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

Abstract

The dry etching method of the embodiment of the present disclosure is a dry etching method characterized by reacting an etched film containing a metal or an oxide of the aforementioned metal having a bond energy of M-O of 5 eV or more formed on the surface of a processing body with a β-diketone and nitrogen dioxide, and performing etching without plasma.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a dry etching method, a manufacturing method of a semiconductor device, and an etching apparatus. BACKGROUND

[0002] In response to the miniaturization of circuit patterns of semiconductor devices, the miniaturization of electric field effect transistors is also advancing, and therefore, a technique of forming a gate insulating film from HfO2 (dielectric constant k = 25) and the like as one of high-k materials instead of SiO2 (dielectric constant k = 3.9) is being studied.

[0003] In order to form a gate insulating film from a high-k material, etching is required after film formation and a prescribed shape is formed.

[0004] In Patent Literature 1, regarding a manufacturing method of a MOS transistor and the like, in a method of etching a metal film and a metal oxide film containing at least any one of Al, Zr, Hf, Y, La, Ce, and Pr formed on a substrate, in order to reduce damage to the substrate, an etching gas containing a β-diketone is used, and in the examples, a method of etching a HfO2 film by bringing the temperature of a wafer to about 450°C and adding oxygen to a hexafluoroacetylacetone gas is disclosed.

[0005] In Patent Literature 2, regarding a manufacturing method of a semiconductor element, a method of etching a high-dielectric-constant film sample such as hafnium oxide formed on a Si film by exciting a CH-based etching gas containing C and H to a plasma state is disclosed.

[0006] In Patent Literature 3, a method of using a β-diketone and a gas containing NO or N2O to screen a metal film attached to a film formation apparatus on which a metal gate material, an electrode material, or a magnetic material is formed on a substrate surface is disclosed.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT LITERATURE

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

[0010] Patent Literature 2: Japanese Patent Application Publication No. 2006-310676

[0011] Patent Literature 3: Japanese Patent Application Publication No. 2013-194307 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] In order to cope with the miniaturization of the circuit pattern of semiconductor devices, a technique of using a high dielectric constant material as a gate insulating film has been developed, but high dielectric constant materials such as hafnium oxide are mostly difficult-to-etch materials.

[0014] In the invention described in Patent Literature 1, it is disclosed that at least either water or alcohol is preferably contained in the etching gas in addition to oxygen, and further, etching does not proceed at a low temperature of 400°C or lower of the temperature of the wafer. That is, as can be understood from FIG. 9 of Patent Literature 1, in the case of a mixed gas of hexafluoroacetylacetone and oxygen, etching does not proceed at a temperature of 400°C or lower of the wafer. In the case where the etching process is performed at a temperature of the wafer exceeding 400°C, damage to the semiconductor device is large, and thus, a method capable of etching hafnium oxide at a low temperature of 400°C or lower, more preferably 300°C or lower, is desired.

[0015] In Patent Literature 2, it is disclosed that an etching rate of 1.0 nm / minute is obtained by using C2H2 as a plasma etching gas, but in the plasma etching method, the plasma causes damage to a portion other than the etching target of the semiconductor device, and further, the device becomes expensive due to an RF power source for generating the plasma, and thus, a method without using the plasma is desired. Further, in Patent Literature 3, only a screening method of a metal film is described, and an example of etching HfO2 is not disclosed.

[0016] In view of the above-described problems, an object of the present disclosure is to provide a dry etching method based on a gas composition capable of etching a specific kind of metal oxide film including a hafnium oxide film or a metal film at a low temperature without using plasma. Further, an object of the present disclosure is to provide a manufacturing method of a semiconductor device using the above-described dry etching method, and the like.

[0017] Solution to the problem

[0018] The present inventors have found that if nitrogen dioxide is used as an additive gas of a β-diketone, etching of a specific metal oxide film such as a hafnium oxide film or a metal film is specifically performed at a temperature of 400°C or lower, further 300°C or lower, compared to the case where other additive gases are used, and thus, the present disclosure has been achieved.

[0019] The dry etching method of the present disclosure is characterized by causing an etched film including a metal or an oxide of the metal having a M-O bond energy of 5 eV or more, which is formed on a surface of a processed body, to react with a β-diketone and nitrogen dioxide, and performing etching without plasma.

[0020] The M-O bond energy refers to a difference in potential energy between a state in which a metal exists in a metallic form and a state in which oxygen exists in an oxygen form, and it can be said that the greater the above-described bond energy, the more firmly the metal and oxygen are combined.

[0021] Among the metals described above in which the M-O bond energy is 5 eV or more, the metal and the metal oxide are firmly combined and the metal oxide is stable, and thus the material is not easily etched. The metal itself is also easily oxidized by nitrogen dioxide, and thus the etching is practically performed on the metal oxide. Therefore, it is considered that the material is not easily etched, but in the dry etching method of the present disclosure, etching can be performed even at 300°C or lower.

[0022] In the dry etching method of the present disclosure, as the metal described above in which the M-O bond energy is 5 eV or more, for example, hafnium, zirconium, titanium, aluminum, and the like can be given, and as the oxide of these metals, hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide, and the like can be given. These metals can be used alone, and can also be an alloy containing two or more kinds. Therefore, the oxide of these metals can be the oxide of one kind of metal, and can also be the oxide of an alloy of these metals.

[0023] As the dry etching method of the present disclosure, a first dry etching method in which an etching gas A containing the aforementioned β-diketone and the aforementioned nitrogen dioxide is brought into contact with the aforementioned etched film, and a second dry etching method in which a second etching method having a first etching step in which an etching gas B containing the aforementioned nitrogen dioxide is brought into contact with the aforementioned etched film, and a second etching step in which an etching gas C containing the aforementioned β-diketone is brought into contact with the aforementioned etched film can be employed.

[0024] The manufacturing method of a semiconductor device of the present disclosure is characterized by having a step of causing an etched film containing a metal or an oxide of the metal in which the M-O bond energy is 5 eV or more on a substrate to react with a β-diketone and nitrogen dioxide, and etching is performed without plasma.

