This application is based upon and claims the benefit of priority to Japanese Patent Application No. 2021-140476 filed on Aug. 30, 2021, the entire contents of which are incorporated herein by reference.
The present disclosure relates to, for example, a film forming apparatus that forms a metal oxide film or a metal nitride film on a subject in a reaction container by using an OH radical or an NH radical through atomic layer deposition (ALD).
By using an OH radical, a resist is removed in JP-A-2008-085231 and JP-A-2008-109050, bacteria in water are killed in JP-A-2012-096141, substances to be purged are decomposed to perform clarification in JP-A-2013-086072, nitric acid is produced in JP-A-2016-150888, an organic binder or a protective agent undergoes oxidative destruction from above a conductive layer to improve conductivity in JP-A-2020-113654, and a metal oxide film is formed on powder by ALD in JP-B-6787621 by the present applicant. In JP-A-2008-085231 JP-A-2008-109050, JP-A-2012-096141, JP-A-2013-086072, JP-A-2016-150888, JP-A-2020-113654, JP-B-6787621, and JP-B-4694209, an OH radical is generated by plasma excitation on water vapor. Furthermore, in JP-B-6787621, a metal nitride film is formed by using an NH radical. The NH radical is generated by plasma excitation on NH3.
In JP-B-4694209, an oxygen radical necessary for forming an oxide film on a substrate is generated by plasma excitation on oxygen O2 and hydrogen H2 in a treatment chamber. Thus, unlike in the use of H2O or ozone O3, a moisture generator or an ozone generator is not necessary, contributing to cost reduction.
According to JP-A-2008-085231, JP-A-2008-109050, JP-A-2012-096141, JP-A-2013-086072, JP-A-2016-150888, JP-A-2020-113654, JP-B-6787621, and JP-B-4694209, a moisture generator for generating an OH radical is necessary, and the introduction of water vapor to a subject of treatment less resistant to moisture may cause damage to a surface of the subject of treatment.
According to JP-B-6787621, in a process of generating NH* (* indicates a radical) by decompose NH3 by plasma, it is assumed that the following states are mixed:
NH3→NH*+2H*→NH*+H2
NH3→NH2+N*→NH*+2H*→NH*+H2
NH3→N*+3H*→NH*+2H*→NH*+H2
An NH radical is generated with low efficiency because of the mixed states.
According to JP-B-4694209, in a process of decomposing oxygen O2 and hydrogen H2 by heat at 500° C. to 600° C. to generate an oxygen radical O*, thermal reactions occur as follows (paragraph [0032]):
H2+O2→H*+HO2
O2+H*→OH*+O*
H2+O*→H*+OH*
H2+OH*→H*+H2O
Although JP-B-4694209 does not aim at generating OH* (OH radical), the thermal excitation of oxygen O2 and hydrogen H2 generates OH* (OH radical). However, an OH radical is generated with low efficiency because of the mixed states. This is because in the treatment chamber of JP-B-4694209, a collision of oxygens or hydrogens leads to a reaction that causes transition to a stabilized system as follows:
O+O→O2
H+H→H2
O+OH O2H
H+OH→H2O
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. These are, of course, merely examples and are not intended to be limiting. In addition, the disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, when a first element is described as being “connected” or “coupled” to a second element, such description includes embodiments in which the first and second elements are directly connected or coupled to each other, and also includes embodiments in which the first and second elements are indirectly connected or coupled to each other with one or more other intervening elements in between.
In the following disclosure, different embodiments and examples are provided for implementing different characteristics of a presented subject. The embodiments and examples are merely exemplary and are not intended to be limiting. Furthermore, in the present disclosure, reference numerals and/or characters may be repeated in various examples. The repetition is performed for simplicity and clarification and does not need to be associated with various embodiments and/or described configurations. Moreover, a description that a first element is “connected” or “coupled” to a second element includes an embodiment in which the first element and the second element are directly connected or coupled to each other and an embodiment in which the first element and the second element are indirectly connected or coupled to each other with at least one element interposed between the first and second elements. When the first element “moves” relative to the second element in a description, such a description includes an embodiment of a movement of at least one of the first element and the second element relative to the other of the elements.
The present disclosure provides a film forming apparatus that efficiently generates an OH radical or an NH radical with high reactivity to improve the efficiency of film formation, the OH or NH radical being necessary for forming a metal oxide film or a metal nitride film on a subject in a reaction container by ALD.
