Method for selectively forming nitride film on nitride surface in a surface where nitride surface and oxide surface are mixed

Abstract

To provide an inhibitor of nitride film formation on an oxide surface.SOLUTION: An inhibitor of nitride film formation is adsorbed on an oxide surface to be used to inhibit nitride film formation on the oxide surface, the inhibitor having a structure shown in the following formula [Chemical formula 1]. M represents one selected from silicon and the like, R1 and R2 each represent one of hydrogen, an alkyl group, an aryl group and an alkylsilyl group, R1 and R2 each may be a cyclic group, R3, R4 and R5 each represent one of hydrogen, an alkyl group, an aryl group and an alkylsilyl group, and two or more of R3, R4 and R5 may be a cyclic group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an inhibitor for the formation of a nitride film on an oxide surface, a method for inhibiting the formation of a nitride film on an oxide surface, and a method for selectively forming a nitride film on a nitride surface in a surface where a nitride surface and an oxide surface are mixed.The present invention is particularly suitable for use in forming an insulating film or a charge trapping film in a semiconductor manufacturing process to fabricate (pattern) a predetermined structure. [Background technology]

[0002] In semiconductor manufacturing, the process of creating microstructures is called patterning. In patterning, a desired two-dimensional structure is created through the steps of thin film deposition, transfer of a mask structure by photolithography, development, and etching of the developed areas.

[0003] In recent years, with the progress of miniaturization and three-dimensionalization, "misalignment" and physical "fluctuations" in the patterning process have had a significant impact on device manufacturing yields and device performance. Self-aligned processes and self-assembled processes have been adopted as processes that are less susceptible to misalignment (Patent Documents 1 and 2). Even now, many engineers and researchers continue to develop and investigate self-aligned and self-assembled processes.

[0004] Among the self-alignment techniques, selective growth techniques using atomic layer deposition have been attracting attention.

[0005] Here, atomic layer deposition is a technology that enables the formation of uniform (conformal) thin films on three-dimensional structures by alternately supplying film-forming raw materials and reactants and utilizing the saturated adsorption of the film-forming raw materials. For example, if a silicon source such as chlorosilanes is used as the film-forming raw material and a nitriding agent such as ammonia or hydrazine is used as the reactant, a silicon nitride film (SiN film) can be formed.

[0006] Selective growth technology is a technique for forming a thin film only on a specific underlayer among multiple types of underlayers. Examples of selective growth include a method for forming a metal film only on a metal film in a mixture of an insulating film made of silicon oxide and a metal film (Patent Document 3), and a method for forming an aluminum oxide film only on a silicon oxide film. Conventionally, a structure such as a silicon oxide film on a silicon oxide film is formed through the processes of film formation, resist coating, exposure, development, etching, and ashing, but selective growth technology can achieve this in a single process. It is expected to contribute to improving reliability and yield, as it can eliminate concerns about defective formation due to misalignment during exposure.

[0007] In addition to reducing the number of steps and improving yields, selective growth technology is also considered a useful process for three-dimensionalization of semiconductor devices. This is because selective growth is one method for realizing patterning on a three-dimensional structure. Patterning on a three-dimensional structure means, for example, forming a pattern on the wall surface of a groove formed by etching. This cannot be achieved by photolithography. As a method for patterning on a three-dimensional structure other than selective growth, there is the use of isotropic etching (recess process) (Patent Document 4), but this causes variation between deep and shallow parts. For this reason, selective growth technology using atomic layer deposition is more preferable.

[0008] There are methods for selective growth that utilize the "difference in the ease with which the film-forming raw material is adsorbed to the underlayer" and the "difference in the ease with which the adsorbed molecules react". An example of utilizing the difference in the ease with which the film-forming raw material is adsorbed to the underlayer is a technology in which an oxide film is formed only on an oxide film without forming a thin film on a metal surface. In this method, an alkylthiol, which has a self-aligning property that easily aggregates on a metal surface, is applied to a surface where a metal surface and an oxide film surface are mixed, and this is used as an inhibitor of the adsorption of the film-forming raw material. An example of utilizing the difference in the ease with which the adsorbed molecules react is a technology in which a continuous thin film is not formed on an oxide film, but a metal film is formed only on a metal surface. In this method, although the film-forming raw material is also adsorbed on the oxide film, only the film-forming raw material adsorbed on the oxide film surface is removed by intentionally adding an etching species during the film-forming process. This utilizes the fact that the adsorbed molecules on the oxide film surface react more easily than the adsorbed molecules on the metal surface in the etching reaction.

