Dry etching method, method for manufacturing semiconductor device, and etching apparatus

Abstract

The dry etching method of the present application is characterized in that it is a dry etching method of etching a metal film formed on a surface of a processed body by bringing an etching gas containing a β-diketone into contact with the metal film, the method comprising: a first etching step of bringing a first etching gas containing a first β-diketone into contact with the metal film; and a second etching step of bringing a second etching gas containing a second β-diketone into contact with the metal film after the first etching step, the first β-diketone being a compound capable of generating a first complex by reaction with the metal film, and the second β-diketone being a compound capable of generating a second complex having a lower sublimation point than the first complex by reaction with the metal film.

Description

Technical Field

[0001] This invention relates to a dry etching method, a method for manufacturing semiconductor equipment, and an etching apparatus. Background Technology

[0002] In the manufacturing process of semiconductor devices, metal films formed on a substrate are sometimes etched as wiring materials, metal gate materials, electrode materials, or magnetic materials.

[0003] With the miniaturization of semiconductor devices, the etching of metal films to form fine structures has always required highly controlled etching. Specifically, research has focused on etching metal films in a manner that suppresses the deviation in the in-plane etching amount of the wafer to less than 1 nm, controlling the surface roughness of the etched metal film, and selectively etching metal films. To achieve this high degree of etching control, wet etching using chemical solutions is difficult; therefore, dry etching using gas to etch metal films has been investigated.

[0004] Patent Document 1 describes an etching method comprising the following etching steps: etching a thin film formed on a substrate at a substrate temperature of 300°C or higher, preferably 450°C or higher, using an etching gas containing at least one of water and alcohol, thereby exposing the surface of the substrate. Patent Document 2 describes a method in which an etching gas containing β-diketone and 1-20% by volume of water or hydrogen peroxide is used to form a complex of β-diketone and metal in a temperature range of 100°C or higher and 350°C or lower, thereby etching the metal film. Examples of metals constituting the metal film in Patent Document 2 include zinc, cobalt, hafnium, iron, manganese, and vanadium. According to Patent Document 2, by adding water or hydrogen peroxide, the etching speed of the metal film is increased compared to using oxygen.

[0005] In addition, although it is not a method for fine etching of metal films on substrates, a method using β-diketones has been proposed as a method for dry cleaning metal films attached to film deposition apparatus used in semiconductor device manufacturing processes.

[0006] Patent Document 3 describes a dry cleaning method that removes a metal film attached to a film-forming apparatus by reacting a cleaning gas containing β-diketone and NOx (either NO or N2O) with a metal film at a temperature range of 200–400°C, preferably 250–370°C. Examples of metals constituting the metal film in Patent Document 3 include nickel, manganese, iron, and cobalt. According to Patent Document 3, by using NOx, the temperature range capable of etching and removing the metal film is expanded compared to using oxygen.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2004-91829

[0010] Patent Document 2: Japanese Patent Application Publication No. 2014-236096

[0011] Patent Document 3: Japanese Patent Application Publication No. 2013-194307 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] The crystallinity of the metal film being etched varies depending on the film formation method, but in most cases it is a polycrystalline film formed by grain aggregation. When etching such a metal film using the methods described in Patent Documents 1-3, achieving uniform etching overall is very difficult. Typically, weakly bonded (i.e., highly reactive) grain boundaries are preferentially etched, thus the etched film can be considered to have a rough surface due to differences in etching rate. In recent years, with advancements in miniaturization, even minute surface roughness has become a significant problem requiring improvement.

[0014] When etching a metal film using an etching gas containing β-diketone, the metal and β-diketone form a complex, thereby etching the metal film. Formation of this complex requires a one-time oxidation of the metal; therefore, in most cases, oxidants such as oxygen or the aforementioned NOx are added to the etching gas. The inventors have consistently attempted to improve surface roughness by adjusting the amount of oxidant added, the timing of its addition, and the processing conditions when using β-diketone, but have not been able to achieve a fundamental improvement.

[0015] The present invention was made in view of the above-mentioned problems, and its object is to provide a dry etching method capable of suppressing surface roughness of metal films. Furthermore, an object of the present invention is to provide a method for manufacturing a semiconductor device using the above-described dry etching method. A further object of the present invention is to provide an etching apparatus capable of suppressing the occurrence of surface roughness in metal films.

[0016] Solution for solving the problem

[0017] The inventors focused on the situation where the sublimation point of the complex formed in the reaction with metal varies significantly depending on the type of β-diketone. Furthermore, they discovered that when the metal film was treated with a first β-diketone that forms a first complex with a high sublimation point, and then treated with a second β-diketone that forms a second complex with a lower sublimation point than the first complex, the surface roughness of the metal film was improved, thus completing the present invention.

[0018] The dry etching method of the present invention is characterized in that it is a dry etching method in which an etching gas containing a β-diketone is contacted with a metal film formed on the surface of a workpiece to etch the metal film. The method includes: a first etching step in which a first etching gas containing a first β-diketone is contacted with the metal film; and a second etching step in which a second etching gas containing a second β-diketone is contacted with the metal film after the first etching step. The first β-diketone is a compound capable of generating a first complex by reacting with the metal film, and the second β-diketone is a compound capable of generating a second complex with a sublimation point lower than that of the first complex by reacting with the metal film.