(1) In accordance with one of some aspect, there is provided a film forming apparatus configured to form a metal oxide film or a metal nitride film through atomic layer deposition by alternately introducing metal compound gas and an OH radical or an NH radical in a reaction container,
the film forming apparatus comprising:
the reaction container; and
at least one plasma generator provided outside the reaction container and configured to generate a first plasma including an oxygen radical or a nitrogen radical when oxygen or nitrogen is supplied and generate a second plasma including a hydrogen radical when hydrogen is supplied,
wherein the OH radical is generated by collision between the oxygen radical and the hydrogen radical or the NH radical is generated by collision between the nitrogen radical and the hydrogen radical in a downstream region from an outlet of the at least one plasma generator to an inner space of the reaction container.
According to one aspect of the present disclosure, from metal compound gas adsorbed to an object in the reaction container, organic substances or inorganic substances other than metallic components are dissociated by an OH radical, and the metal compound gas is oxidized into metal oxide by the OH radical. Alternatively, from metal compound gas adsorbed to an object in the reaction container, organic substances or inorganic substances other than metallic components are dissociated by an NH radical, and the metal compound gas is nitrided into metal nitride by the NH radical. The metal oxide or the metal nitride is sequentially deposited at an atomic layer level, so that a metal oxide film or a metal nitride film is formed on the object.
If the carrier gas is, for example, argon Ar, the first plasma includes an oxygen radical O* or a nitrogen radical N* that is dissociated from an oxygen molecule or a nitrogen molecule as indicated in expressions (1) and (2) below. Moreover, electrons and ions are dissociated in the first plasma. It is assumed that many of the electrons and the ions are deactivated downstream of the first plasma and only the oxygen radical and the nitrogen radical, which are protected by carrier gas Ar, are left in the pipe.
O2+Ar→2O*+Ar (1)
N2+Ar→2N*+Ar (2)
In the second plasma, a hydrogen radical dissociated from a hydrogen molecule is included as indicated by expression (3) below. Also in this case, it is assumed that electrons and ions in the second plasma are deactivated and only the hydrogen radical protected by the carrier gas Ar is left.
H2+Ar→2H*+Ar (3)
In a downstream region from an outlet of the at least one plasma generator to an inner space of the reaction container, the oxygen radical O* or the nitrogen radical N* and the hydrogen radical H* are in time division or simultaneously introduced and merged each other. With this configuration, the oxygen radical O* or the nitrogen radical N* and the hydrogen radical H* are joined to collide with each other, thereby generating an OH radical or an NH radical by a reaction expressed in (4) or (5) below.
O*+H*+Ar→OH*+Ar (4)
N*+H*+Ar→NH*+Ar (5)
In other words, in (4), the oxygen radical O* and the hydrogen radical H*, which are in time division or simultaneously introduced into the reaction container and are caused to collide and are coupled with each other for the first time in the reaction container so as to mainly generate an OH radical. Thus, as compared with the generation process of JP-B-4694209 in which thermal excitation is simultaneously performed on oxygen O2 and hydrogen H2 in a treatment container so as to generate an OH radical, the present disclosure can more efficiently generate an OH radical. Likewise, mainly in (5), a nitrogen radical N* and a hydrogen radical H* are coupled to each other to mainly generate an NH radical. Thus, as compared with the generation process of JP-B-6787621 in which NH3 is excited to generate an NH radical, the present disclosure can more efficiently generate an NH radical.
(2) In aspect (1) of the present disclosure, the film forming apparatus may further comprises:
a first gas source configured to supply oxygen or nitrogen;
a second gas source configured to supply hydrogen;
a third gas source configured to supply carrier gas;
a first pipe causing the first gas source and the third gas source to communicate with the reaction container; and
a second pipe causing the second gas source and the third gas source to communicate with the reaction container; and
wherein the at least one plasma generator includes:
a first plasma generator attached to the first pipe and configured to generate the first plasma;
a second plasma generator attached to the second pipe and configured to generate the second plasma.
In this way, oxygen radicals and hydrogen radicals are supplied to the reaction container through separate routes. In this way, oxygen radicals and hydrogen radicals can be simultaneously supplied, for example, to the inner space of the reaction container located downstream of the outlets of the first and second plasma generators.