[0009] The basic idea of ​​selective growth is being discussed, and applications are expected for various combinations of underlayers and thin films. Among them, the method of forming a nitride film only on a nitride film in a mixture of oxide and nitride films is considered to be highly useful. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2010-114424 A [Patent Document 2] U.S. Patent No. 8,349,203 [Patent Document 3] JP 2011-18742 A [Patent Document 4] U.S. Patent No. 10312350 Summary of the Invention [Problem to be solved by the invention]

[0011] However, despite these high expectations, there are only a few examples of selective growth technology. In particular, a method for forming a nitride film only on a nitride film in a mixed oxide film and nitride film, and in particular a technology for forming a silicon nitride film or a titanium nitride film only on a silicon nitride film in a mixed silicon oxide film and silicon nitride film, may be promising for practical use, but no effective inventions have been reported.

[0012] In view of the above problems, the present invention aims to provide an inhibitor of nitride film formation on an oxide surface, which enables a nitride film to be selectively formed on a nitride surface in a surface where a nitride surface and an oxide surface are mixed, and a method for inhibiting nitride film formation on an oxide surface.

[0013] Another object of the present invention is to provide a method for forming a nitride film, which is capable of selectively forming a nitride film on a nitride surface where a nitride surface and an oxide surface are mixed. [Means for solving the problem]

[0014] In order to solve the above problems, the present inventors came up with the idea of ​​using a molecule (coating molecule) that is easily adsorbed on an oxide surface but is difficult to adsorb on a nitride surface as an inhibitor. By coating the oxide surface with such a coating molecule to inhibit the adsorption of a nitride film-forming raw material on the oxide surface and using a reactant (nitriding agent) that reacts at an appropriate temperature, it becomes possible to selectively form a nitride film on the nitride surface, thereby realizing the above-mentioned selective growth. As a result of intensive research by the present inventors, it was found that aminosilane molecules having a specific structure are more easily selectively adsorbed on an oxide surface than on a nitride surface, and that the nitride film-forming raw material is less likely to adsorb on the oxide surface to which the aminosilane molecules are adsorbed.

[0015] The present invention, which has been completed based on the above findings, has the following essential features. [1] An inhibitor that is supplied as a gas to an oxide surface and adsorbed on the oxide surface, and is then used to inhibit the formation of a nitride film on the oxide surface, having the structure shown in the formula: [ka] M is one selected from the group consisting of silicon, aluminum, boron, tin, germanium, and gallium; R1 and R2 are one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R1 and R2 may be cyclic groups; R3, R4, and R5 are each one selected from the group consisting of hydrogen; a linear or branched alkyl group; an aryl group; and an alkylsilyl group; and two or more selected from R3, R4, and R5 may be cyclic groups. 1. An inhibitor of nitride film formation on an oxide surface.

[0016] [2] M is silicon; R1 and R2 are (i) a linear or branched alkyl group having 1 to 10 carbon atoms, (ii) forming a piperidine ring together with N, or (iii) forming a pyrrolidine ring together with N; The inhibitor of nitride film formation on an oxide surface according to the above [1], wherein R3, R4 and R5 are linear or branched alkyl groups having 1 to 10 carbon atoms.

[0017] [3] The inhibitor of nitride film formation on an oxide surface according to [1] above, which is one or more selected from the group consisting of dimethylaminotrimethylsilane, dimethylaminotriethylsilane, diethylaminotrimethylsilane, diethylaminotriethylsilane, trimethylsilylpiperidine, triethylsilylpiperidine, trimethylsilylpyrrolidine, and triethylsilylpyrrolidine.

[0018] [4] The inhibitor of nitride film formation on an oxide surface according to any one of the above [1] to [3], wherein the oxide is one or more oxides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0019] [5] The inhibitor of nitride film formation on an oxide surface according to any one of [1] to [4] above, wherein the nitride film is a film made of one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0020] [6] Having the structure shown in the formula: [ka] M is one selected from the group consisting of silicon, aluminum, boron, tin, germanium, and gallium; R1 and R2 are one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R1 and R2 may be cyclic groups; R3, R4, and R5 are each one selected from the group consisting of hydrogen; a linear or branched alkyl group; an aryl group; and an alkylsilyl group; and two or more selected from R3, R4, and R5 may be cyclic groups. 1. A method for inhibiting the formation of a nitride film on an oxide surface, comprising: supplying one or more inhibitors as a gas to an oxide surface and allowing them to be adsorbed on the oxide surface, thereby inhibiting the formation of a nitride film on the oxide surface.

[0021] [7] M is silicon; R1 and R2 are (i) a linear or branched alkyl group having 1 to 10 carbon atoms, (ii) forming a piperidine ring together with N, or (iii) forming a pyrrolidine ring together with N; The method for inhibiting the formation of a nitride film on an oxide surface according to the above [6], wherein R3, R4 and R5 are linear or branched alkyl groups having 1 to 10 carbon atoms.

[0022] [8] The method for inhibiting the formation of a nitride film on an oxide surface according to [6] above, wherein the inhibitor is one or more selected from the group consisting of dimethylaminotrimethylsilane, dimethylaminotriethylsilane, diethylaminotrimethylsilane, diethylaminotriethylsilane, trimethylsilylpiperidine, triethylsilylpiperidine, trimethylsilylpyrrolidine, and triethylsilylpyrrolidine.

