasma generated using a fourth gas, wherein the second and third steps are repeated until the etching depth of the metal film reaches a predetermined depth. [Effects of the Invention]

[0011] According to the plasma processing method of the present invention, in the etching process of the ruthenium layer located at the bottom, side etching and surface damage to the sidewalls of the ruthenium layer located above can be suppressed. Furthermore, the verticality of the pattern grooves in the ruthenium layer located at the bottom can be improved, and residue can be removed. Through these processes, it is expected that the electrical conductivity of each ruthenium wiring layer processed into a pattern can be improved. As a result, vertical ruthenium wiring layers with precisely controlled pattern dimensions can be produced with a minimum number of processes and high throughput. [Brief explanation of the drawing]

[0012] [Figure 1] This is an explanatory diagram illustrating the structure of ruthenium wiring obtained by conventional methods. [Figure 2] This is an explanatory diagram illustrating the structure of ruthenium wiring obtained by other conventional methods. [Figure 3] This is an explanatory diagram illustrating the problems with ruthenium wiring obtained using conventional methods. [Figure 4] This is an explanatory diagram illustrating the challenges of ruthenium wiring structures obtained by other conventional methods. [Figure 5]It is an explanatory diagram showing an example of the internal structure of the plasma processing apparatus (Apparatus A) of this embodiment. [Figure 6] It is an explanatory diagram showing an example of the internal structure of the plasma processing apparatus (Apparatus B) of this embodiment. [Figure 7] It is a process flow diagram when using Apparatus A to protect with a modified film in this embodiment. [Figure 8] It is an explanatory diagram of the process flow when using Apparatus A to protect with a modified film in this embodiment. [Figure 9] It is a process flow diagram when using Apparatus B to protect with a modified film in this embodiment. [Figure 10] It is an explanatory diagram of the process flow when using Apparatus B to protect with a modified film in this embodiment. [Figure 11] It is a diagram showing the etching rate of ruthenium according to the flow rate ratio of oxygen and chlorine. [Figure 12] It is a diagram showing an example of a ruthenium compound expected to be generated by ruthenium etching, and its melting point and boiling point. [Figure 13] It is a process flow diagram when using Apparatus A to protect with a deposited film in this embodiment. [Figure 14] It is an explanatory diagram of the process flow when using Apparatus A to protect with a deposited film in this embodiment. [Figure 15] It is a process flow diagram when protecting each of the ruthenium layers located at the top and bottom with a modified film in this embodiment. [Figure 16] It is an explanatory diagram of the process flow when protecting each of the ruthenium layers located at the top and bottom with a modified film in this embodiment. [Figure 17] It is an explanatory diagram of the process flow applying this embodiment to the structure of the ruthenium wiring shown in FIG. 2. [Figure 18] It is an explanatory diagram of the process flow applying this embodiment to another structure of ruthenium wiring.

Mode for Carrying Out the Invention

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings. In all drawings, components having the same function will be denoted by the same reference numerals, and repeated explanations may be omitted. In order to make the explanation clearer, the drawings may be more schematic than the actual embodiments, but they are merely examples and do not limit the interpretation of this disclosure.

[0014] Figures 5 and 6 are explanatory diagrams illustrating an example of the internal structure of the plasma processing apparatus of this embodiment. Etching in this embodiment can be performed, for example, by a microwave-electron cyclotron resonance (M-ECR) plasma processing apparatus.

[0015] Figure 5 shows a diagram of the plasma processing apparatus (hereinafter referred to as apparatus A). Apparatus A is equipped with an electromagnetic coil 101 for generating plasma, a microwave source 103, a circular waveguide 102, and a housing 105. The plasma 104 generated from the etchant gas contains radicals 111 and ions 112, and is irradiated onto the ruthenium multilayer wiring formed on the main surface of a semiconductor wafer (also called a substrate) 113, which is placed on a temperature-controlled stage 114, which is the sample stage. A bias power supply 115 is connected to the temperature-controlled stage 114, and the incident energy of the ions 112 used for etching can be adjusted by controlling the applied bias.