(3) In aspect (2) of the present disclosure, at least one of the first pipe and the second pipe includes a first charged particle remover, and the first charged particle remover can remove charged particles including dissociated ions and/or electrons in the plasma in the first plasma generator and the second plasma generator, by using charge of the charged particles. With this configuration, positive ions having positive charge, negative ions having negative charge, and electrons or the like are neutralized by emitting/injecting excessive electrons or additionally required electrons from the metallic pipe. In this way, charged particles including positive ions, negative ions, and electrons that are generated by the first and second plasma generators are removed by using charge held by the charged particles. Thus, an oxygen radical or a nitrogen radical and a hydrogen radical are mainly supplied into the reaction container. This can more efficiently generate an OH radical or an NH radical in the reaction container.
(4) In aspect (2) of the present disclosure, the first pipe and the second pipe may be coupled to the reaction container via a junction pipe. Thus, the reaction in (4) or (5) can be more efficient in a junction pipe that can be designed with a sufficiently smaller capacity than the reaction container, so that an OH radical or an NH radical that is generated in the junction pipe can be supplied into the reaction container.
(5) Also in aspect (3) of the present disclosure, the first pipe and the second pipe may be coupled to the reaction container via the junction pipe. Thus, the same effect can be obtained as in aspects (1) to (3) of the present disclosure.
(6) Also in aspect (4) or (5) of the present disclosure, the junction pipe includes a second charged particle remover, and the second charged particle remover can remove charged particles including dissociated ions and/or electrons in the plasma in the first plasma generator and the second plasma generator, by using charge of the charged particles. Thus, the same effect can be obtained as in aspects (1), (2) and (4) of the present disclosure. In other words, charged particles including positive ions, negative ions, and electrons that are generated by the first and second plasma generators are removed by using charge held by the charged particles. Thus, an oxygen radical or a nitrogen radical and a hydrogen radical are mainly supplied into the junction pipe. Furthermore, positive ions, negative ions, and electrons or the like that are left in the junction pipe are removed by using charge held by the ions and electrons. This can more efficiently supply an OH radical or an NH radical into the reaction container.
(7) In aspect (2) or (3) of the present disclosure, the first pipe has a first valve between the first plasma generator and the reaction container, the second pipe has a second valve between the second plasma generator and the reaction container, and one of the first valve and the second valve may be closed while the other of the first valve and the second valve is opened. Thus, when the first valve is opened, an oxygen radical or a nitrogen radical that is generated by the first plasma generator is supplied into the reaction container. At this point, the second valve is closed, thereby preventing the oxygen radical or the nitrogen radical from flowing into the second plasma generator. Before or after this point, when the second valve is opened, a hydrogen radical generated by the second plasma generator is supplied into the reaction container. At this point, the first valve is closed, thereby preventing the hydrogen radical from flowing into the first plasma generator.
(8) In aspect (1) of the present disclosure,
the film forming apparatus further comprising:
a first gas source configured to supply oxygen or nitrogen;
a second gas source configured to supply hydrogen;
a third gas source configured to supply carrier gas;
a first pipe coupled to the first gas source and the third gas source; and
a second pipe coupled to the second gas source and the third gas source; and
a junction pipe having one end coupled to the first pipe and the second pipe and the other end coupled to the reaction container; and
wherein the at least one plasma generator is a plasma generator attached to the junction pipe and configured to generate the first and the second plasma, and wherein:
the first pipe has a first valve upstream of the plasma generator;
the second pipe has a second valve upstream of the plasma generator;
the plasma generator generates plasma including an oxygen radical or a nitrogen radical when the first valve is opened and the second valve is closed, the radical being dissociated from the oxygen or the nitrogen;
the plasma generator generates plasma including a hydrogen radical when the second valve is opened and the first valve is closed, the radical being dissociated from the hydrogen; and
in the reaction container, the OH radical is generated by collision between the oxygen radical and the hydrogen radical, or the NH radical is generated by collision between the nitrogen radical and the hydrogen radical.
Thus, when the first valve is opened and the second valve is closed, an oxygen radical or a nitrogen radical that is generated by only one plasma generator is supplied into the reaction container. Before or after this point, when the second valve is opened and the first valve is closed, a hydrogen radical generated by one plasma generator is supplied into the reaction container.