[0023] [9] The method for inhibiting the formation of a nitride film on an oxide surface according to any one of [6] to [8] above, wherein the oxide is one or more oxides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0024]

[10] The method for inhibiting the formation of a nitride film on an oxide surface according to any one of [6] to [9] above, wherein the nitride film is a film made of one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0025]

[11] Providing a surface having a mixture of nitride and oxide surfaces; having the structure shown in the formula: [ka] M is one selected from the group consisting of silicon, aluminum, boron, tin, germanium, and gallium; R1 and R2 are one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R1 and R2 may be cyclic groups; R3, R4, and R5 are each one selected from the group consisting of hydrogen; a linear or branched alkyl group; an aryl group; and an alkylsilyl group; and two or more selected from R3, R4, and R5 may be cyclic groups. delivering one or more inhibitors to the surface as a gas and allowing the inhibitors to selectively adsorb onto the oxide surface; supplying a nitride film precursor to the surface as a gas and allowing the nitride film precursor to selectively react with the nitride surface by the action of the inhibitor, thereby selectively forming a nitride film on the nitride surface; 1. A method for selectively forming a nitride film on a nitride surface in a surface having a mixture of a nitride surface and an oxide surface, comprising:

[0026]

[12] M is silicon; R1 and R2 are (i) a linear or branched alkyl group having 1 to 10 carbon atoms, (ii) forming a piperidine ring together with N, or (iii) forming a pyrrolidine ring together with N; The method for forming a nitride film according to the above item

[11] , wherein R3, R4 and R5 are linear or branched alkyl groups having 1 to 10 carbon atoms.

[0027]

[13] The method for forming a nitride film according to

[11] above, wherein the inhibitor is one or more selected from the group consisting of dimethylaminotrimethylsilane, dimethylaminotriethylsilane, diethylaminotrimethylsilane, diethylaminotriethylsilane, trimethylsilylpiperidine, triethylsilylpiperidine, trimethylsilylpyrrolidine, and triethylsilylpyrrolidine.

[0028]

[14] The method for forming a nitride film according to any one of the above

[11] to

[13] , wherein the oxide is one or more oxides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0029]

[15] The method for forming a nitride film according to any one of the above

[11] to

[14] , wherein the nitride is one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

[0030]

[16] The step of forming the nitride film comprises: (A) supplying, to the surface, one or more chlorides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum as the nitride film raw material, and allowing the chlorides to be selectively adsorbed to the nitride surface by the action of the inhibitor; (B) subsequently supplying molecules containing N as the nitride film raw material to the surface and reacting them with the chloride adsorbed on the nitride surface, thereby selectively forming a film made of one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum on the nitride surface; The method for forming a nitride film according to any one of the above

[11] to

[15] , wherein the above steps are repeated.

[0031]

[17] The method for forming a nitride film according to the above

[16] , wherein the N-containing molecule is one or both of ammonia and hydrazine.

[0032]

[18] The inhibitor used in the method for forming a nitride film according to any one of the above

[11] to

[17] . Effect of the Invention

[0033] The inhibitor of nitride film formation on an oxide surface and the method of inhibiting nitride film formation on an oxide surface according to the present invention make it possible to selectively form a nitride film on a nitride surface in a surface where a nitride surface and an oxide surface are mixed.

[0034] The method for forming a nitride film according to the present invention makes it possible to selectively form a nitride film on a nitride surface in a surface where a nitride surface and an oxide surface are mixed. [Brief description of the drawings]

[0035] [Figure 1]FIG. 1 is a diagram illustrating a method for selectively forming a nitride film on a nitride surface in a surface having a mixture of nitride and oxide surfaces according to an embodiment of the present invention, in which the left side is a flowchart and the right side is a schematic diagram showing the surface state corresponding to each step of the flowchart. [Diagram 2] FIG. 2 is a diagram showing the activation energy Ea and enthalpy change ΔH of the adsorption reaction of an inhibitor (dimethylaminotrimethylsilane) according to one embodiment of the present invention on the surfaces of a silicon oxide film and a silicon nitride film. [Diagram 3] FIG. 1 shows the activation energy Ea and enthalpy change ΔH of the adsorption reaction of dichlorosilane, a silicon nitride film forming raw material (Si source), on the surface of a silylmethyl-modified silicon oxide film (a SiOX film whose surface is modified with -OSi(CH3)3). [Figure 4] FIG. 1 shows the activation energy Ea and enthalpy change ΔH of various reactions of ammonia and hydrazine, which are reactants (nitriding agents) for forming a silicon nitride film, on the surface of a silylmethyl-modified silicon oxide film (a SiOX film whose surface is modified with -OSi(CH3)3). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] An inhibitor of nitride film formation on an oxide surface according to one embodiment of the present invention is supplied to an oxide surface as a gas and adsorbed on the oxide surface, and is then used to inhibit nitride film formation on the oxide surface.