[0016] Figure 6 is an explanatory diagram of another example of the internal structure of the plasma processing apparatus of this embodiment, where (a) shows the case where the ECR surface on which the plasma is formed is located below the ion shielding plate, and (b) shows the case where the ECR surface on which the plasma is formed is located above the ion shielding plate. Figure 6 also shows a configuration diagram of another plasma processing apparatus (hereinafter referred to as apparatus B). In apparatus B, in addition to apparatus A in Figure 5, an ion shielding plate 106 is installed inside the housing 105. The ion shielding plate 106 has the characteristic of allowing radicals 111 in the plasma 104 to pass through but preventing ions 112 from passing through.

[0017] Therefore, when the ECR surface on which plasma 104 is formed is located below the ion shielding plate 106 (Figure 6(a)), the ruthenium film formed on the main surface (surface) of the substrate 113 is irradiated with a plasma gas containing radicals 111 and ions 112, similar to apparatus A in Figure 5. On the other hand, when the ECR surface on which plasma 104 is formed is located above the ion shielding plate 106 (Figure 6(b)), the ruthenium film formed on the main surface (surface) of the substrate 113 is irradiated with a plasma gas containing many radicals 111 that have passed through the ion shielding plate 106. In other words, by controlling the height of the plasma 104 generation region, it is possible to easily switch between a mode in which radicals 111 and ions 112 contained in the plasma 104 are irradiated anisotropically (first etching mode: plasma irradiation) and a mode in which radicals 111 are irradiated isotropically (second etching mode: radical irradiation) within the same chamber.

[0018] Figures 7, 8 and 9, 10 are flowcharts and explanatory diagrams of the etching method for ruthenium multilayer wiring, describing the case where the ruthenium pattern located at the top is protected by a modified protective film. Furthermore, Figures 7 and 8 describe the case when apparatus A from Figure 5 is applied, and Figures 9 and 10 describe the case when apparatus B from Figure 6 is applied.

[0019] Figures 7-10 describe an etching method in which a protective film is formed by a modified film, and an etching gas containing oxygen and chlorine is used during ruthenium etching. The example describes a multilayer wiring in which the ruthenium patterns 31 and 131 located at the top, which have been pre-processed into a pattern via masks 30 and 130, are partially connected to the ruthenium layers 33 and 133 located at the bottom, and the other areas are insulated via insulating layers 32 and 132. As materials for the masks 30 and 130, for example, silicon oxide, silicon nitride, or titanium nitride, which have a low etching selectivity ratio for ruthenium 31 and 131, can be used. This multilayer wiring is deposited on a base layer 34 and 134 made of silicon or the like.

[0020] Figure 11 is an explanatory diagram illustrating the dependence of the etching rate of a ruthenium film on the gas mixing ratio when etched using apparatus B with a plasma using a mixed gas of oxygen and chlorine. The vertical axis represents the etching rate (nm / min), and the horizontal axis represents the gas mixing ratio of the oxygen and chlorine mixed gas (O2 / (Cl2+O2))%. In Figure 11, black circles indicate plasma irradiation (first etching mode), and black squares indicate radical irradiation (second etching mode). In both etching modes, it can be confirmed that the etching rate of the ruthenium film is maximized by adding a small amount (10-20%) of chlorine. Generally, dry etching proceeds as the material to be etched changes into low-boiling-point volatile compounds through chemical reactions, and etching stops when it changes into non-volatile products.

[0021] Figure 12 shows an example of a ruthenium compound produced by the chemical reaction of ruthenium with a plasma gas containing oxygen and chlorine, along with its melting point (°C) and boiling point (°C). Ruthenium dioxide (RuO2) has a melting point above 1300°C and is non-volatile, and is expected to be formed as an intermediate in the etching reaction. Further oxidation forms RuO4, which has a low boiling point and is volatile. In other words, the oxidation reaction rate of ruthenium increases with the addition of a small amount of chlorine, and RuO4 and ruthenium chloride (RuCl) are produced. x O yIt is expected that etching will proceed as a result of the formation of volatile ruthenium compounds such as ).