[0025] In the manufacturing method of a semiconductor device of the present disclosure, the aforementioned first dry etching method can be employed, and a second dry etching method can also be employed.

[0026] The etching device of the present disclosure is characterized by having: a placement portion provided in a process container capable of being heated, and on which a processed object in which an etched film containing a metal or an oxide of the metal in which the M-O bond energy is 5 eV or more is formed on a surface is placed; a β-diketone supply portion that supplies a β-diketone to the processed object; and a nitrogen dioxide gas supply portion that supplies nitrogen dioxide to the processed object.

[0027] Effects of the Invention

[0028] According to the dry etching method of the present disclosure, a dry etching method in which an etched film described above in which the M-O bond energy is 5 eV or more, or an oxide of the metal described above, which is difficult to etch, can be etched without plasma even at a temperature of 400°C or lower, and further at 300°C or lower, can be provided.

[0029] According to the dry etching method of the present disclosure, the same effects as described above can be provided in the case of using the above-described first dry etching method or in the case of using the above-described second dry etching method.

[0030] According to the manufacturing method of a semiconductor device of the present disclosure, a manufacturing method of a semiconductor device can be provided in which an etching film having difficulty in etching, which contains a metal or an oxide of the metal having a M-O bond energy of 5 eV or more, formed on a substrate can be etched without plasma even at a temperature of 400°C or lower, further 300°C or lower.

[0031] According to the manufacturing method of a semiconductor device of the present disclosure, the same effects as described above can be provided in the case of using the above-described first dry etching method or in the case of using the above-described second dry etching method.

[0032] According to the etching apparatus of the present disclosure, by using the etching apparatus, an etching film having difficulty in etching, which contains a metal or an oxide of the metal having a M-O bond energy of 5 eV or more, can be etched without plasma even at a temperature of 400°C or lower, further 300°C or lower.

[0033] By using the etching apparatus of the present disclosure, the same effects as described above can be obtained in the case of using the above-described first dry etching method or in the case of using the above-described second dry etching method. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A schematic diagram of an etching apparatus according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0035] Hereinafter, an embodiment of the present disclosure will be specifically described.

[0036] However, the present disclosure is not limited to the following embodiment, and can be appropriately changed and applied within the scope of the gist of the present disclosure.

[0037] [Dry etching method]

[0038] The dry etching method of the present disclosure is a dry etching method characterized by reacting an etching film containing a metal or an oxide of the metal having a M-O bond energy of 5 eV or more, which is formed on a surface of a processed body, with a β-diketone and nitrogen dioxide, and etching without plasma.

[0039] The metal having an M-O bond energy of 5 eV or more or the oxide of the metal is preferably at least one selected from the group consisting of hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide, hafnium metal, zirconium metal, titanium metal, and aluminum metal.

[0040] Further, the etched film containing the metal having an M-O bond energy of 5 eV or more or the oxide of the metal is preferably at least one film selected from the group consisting of a hafnium oxide film, a zirconium oxide film, a titanium oxide film, an aluminum oxide film, a hafnium metal film, a zirconium metal film, a titanium metal film, and an aluminum metal film.

[0041] The etched film can be a film of the metal or the oxide of the metal alone or a film containing an alloy of two or more of the metals or an oxide of the alloy.

[0042] According to the dry etching method of the present disclosure, it is possible to provide a dry etching method in which an etched film having a low etching property containing a metal having an M-O bond energy of 5 eV or more or an oxide of the metal can be etched without plasma at a temperature of 400°C or lower, further 300°C or lower.

[0043] The decomposition temperature of hexafluoroacetylacetone (hereinafter, also referred to as HFAc), which is one of β-diketones, is 375°C, and thus, in the case where the etching temperature exceeds 400°C as described in Patent Document 1, decomposition of HFAc occurs, and carbon components are deposited on the etched film as an etching target, and it is completely predictable that a failure will occur in the subsequent process.

[0044] On the other hand, in the dry etching method of the present disclosure, by using HFAc and NO2 as etching gas, it is possible to reduce the etching temperature to 375°C or lower, and thus, it is possible to suppress the formation of a carbon film due to the decomposition of HFAc.

[0045] As a reason why the etching temperature can be reduced, it is presumed that the reason is that NO2, which constitutes the etching gas, is adsorbed to the surface of the etched film, the binding force between the metal constituting the oxide of the metal and oxygen is weakened, the reactivity with HFAc is improved, and etching can be performed at a low temperature.

[0046] [1st Dry Etching Method]

[0047] First, a 1st dry etching method of the dry etching method of the present disclosure, in which etching gas A containing the above-described β-diketone and the above-described nitrogen dioxide is brought into contact with the above-described etched film, will be described.

[0048] As the object to be processed in the first dry etching method of the present disclosure, a silicon substrate, a compound semiconductor substrate, a quartz substrate, a glass substrate can be given. On the surface of the object to be processed, a silicon film, a silicon oxide film, a silicon nitride film, a metal wiring film other than the above metal, and the like can be formed in addition to the film containing the metal having a M-O bond energy of 5 eV or more or the oxide of the above metal. The object to be processed is placed on the placement portion, and by heating the placement portion, the object to be processed and the etching film containing the metal having a M-O bond energy of 5 eV or more or the oxide of the above metal formed on the surface of the object to be processed can be heated.

[0049] The temperature of the object to be processed is substantially equal to the temperature of the above etching film. If the above etching film in the heated state is brought into contact with the etching gas containing the β-diketone and the nitrogen dioxide, the β-diketone and the nitrogen dioxide react with the metal having a M-O bond energy of 5 eV or more or the oxide of the above metal, and a complex is generated on the above etching film. Since the vapor pressure of the complex is high, the complex is vaporized, and thus the etching film can be etched.