[0019] In the dry etching method of the present invention, the combination of the first β-diketone and the second β-diketone is preferably (first β-diketone, second β-diketone) = (acetylacetone, hexafluoroacetylacetone), (acetylacetone, trifluoroacetylacetone) or (trifluoroacetylacetone, hexafluoroacetylacetone).

[0020] In the dry etching method of the present invention, the first etching step and the second etching step described above can be repeated.

[0021] In the dry etching method of the present invention, the metal film preferably contains at least one metal element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt and Ni.

[0022] In the dry etching method of the present invention, preferably the first etching gas and the second etching gas each independently further include at least one additive gas selected from the group consisting of NO, NO2, N2O, O2, O3, H2O and H2O2.

[0023] In the dry etching method of the present invention, preferably: the metal film contains Co element, the first etching gas contains acetylacetone as the first β-diketone and NO as an additive gas, and the second etching gas contains hexafluoroacetylacetone as the second β-diketone and NO as an additive gas.

[0024] In the dry etching method of the present invention, preferably the first etching gas and the second etching gas each independently further comprise at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr.

[0025] The dry etching method of the present invention preferably further includes a pretreatment step of supplying a reducing gas to the metal film before the first etching step described above.

[0026] The semiconductor device manufacturing method of the present invention is characterized by having a step of etching a metal film on a substrate using the dry etching method of the present invention.

[0027] The etching apparatus of the present invention is characterized by comprising: a mounting section disposed within a heatable processing container, wherein a workpiece is disposed thereon and a metal film is formed on the mounting surface; a first β-diketone supply section supplying a first β-diketone to the workpiece, wherein the first β-diketone is a compound capable of generating a first complex by reacting with the metal film; a second β-diketone supply section supplying a second β-diketone to the workpiece, wherein the second β-diketone is a compound capable of generating a second complex with a sublimation point lower than the first complex by reacting with the metal film; and a control section outputting control signals for performing a first step and a second step, wherein the first step involves supplying a first etching gas containing the first β-diketone to the workpiece, and the second step involves supplying a second etching gas containing the second β-diketone to the workpiece after the first step.

[0028] The etching apparatus of the present invention further includes a reducing gas supply unit for supplying a reducing gas to the workpiece, and the control unit preferably outputs a control signal for supplying the reducing gas to the workpiece before supplying the first etching gas to the workpiece.

[0029] The effects of the invention

[0030] According to the present invention, a dry etching method capable of suppressing surface roughness of metal films can be provided. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating an etching apparatus according to one embodiment of the present invention.

[0032] Figure 2 This is a flowchart illustrating the test steps of Examples 1 and 2.

[0033] Figure 3 This is a flowchart showing the test procedures for Comparative Example 1.

[0034] Figure 4 This is a graph showing the relationship between the etching amount and RMS in Example 1 and Comparative Example 1.

[0035] Figure 5 This is a graph showing the relationship between the etching amount and RMS in Examples 1 and 2. Detailed Implementation

[0036] The embodiments of the present invention will be described in detail below.

[0037] However, the present invention is not limited to the following embodiments, and can be applied by appropriate modifications without changing the spirit of the present invention.

[0038] [Dry Etching Method]

[0039] One embodiment of the present invention provides a dry etching method for etching a metal film formed on the surface of a workpiece by contacting an etching gas containing a β-diketone with the metal film. When the etching gas containing a β-diketone is contacted with a heated metal film, the β-diketone reacts with the metal film to form a complex. Because the complex has a high vapor pressure, the metal film can be removed by vaporizing the complex.

[0040] The dry etching method according to one embodiment of the present invention is characterized in that, after a first etching step in which a first etching gas containing a first β-dione is brought into contact with a metal film, a second etching step in which a second etching gas containing a second β-dione is brought into contact with a metal film, wherein the first β-dione can generate a first complex with a high sublimation point, and the second β-dione can generate a second complex with a lower sublimation point than the first complex.

[0041] This allows for the suppression of surface roughness in the etched metal film. The underlying mechanism can be deduced as follows: First, when the metal film is treated with the 1β-diketone, it preferentially forms complexes relative to the weaker (i.e., more reactive) grain boundaries. Next, when the metal film is treated with the 2β-diketone, the complexes formed in the 1β-diketone act as a protective film at the grain boundaries, thus the 2β-diketone attacks the less reactive grain regions. Then, as the grains are etched, the protected grain boundaries are also etched. As a result, the entire metal film can be considered uniformly etched.

[0042] The metal film targeted by the dry etching method according to one embodiment of the present invention is formed from a metal element capable of forming a complex with β-diketone. Specifically, at least one metal element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt, and Ni can be used. The metal film can be composed of only one metal element or multiple metal elements. The dry etching method according to one embodiment of the present invention is effective for metal films containing Co. It should be noted that in the dry etching method according to one embodiment of the present invention, known substrates such as semiconductor substrates and glass substrates can be used as the substrate of the workpiece.