(9) Also in aspect (8) of the present disclosure, the junction pipe includes a charged particle remover, and the charged particle remover can remove charged particles including dissociated ions and/or electrons in the plasma in the plasma generator, by using charge of the charged particles. Thus, the same effect can be obtained as in aspect (5) of the present disclosure.
A source gas source 30 supplies metal compound gas, e.g., organic metallic gas that is source gas selected for a film deposited on the workpiece 1. The source gas source 30 and the reaction container 20 are coupled to each other via a pipe 33 including a flow controller (MFC) 31 and a valve 32. Source gas is supplied from the source gas source 30 into the reaction container 20 through the pipe 33 including the flow controller 31 and the valve 32 while the timing of supply and the flow rate are controlled.
An oxygen/nitrogen gas source 40 and a hydrogen gas source 50 are reactant gas sources. The oxygen/nitrogen gas source (first gas source) 40 contains oxygen when an oxide film is formed, and contains nitrogen when a nitride film is formed. The oxygen/nitrogen gas source 40 and the reaction container 20 are coupled to each other via a pipe 43 including a flow controller (MFC) 41, a valve 42, and a first plasma generator 44. A valve 47 on the pipe 43 is optional in the first embodiment. If the valve 47 is installed, the valve 47 is fully opened all the time. The hydrogen gas source 50 and the reaction container 20 are coupled to each other via a pipe 53 including a flow controller (MFC) 51, a valve 52, and a second plasma generator 54. A valve 57 on the pipe 53 is optional in the first embodiment. If the valve 57 is installed, the valve 57 is fully opened all the time.
A carrier gas source 60 contains inert gas, for example, argon Ar. In the present embodiment, argon Ar in the carrier gas source 60 is used as purge gas as well as carrier gas. For the use of gas, the carrier gas source 60 and the reaction container 20 can be coupled to each other via a pipe 63 including a flow controller (MFC) 61, a valve 62, and a valve 66. Thus, argon Ar is supplied as purge gas into the reaction container 20 through the pipe 63 while the timing of supply and the flow rate are controlled. This can substitute argon gas Ar for an atmosphere in the reaction container 20. The pipe 63 includes first to third branch pipes 63A to 63C downstream of the valve 62. The first branch pipe 63A is coupled to the pipe 33 via a valve 64. The second branch pipe 63B is coupled to the pipe 43 via a valve 65. The third branch pipe 63C is coupled to the pipe 53 via the valve 66. With this configuration, argon Ar can be used as a carrier gas for source gas, oxygen, nitrogen, or hydrogen.
The first plasma generator 44 includes an induction coil 46 that serves as exciting means of oxygen or nitrogen and is wound around a nonmetallic pipe 45 made of, for example, quartz. A high-frequency power supply, which is not illustrated, is connected to the induction coil 46. For example, the induction coil 46 applies electromagnetic energy of 20 W at a frequency of 13.56 MHz. The induction coil 46 generates inductively coupled plasma P1 of gas in the first plasma generator 44. The plasma P1 contains an oxygen radical or a nitrogen radical that is dissociated from an oxygen molecule or a nitrogen molecule.
Likewise, the second plasma generator 54 includes an induction coil 56 that serves as exciting means of hydrogen and is wound around a nonmetallic pipe 55 made of, for example, quartz. The induction coil 56 generates inductively coupled plasma P2 of gas in the second plasma generator 54. The plasma. P2 contains a hydrogen radical dissociated from a hydrogen molecule.