[0037] A method for inhibiting the formation of a nitride film on an oxide surface according to one embodiment of the present invention is characterized in that one or more of the inhibitors described above are supplied as a gas to the oxide surface and adsorbed on the oxide surface, thereby inhibiting the formation of a nitride film on the oxide surface.

[0038] A method for selectively forming a nitride film on a nitride surface where a nitride surface and an oxide surface are mixed according to one embodiment of the present invention is characterized by comprising the steps of: preparing a surface where a nitride surface and an oxide surface are mixed; supplying one or more of the inhibitors as described above as a gas to the mixed surface and selectively adsorbing the inhibitor onto the oxide surface; and supplying a nitride film precursor as a gas to the mixed surface and selectively acting the nitride film precursor on the nitride surface by the action of the inhibitor, thereby selectively forming a nitride film on the nitride surface.

[0039] The inhibitor in these embodiments has the structure shown in the formula: [ka]

[0040] M is one selected from the group consisting of silicon, aluminum, boron, tin, germanium, and gallium, and is preferably silicon.

[0041] R1 and R2 are one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R1 and R2 may be a cyclic group. R1 and R2 are preferably linear or branched alkyl groups having 1 to 10 carbon atoms, more preferably unsubstituted linear alkyl groups having 1 to 5 carbon atoms, and most preferably methyl or ethyl groups. The branching mode of the alkyl group is not particularly limited. In addition, when R1 and R2 are a cyclic group, R1 and R2 preferably form a piperidine ring together with N, or form a pyrrolidine ring together with N.

[0042] R3, R4 and R5 are one selected from the group consisting of hydrogen, linear or branched alkyl groups, aryl groups and alkylsilyl groups, and two or more selected from R3, R4 and R5 may be cyclic groups. R3, R4 and R5 are preferably linear or branched alkyl groups having 1 to 10 carbon atoms, more preferably unsubstituted linear alkyl groups having 1 to 5 carbon atoms, and most preferably methyl or ethyl groups. The branching mode of the alkyl group is not particularly limited.

[0043] Specifically, the inhibitor is preferably one or more selected from the group consisting of dimethylaminotrimethylsilane, dimethylaminotriethylsilane, diethylaminotrimethylsilane, diethylaminotriethylsilane, trimethylsilylpiperidine, triethylsilylpiperidine, trimethylsilylpyrrolidine, and triethylsilylpyrrolidine.

[0044] The oxide constituting the oxide surface of the base is preferably one or more oxides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum. The oxide is preferably silicon oxide (SiO x ) or aluminum oxide (AlO x SiO x Examples of the oxide include SiO and SiO2, and it is preferable that one or both of these constitute the oxide. AlO x Examples of the oxide include AlO and Al2O3, and it is preferable that one or both of these constitute the oxide.

[0045] The nitride constituting the underlying nitride surface is preferably one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum. The nitride is preferably silicon nitride (SiN x ) is more preferable. xExamples of the nitride include SiN and Si3N4, and it is preferable that one or both of these constitute the nitride.

[0046] An example of an object (base) having a surface in which a nitride surface and an oxide surface are mixed is a substrate used in semiconductor processing, in which a nitride film and an oxide film are mixed.

[0047] The nitride film whose formation can be inhibited by the inhibitor and inhibition method of this embodiment, and the nitride film that can be formed by the selective nitride film formation method of this embodiment, are preferably films made of one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum, and are more preferably silicon nitride (SiN) films or titanium nitride (TiN) films.

[0048] In the method for selectively forming a nitride film in this embodiment, the nitride film formation process can repeatedly include the steps of: (A) supplying one or more chlorides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum as nitride film raw materials (film formation raw materials) to the mixed surface, and selectively adsorbing them to the nitride surface by the action of the inhibitor; and (B) subsequently supplying N-containing molecules as nitride film raw materials (reactant; nitriding agent) to the mixed surface, and reacting them with the chlorides adsorbed to the nitride surface, thereby selectively forming a film made of one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum on the nitride surface.

[0049] When a silicon nitride (SiN) film is formed as the nitride film, chlorosilane can be used as the nitride film raw material (film-forming raw material; Si source). As the chlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, and hexachlorodisilane can be preferably used, and one or more of these can be used. When a titanium nitride (TiN) film is formed as the nitride film, chlorotitanium can be used as the nitride film raw material (film-forming raw material; Ti source). As the chlorotitanium, titanium tetrachloride can be preferably used. As other nitride film raw materials (film-forming raw materials), chloroaluminum, chlorozirconium, chlorogermanium, chlorohafnium, etc. can be used.