[0050] As the oxide of hafnium constituting the metal having a M-O bond energy of 5 eV or more, hafnium oxide (HfO x (x is 1 or more and 3 or less), particularly HfO2), silicon hafnium oxide, aluminum hafnium oxide can be given. As the silicon hafnium oxide, Hf 1- x Si x O y , Hf 1-x Si x O y N z , and as the aluminum hafnium oxide, Hf 1-x Al x O m , Hf 1-x Al x O m N n . Among them, x, y, z, m, n represent 0 < x < 1, 0 < y ≤ 2, 0 < z ≤ 1.33, 0 < m ≤ 1.5, 0 < n ≤ 1.

[0051] As the oxide of zirconium, zirconium oxide (ZrO u (u is 1 or more and 3 or less), particularly ZrO 2) . As the oxide of aluminum, aluminum oxide (AlO v (v is 1 or more and 2 or less), particularly Al2O3) can be given. As the oxide of titanium, titanium oxide (TiO w (w is 1 or more and 3 or less), particularly TiO2) can be given.

[0052] The method for forming the etched film containing a metal or an oxide of the metal having a M-O bond energy of 5 eV or more on the surface of the object to be processed is not particularly limited, and for example, a chemical vapor deposition (CVD) method, a sputtering method can be given. Further, the thickness of the etched film containing a metal or an oxide of the metal having a M-O bond energy of 5 eV or more is not particularly limited, and for example, the thickness can be set to 0.1 nm or more and 1 μm or less.

[0053] The kind of the β-diketone is not particularly limited, and for example, hexafluoroacetylacetone (HFAc, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), trifluoroacetylacetone (1,1,1-trifluoro-2,4-pentanedione), and the like can be given. As the β-diketone, one compound can be used, or two or more compounds can be used.

[0054] The volume ratio of the β-diketone to the nitrogen dioxide contained in the etching gas A is preferably β-diketone:nitrogen dioxide = 10:0.001 or more and 100 or less, more preferably β-diketone:nitrogen dioxide = 10:0.01 or more and 10 or less, further preferably β-diketone:nitrogen dioxide = 10:0.1 or more and 10 or less. If the β-diketone is too small in the etching gas, there is a tendency that the etching rate decreases, and if the β-diketone is too large, the etching gas becomes too expensive. Further, if the nitrogen dioxide is too small or too large in the etching gas, the etching becomes difficult to perform.

[0055] The above etching gas A can be composed of only the β-diketone and the nitrogen dioxide, or can further contain at least one additive gas selected from the group consisting of O2, NO, N2O, CO, CO2, H2O, H2O2, and alcohol, or can further contain at least one non-active gas selected from the group consisting of N2, Ar, He, Ne, and Kr. Further, as the alcohol, methanol, ethanol, propanol, isopropanol, and the like can be given.

[0056] In the case where the etching gas A contains an additive gas other than the nitrogen dioxide, the total content ratio of the nitrogen dioxide and the additive gas other than the nitrogen dioxide contained in the etching gas A can be set to the same as the content ratio of the aforementioned nitrogen dioxide.

[0057] In the case where the etching gas A contains a non-active gas, the content ratio of the non-active gas contained in the etching gas A is preferably 1 vol% or more and 90 vol% or less, more preferably 10 vol% or more and 80 vol% or less, further preferably 30 vol% or more and 50 vol% or less.

[0058] [2nd Dry Etching Method]

[0059] Next, a second dry etching method as the dry etching method of the present disclosure, which has a first etching step of bringing an etching gas B containing nitrogen dioxide into contact with an etched film, and a second etching step of bringing an etching gas C containing a β-diketone into contact with the etched film, will be described.

[0060] In the second dry etching method of the present disclosure, as the object to be processed, a silicon substrate, a compound semiconductor substrate, a quartz substrate, and a glass substrate can be cited as in the case of the first dry etching method. On the surface of the object to be processed, a silicon film, a silicon oxide film, a silicon nitride film, a metal wiring film other than the above-mentioned metal, or the like can be formed in addition to the film of the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more. The object to be processed is placed on the placement portion, and the object to be processed and the etched film including the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more formed on the surface of the object to be processed are heated by heating the placement portion.

[0061] The temperature of the object to be processed is substantially equal to the temperature of the above-mentioned etched film. When the etching gas B containing nitrogen dioxide is brought into contact with the above-mentioned etched film in a heated state as the first etching step, nitrogen dioxide is adsorbed to the surface of the etched film. Then, when the etching gas C containing a β-diketone is brought into contact with the above-mentioned etched film as the second etching step, the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more to which nitrogen dioxide is attached to the surface reacts with the β-diketone, and a complex is generated on the etched film as in the case of the first dry etching method. Since the vapor pressure of the complex is high, the complex is vaporized, and thus the etched film including the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more can be etched.

[0062] In the second dry etching method of the present disclosure, the above-mentioned steps can be repeated a plurality of times in order to repeatedly etch the etched film. In one cycle of the etching steps, constant-thickness etching can be performed, and thus by determining the number of cycles, the layer can be precisely etched to a desired thickness.

[0063] As the hafnium oxide that constitutes the oxide of the metal having a M-O bond energy of 5 eV or more, the same as in the case of the first dry etching method can be used.

[0064] The method of forming the etched film including the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more on the surface of the object to be processed is not particularly limited, and for example, a chemical vapor deposition (CVD) method, a sputtering method, or the like can be cited. In addition, the thickness of the etched film including the metal or the oxide of the above-mentioned metal having a M-O bond energy of 5 eV or more is not particularly limited, and for example, the thickness can be set to 0.1 nm or more and 1 μm or less.

[0065] As the β-diketone, the same as in the case of the above-described first dry etching method can be used.

[0066] The above-described etching gas C can be composed of only the β-diketone, and the etching gas B can be composed of only the nitrogen dioxide, but can further contain at least one additive gas selected from the group consisting of O2, NO, N2O, CO, CO2, H2O, H2O2, and alcohol, and can further contain at least one non-active gas selected from the group consisting of N2, Ar, He, Ne, and Kr. In addition, as the alcohol, methanol, ethanol, propanol, isopropanol, and the like can be used.