[0022] On the other hand, Figure 11 shows that when the chlorine flow rate ratio increases above 20%, the etching rate of ruthenium decreases, and when the chlorine gas flow rate ratio is close to 100%, etching hardly proceeds at all. This is because when a chlorine plasma is irradiated onto the ruthenium surface, non-volatile ruthenium chloride (RuCl3) with a melting point of over 500°C is generated. In other words, when a plasma gas containing a large amount of chlorine is irradiated onto the ruthenium surface, a non-volatile film is formed on the ruthenium surface, which is thought to inhibit the etching reaction of ruthenium. In the examples in Figures 7-10, this non-volatile ruthenium film is used as a protective film for the sidewalls of pattern etching.

[0023] First, an example of a pattern etching method using apparatus A and protecting the ruthenium pattern 31 located at the top with a modified film 35 is described (see Figures 5, 7, and 8). In Figure 8, the figures at the end of the arrows S31, S32, S33, S34, and S35 correspond to the cross-sectional views after each step (S31, S32, S33, S34, and S35) in Figure 7.

[0024] In a wiring structure in which the ruthenium pattern 31 located at the top has been pre-etched, in the first step (S31: protective film formation), the side walls of the ruthenium pattern 31 located at the top are irradiated with a plasma gas containing a large amount of chlorine to protect them with a modified film 35 derived from ruthenium chloride. At this time, the plasma contains both ions and radicals, and the modified film 35 is formed on the entire ruthenium surface that comes into contact with it. Therefore, the modified film 35 is formed not only on the side walls of the ruthenium pattern 31 located at the top, but also on the portion of the ruthenium layer 33 located at the bottom that is exposed to the plasma interface. Note that in this step, if a plasma generated from a gas containing sulfur (such as SO2) is irradiated instead of chlorine, ruthenium sulfide is formed as the modified film 35, and if a plasma generated from a gas containing nitrogen (such as N2) is irradiated, ruthenium nitride is formed as the modified film 35, so these gases may also be used.

[0025] In the second step (S32: vertical processing of the ruthenium layer at the bottom), the ruthenium layer 33 at the bottom is processed vertically by ions 36. The bias of the high-frequency power applied to the substrate 113 from the bias power supply 115 via the temperature control stage 114 is set to be large enough to pass through the altered layer 35 on the surface of the ruthenium layer 33 at the bottom, and a mixed gas with an oxygen-chlorine flow rate ratio of approximately 80% and 20% is used. In this step, in order to etch the ruthenium pattern 31 vertically, it is desirable to apply a high bias to the high-frequency power supplied to the temperature control stage 114 and then irradiate the substrate 113 with plasma gas. Furthermore, the power value of the high-frequency power applied to the substrate 113 via the temperature control stage 114 is set to the power value necessary to sputter and remove the altered film 35 formed on the surface of the ruthenium layer 33 at the bottom.

[0026] In the third step (S33: taper angle adjustment), a plasma gas generated from a gas containing oxygen and chlorine is used to etch the pattern grooves of the ruthenium layer 33 located at the bottom in a horizontal direction, thereby adjusting the pattern shape to be vertical. Since horizontal etching is caused by a chemical reaction by radicals, it is desirable to set the applied bias in this step to zero or a low bias. In addition, the substrate temperature may be adjusted using the temperature control stage 114 to control the rate of the chemical reaction by radicals. In this step, the etching conditions are adjusted so that the dimensions of the pattern grooves become the desired dimensions.

[0027] In the fourth step (S34: residue removal), a plasma gas generated from a gas containing oxygen and chlorine is irradiated to remove the residue 37 from the ruthenium 33 pattern grooves located at the bottom. Since the fourth step also proceeds through a chemical reaction by radicals, it is desirable to set the applied bias to zero or a low bias. As the main component of the residue 37 is expected to be ruthenium, it is thought that it can be removed by etching with radicals derived from oxygen and chlorine. In addition, the substrate temperature may be adjusted with the temperature control stage 114 to control the rate of the chemical reaction by radicals.