[0050] The N-containing molecule (nitriding agent) is preferably one or both of ammonia (NH3) and hydrazine (N2H4).

[0051] [Actions and effects of inhibitors] With reference to FIG. 1, the effect of the inhibitor (R)3-MN-(R')2 of this embodiment in the selective nitride film forming method according to this embodiment will be described. In this case, in the above-mentioned structural formula, R1 and R2 bonded to N are represented as R', and R3, R4 and R5 bonded to M are represented as R. In the following, the case where M=Si, that is, the case where the inhibitor (R)3-Si-N-(R')2 is used will be described as an example. In addition, the case where a surface where silicon nitride (SiN) and silicon oxide (SiO) are mixed is adopted as a surface where a nitride surface and an oxide surface are mixed, and a silicon nitride film (SiN film) is formed as a nitride film will be described as an example.

[0052] At the start of film formation (step S1), =NH and -NH2 are present on the surface of silicon nitride (SiN), and -OH is present on the surface of silicon oxide (SiO).

[0053] In the inhibitor exposure step (step S2), the inhibitor (R)3-Si-N-(R')2 of this embodiment is supplied as a gas to the mixed surface. Here, the inhibitor (R)3-Si-N-(R')2 of this embodiment has a lower activation energy of adsorption to the surface of silicon oxide (SiO) than that of silicon nitride (SiN). Therefore, the inhibitor (R)3-Si-N-(R')2 is selectively adsorbed to the surface of silicon oxide (SiO) rather than the surface of silicon nitride (SiN). At this time, the surface of silicon oxide (SiO) is modified with -Si-(R)3. When R (i.e., R3, R4, and R5 in the above structural formula) is an alkyl group, the surface of silicon oxide (SiO) is "silyl alkylated". Note that the magnitude relationship of the activation energy described above is not limited to the combination of silicon nitride (SiN) and silicon oxide (SiO), but applies to any combination of nitride and oxide described above as the underlying nitride and oxide.

[0054] Next, in the SiN Si source exposure process (step S3), chlorosilane (e.g., dichlorosilane) is supplied to the mixed surface as a nitride film raw material (film forming raw material). Here, the activation energy of the adsorption reaction of chlorosilane to the surface of silicon oxide (SiO) modified with -Si-(R)3 is high, and the reaction does not occur easily. In contrast, the activation energy of the adsorption reaction of chlorosilane to the surface of silicon nitride (SiN) is low, and the reaction occurs easily. Therefore, chlorosilane is selectively adsorbed to the surface of silicon nitride (SiN). At this time, the surface of silicon nitride (SiN) is in a state where =N-SiH2-Cl and -NH-SiH2-Cl exist.

[0055] Next, in the nitriding agent exposure step (step S4), molecules containing N (e.g., ammonia, hydrazine) are supplied to the mixed surface as a nitride film raw material (nitriding agent). Here, as shown in FIG. 4, the activation energy of various reactions of ammonia and hydrazine with the surface of silicon oxide (SiO) modified with -Si-(R)3 is high, and these reactions (reactions of removing adsorbed inhibitors by ammonia and hydrazine) are unlikely to occur. For this reason, the nitriding agent reacts with the chlorosilane selectively adsorbed on the surface of silicon nitride (SiN), and as a result, a silicon nitride film (SiN film) is selectively formed on the surface of silicon nitride (SiN).

[0056] In the nitride film formation method of this embodiment, the inhibitor exposure step (step S2), the SiN Si source exposure step (step S3), and the nitriding agent exposure step (step S4) may be repeated multiple cycles, or after the initial inhibitor exposure step (step S2), the SiN Si source exposure step (step S3) and the nitriding agent exposure step (step S4) may be repeated multiple cycles, with the inhibitor exposure step (step S2) being performed every few cycles.

[0057] At the end of the film formation (step S5), a silicon nitride film (SiN film) is formed on the surface of the silicon nitride (SiN), and =NH and -NH2 are present on the surface, while the surface of the silicon oxide (SiO) remains modified with -Si-(R)3.

[0058] Hereinafter, specific conditions for carrying out the inhibitor exposure step (step S2), the Si source for SiN exposure step (step S3), and the nitriding agent exposure step (step S4) will be described.

[0059] These steps can be carried out by placing an object having a surface in which a nitride surface and an oxide surface are mixed in a reactor, controlling the pressure in the reactor to a predetermined value while heating the object, and sequentially supplying various gases (inhibitor, Si source, and nitriding agent) into the reactor. The reactor is not particularly limited as long as it is configured to be capable of containing the target substance, capable of controlling the heating and pressure in the reactor, and capable of supplying various gases.