An example of the formation of a metal oxide film, e.g., an Al2O3 film on the workpiece 1 will be described below. The oxygen/nitrogen gas source 40 contains oxygen and thus is also referred to as an oxygen gas source 40 hereafter. First, the workpiece 1 is conveyed into the reaction container 20. In the first embodiment, the valves in
First, the reaction container 20 is evacuated by the vacuum pump 71 and is set at, for example, 10−4 Pa. Subsequently, as illustrated in
Thereafter, as the second step of the ALD cycle, the valves 32 and 64 are closed, the valve 62 is kept opened, and a valve 67 is opened over a period T2 as indicated in
Thereafter, as the third step of the ALD cycle, the valve 67 is closed, the valve 62 is kept opened, and the valves 42, 52, 65, and 66 are opened over a period T3 as indicated in
In the reaction container 20, the oxygen radical and the hydrogen radical join for the first time. Thus, in the reaction container 20, an OH radical is generated by collision and combination of the oxygen radical and the hydrogen radical as indicated by the foregoing expression (4). The reaction container 20 is filled with the OH radical (OH*) as reactant gas with a predetermined pressure, e.g., 1 to 10 Pa (the period T3 in
Thereafter, as the fourth step of the ALD cycle, the valves 42, 52, 65, and 66 are closed, the valve 62 is kept opened, and the valve 67 is opened over a period T4 as indicated in
In a second embodiment, in the ALD apparatus 10 of
As illustrated in
Thereafter, as the second step of the ALD cycle, the valves 32 and 64 are closed, the valve 62 is kept opened, and a valve 67 is opened over a period T2 as indicated in
Subsequently, as the third step of the ALD cycle, the valve 67 is closed, the valve 62 is kept opened, and a valve 42, the valve 47, and a valve 65 are opened over a period T3 as indicated in
Thereafter, as indicated in
In the reaction container 20, the oxygen radical and the hydrogen radical join for the first time. Thus, in the reaction container 20, an OH radical is generated by collision and combination of the oxygen radical and the hydrogen radical as indicated by the foregoing expression (4). The reaction container 20 is filled with the OH radical (OH*) as reactant gas with a predetermined pressure, e.g., 1 to 10 Pa (the period T4 in
Thereafter, as the fourth step of the ALD cycle, the valves 52, 57, and 66 are closed, the valve 62 is kept opened, and the valve 67 is opened over a period T5 as indicated in
In a third embodiment, in the ALD apparatus 11 of
As the third step of the ALD cycle, a valve 67 is closed, a valve 62 is kept opened, and valves 42, 52, 65, and 66 are opened over the period T3 as indicated in
The oxygen radical and the hydrogen radical join for the first time in the junction pipe 80 located downstream of the outlets of the first and second plasma generators 44 and 54, for example. Thus, in the junction pipe 80, an OH radical is generated by collision and combination of the oxygen radical and the hydrogen radical as indicated by the foregoing expression (4). The OH radical (OH*) as reactant gas is supplied from the junction pipe 80 into the reaction container 20. The reaction container 20 is filled with the OH radical with a predetermined pressure, e.g., 1 to 10 Pa, so that the OH radical (OH*) penetrates the exposed surface of a workpiece 1. This forms a metal oxide film over the exposed surface of the workpiece 1 as in the first embodiment.
In the fourth embodiment, in the ALD apparatus 12 of
In
Subsequently, the valve 42 is closed, the valve 62 is kept opened, and a valve 52 and the valve 68 are opened over the period T4 as indicated in
The oxygen radical and the hydrogen radical join for the first time in the reaction container 20 located downstream of the outlet of the plasma generators 94, for example. Thus, in the reaction container 20, an OH radical is generated by collision and combination of the oxygen radical and the hydrogen radical as indicated by the foregoing expression (4). The reaction container 20 is filled with the OH radical (OH*) as reactant gas with a predetermined pressure, e.g., 1 to 10 Pa (the period T4 in
Instead of reactant gas used for forming a metal oxide film, nitrogen gas can be used to form a metal oxide film. In this case, the oxygen/nitrogen gas source 40 in, for example,
The source gas is not limited to the foregoing organometallic compounds, and an inorganic metal compound may be used instead. For example, if SiCl4 is supplied as inorganic metal compound gas to the surface of the substrate 1, the gas is adsorbed by SiCl2, and then the gas is exhausted after Cl2 is desorbed.
SiCl4→SiCl2+Cl2↑
When an OH radical is supplied in this state, SiCl2 is oxidized into SiO2, and then the gas is exhausted after HCl is desorbed.
SiCl2+OH→SiO2+2HCl↑
Additionally, a metal oxide film can be similarly formed by using TiCl4 or SiH2Cl2 as another inorganic metal compound gas.
Downstream of the first and second plasma generator 44 and 54 or the plasma generator 94, the pipe 43 and the pipe 53, which supply an oxygen radical, a hydrogen radical, or an OH radical into the reaction container 20 in
Although only some embodiments of the present disclosure have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of this disclosure. Accordingly, all such modifications are intended to be included within scope of this disclosure.
Number | Date | Country | Kind |
---|---|---|---|
2021-140476 | Aug 2021 | JP | national |
2021140476 | Aug 2021 | JP | national |