[0028] Subsequently, steps two through four are repeated until the ruthenium layer 33 located at the bottom reaches a predetermined pattern groove depth. If the ruthenium layer 33 located at the bottom has reached the predetermined pattern groove depth after step four (S34), the process proceeds to step five (S35).

[0029] In the fifth step (S35: Reduction and removal of the altered film), the altered film 35 is reduced to return the surface of the ruthenium pattern 31 located on top to metallic ruthenium by irradiation with a reducing gas or a plasma gas derived from a reducing gas. For example, hydrogen radicals (H) contained in the plasma generated from a gas containing hydrogen gas. * When ruthenium chloride is irradiated with ), RuCl3+3H * →Ru+3HCl Because of this reaction, the altered film 35 on the pattern surface can be reduced to metallic ruthenium. In other words, the fifth step (S35) is a step in which the ruthenium compound is reduced to metallic ruthenium after the fourth step (S34). When the fifth step (S35) is completed, the pattern etching of the ruthenium layer 33 located at the bottom is completed (S36).

[0030] A key advantage of this embodiment lies in the first step (S31), which involves forming a protective altered film 35 on the upper ruthenium pattern 31 of the two stacked ruthenium wiring layers. If the lower ruthenium layer 33 is processed vertically without applying this step, both the upper ruthenium pattern 31 and the lower ruthenium layer 33 are exposed to the plasma. As a result, there is a concern that the sidewalls of the upper ruthenium pattern 31 will be etched, resulting in an unintended pattern shape. By applying this step, the sidewalls of the upper ruthenium pattern 31 are protected by the altered film 35 and are not exposed to the etching gas, thus suppressing etching of the sidewalls of the upper ruthenium pattern 31. Although the altered film 35 is also formed on the surface of the lower ruthenium layer 33, in the second step (S32), the lower ruthenium layer 33 is etched vertically, allowing the altered film 35 to be removed by physical sputtering due to ion collisions. Therefore, the ruthenium layer 33 located at the bottom can be selectively processed vertically while protecting the side walls of the ruthenium pattern 31 located at the top.

[0031] The process of this embodiment includes the steps of isotropically forming a modified layer 35 on the pattern surface (S31), adjusting the pattern dimensions (S33), removing residue (S34), and forming a pattern by anisotropic etching (S32). Therefore, using apparatus B, these steps can be performed in the same chamber. The following describes the process of using apparatus B and protecting the ruthenium pattern 131 located at the top with the modified film 135 (see Figures 6, 9, and 10). In Figure 10, the figures at the end of the arrows S131, S132, S133, S134, and S135 correspond to the cross-sectional views after each step in Figure 9 (S131, S132, S133, S134, and S135).

[0032] Apparatus B is characterized by its ability to process the ruthenium layer 133 located at the bottom by using the first and second etching modes complementaryly. The process using a gas containing oxygen and chlorine will be described below. In addition, when applying the first and second etching modes, the applied bias and substrate temperature may be adjusted to optimize the pattern shape.

[0033] In the first step (S131: protective film formation) in which the altered film 135 is formed, a gas mainly composed of chlorine is used, and plasma is generated in the second etching mode, thereby irradiating the surface with a plasma containing many chlorine radicals. By applying this method, surface damage due to ion collisions can be suppressed compared to the corresponding step (S31) method of apparatus A, which irradiates with both ions and radicals, and the altered film 135 made of ruthenium chloride can be formed homogeneously.

[0034] In the second step (S132), the first etching mode is applied, and the ruthenium layer 133 located at the bottom is etched in the same manner as in the corresponding step (S32) using apparatus A.

[0035] In the third step (S133: taper angle adjustment), plasma is generated in the second etching mode, and the taper angle of the pattern grooves of the ruthenium layer 133 located at the bottom is adjusted by hysteretic etching.

[0036] In the fourth step (S134: Residue Removal), plasma is generated in the second etching mode, and the residue 137 in the pattern grooves of the ruthenium layer 133 located at the bottom is removed by hysterical etching.