[0067] In the case where the etching gas B contains an additive gas other than the nitrogen dioxide, the total volume ratio of the nitrogen dioxide contained in the etching gas A to the additive gas other than the nitrogen dioxide can be set to be the same as the volume ratio of the β-diketone to the nitrogen dioxide contained in the above-described etching gas A.

[0068] In addition, in the case where the etching gas C contains an additive gas other than the β-diketone, the total volume ratio of the β-diketone contained in the etching gas C to the additive gas other than the β-diketone can be set to be the same as the volume ratio of the β-diketone to the nitrogen dioxide contained in the above-described etching gas A.

[0069] In the case where the etching gas B and the etching gas C contain a non-active gas, the content rate of the non-active gas contained in the etching gas B and the etching gas C is preferably 1 vol% or more and 90 vol% or less, more preferably 10 vol% or more and 80 vol% or less, and further preferably 30 vol% or more and 50 vol% or less.

[0070] [Etching apparatus]

[0071] The dry etching method of the present disclosure can be implemented, for example, by using a general etching apparatus used in a semiconductor manufacturing process. Such an etching apparatus is also one of the present disclosure.

[0072] Figure 1 A schematic diagram of an etching apparatus of an embodiment of the present disclosure is shown schematically.

[0073] Figure 1 The etching apparatus 100 shown is provided with a processing vessel 110 in which a processed object 10 on the surface of which a metal or an oxide of the above-described metal having a M-O bond energy of 5 eV or more is formed, a β-diketone supply part 140 connected to the processing vessel 110 and supplying a β-diketone gas, a nitrogen dioxide gas supply part 150 supplying a nitrogen dioxide gas, a non-active gas supply part 160 supplying a non-active gas, and a heating unit 170 heating the processing vessel 110. Note that the etching apparatus 100 can not be provided with the non-active gas supply part 160.

[0074] The etching apparatus 100 is provided with a control unit not shown. The control unit is constituted by, for example, a computer, and is provided with a program, a memory, and a CPU. The program incorporates a step group in a manner to implement a series of actions of the first etching method or the second etching method, and, in accordance with the program, performs adjustment of the temperature of the object 10, opening and closing of the valves of the respective supply units, adjustment of the flow rates of the respective gases, adjustment of the pressure in the processing vessel 110, and the like. The program is stored in a computer storage medium such as an optical disk, a hard disk, a magneto-optical disk, a memory card, or the like, and is installed in the control unit.

[0075] The processing vessel 110 is provided with a placement unit 111 for placing the object 10. The processing vessel 110 is not particularly limited as long as it has resistance to the β-diketone used and can be depressurized to a prescribed pressure, and a general processing vessel or the like provided in an etching apparatus for semiconductors is generally used. In addition, a supply pipe for supplying the etching gas, other pipes, and the like are not particularly limited as long as they have resistance to the β-diketone, and a general one can be used.

[0076] The β-diketone supply unit 140 adjusts the supply amount by the valves V1 and V2 and the flow rate adjustment unit MFC1, and supplies the β-diketone from the pipes 141 and 142 to the pipe 121.

[0077] The nitrogen dioxide gas supply unit 150 adjusts the supply amount by the valves V3 and V4 and the flow rate adjustment unit MFC2, and supplies nitrogen dioxide from the pipes 151 and 152 to the pipe 121.

[0078] The non-active gas supply unit 160 adjusts the supply amount by the valves V5 and V6 and the flow rate adjustment unit MFC3, and supplies the non-active gas from the pipes 161 and 162 to the pipe 121.

[0079] A heating unit 170 for heating the processing vessel 110 is provided outside the processing vessel 110. In addition, a heater (not shown) can be provided as the second heating unit inside the placement unit 111. Note that, in the case where a plurality of placement units are arranged in the processing vessel 110, the temperature of the object on each placement unit can be set to a prescribed temperature by providing a heater for each placement unit.

[0080] A gas discharge unit for discharging the gas after the reaction is provided in one of the processing vessels 110. The gas after the reaction is discharged from the processing vessel 110 by the vacuum pump 173 of the gas discharge unit via the pipe 171. The gas after the reaction is recovered by the liquid nitrogen trap 174 provided between the pipes 171 and 172. Valves V7 and V8 are provided on the pipes 171 and 172, and the pressure can be adjusted. In addition, Figure 1 In this case, PIl and PI2 are pressure gauges, and the control unit can control the respective flow rate adjustment units and the respective valves based on the indicated values thereof.

[0081] The etching method will be described in detail with the etching apparatus 100 as an example.

[0082] [1st Dry Etching Method Using the Above Etching Apparatus]

[0083] In the 1st dry etching method of the present disclosure, an etching gas A containing a β-diketone and nitrogen dioxide is brought into contact with an etched film.

[0084] In the 1st dry etching method, first, the processed object 10 in which the etched film containing a metal or an oxide of the above metal having a M-O bond energy of 5 eV or more is formed is disposed in the processing vessel 110. Next, the inside of the processing vessel 110, the pipes 121, 141 and 142, the pipes 151 and 152, the pipes 161 and 162, the liquid nitrogen trap 174, and the pipes 171 and 172 are vacuumed to a prescribed pressure by the vacuum pump 173, and then the processed object 10 is heated by the heating unit 170.

[0085] After the processed object 10 reaches a prescribed temperature, a β-diketone and a nitrogen dioxide gas are supplied to the pipe 121 at prescribed flow rates from the β-diketone supply unit 140 and the nitrogen dioxide gas supply unit 150. Note that a non-active gas can be supplied to the pipe 121 at a prescribed flow rate from the non-active gas supply unit 160.