[0043] (Etching process 1)

[0044] The first etching gas contains a first β-diketone. The type of first β-diketone depends on its relationship with the second β-diketone and is not particularly limited; examples include acetylacetone and trifluoroacetylacetone. One or more compounds can be used as the first β-diketone.

[0045] From the viewpoint of obtaining a sufficient etching rate, the content of the first β-dione contained in the first etching gas is preferably 10% by volume or more and 90% by volume or less, more preferably 30% by volume or more and 60% by volume or less.

[0046] The first etching gas preferably further comprises at least one additive gas selected from the group consisting of NO, NO2, N2O, O2, O3, H2O and H2O2.

[0047] When the first etching gas contains an additive gas, from the viewpoint of obtaining a sufficient etching rate, the content of the additive gas contained in the first etching gas is preferably 0.01 vol% or more and 10 vol% or less, more preferably 0.05 vol% or more and 8 vol% or less, and even more preferably 0.1 vol% or more and 5 vol% or less.

[0048] The first etching gas preferably further comprises at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr.

[0049] When the first etching gas contains an inactive gas, the content of the inactive gas in the first etching gas is preferably 1% or more and 90% or less by volume, more preferably 10% or more and 80% or less by volume, and even more preferably 30% or more and 50% or less by volume.

[0050] (Second Etching Process)

[0051] The second etching gas contains a second β-diketone. The type of second β-diketone depends on its relationship to the first β-diketone and is not particularly limited; examples include hexafluoroacetylacetone and trifluoroacetylacetone. One or more compounds can be used as the second β-diketone.

[0052] As combinations of 1β-diketone and 2β-diketone, examples include (1β-diketone, 2β-diketone) = (acetylacetone, hexafluoroacetylacetone), (acetylacetone, trifluoroacetylacetone), (trifluoroacetylacetone, hexafluoroacetylacetone), etc.

[0053] From the viewpoint of obtaining a sufficient etching rate, the content of the second β-dione contained in the second etching gas is preferably 10% by volume or more and 90% by volume or less, more preferably 30% by volume or more and 60% by volume or less.

[0054] The second etching gas preferably further includes at least one additive gas selected from the group consisting of NO, NO2, N2O, O2, O3, H2O, and H2O2. When the first and second etching gases include additive gases, the additive gas included in the first etching gas and the additive gas included in the second etching gas may be the same or different.

[0055] When the second etching gas contains an additive gas, from the viewpoint of obtaining a sufficient etching rate, the content of the additive gas in the second etching gas is preferably 0.01 vol% or more and 10 vol% or less, more preferably 0.05 vol% or more and 8 vol% or less, and even more preferably 0.1 vol% or more and 5 vol% or less. When both the first and second etching gases contain additive gases, the content of the additive gas in the first etching gas and the content of the additive gas in the second etching gas may be the same or different.

[0056] The second etching gas preferably further comprises at least one inactive gas selected from the group consisting of N2, Ar, He, Ne, and Kr. When the first and second etching gases contain inactive gases, the inactive gas contained in the first etching gas may be the same as or different from the inactive gas contained in the second etching gas.

[0057] When the second etching gas contains an inactive gas, the content of the inactive gas in the second etching gas is preferably 1% by volume or more and 90% by volume or less, more preferably 10% by volume or more and 80% by volume or less, and even more preferably 30% by volume or more and 50% by volume or less. When both the first and second etching gases contain inactive gases, the content of the inactive gas in the first etching gas and the content of the inactive gas in the second etching gas may be the same or different.

[0058] In a dry etching method according to one embodiment of the present invention, the first etching step and the second etching step can be repeated. In this case, the conditions for the first etching step can be the same or different. Similarly, the conditions for the second etching step can be the same or different.

[0059] (Pretreatment process)

[0060] In a dry etching method according to one embodiment of the present invention, a pretreatment step of supplying a reducing gas to the metal film is preferably performed before the first etching step. For example, when the metal film to be removed contains Co, reducing the cobalt natural oxide film can improve the deviation in etching rate caused by the thickness of the natural oxide film.

[0061] In the pretreatment process, reducing gases such as hydrogen (H2), carbon monoxide (CO), and formaldehyde (HCHO) can be used. There can be only one reducing gas or two or more.

[0062] In the pretreatment process, only reducing gases such as H2 can be supplied, or the reducing gases can be diluted with inactive gases such as N2.

[0063] Furthermore, in the pretreatment process, it is preferable not to supply β-diketone and added gas. Specifically, in the pretreatment process, the ratio of the amount of β-diketone and added gas to the total amount of gas supplied is preferably less than 0.01% by volume, more preferably less than 0.001% by volume, and particularly preferably 0% by volume.

[0064] [Etching apparatus]

[0065] The dry etching method of one embodiment of the present invention can be implemented, for example, by using a conventional etching apparatus used in semiconductor manufacturing processes. Such an etching apparatus is also one embodiment of the present invention.

[0066] Figure 1 This is a schematic diagram illustrating an etching apparatus according to one embodiment of the present invention.