[0060] In the inhibitor exposure step (step S2), the inhibitor is supplied as a gas into the reactor. An inert gas such as nitrogen may be supplied at the same time as a carrier gas. In general, in order to sufficiently adsorb the inhibitor on the oxide surface, the higher the concentration of the inhibitor gas, the shorter the gas supply time, and the lower the concentration of the inhibitor gas, the longer the gas supply time. From this viewpoint, it is preferable to appropriately select the inhibitor gas flow rate within the range of 1 to 300 sccm and the gas supply time within the range of 1 to 180 seconds. The inert gas flow rate is not particularly limited, but can be within the range of 0.3 to 3 slm.

[0061] In the SiN Si source exposure step (step S3), the Si source, which is a film formation raw material, is supplied as a gas into the reaction furnace. The type of Si source is as described above. An inert gas such as nitrogen may be supplied simultaneously as a carrier gas. In general, in order to sufficiently adsorb the Si source on the nitride surface, the higher the concentration of the Si source gas, the shorter the gas supply time, and the lower the concentration of the Si source gas, the longer the gas supply time. From this viewpoint, it is preferable to appropriately select the flow rate of the Si source gas within the range of 1 to 300 sccm and the gas supply time within the range of 1 to 180 seconds. The flow rate of the inert gas is not particularly limited, but can be within the range of 0.3 to 3 slm.

[0062] In the nitriding agent exposure step (step S4), the nitriding agent is supplied as a gas into the reaction furnace. The types of nitriding agents are as described above. In general, in order to sufficiently react the Si source adsorbed on the nitride surface with the nitriding agent, the higher the concentration of the nitriding agent gas, the shorter the gas supply time, and the lower the concentration of the nitriding agent gas, the longer the gas supply time. From this viewpoint, it is preferable to appropriately select the flow rate of the nitriding agent gas from 10 sccm to 10 slm and the gas supply time from 1 to 180 seconds.

[0063] It is preferable to perform a purge step immediately after the inhibitor exposure step (step S2), the SiN Si source exposure step (step S3), and the nitriding agent exposure step (step S4), and then perform the next step. The purge step is performed by supplying an inert gas such as nitrogen to the reaction furnace. The flow rate of the inert gas is not particularly limited, but can be in the range of 10 sccm to 10 slm. The gas supply time is not particularly limited, but can be in the range of 0.5 to 90 seconds.

[0064] The pressure inside the reaction furnace during the series of steps is not particularly limited, but can be within the range of 0.1 to 10 Torr.

[0065] The temperature of the target material during the series of steps may be set appropriately depending on the type of nitride film to be formed. For example, when forming a silicon nitride film, the temperature of the target material is preferably set within a range of 450 to 600°C, and when forming a titanium nitride film, the temperature of the target material is preferably set within a range of 300 to 500°C.

[0066] The number of cycles of the SiN Si source exposure step (step S3) and the nitriding agent exposure step (step S4) is not particularly limited and may be appropriately set according to the thickness of the nitride film to be formed. The inhibitor exposure step (step S2) is preferably performed once every 1 to 20 cycles, more preferably once every 2 to 5 cycles. EXAMPLES

[0067] Example 1 Silicon oxide film (SiO X film), silicon nitride film (SiN X film), and silylmethyl-modified silicon oxide film (SiO XThe activation energy for the adsorption reaction of dichlorosilane, a raw material (Si source) for silicon nitride films, on SiO2 (SiN2O3) is shown in Table 1. The activation energy was calculated by quantum chemical calculations using the cc-pVDZ basis in the density functional method B3LYP. The smaller the activation energy, the more preferentially the reaction will proceed.

[0068] [Table 1]

[0069] Referring to Table 1 and Figure 3, it was found that the activation energy of the adsorption reaction of dichlorosilane to the silylmethyl-modified silicon oxide film surface is high and the reaction is unlikely to occur, that is, dichlorosilane is unlikely to be adsorbed to the silylmethyl-modified silicon oxide film surface. From this, it is presumed that the formation of a silicon nitride film on a silicon oxide film surface can be inhibited by using a molecule having a hydrocarbon-silicon bond (-Si(R)3) as an inhibitor.

[0070] Example 2 Silicon oxide film (SiO X film), aluminum oxide film (AlO X film), and silicon nitride film (SiN X The activation energy for the adsorption reaction of dimethylaminotrimethylsilane on a SiO2 film is shown in Table 2. The activation energy was calculated by quantum chemical calculations using the density functional method B3LYP with the cc-pVDZ basis. The smaller the activation energy, the more preferentially the reaction will proceed.

[0071] [Table 2]

[0072] Referring to FIG. 2 in addition to Table 2, it was found that the activation energy of the adsorption reaction of dimethylaminotrimethylsilane to silicon oxide film and aluminum oxide film is smaller than that of the adsorption reaction of dimethylaminotrimethylsilane to silicon nitride film, that is, dimethylaminotrimethylsilane is preferentially adsorbed to silicon oxide film and aluminum oxide film rather than to silicon nitride film. In other words, a molecule having an amino group and a hydrocarbon-silicon bond is preferentially adsorbed to the surface of silicon oxide film and aluminum oxide film rather than to the surface of silicon nitride film. After the molecule is adsorbed, the surface of silicon oxide film and aluminum oxide film is modified by silylmethyl group (-OSi(CH3)3). In conjunction with Example 1, it was confirmed that the formation of silicon nitride film on silicon oxide film can be suppressed by using the molecule.