[0086] The β-diketone and the nitrogen dioxide are mixed at a prescribed composition and supplied to the processing vessel 110. While the mixed etching gas is introduced into the processing vessel 110, the inside of the processing vessel 110 is controlled to a prescribed pressure. By causing the etching gas to react with the etched film containing a metal or an oxide of the above metal having a M-O bond energy of 5 eV or more for a prescribed time, a complex is formed and etching is performed. In this etching method, etching can be performed without plasma, and there is no need for excitation of the etching gas by plasma or the like at the time of etching. The flow rate of the etching gas can be appropriately set based on the volume and pressure of the processing vessel, and the like.

[0087] Note that etching with a plasma state means that, for example, a gas at around 0.1 to 10 Torr or the like is introduced into the inside of a reaction apparatus, high-frequency power is applied to a coil or a counter electrode on the outside, a low-temperature gas plasma is generated in the reaction apparatus, and etching is performed using active chemical species such as ions and radicals generated therein.

[0088] In the dry etching method of the present disclosure, the gas is brought into contact without a plasma state, and dry etching is performed without generating the above-described gas plasma.

[0089] After the etching process, the heating based on the heating unit 170 is stopped and the temperature is decreased, and the vacuum pump 173 is stopped, the vacuum is replaced with an inactive gas and opened. As above, by using the first dry etching method of the etching apparatus, etching of the etched film including a metal or an oxide of the metal having a M-O bond energy of 5 eV or more can be performed.

[0090] (Etching conditions in the first dry etching method)

[0091] In the first dry etching method of the present disclosure, the temperature of the etched film when the etching gas A is brought into contact with the etched film is only required to be a temperature at which the complex can be vaporized, and particularly, the temperature of the etched film which is a target of removal is preferably 250°C or higher and 375°C or lower, more preferably 275°C or higher and 375°C or lower, further more preferably 275°C or higher and 350°C or lower, further more preferably 275°C or higher and 325°C or lower.

[0092] In addition, the pressure in the processing container in which the processed body on which the etched film is formed is placed when the etching gas A is brought into contact with the etched film is not particularly limited, and is generally a pressure range of 0.1 kPa or higher and 101.3 kPa or lower.

[0093] From the viewpoint of obtaining a sufficient etching rate, the pressure in the processing container in the etching process is preferably 20 Torr or higher and 300 Torr or lower (2.67 kPa or higher and 39.9 kPa or lower), more preferably 20 Torr or higher and 200 Torr or lower (2.67 kPa or higher and 26.7 kPa or lower), further more preferably 20 Torr or higher and 100 Torr or lower (2.67 kPa or higher and 13.3 kPa or lower).

[0094] The processing time of the etching process is not particularly limited, and is preferably within 60 minutes if the efficiency of the semiconductor device manufacturing process is taken into consideration. Here, the processing time of the etching process refers to the time from when the etching gas is introduced into the processing container in which the processed body is placed to when the etching gas in the processing container is exhausted by a vacuum pump or the like to complete the etching process.

[0095] [Second dry etching method using the etching apparatus 100]

[0096] In the second dry etching method of the present disclosure, the following processes are provided: a first etching process in which an etching gas B including nitrogen dioxide is brought into contact with the etched film; and a second etching process in which an etching gas C including a β-diketone is brought into contact with the etched film.

[0097] In the second dry etching method, first, the object to be processed 10 on which an etching film containing a metal or an oxide of the metal having a bond energy of 5 eV or more is formed is arranged in the processing container 110. Next, the inside of the processing container 110, the pipes 121, 141 and 142, the pipes 151 and 152, the pipes 161 and 162, the liquid nitrogen trap 174, and the pipes 171 and 172 are vacuumed to a predetermined pressure by the vacuum pump 173, and the object to be processed 10 is heated by the heating unit 170.

[0098] After the object to be processed 10 reaches a predetermined temperature, first, the nitrogen dioxide gas is supplied to the pipe 121 from the nitrogen dioxide gas supply unit 150 at a predetermined flow rate. Note that the inert gas can be supplied to the pipe 121 from the inert gas supply unit 160 at a predetermined flow rate. While the nitrogen dioxide gas or the nitrogen dioxide gas and the inert gas are introduced into the processing container 110, the inside of the processing container 110 is controlled to a predetermined pressure. By introducing the nitrogen dioxide gas into the processing container 110 for a predetermined time, the nitrogen dioxide is adsorbed to the etching film.

[0099] After the gas containing the nitrogen dioxide gas is vacuumed, the β-diketone gas is supplied to the pipe 121 from the β-diketone supply unit 140 at a predetermined flow rate. Note that the inert gas can be supplied to the pipe 121 from the inert gas supply unit 160 at a predetermined flow rate. While the β-diketone gas or the β-diketone gas and the inert gas are introduced into the processing container 110, the inside of the processing container 110 is controlled to a predetermined pressure. By introducing the β-diketone gas into the processing container 110 for a predetermined time, the nitrogen dioxide adsorbed first reacts with the β-diketone to form a complex, and further, the complex reacts with the etching film, and thus the etching film can be etched.

[0100] In the second dry etching method of the present disclosure, the first etching process of introducing the nitrogen dioxide gas into the processing container 110 and the second etching process of introducing the β-diketone into the processing container 110 can be repeatedly performed as a process of one cycle.

[0101] In the second dry etching method of the present disclosure, by setting the etching conditions of one cycle to predetermined conditions, the thickness of the etching film that can be etched in one cycle can be controlled, and thus the thickness of the etching film that can be etched in one cycle can be set to be thin, and the thickness of the etching film can be precisely controlled.

[0102] Note that the second dry etching method can also be performed without plasma, and thus the etching gas does not need to be excited by plasma or the like at the time of etching. The flow rates of the nitrogen dioxide and the β-diketone can be appropriately set based on the volume and the pressure of the processing container, and the like.

[0103] Thus, in the second dry etching method of the present disclosure using the above-described etching apparatus, the gas can be contacted without plasma, and dry etching can be performed without generating plasma of the above-described gas.