[0067] Figure 1 The etching apparatus 100 shown includes: a processing container 110 for holding a workpiece 10 on which a metal film has been formed; a first β-diketone supply unit 130 connected to the processing container 110 and supplying a first β-diketone; a second β-diketone supply unit 140 for supplying a second β-diketone; an additive gas supply unit 150 for supplying an additive gas; an inactive gas supply unit 160 for supplying an inactive gas; a reducing gas supply unit 170 for supplying a reducing gas; and a heating device 180 for heating the processing container 110. A gas flow control unit (not shown) is connected to the first β-diketone supply unit 130, etc., and outputs a valve control signal to supply the first β-diketone, etc., to the workpiece 100. It should be noted that the etching apparatus 100 may also include an additive gas supply unit 150, an inactive gas supply unit 160, and a reducing gas supply unit 170.

[0068] The processing container 110 includes a mounting section 111 for holding the workpiece 10 to be processed. The processing container 110 is resistant to the β-diketone used, and there are no particular limitations as long as the pressure can be reduced to a specified pressure. Generally, a conventional processing container used in semiconductor etching apparatus can be used. In addition, the supply pipe for the etching gas, other piping, etc., can also be general-purpose without particular limitations as long as they are resistant to β-diketone.

[0069] The first β-diketone supply unit 130 regulates the supply amount through valves V1 to V5 and flow regulating device MFC1, supplying bubbling gas such as N2 to the first β-diketone container 137 through pipes 131, 132 and 133, and supplying the first β-diketone from the first β-diketone container 137 to pipes 134, 135 and 121. Figure 1 In the middle, piping 133 and piping 134 are connected by piping 136, but piping 136 may not be installed.

[0070] The 2β-diketone supply unit 140 regulates the supply amount through valves V6 and V7 and flow regulating device MFC2, supplying the 2β-diketone to pipe 121 via pipes 141 and 142.

[0071] The gas supply unit 150 adjusts the supply amount through valves V8 and V9 and flow regulating device MFC3, and supplies the gas to pipe 121 through pipes 151 and 152.

[0072] The inactive gas supply unit 160 regulates the supply amount through valves V10 and V11 and flow regulating device MFC4, supplying inactive gas from piping 161 and 162 to piping 121.

[0073] The reducing gas supply unit 170 regulates the supply amount through valves V12 and V13 and flow regulating device MFC5, supplying reducing gas from pipes 171 and 172 to pipe 121.

[0074] In the etching apparatus 100, for β-diketones, it is preferable that the β-diketone is diluted to a predetermined concentration by an inert gas supplied by the inert gas supply unit 160 and then supplied to the processing container 110 in a state of being mixed with an additive gas supplied by the additive gas supply unit 150 at a predetermined concentration. However, β-diketones may also be supplied without dilution by an inert gas.

[0075] A heating device 180 for heating the processing container 110 is disposed on the outside of the processing container 110. Additionally, a heater (not shown) can be disposed inside the mounting section 111 as a second heating device. It should be noted that when multiple mounting sections are disposed in the processing container 110, by equipping each mounting section with a heater, each mounting section can be set to a predetermined temperature.

[0076] On one side of the processing container 110, a gas discharge device for discharging the reacted gas can be installed. The reacted gas is discharged from the processing container 110 via a vacuum pump 183 through a pipe 181. The reacted gas can be recovered by a liquid nitrogen collector 184 installed between pipes 181 and 182. Valves V14 and V15 are installed on pipes 181 and 182 to regulate the pressure. Additionally, Figure 1 In this system, PI1 and PI2 are pressure gauges, and the control unit can control each flow regulating device and each valve based on their indicated values.

[0077] Taking etching apparatus 100 as an example, the etching method will be explained in detail.

[0078] A treatment object 10 is disposed within a processing container 110, the treatment object 10 having a metal film containing a metal element capable of forming a complex with β-diketone. Using a vacuum pump 183, the internal vacuum of the processing container 110, piping 121, piping 131-136, piping 141 and 142, piping 151 and 152, piping 161 and 162, piping 171 and 172, liquid nitrogen collector 184, and piping 181 and 182 is replaced to a predetermined pressure, and then the treatment object 10 is heated by a heating device 180. Once the predetermined temperature is reached, the first β-diketone supply unit 130, the additive gas supply unit 150, and the inactive gas supply unit 160 supply the first β-diketone, additive gas, and inactive gas to piping 121 at a predetermined flow rate.

[0079] A diluted first β-diketone and an additive gas, mixed according to a prescribed composition, are supplied to the processing container 110. While introducing the mixed first etching gas into the processing container 110, the pressure inside the processing container 110 is controlled at a prescribed pressure. The first etching process is performed by allowing the first etching gas to react with the metal film for a prescribed time. In the first etching process, etching can be performed without plasma, and it is not necessary to use plasma or other methods to excite the etching gas during etching.

[0080] After the first etching process is completed, vacuum replacement is performed again. Then, the second β-diketone, additive gas, and inactive gas are supplied to the piping 121 at a specified flow rate by the second β-diketone supply unit 140, the additive gas supply unit 150, and the inactive gas supply unit 160.

[0081] A diluted second β-diketone and an additive gas are mixed according to a specified composition and supplied to the processing container 110. While introducing the mixed second etching gas into the processing container 110, the pressure inside the processing container 110 is controlled at a specified pressure. The second etching process is performed by allowing the second etching gas to react with the metal film for a specified time. In the second etching process, etching can be performed without plasma, and it is not necessary to use plasma or other methods to excite the etching gas during etching.