[0073] Example 3 Silylmethyl-modified silicon oxide film (SiO2 surface modified with -OSi(CH3)3) X The activation energy Ea and enthalpy change ΔH of various reactions of ammonia and hydrazine, which are reactants (nitriding agents) for forming a silicon nitride film, on the surface of a silicon nitride film (film) are shown in Figure 4. Figure 4 shows that the activation energy of these reactions is high, and that these reactions (reactions of removing adsorbed inhibitors by ammonia and hydrazine) are difficult to occur.

[0074] [Considerations of Examples 1 to 3] From Example 1, it was revealed that dichlorosilane, which is a raw material for forming a silicon nitride film, is less likely to be adsorbed by silylmethylating the underlying silicon oxide film. Furthermore, from Example 2, when the reactivity of dimethylaminotrimethylsilane, which is one of the raw materials for silylmethylation, with the underlying film (silicon oxide film, aluminum oxide film, and silicon nitride film) was examined, it was revealed that silylmethylation proceeds preferentially with respect to the silicon oxide film and the aluminum oxide film. Furthermore, from Example 3, it was revealed that the silylmethylated silicon oxide film is less likely to react with ammonia and hydrazine, which are reactants (nitriding agents) for forming a silicon nitride film. From the above, it is possible to selectively silylmethylate an oxide film, and an effect of suppressing the formation of a nitride film on an oxide film can be expected.

[0075] (Experimental Example 1) The substrates covered with a silicon oxide film and the substrates covered with an aluminum oxide film were introduced into a reactor and heated to a predetermined substrate temperature. The pressure in the reactor was controlled to 133 Pa, and various gases were sequentially supplied to the reactor under the gas conditions of steps 1 to 6 shown in Tables 3 and 4, which were repeated 70 times. In Example 1 and Comparative Examples 1 and 3, which were intended to form a silicon nitride film, the substrates were heated to 600°C, and in Example 2 and Comparative Examples 2 and 4, which were intended to form a titanium nitride film, the substrates were heated to 350°C.

[0076] [Table 3]

[0077] [Table 4]

[0078] In Examples 1 and 2, dimethylaminotrimethylsilane acted as an inhibitor, so that a silicon nitride film or a titanium nitride film was not formed. In contrast, a silicon nitride film or a titanium nitride film was formed in Comparative Examples 1 to 4. In this way, it was confirmed that the formation of a silicon nitride film or a titanium nitride film on a silicon oxide film and an aluminum oxide film is inhibited by using a molecule having an amino group and a hydrocarbon-silicon bond. The silicon nitride film and the titanium nitride film were identified and confirmed by measuring the refractive index using an ellipsometer. The refractive index of the silicon nitride film is about 1.8 to 2.2, and the refractive index of the titanium nitride film is about 1.5 to 1.8.

[0079] (Experimental Example 2) A substrate coated with a silicon oxide film, a substrate coated with an aluminum oxide film, and a substrate coated with a silicon nitride film were each introduced into a reactor and heated to five levels: 500° C., 550° C., 600° C., 650° C., and 700° C. The pressure inside the reactor was controlled at 133 Pa, and various gases were sequentially supplied to the reactor under the gas conditions of steps 1 to 6 shown in Table 5, which were repeated 70 times.

[0080] [Table 5]

[0081] Table 6 shows whether a film could be formed on each substrate at each substrate temperature. × indicates that a silicon nitride film was not formed, and ○ indicates that a silicon nitride film was formed. △ indicates that a silicon nitride film was formed, but the film density was low and a thin film with a large amount of impurities in the film was formed. The silicon nitride film was identified and confirmed by measuring the refractive index using an ellipsometer, as in Experimental Example 1. The film density and impurities were confirmed by the bonding state in the film using FTIR. Specifically, the film density can be understood by normalizing the film thickness to a predetermined thickness (for example, 100 nm) and comparing the main peak intensity at that time. The smaller the main peak intensity, the smaller the film density. As for impurities, since the peak top position of a pure silicon nitride film is known, the presence or absence of impurities can be confirmed by the presence or absence of a peak shift relative to that.

[0082] [Table 6]

[0083] As shown in Table 6, it was confirmed that by using a combination of the film-forming raw material (Si source), nitriding agent, inhibitor, and substrate temperature, the formation of a nitride film on a silicon oxide film or an aluminum oxide film can be inhibited, and a nitrogen film can be formed only on the nitride film.