[0037] In the fifth step (S135: Reduction and removal of altered film), plasma is generated in the second etching mode to hysterically reduce the altered film on the surface of the ruthenium pattern 131 located above.

[0038] Next, we will describe the method for using apparatus A and protecting the ruthenium pattern 41 located at the top with a deposited film 45 (see Figures 13 and 14). In Figure 14, the figures at the end of the arrows S41, S42, S43, S44, and S45 correspond to the cross-sectional views after each step (S41, S42, S43, S44, S45) in Figure 13.

[0039] In the first step (S41), a precursor gas for the deposited film 45 is irradiated to protect the ruthenium pattern 41 located on top with the deposited film 45. For example, when irradiating with a carbon-based precursor gas such as carbon dioxide or methane, an organic deposited film is formed at the interface. When irradiating with a silane-based or tungsten halide-based precursor gas, an inorganic deposited film derived from silicon or tungsten, respectively, is formed. The flow rate and pressure of the precursor gas, irradiation time, and substrate temperature are determined based on previously acquired data, and the deposited film 45 is formed to achieve an appropriate film thickness.

[0040] In the second (S42), third (S43), and fourth (S44) processes, the same process is used as shown in Figure 7 for the corresponding process flows (S32, S33, S44) described above.

[0041] In the fifth step (S45), the deposited film 45 remaining on the ruthenium pattern 41 is removed by plasma treatment. If the deposited film 45 is organic, it can be removed by ashing with a plasma gas containing oxygen, for example. If the deposited film 45 is silicon-based or metallic, it is removed by irradiating it with a plasma gas that generates volatile silicon compounds or volatile metal compounds (for example, a gas mainly composed of halogen-based gases).

[0042] Next, we describe a plasma treatment method that more precisely controls the pattern shape by adding a step (S151) to form a protective film in the pattern groove of the ruthenium layer 53 located at the bottom (see Figures 15 and 16). In Figure 16, the figures at the end of the arrows S51, S52, S53, S54, S151, and S55 correspond to the cross-sectional views after each step (S51, S52, S53, S54, S151, S55) in Figure 13. Also, the steps (S51, S52, S53, S54, S55, S56) shown in Figures 15 and 16 correspond to the steps (S31, S32, S33, S34, S35, S36) shown in Figures 7 and 8.

[0043] In this plasma processing method, etching of the ruthenium layer 53 located at the bottom in the second step (S52) is temporarily stopped before bowing or surface roughness is formed. In the third step (S53), the pattern groove taper angle of the ruthenium layer 53 located at the bottom is corrected, and in the fourth step (S54), the residue 57 is removed.

[0044] Subsequently, returning to the second step (S52), a sixth step (S151) is added to form a protective film 58 in the pattern grooves of the ruthenium layer 53 located at the bottom, before resuming etching of the ruthenium layer 53 located at the bottom. In this step, a protective film 58 is formed in the region of the pattern grooves of the ruthenium layer 53 located at the bottom that is in contact with the plasma, using the same method (halogenation, sulfidation, or nitridation) as the protective film 55 of the ruthenium pattern located at the top.

[0045] As described above, by repeatedly performing the second (S52), third (S53), fourth (S54), and sixth (S151) steps, plasma processing can be carried out while suppressing the etching of the sidewalls of the ruthenium layer 53 located at the bottom. In the fifth step (S56), the protective film 55 of the ruthenium pattern 51 located at the top and the protective film 58 formed on the ruthenium layer 53 located at the bottom are reduced to metallic ruthenium using the same method as in S35 in Figure 7.

[0046] Figure 17 shows an explanatory diagram of the process flow in which this embodiment is applied to a plasma processing step in which the ruthenium layer 74 located at the bottom, which is embedded in the insulating layer 72, is vertically processed along the side wall of the pattern groove of the ruthenium layer 71 located at the top, in the ruthenium wiring structure shown in Figure 2. Each step in Figure 17 (S71, S72, S73, S74, S171, S75) corresponds to each step (S51, S52, S53, S54, S151, S55) described in Figures 15 and 16, and each step is carried out in the same manner as the steps in Figures 15 and 16.