[0082] When repeating the first and second etching processes, after the second etching process is completed, vacuum replacement is performed again. Then, the first and second etching processes are performed in the same manner as described above.

[0083] After the second etching process is completed, heating based on heating device 180 is stopped and the temperature is lowered. At the same time, vacuum pump 183 is stopped and the vacuum is released. Through the above operations, the etching of the metal film can be performed.

[0084] It should be noted that, prior to the first etching step, a reducing gas is supplied to the workpiece 10 via the reducing gas supply unit 170, thereby enabling a pretreatment step. Preferably, vacuum purging is performed after the pretreatment step and before the first etching step.

[0085] (Etching conditions)

[0086] In a dry etching method according to one embodiment of the present invention, the temperature during the first and second etching steps is sufficient to vaporize the complex. In particular, the temperature at which the metal film to be removed is preferably 100°C or higher and 350°C or lower, more preferably 130°C or higher and 250°C or lower. The temperature of the metal film may be the same as or different from that of the first and second etching steps.

[0087] Furthermore, the pressure inside the processing container in the first and second etching processes is not particularly limited, and is typically in the range of 0.1 kPa to 101.3 kPa. The pressure inside the processing container can be the same as or different from that in the first and second etching processes.

[0088] In particular, when the metal film to be removed contains Co, the first etching gas contains acetylacetone as a first β-diketone and NO as an additive gas, and the second etching gas contains hexafluoroacetylacetone as a second β-diketone and NO as an additive gas, etching is sometimes performed at a high temperature of around 300 to 400°C, where hexafluoroacetylacetone sometimes decomposes to form a carbon film, damaging the structure of the component. Therefore, it is preferable to heat the object to be processed to below 250°C.

[0089] Regarding the aforementioned temperature range, from the viewpoint of obtaining a sufficient etching rate, the pressure inside the processing container in the first etching step is preferably 20 Torr or more and 300 Torr or less (2.67 kPa or more and 39.9 kPa or less), more preferably 20 Torr or more and 100 Torr or less (2.67 kPa or more and 13.3 kPa or less), and even more preferably 20 Torr or more and 50 Torr or less (2.67 kPa or more and 6.67 kPa or less). Furthermore, the pressure inside the processing container in the second etching step is preferably 20 Torr or more and 300 Torr or less (2.67 kPa or more and 39.9 kPa or less), more preferably 50 Torr or more and 250 Torr or less (6.67 kPa or more and 33.3 kPa or less), and even more preferably 100 Torr or more and 200 Torr or less (13.3 kPa or more and 26.7 kPa or less).

[0090] The processing time for the first and second etching processes is not particularly limited, but considering the efficiency of semiconductor equipment manufacturing processes, it is preferable to keep it within 60 minutes. Here, the processing time for each etching process refers to the time required to introduce etching gas into a processing container containing the workpiece, and then to expel the etching gas from the processing container using a vacuum pump or the like to complete the etching process.

[0091] During the pretreatment process, the processing temperature is not particularly limited as long as it is sufficient to reduce the natural oxide film. At low temperatures, the reduction reaction is almost negligible. While the pretreatment temperature can also be high, it is preferable, from the perspective of operating the etching apparatus, to be the same as the processing temperature of the first etching process. Based on the above, in the pretreatment process, the workpiece is preferably heated to 100°C or higher and 350°C or lower, more preferably to 150°C or higher and 250°C or lower.

[0092] In the pretreatment process, the flow rate of the reducing gas depends on the volume of the treatment container. The pressure inside the treatment container is not particularly limited in the pretreatment process; for example, it can be set appropriately according to the equipment within the range of 10–500 Torr (1.33–66.5 kPa).

[0093] The processing time of the pretreatment process can be adjusted appropriately according to the film formation method of the metal film formed on the substrate.

[0094] [Semiconductor equipment manufacturing methods]

[0095] The dry etching method of one embodiment of the present invention can be used as an etching method for forming a predetermined pattern on a metal film of an existing semiconductor device. By using the dry etching method of one embodiment of the present invention to etch the metal film on a substrate, semiconductor devices can be manufactured inexpensively.

[0096] Examples of such semiconductor devices include solar cells, hard disk drives, dynamic random access memory, phase change memory, ferroelectric memory, magnetoresistive memory, resistive random access memory, and microelectromechanical systems (EMS).

[0097] Example

[0098] The following describes embodiments of the present invention in more detail. It should be noted that the present invention is not limited to these embodiments.

[0099] In Examples 1, 2, and Comparative Example 1, the following were used: Figure 1 The etching apparatus 100 shown etched a cobalt film (1cm×1cm in shape and 200nm thick) formed on the surface of a silicon wafer.

[0100] Figure 2 This is a flowchart illustrating the test steps of Examples 1 and 2. Figure 3 This is a flowchart showing the test procedures for Comparative Example 1. Figure 2 and Figure 3 In this context, Vac represents vacuum displacement.