[0104] After the etching step, the heating based on the heating unit 170 is stopped and the temperature is decreased, and the vacuum pump 173 is stopped, and the vacuum is replaced with a non-reactive gas and opened. According to the above, etching of the etched film including a metal or an oxide of the above-described metal having a bond energy of 5 eV or more can be performed.

[0105] (Etching conditions in the second dry etching method)

[0106] In the second dry etching method of the present disclosure, the temperature of the etched film during the etching step is only required to be a temperature at which the complex can be vaporized, and particularly, the temperature of the etched film to be removed is more preferably 250°C or higher and 375°C or lower, more preferably 275°C or higher and 375°C or lower, more preferably 275°C or higher and 350°C or lower, and more preferably 275°C or higher and 325°C or lower. It is desirable that the temperature of the etched film in the first etching step and the second etching step be the same.

[0107] In addition, the pressure in the processing container during the etching step is not particularly limited, and is typically in a pressure range of 0.1 kPa or higher and 101.3 kPa or lower.

[0108] From the viewpoint of obtaining a sufficient etching rate, the pressure in the processing container in the first etching step and the second etching step is preferably 20 Torr or higher and 300 Torr or lower (2.67 kPa or higher and 39.9 kPa or lower), more preferably 20 Torr or higher and 200 Torr or lower (2.67 kPa or higher and 26.7 kPa or lower), and further preferably 20 Torr or higher and 100 Torr or lower (2.67 kPa or higher and 13.3 kPa or lower). It is desirable that the pressure in the processing container in the second etching step be higher than the pressure in the processing container in the first etching step.

[0109] The processing time in the first etching step and the second etching step is not particularly limited, and the processing time in one cycle of the first etching step is preferably 60 minutes or less, and the processing time in one cycle of the second etching step is preferably 60 minutes or less. Here, the processing time of the etching step refers to the time from when the etching gas is introduced into the processing container in which the processed object is disposed, to when the etching gas in the processing container is exhausted by a vacuum pump or the like to complete the etching processing.

[0110] [Method for manufacturing semiconductor device]

[0111] The dry etching method disclosed herein can be used as an etching method for forming predetermined patterns on hafnium oxide films, hafnium metals, etc., in existing semiconductor devices. By using the dry etching method of this disclosure to etch hafnium oxide films, hafnium metals, etc., on a substrate, semiconductor devices can be manufactured inexpensively.

[0112] Example

[0113] The following embodiments are shown to make this disclosure more specific. It should be noted that this disclosure is not limited to these embodiments.

[0114] (Example 1)

[0115] use Figure 1 The etching apparatus 100 shown etches the workpiece 10 having an etchable film formed on the surface of a silicon wafer, which is a hafnium oxide (HfO2) film (1 cm × 1 cm in shape and 5 nm in thickness).

[0116] The processing container 110, piping 121, piping 141 and 142, piping 151 and 152, piping 161 and 162, liquid nitrogen trap 174, and piping 171 and 172 are evacuated to below 10 Pa. Then, the workpiece 10 placed in the mounting section 111 is heated using the heating unit 170 and a heater disposed inside the mounting section 111. After confirming that the temperature of the workpiece 10 reaches 300°C, hexafluoroacetylacetone (HFAc) gas is supplied to piping 121 from the β-diketone supply section 140 at a predetermined flow rate, and NO2 gas is supplied to piping 121 from the nitrogen dioxide gas supply section 150 at a predetermined flow rate. This allows etching gas to be introduced into the processing container 110 while the pressure inside the processing container 110 is controlled at 90 Torr for etching. The temperature of the workpiece is set to 300°C, and the flow rates of the etching gas are set to HFAc = 10 sccm and NO2 = 1 sccm. After 30 minutes of introducing the etching gas, the introduction of the etching gas is stopped. Then, the interior of the processing container 110 is evacuated to below 10 Pa, replaced with N2 gas supplied from the inactive gas supply unit 160, and the processed object 10 is removed to measure the film thickness and evaluate the etching amount.

[0117] It should be noted that in Examples 1 to 22, which include Examples 2 to 20 described below, the first dry etching method was used, in which an etching gas A containing β-diketone and nitrogen dioxide was brought into contact with the film to be etched. In Comparative Examples 1 to 17, except for Comparative Examples 4, 7, 10, 12, and 17, an etching gas containing β-diketone and the gases shown in Tables 1 and 2 was also brought into contact with the film to be etched. It should be noted that in Comparative Examples 4, 7, 10, 12, and 17, an etching gas containing only β-diketone was brought into contact with the film to be etched.

[0118] (Examples 2-4, Comparative Examples 1-4)

[0119] Table 1 below shows the type of gas added during the above etching process, the flow rate of HFAc, the flow rate of the added gas, the pressure inside the processing container, the temperature during etching, the etching time, and whether etching is possible.

[0120] Whether etching is permissible is as follows: If the etching rate is 0.1 nm / min or higher, it is marked as ○; if the etching rate is lower than 0.1 nm / min, it is marked as ×. Etching rate refers to the change in film thickness before and after etching, divided by the time required for etching.

[0121] The differences between Examples 2-4 and Example 1 of Comparative Examples 1-4 will be explained. In Example 2, the flow rate of NO2 as the additive gas was changed. In Example 3, the flow rate of NO2 as the additive gas, the etching time, and the temperature of the processed body 10 were changed. In Example 4, the temperature of the processed body 10 was changed. In Comparative Examples 1-3, nitric oxide (NO), oxygen (O2), and nitrous oxide (N2O) were used as additive gases, respectively. In Comparative Example 4, the processing was performed without using any additive gas. In other aspects, the same operations as in Example 1 were performed to evaluate whether the hafnium oxide (HfO2) film could be etched.

[0122] [Table 1]

[0123]

[0124] (Examples 5-22, Comparative Examples 5-17)

[0125] use Figure 1 The etching apparatus 100 shown etches a workpiece having an etchable film formed on the surface of a silicon wafer, consisting of an aluminum oxide (Al2O3) film, a zirconium oxide (ZrO2) film, a hafnium oxide (HfO2) film, and a titanium oxide (TiO2) film, each with a shape of 1 cm × 1 cm and a film thickness of 60 nm.