[0047] Figure 18 shows an explanatory diagram of the process flow when this embodiment is applied to a different ruthenium wiring structure. In the ruthenium wiring structure of Figure 18, the ruthenium pattern 81 located at the top and the ruthenium layer 82 located at the bottom are cut from the same bulk ruthenium, and the objective is to form ruthenium patterns of different heights by etching them vertically through a mask 80. Each step in Figure 18 (S81, S82, S83, S84, S181, S85) corresponds to each step (S51, S52, S53, S54, S151, S55) described in Figures 15 and 16, and each step is carried out in the same manner as the steps in Figures 15 and 16.

[0048] Although this embodiment describes the etching of a ruthenium pattern as an example, since plasma etching is also possible for metal materials such as molybdenum, it is possible to process patterns using a similar method while protecting the side walls of the pattern.

[0049] Although the present invention has been described in detail based on the examples above, it goes without saying that the present invention is not limited to the above examples and can be modified in various ways without departing from the spirit of the invention. For example, the above examples are described in detail in order to explain the present invention in an easy-to-understand manner and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to add, delete, or replace some of the configurations in each example with other configurations. [Explanation of Symbols]

[0050] 10: Mask, 11: Ruthenium pattern located at the top, 12: Insulating layer, 13: Ruthenium layer located at the bottom, 14: Underlayer, 15: Ions, 16: Residue, 21: Mask, 22: Ruthenium pattern located at the top, 23: Insulating layer, 24: Underlayer, 25: Ruthenium layer located at the bottom, 26: Residue, 101: Electromagnetic coil, 102: Circular waveguide, 103: Microwave source, 104: Plasma, 105: Housing, 10 6: Ion shielding plate, 111: Radical, 112: Ion, 113: Substrate, 114: Temperature control stage, 115: Bias power supply, 30: Mask, 31: Ruthenium pattern located at the top, 32: Insulating layer, 33: Ruthenium layer located at the bottom, 34: Underlayer, 35: Modified film, 36: Ion, 37: Residue, 130: Mask, 131: Ruthenium pattern located at the top, 132: Insulating layer, 133: Bottom 134: Ruthenium layer located in the middle, 135: Underlayer, 136: Ion, 137: Residue, 40: Mask, 41: Ruthenium pattern located at the top, 42: Insulating layer, 43: Ruthenium layer located at the bottom, 44: Underlayer, 45: Deposited film, 46: Ion, 47: Residue, 50: Mask, 51: Ruthenium pattern located at the top, 52: Insulating layer, 53: Ruthenium layer located at the bottom, 54: Underlayer, 55: Altered 56: film, 57: residue, 58: altered film, 70: mask, 71: ruthenium pattern located at the top, 72: insulating layer, 73: base layer, 74: ruthenium layer located at the bottom, 75: altered film, 76: ions, 77: residue, 78: altered film, 80: mask, 81: ruthenium pattern located at the top, 82: ruthenium layer located at the bottom, 83: base layer, 84: altered film, 85: ions, 86: residue, 87: altered film.

Claims

1. In a plasma treatment method for plasma etching a ruthenium film, which is a metal film deposited beneath a metal wiring pattern, using the metal wiring pattern, A first step of forming a protective film on the metal wiring pattern using plasma generated with a first gas, After the first step, a second step is performed in which the ruthenium film is etched with plasma generated using a second gas, A third step is performed in which, after the second step, the ruthenium film after the second step is etched using a plasma generated with a third gas so that the etching shape of the ruthenium film becomes vertical. The process includes a fourth step of removing the protective film formed on the metal wiring pattern using plasma generated with a fourth gas, A plasma treatment method characterized by repeating the second step and the third step until the etching depth of the ruthenium film reaches a predetermined depth.