[0101] (Example 1)

[0102] The internal vacuum of the processing container 110, piping 121, piping 131-136, piping 141 and 142, piping 151 and 152, piping 161 and 162, piping 171 and 172, liquid nitrogen collector 184, and piping 181 and 182 was purged to below 10 Pa. Then, the weighted subject 10, placed in the mounting section 111, was heated by the heating device 180 and a heater disposed inside the mounting section 111. After confirming that the heating device 180 and the heater disposed inside the mounting section 111 reached 200°C, a pretreatment process was performed by supplying H2 gas at a pressure of 50 Torr for 10 minutes at 10 sccm through the reducing gas supply section 170.

[0103] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, acetylacetone (Acac), NO gas from the additive gas supply unit 150, and N2 gas from the inactive gas supply unit 160 are supplied to the piping 121 at specified flow rates. This introduces the first etching gas into the processing container 110 while maintaining the pressure inside the container at 21 Torr, thus performing the first etching process. The temperature of the object being processed is 200°C, and the flow rate of the first etching gas is Acac / NO / N2 = 10 / 1 / 10 sccm. The introduction of the first etching gas is stopped 1 to 5 minutes after its initiation.

[0104] After the first etching process, the pressure is purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), NO gas, and N2 gas are supplied to piping 121 at specified flow rates from the second β-diketone supply unit 140, the additive gas supply unit 150, and the inactive gas supply unit 160, thereby introducing the second etching gas into the processing container 110 while maintaining the pressure inside the processing container 110 at 100 Torr, and the second etching process is performed. The temperature of the object being processed is 200°C, and the flow rate of the second etching gas is HFAc / NO / N2 = 50 / 1 / 49 sccm. The introduction of the second etching gas is stopped 1 to 5 minutes after the start of the second etching gas introduction.

[0105] Repeat the first and second etching processes 1 to 8 times.

[0106] (Example 2)

[0107] The temperature of the object to be processed was changed to 150°C. Otherwise, the pretreatment process, the first etching process and the second etching process were performed in the same manner as in Example 1, thereby etching the object to be processed.

[0108] (Comparative Example 1)

[0109] First, a pretreatment process is performed under the same conditions as in Example 1.

[0110] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), NO gas, and N2 gas are supplied to piping 121 at specified flow rates from the second β-diketone supply unit 140, the additive gas supply unit 150, and the inactive gas supply unit 160. The etching gas is introduced into the processing container 110 while the pressure inside the container is controlled at 100 Torr, and the etching process is performed. The temperature of the object being processed is 200°C, and the flow rate of the etching gas is HFAc / NO / N2 = 50 / 1 / 49 sccm. The etching gas is stopped 2–60 minutes after the start of the etching gas introduction.

[0111] In Example 3 and Comparative Example 2, using Figure 1 The etching apparatus 100 shown etched an iron film (1cm×1cm in shape and 200nm thick) formed on the surface of a silicon wafer.

[0112] (Example 3)

[0113] First, a pretreatment process is performed under the same conditions as in Example 1.

[0114] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, acetylacetone (Acac) is supplied from the first β-diketone supply unit 130, H2O gas is supplied from the additive gas supply unit 150, and N2 gas is supplied from the inactive gas supply unit 160 to the piping 121. The first etching gas is introduced into the processing container 110 while the pressure inside the processing container 110 is controlled at 21 Torr, and the first etching process is performed. The temperature of the object being processed is 250°C, and the flow rate of the first etching gas is Acac / H2O / N2 = 10 / 1 / 10 sccm. The introduction of the first etching gas is stopped 1 to 5 minutes after the start of the first etching gas introduction.

[0115] After the first etching process, the pressure was purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), H2O gas from the second β-diketone supply unit 140, and N2 gas from the inactive gas supply unit 160 were supplied to pipe 121 at specified flow rates. The second etching gas was introduced into the processing container 110 while the pressure inside the processing container 110 was controlled at 100 Torr, and the second etching process was performed. The temperature of the object being processed was 250°C, and the flow rate of the second etching gas was HFAc / H2O / N2 = 50 / 1 / 49 sccm. The introduction of the second etching gas was stopped 1 to 5 minutes after the start of the second etching gas introduction.

[0116] Repeat the first and second etching processes 1 to 8 times.

[0117] (Comparative Example 2)

[0118] First, a pretreatment process is performed under the same conditions as in Example 1.

[0119] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), H2O gas from the additive gas supply unit 150, and N2 gas from the inactive gas supply unit 160 are supplied to pipe 121 at specified flow rates. The etching gas is introduced into the processing container 110 while the pressure inside the container is controlled at 100 Torr, and the etching process is performed. The temperature of the object being treated is 250°C, and the flow rate of the etching gas is HFAc / H2O / N2 = 50 / 1 / 49 sccm. The etching gas is stopped 2–60 minutes after the start of the etching gas introduction.

[0120] In Example 4 and Comparative Example 3, using Figure 1 The etching apparatus 100 shown etched a hafnium film (1cm×1cm in shape and 200nm thick) formed on the surface of a silicon wafer.

[0121] (Example 4)

[0122] First, a pretreatment process is performed under the same conditions as in Example 1.