[0126] As shown in Table 2 (275°C, 300°C, 350°C), the material of the etched film, the type and flow rate of the etching gas, the pressure inside the processing container, and the temperature of the workpiece during etching were varied. Otherwise, the same operation as in Example 1 was performed, and the etching rate of the etched film was measured. The results are shown in Table 2.

[0127] In Table 2, etching rates of 0.1 nm / min or higher but lower than 1.0 nm / min are represented as A, 1.0 nm / min or higher but lower than 10.0 nm / min as B, 10.0 nm / min or higher but lower than 50.0 nm / min as C, and lower than 0.1 nm as X.

[0128] [Table 2]

[0129]

[0130] Based on the above results, when using HFAc and NO2 as etching gases, etching of alumina films, zirconium oxide films, hafnium oxide films, hafnium metal films, and titanium oxide films can be performed at a rate of 0.1 nm / min or higher at a workpiece temperature below 350°C, especially when the workpiece temperature is 300°C. Furthermore, etching can be performed when the workpiece temperature is below the decomposition temperature of HFAc (375°C). Therefore, in Examples 1-4, no carbon film was formed on the workpiece surface.

[0131] On the other hand, when NO, O2, and N2O are used as additive gases, or when no additive gases are used, etching of alumina films, zirconium oxide films, hafnium oxide films, hafnium metal films, and titanium oxide films cannot be performed at a temperature of 350°C on the substrate.

[0132] (Examples 23-26)

[0133] In these embodiments, a second dry etching method is used to etch a hafnium oxide (HfO2) film (1 cm × 1 cm in shape and 60 nm in thickness) formed on the surface of a silicon wafer. This method involves repeatedly performing a first etching step in which an etching gas B containing nitrogen dioxide is brought into contact with the film to be etched, and a second etching step in which an etching gas C containing β-diketone is brought into contact with the film to be etched.

[0134] First, the interior of the processing container 110, piping 121, piping 141 and 142, piping 151 and 152, piping 161 and 162, liquid nitrogen trap 174, and piping 171 and 172 are evacuated to below 10 Pa. Then, the object to be processed 10, which has a hafnium oxide (HfO2) film, is heated in the mounting section 111 using the heating unit 170 and a heater disposed inside the mounting section 111.

[0135] After confirming that the temperature of the workpiece 10 reaches 350°C, NO2 gas is supplied from the nitrogen dioxide gas supply unit 150 to the piping 121 while maintaining the pressure inside the processing container 110 at 30 Torr, and the NO2 gas is allowed to flow inside the processing container 110. The temperature of the workpiece is set to 350°C, and the flow rate of the etching gas is set to NO2 = 5 sccm. The NO2 gas is allowed to flow for the time shown in Table 3, contacting the film to be etched. Afterwards, the introduction of the etching gas is stopped, and the inside of the processing container 110 is evacuated to below 10 Pa.

[0136] Next, while the pressure inside the processing vessel 110 is controlled to 60 Torr, the HFAc gas is caused to flow inside the processing vessel 110 from the β-diketone supply section 140 which supplies the gas of hexafluoroacetylacetone (HFAc). The temperature of the object to be processed is set to 350°C, the flow rate of the etching gas is set to HFAc = 10 seem, and the HFAc gas is caused to flow in contact with the etched film for the time shown in Table 3. After that, the introduction of the etching gas is stopped, and the inside of the processing vessel 110 is vacuumed to less than 10 Pa.

[0137] After the process of causing the above NO2 gas to flow inside the processing vessel 110 and the process of causing the HFAc gas to flow inside the processing vessel 110 are repeated as the process of one cycle for the number of times (cycle number) shown in Table 3, the inside of the processing vessel 110 is vacuumed to less than 10 Pa, the inside of the processing vessel 110 is replaced with the N2 gas supplied from the non-active gas supply section 160, and the object to be processed 10 is taken out, the film thickness is measured, the total etching thickness is measured, and the etching thickness per cycle is calculated. The results are shown in Table 3.

[0138] [Table 3]

[0139]

[0140] From the results shown in Table 3, it is clear that by making the conditions of etching constant, the thickness of the etched film which can be etched per cycle becomes substantially constant, and therefore, by setting the cycle number, the etched film can be etched almost accurately to the desired thickness.

[0141] Explanation of Reference Numerals

[0142] 10 object to be processed

[0143] 100 etching apparatus

[0144] 110 processing vessel

[0145] 111 loading section

[0146] 121 pipe

[0147] 140 β-diketone supply section

[0148] 141, 142 pipe

[0149] 150 nitrogen dioxide gas supply section

[0150] 151, 152 pipe

[0151] 160 non-active gas supply section

[0152] 161, 162 pipe

[0153] 170 heating unit

[0154] 171, 172 piping

[0155] 173 vacuum pump

[0156] 174 liquid nitrogen trap

[0157] MFC1, MFC2, MFC3 flow regulating unit

[0158] PI1, PI2 pressure gauge

[0159] V1, V2, V3, V4, V5, V6, V7, V8 valve

Claims

1. A dry etching method, characterized in that, The etched film, consisting of an oxide layer containing metals with MO bond energies greater than 5 eV and formed on the surface of the substrate, is reacted with β-diketone and nitrogen dioxide, and etched without plasma. The etched film is a film selected from at least one of the following groups: hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide, and two or more oxides of hafnium, zirconium, titanium, and aluminum.

2. The dry etching method according to claim 1, wherein, The oxide of the metal with a MO bond energy of 5 eV or higher is selected from at least one of the group consisting of hafnium oxide, zirconium oxide, titanium oxide and aluminum oxide.

3. The dry etching method according to claim 1 or 2, wherein, The etched film is at least one type of film selected from the group consisting of hafnium oxide film, zirconium oxide film, titanium oxide film and aluminum oxide film.