2. A plasma treatment method for plasma etching a metal film deposited below a metal wiring pattern using the metal wiring pattern, A first step of forming a protective film on the metal wiring pattern using plasma generated with a first gas, After the first step, a second step is performed in which the metal film is etched with plasma generated using a second gas, A third step is performed in which, after the second step, the metal film after the second step is etched using plasma generated with a third gas so that the etched shape of the metal film becomes vertical. The process includes a fourth step of removing the protective film formed on the metal wiring pattern using plasma generated with a fourth gas, The second and third steps are repeated until the etching depth of the metal film reaches a predetermined depth. A plasma treatment method characterized in that the metal film is embedded in a groove formed below the metal wiring pattern.

3. A plasma treatment method for plasma etching a metal film deposited below a metal wiring pattern using the metal wiring pattern, A first step of forming a protective film on the metal wiring pattern using plasma generated with a first gas, After the first step, a second step is performed in which the metal film is etched with plasma generated using a second gas, A third step is performed in which, after the second step, the metal film after the second step is etched using plasma generated with a third gas so that the etched shape of the metal film becomes vertical. The process includes a fourth step of removing the protective film formed on the metal wiring pattern using plasma generated with a fourth gas, The second and third steps are repeated until the etching depth of the metal film reaches a predetermined depth. A plasma treatment method characterized in that all of the aforementioned metal wiring patterns are connected to the aforementioned metal film.

4. In the plasma processing method according to claim 2 or claim 3, A plasma treatment method characterized in that the metal film is a ruthenium film or a molybdenum film.

5. In the plasma processing method according to any one of claims 1 to 3, The aforementioned protective film is a modified film, The plasma treatment method is characterized in that the altered film is formed by plasma generated using a gas that produces a non-volatile compound containing a metal element.

6. In the plasma treatment method described in claim 5, The plasma treatment method is characterized in that the non-volatile compound is a nitrided compound, a sulfurized compound, or a halogenated compound.

7. In the plasma processing method according to any one of claims 1 to 3, The aforementioned protective film is formed by plasma generated using a precursor gas containing carbon, silicon, or metallic elements, characterized in that the plasma treatment method is characterized by this formation of the protective film.

8. In the plasma processing method according to any one of claims 1 to 3, A plasma treatment method characterized by etching the metal film after the second step using radicals generated by the plasma in the third step.

9. In the plasma processing method according to any one of claims 1 to 3, A plasma treatment method further comprising the step of removing residue from the metal film.

10. In the plasma processing method according to any one of claims 1 to 3, The aforementioned protective film is a modified film, The fourth step is a plasma treatment method characterized by removing the altered film by reduction treatment.

11. In the plasma processing method according to Claim 1, A plasma treatment method characterized in that the second gas and the third gas are a mixed gas of oxygen gas and halogen gas.

12. In the plasma processing method according to claim 2 or claim 3, The aforementioned metal film is a ruthenium film. A plasma treatment method characterized in that the second gas and the third gas are a mixed gas of oxygen gas and halogen gas.

13. In the plasma processing method according to Claim 1, A plasma treatment method characterized in that a portion of the metal wiring pattern is connected to the ruthenium film.

14. In the plasma processing method according to claim 2 or claim 3, A plasma processing method characterized in that a portion of the metal wiring pattern is connected to the metal film.

15. In the plasma processing method according to Claim 1, A plasma treatment method characterized in that the ruthenium film is embedded in a groove formed below the metal wiring pattern.

16. In the plasma processing method according to claim 1 or claim 3, A plasma treatment method characterized in that the metal film is embedded in a groove formed below the metal wiring pattern.

17. In the plasma processing method according to Claim 1, A plasma treatment method characterized in that all of the aforementioned metal wiring patterns are connected to the ruthenium film.

18. In the plasma processing method according to claim 2, A plasma treatment method characterized in that all of the aforementioned metal wiring patterns are connected to the aforementioned metal film.

19. In the plasma processing method according to claim 3, The plasma processing method is characterized in that the second step involves etching the metal wiring pattern and the metal film with plasma generated using the second gas.

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