[0084] [Considerations for Experimental Examples 1 and 2] In the invention examples 1 and 2, the surfaces of the silicon oxide film and the aluminum oxide film were silylmethylated by dimethylaminotrimethylsilane, so the formation of the silicon nitride film and the titanium nitride film was not promoted. In contrast, in the comparative examples 1 and 2, the surfaces of the silicon oxide film and the aluminum oxide film were not silylmethylated, so the formation of the silicon nitride film and the titanium nitride film was promoted.

[0085] In Comparative Examples 3 and 4, aminosilane that cannot silylmethylate the surfaces of silicon oxide and aluminum oxide films was used, and the formation of silicon nitride and titanium nitride films was promoted as in Comparative Examples 1 and 2.

[0086] Comparing Example 3 and Example 4, it was found that by using hydrazine instead of ammonia as the nitriding agent, it was possible to form a silicon nitride film on a silicon nitride film at a substrate temperature range of 550 to 650°C while preventing the formation of a nitride film on a silicon oxide film and an aluminum oxide film.

[0087] Comparing Example 4 and Example 5, it was found that by using hexachlorodisilane instead of dichlorosilane as a film-forming raw material, it was possible to form a silicon nitride film on a silicon nitride film at a substrate temperature range of 500 to 650°C while preventing the formation of a nitride film on a silicon oxide film and an aluminum oxide film.

[0088] Comparing Example 5 and Example 6, by increasing the amount of dimethylaminotrimethylsilane adsorbed onto the surfaces of a silicon oxide film and an aluminum oxide film, it was possible to form a silicon nitride film on the silicon nitride film at a substrate temperature range of 500 to 650°C while preventing the formation of a nitride film on these oxide films.

[0089] Examples 3 to 6 of the invention show that selective growth is possible in various temperature ranges by changing the supply conditions of the film-forming raw material, the nitriding agent, and the inhibitor. [Industrial Applicability]

[0090] The present invention can be suitably applied to a semiconductor manufacturing process in which an insulating film or a charge trapping film is formed and a predetermined structure is fabricated (patterned).

Claims

1. Providing an object having a surface that is a mixture of nitride and oxide surfaces; having the structure shown in the formula: 【Chemistry 1】 M is one selected from the group consisting of silicon, aluminum, boron, tin, germanium, and gallium; R １ and R ２ is one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R １ and R ２ may be a cyclic group, R ３ , R ４ and R ５ is one selected from the group consisting of hydrogen; linear or branched alkyl groups; aryl groups; and alkylsilyl groups; and R ３ , R ４ and R ５ Two or more selected from the following may be cyclic groups: an inhibitor exposure step of supplying one or more inhibitors to the surface as a gas and allowing the inhibitors to selectively adsorb onto the oxide surface; a nitride film forming step of supplying a nitride film precursor to the surface as a gas and selectively acting the nitride film precursor on the nitride surface by the action of the inhibitor, thereby selectively forming a nitride film which is a silicon nitride film or a titanium nitride film on the nitride surface; wherein the temperature of the object during the inhibitor exposure step and the nitride film formation step is within a range of 450 to 650°C when forming the silicon nitride film, and within a range of 300 to 500°C when forming the titanium nitride film.

2. M is silicon; R １ and R ２ (i) is a linear or branched alkyl group having 1 to 10 carbon atoms, (ii) forms a piperidine ring together with N, or (iii) forms a pyrrolidine ring together with N, R ３ , R ４ and R ５ 2. The method for forming a nitride film according to claim 1, wherein is a linear or branched alkyl group having 1 to 10 carbon atoms.

3. 2. The method of claim 1, wherein the inhibitor is one or more selected from the group consisting of dimethylaminotrimethylsilane, dimethylaminotriethylsilane, diethylaminotrimethylsilane, diethylaminotriethylsilane, trimethylsilylpiperidine, triethylsilylpiperidine, trimethylsilylpyrrolidine, and triethylsilylpyrrolidine.

4. 4. The method for forming a nitride film according to claim 1, wherein the oxide is one or more oxides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

5. 4. The method for forming a nitride film according to claim 1, wherein the nitride is one or more nitrides selected from the group consisting of silicon, aluminum, zirconium, germanium, tin, hafnium, copper, tungsten, titanium, and tantalum.

6. The nitride film forming step includes: (A) supplying silicon or titanium chloride as the nitride film raw material to the surface and selectively adsorbing it on the nitride surface by the action of the inhibitor; (B) subsequently supplying molecules containing N as the nitride film raw material to the surface and reacting them with the chloride adsorbed on the nitride surface, thereby selectively forming the silicon nitride film or the titanium nitride film on the nitride surface; 4. The method for forming a nitride film according to claim 1, further comprising repeating the steps of:

7. 7. The method for forming a nitride film according to claim 6, wherein the molecule containing N is one or both of ammonia and hydrazine.

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