[0123] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, acetylacetone (Acac) is supplied from the first β-diketone supply unit 130, NO2 gas is supplied from the additive gas supply unit 150, and N2 gas is supplied from the inactive gas supply unit 160 to the piping 121, thereby introducing the first etching gas into the processing container 110. The pressure inside the processing container 110 is controlled at 21 Torr, and the first etching process is performed. The temperature of the object being processed is 300°C, and the flow rate of the first etching gas is Acac / NO2 / N2 = 10 / 1 / 10 sccm. The introduction of the first etching gas is stopped 1 to 5 minutes after the start of the first etching gas introduction.

[0124] After the first etching process, the pressure is purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), NO2 gas from the second β-diketone supply unit 140, and N2 gas from the inactive gas supply unit 160 are supplied to pipe 121 at specified flow rates. The second etching gas is introduced into the processing container 110 while the pressure inside the processing container 110 is controlled at 100 Torr, and the second etching process is performed. The temperature of the object being processed is 300°C, and the flow rate of the second etching gas is HFAc / NO2 / N2 = 50 / 1 / 49 sccm. The introduction of the second etching gas is stopped 1 to 5 minutes after the start of the second etching gas introduction.

[0125] Repeat the first and second etching processes 1 to 8 times.

[0126] (Comparative Example 3)

[0127] First, a pretreatment process is performed under the same conditions as in Example 1.

[0128] After the pretreatment process, the pressure is purged again to below 10 Pa. Then, hexafluoroacetylacetone (HFAc), NO2 gas is supplied from the second β-diketone supply unit 140, and N2 gas is supplied from the inactive gas supply unit 160 to the piping 121 at specified flow rates. This allows the etching gas to be introduced into the processing container 110 while maintaining the pressure inside the container at 100 Torr, thus performing the etching process. The temperature of the object being treated is 300°C, and the flow rate of the etching gas is HFAc / NO2 / N2 = 50 / 1 / 49 sccm. The etching gas is stopped 2–60 minutes after the start of its introduction.

[0129] In Examples 1 to 4 and Comparative Examples 1 to 3, after the vacuum inside the processing container 110 was released, the workpiece 10 was removed and its weight was measured. The volume was calculated based on the weight change of the workpiece 10 before and after the test and the density of the cobalt film, iron film, or hafnium film. The etching amount was calculated by dividing the volume by the area of ​​the cobalt film, iron film, or hafnium film.

[0130] In addition, in Examples 1 to 4 and Comparative Examples 1 to 3, the surface roughness of the etched cobalt, iron, or hafnium films was measured using an AFM (SHIMADDZU, model SPM-9700). The root mean square roughness (RMS) based on the AFM measurements was calculated as an indicator of surface roughness.

[0131] The etching conditions in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1. Furthermore, the slope of the RMS relative to the etching amount is shown in Table 1.

[0132] [Table 1]

[0133]

[0134] Figure 4 This is a graph showing the relationship between the etching amount and RMS in Example 1 and Comparative Example 1.

[0135] Depend on Figure 4 When calculating the slope of the RMS relative to the etching amount, Comparative Example 1 showed a slope of 0.095, while Example 1 showed a slope of 0.063. Figure 4 The results confirm that the surface roughness after etching in Example 1 was suppressed.

[0136] Figure 5 This is a graph showing the relationship between the etching amount and RMS in Examples 1 and 2.

[0137] Depend on Figure 5 When calculating the slope of the RMS relative to the etching amount, the slope for Example 1 with an etching temperature of 200°C was 0.063, and for Example 2 with an etching temperature of 150°C it was 0.058. Figure 5 The results confirm that there is almost no temperature dependence. Since the etching rates of both the first and second etching processes decrease as the etching temperature decreases, the difference in etching rates can be considered to be maintained.

[0138] As shown in Table 1, when the etched film was an iron film, the value in Comparative Example 2 was 0.102, while in Example 3 it decreased to 0.082. Similarly, when the etched film was a hafnium film, the value in Comparative Example 3 was 0.113, while in Example 4 it decreased to 0.076. These results confirm that the surface roughness after etching in Examples 3 and 4 was also suppressed.

[0139] Based on the above results, it can be concluded that etching was performed through the aforementioned hypothetical mechanism.

[0140] This application is based on Japanese Patent Application No. 2019-037591, filed on March 1, 2019, and claims priority based on the Paris Convention or the regulations of the country of entry. The contents of that application are incorporated herein by reference in their entirety.