4. The dry etching method according to claim 1 or 2, wherein, The β-diketone is hexafluoroacetylacetone or trifluoroacetylacetone.

5. The dry etching method according to claim 1 or 2, wherein, The etching gas A, which contains the β-diketone and the nitrogen dioxide, is brought into contact with the etched film.

6. The dry etching method according to claim 5, wherein, The temperature of the etched film when the etching gas A comes into contact with the etched film is above 250°C and below 375°C.

7. The dry etching method according to claim 5, wherein, The volume ratio of the β-diketone to the nitrogen dioxide in the etching gas A is β-diketone:nitrogen dioxide = 10:0.001 or more and 10:100 or less.

8. The dry etching method according to claim 7, wherein, The volume ratio of the β-diketone to the nitrogen dioxide in the etching gas A is β-diketone:nitrogen dioxide = 10:0.01 or higher and 10: Below 10.

9. The dry etching method according to claim 5, wherein, When the etched film comes into contact with the etching gas A, the pressure inside the processing container where the workpiece on which the etched film is placed is in the pressure range of 0.1 kPa or more and 101.3 kPa or less.

10. The dry etching method according to claim 5, wherein, The etched film is selected from hafnium oxide (HfO). x Zirconium oxide (ZrO) u ), aluminum oxide (AlO) v ) and titanium dioxide (TiO) w The membrane formed by at least one of the following groups, wherein x is 1 or more and 3 or less, u is 1 or more and 3 or less, v is 1 or more and 2 or less, and w is 1 or more and 3 or less. The β-diketone is hexafluoroacetylacetone. The temperature of the etched film when the β-diketone and nitrogen dioxide come into contact with the etched film is above 250°C and below 375°C. The volume ratio of β-diketone to nitrogen dioxide in the etching gas A is greater than 10:0.001 and less than 10:

100. When the etched film comes into contact with the etching gas A, the pressure inside the processing container where the workpiece on which the etched film is formed is in the pressure range of 0.1 kPa or more and 101.3 kPa or less. The etching rate of the etched film is above 0.1 nm / min.

11. The dry etching method according to claim 5, wherein, The etching gas A further comprises at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr.

12. The dry etching method according to claim 11, wherein, The content of inactive gas in the etching gas A is more than 1% by volume and less than 90% by volume.

13. The dry etching method according to claim 11, wherein, The content of inactive gas in the etching gas A is more than 30% by volume and less than 50% by volume.

14. The dry etching method according to claim 1 or 2, comprising the following steps: In the first etching step, the etching gas B containing the nitrogen dioxide is brought into contact with the film to be etched; and, The second etching process involves contacting the etching gas C containing the β-diketone with the etched film.

15. The dry etching method according to claim 14, wherein the first etching step and the second etching step are repeated multiple times.

16. The dry etching method according to claim 14, wherein, The temperature of the etched film when the etching gas B comes into contact with the etched film, and the temperature of the etched film when the etching gas C comes into contact with the etched film, are above 250°C and below 375°C.

17. The dry etching method according to claim 14, wherein, When the etched film is in contact with the etching gas B and when the etched film is in contact with the etching gas C, the pressure inside the processing container where the processed body on which the etched film is formed is in the pressure range of 0.1 kPa or more and 101.3 kPa or less.

18. The dry etching method according to claim 14, wherein, The etched film is selected from hafnium oxide (HfO). x Zirconium oxide (ZrO) u ), aluminum oxide (AlO) V ) and titanium dioxide (TiO) w The membrane formed by at least one of the following groups, wherein x is 1 or more and 3 or less, u is 1 or more and 3 or less, v is 1 or more and 2 or less, and w is 1 or more and 3 or less. The β-diketone is hexafluoroacetylacetone. The temperature of the etched film when the etching gas B comes into contact with the etched film, and the temperature of the etched film when the etching gas C comes into contact with the etched film, are both above 250°C and below 375°C. When the etched film is in contact with the etching gas B and when the etched film is in contact with the etching gas C, the pressure inside the processing container where the processed body on which the etched film is formed is in the pressure range of 0.1 kPa or more and 101.3 kPa or less.

19. The dry etching method according to claim 14, wherein, The etching gas B and the etching gas C further comprise at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr.

20. The dry etching method according to claim 19, wherein, The content of inactive gases in the etching gas B and the etching gas C is more than 1% by volume and less than 90% by volume.

21. The dry etching method according to claim 20, wherein, The content of inactive gases in etching gas B and etching gas C is more than 30% by volume and less than 50% by volume.

22. A method for manufacturing a semiconductor device, characterized in that, The process includes the following steps: reacting an etchable film containing an oxide of a metal with a MO bond energy of 5 eV or higher on a substrate with β-diketone and nitrogen dioxide, and etching is performed without plasma. The etched film is a film selected from at least one of the following groups: hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide, and two or more oxides of hafnium, zirconium, titanium, and aluminum.

23. The method for manufacturing a semiconductor device according to claim 22, wherein, The etched film is at least one type of film selected from the group consisting of hafnium oxide film, zirconium oxide film, titanium oxide film and aluminum oxide film.

24. An etching apparatus, characterized in that, have: The carrier is disposed in a heatable processing container and is placed on a workpiece having an etched film formed on its surface containing an oxide of a metal with a MO bond energy of 5 eV or more. β-Diketone supply section, which supplies β-diketone to the body being treated; and, The nitrogen dioxide gas supply unit supplies nitrogen dioxide to the object being treated. The etched film is a film selected from at least one of the following groups: hafnium oxide, zirconium oxide, titanium oxide, aluminum oxide, and two or more oxides of hafnium, zirconium, titanium, and aluminum.

25. The etching apparatus according to claim 24, characterized in that, It also includes a non-reactive gas supply unit that supplies non-reactive gas to the object being processed.

26. The etching apparatus according to claim 24 or 25, wherein, The etched film is at least one type of film selected from the group consisting of hafnium oxide film, zirconium oxide film, titanium oxide film and aluminum oxide film.

Images