[0141] Explanation of reference numerals in the attached figures

[0142] 10. Subjects to be processed

[0143] 100 Etching Device

[0144] 110 Handling Container

[0145] 111 Loading section

[0146] 130 First β-Diketone Supply Section

[0147] 131, 132, 133, 134, 135, 136 piping

[0148] 137 First β-Diketone Container

[0149] 140 2β-Diketone Supply Section

[0150] 141, 142 Piping

[0151] 150 Add gas supply unit

[0152] 151, 152 Piping

[0153] 160 Inactive Gas Supply Department

[0154] 161, 162 Piping

[0155] 170 Reducing Gas Supply Department

[0156] 171, 172 Piping

[0157] 180 heating device

[0158] 181, 182 Piping

[0159] 183 Vacuum Pump

[0160] 184 Liquid nitrogen collector

[0161] MFC1, MFC2, MFC3, MFC4, MFC5 Flow Control Device

[0162] PI1 and PI2 pressure gauges

[0163] V1, V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13,

[0164] V14 and V15 valves

Claims

1. A dry etching method, characterized in that, It is a dry etching method that involves contacting an etching gas containing β-diketone with a metal film formed on the surface of the object being treated to etch the metal film, the method comprising: The first etching step involves contacting the metal film with a first etching gas containing the first β-diketone; and The second etching step involves contacting the metal film with a second etching gas containing the second β-diketone after the first etching step. The first β-diketone is a compound capable of forming a first complex through reaction with the metal membrane. The second β-diketone is a compound capable of reacting with the metal film to form a second complex with a lower sublimation point than the first complex. The first etching gas and the second etching gas each independently further comprise at least one additive gas selected from the group consisting of NO, NO2, N2O, O2, O3, H2O and H2O2.

2. The dry etching method according to claim 1, wherein, The combination of the first β-dione and the second β-dione, i.e., the first β-dione and the second β-dione, is acetylacetone and hexafluoroacetylacetone, acetylacetone and trifluoroacetylacetone, or trifluoroacetylacetone and hexafluoroacetylacetone.

3. The dry etching method according to claim 1 or 2, wherein, The first etching process and the second etching process are repeated.

4. The dry etching method according to claim 1 or 2, wherein, The metal film contains at least one metallic element selected from the group consisting of Zr, Hf, Fe, Mn, Cr, Al, Ru, Co, Cu, Zn, Pt, and Ni.

5. The dry etching method according to claim 1, wherein, The metal film is a metal film containing Co.

6. The dry etching method according to claim 1, wherein, The first β-dione contained in the first etching gas is present in a concentration of 10% by volume or more and 90% by volume or less.

7. The dry etching method according to claim 1, wherein, The first β-dione contained in the first etching gas is present in a concentration of 30% to 60% by volume.

8. The dry etching method according to claim 1, wherein, The content of the added gas in the first etching gas is more than 0.01% by volume and less than 10% by volume.

9. The dry etching method according to claim 1, wherein, The content of the added gas in the first etching gas is more than 0.1% by volume and less than 5% by volume.

10. The dry etching method according to claim 1, wherein, The second β-dione contained in the second etching gas is present in a concentration of 10% by volume or more and 90% by volume or less.

11. The dry etching method according to claim 1, wherein, The second β-dione contained in the second etching gas is present in a concentration of 30% to 60% by volume.

12. The dry etching method according to claim 1, wherein, The content of the added gas in the second etching gas is more than 0.01% by volume and less than 10% by volume.

13. The dry etching method according to claim 1, wherein, The content of the added gas in the second etching gas is more than 0.1% by volume and less than 5% by volume.

14. The dry etching method according to claim 1, wherein, In the first etching step and the second etching step, the temperature at which the metal film of the object is removed is independently above 100°C and below 350°C.

15. The dry etching method according to claim 1, wherein, The pressure inside the processing container in the first etching process and the second etching process is independently within a pressure range of 0.1 kPa or more and 101.3 kPa or less.

16. The dry etching method according to claim 1, wherein, The pressure inside the processing container in the first etching process is above 2.67 kPa and below 6.67 kPa.

17. The dry etching method according to claim 1, wherein, The pressure inside the processing container in the second etching process is above 13.3 kPa and below 26.7 kPa.

18. The dry etching method according to claim 1, wherein, The metal film contains Co. The first etching gas contains acetylacetone as the first β-diketone and NO as an additive gas. The second etching gas contains hexafluoroacetylacetone as the second β-diketone and NO as an additive gas.

19. The dry etching method according to claim 18, wherein, The object being processed is heated to below 250°C.

20. The dry etching method according to claim 1 or 2, wherein, The first etching gas and the second etching gas each independently further comprise at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr.

21. The dry etching method according to claim 1 or 2, further comprising: a pretreatment step of supplying a reducing gas to the metal film prior to the first etching step.

22. A method for manufacturing a semiconductor device, characterized in that, The process includes etching a metal film on a substrate using the dry etching method according to any one of claims 1 to 21.

23. An etching apparatus, characterized in that, have: The substrate is disposed in a heatable processing container, and a metal film is formed on the substrate surface. The first β-diketone supply section supplies the first β-diketone to the body being treated, wherein the first β-diketone is a compound capable of generating a first complex by reacting with the metal film; A 2β-diketone supply section supplies a 2β-diketone to the treated body, wherein the 2β-diketone is a compound capable of generating a second complex with a lower sublimation point than the first complex through reaction with the metal film; and The control unit outputs control signals for performing steps 1 and 2. Step 1 involves supplying a first etching gas containing the first β-diketone to the workpiece, and step 2 involves supplying a second etching gas containing the second β-diketone to the workpiece after step 1. The first etching gas and the second etching gas each independently further comprise at least one additive gas selected from the group consisting of NO, NO2, N2O, O2, O3, H2O and H2O2.

24. The etching apparatus according to claim 23, further comprising a reducing gas supply unit for supplying a reducing gas to the workpiece, The control unit outputs a control signal for supplying the reducing gas to the workpiece before supplying the first etching gas to the workpiece.

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