Method for forming capacitor electrodes

Abstract

A method for forming a capacitor electrode according to an embodiment of the present invention includes the steps of spraying a titanium (Ti)-containing source and a nitrogen-containing reactant to form a TiN thin film, and spraying a silicon (Si)-containing source and a nitrogen-containing reactant to form a SiN thin film, in which at least one of the titanium (Ti)-containing source and the silicon (Si)-containing source is sprayed multiple times. Therefore, according to an embodiment of the present invention, when a TiN thin film and a SiN thin film are stacked to form at least one of a lower electrode and an upper electrode of a capacitor, the deposition rate of the SiN thin film can be improved and the step coverage of the thin film can be improved.

Description

[Technical field]

[0001] The present invention relates to a method for forming a capacitor electrode, and more particularly to a method for forming a capacitor electrode that can improve a deposition rate. [Background technology]

[0002] A capacitor applied to a semiconductor device includes a lower electrode formed on a substrate, a dielectric layer formed on the lower electrode, and an upper electrode formed on the dielectric layer. The substrate may have a trench, and the lower electrode, the dielectric layer, and the upper electrode may be stacked on the substrate to provide a capacitor. The upper electrode and the lower electrode are formed by stacking a TiN thin film (titanium nitride thin film) and a SiN thin film (silicon nitride thin film).

[0003] On the other hand, when forming a SiN thin film, SiH4 (silane) is used as a source, but SiH4 has a low deposition rate and a low deposition ratio, which results in low step coverage of the lower and upper electrodes, which causes a deterioration in the characteristics of the capacitor.

[0004] In order to improve the low step coverage, there is a method of forming the lower electrode and the upper electrode thicker, but in this case, there is a problem that it takes a long time to form the lower electrode and the upper electrode with a target thickness.

[0005] In addition, as the deposition time increases, the bottom electrode becomes thicker, which narrows the space inside the trench in which the dielectric layer is formed, which may act as a factor in reducing the dielectric constant of the dielectric layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent No. 10-1110077 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a method for forming a capacitor electrode that can improve the deposition rate.

[0008] The present invention provides a method for forming a capacitor electrode that can improve step coverage. [Means for solving the problem]

[0009] A method for forming a capacitor electrode according to an embodiment of the present invention includes the steps of spraying a source containing titanium (Ti) and a reactant containing nitrogen to form a TiN thin film, and spraying a source containing silicon (Si) and a reactant containing nitrogen to form a SiN thin film, in which at least one of the source containing titanium (Ti) and the source containing silicon (Si) is sprayed multiple times.

[0010] The step of forming the TiN thin film and the step of forming the SiN thin film are carried out successively.

[0011] The step of forming the TiN thin film is performed more times in succession than the step of forming the SiN thin film.

[0012] The ratio (T1:T2) of the number of times (T2) the step of forming the TiN thin film is performed to the number of times (T1) the step of forming the SiN thin film is performed is adjusted to 1:1 to 4:1.

[0013] The silicon (Si)-containing source may be a silicon (Si) gas containing hydrogen (H) or a silicon (Si) precursor containing chlorine (Cl), or may be a mixed gas of a silicon (Si) gas containing hydrogen (H) and a silicon (Si) precursor containing chlorine (Cl).

[0014] The silicon (Si) precursor containing chlorine (Cl) may be hexachlorodisilane (HCDS:Si2Cl6), and the silicon (Si) gas containing hydrogen (H) may contain silane (SiH4).

[0015] The step of forming the SiN thin film may include a step of spraying a silicon (Si) gas containing hydrogen (H) to form a first SiN thin film, and a step of spraying a silicon (Si) precursor containing chlorine (Cl) to form a second SiN thin film.

[0016] The ratio of the number of times the step of forming the second SiN thin film is performed to the number of times the step of forming the first SiN thin film is performed may be adjusted to 1:3 to 3:1.

[0017] A step of blowing a purge gas may be added between the steps of blowing different types of gas. Effect of the Invention

[0018] According to an embodiment of the present invention, when forming at least one of a lower electrode and an upper electrode of a capacitor by stacking a TiN thin film and a SiN thin film, a source containing a plurality of Si atoms is used to form the SiN thin film, thereby improving the deposition rate of the SiN thin film and the step coverage of the thin film. [Brief description of the drawings]

[0019] [Figure 1] 1 is a conceptual diagram showing a capacitor having electrodes formed by a method for forming a capacitor electrode according to an embodiment of the present invention; [Diagram 2] 1 shows a bottom electrode formed on a substrate by a method according to a first embodiment of the present invention; [Diagram 3] FIG. 2 is a conceptual diagram for explaining a method for forming a lower electrode by the method according to the first embodiment of the present invention. [Figure 4] 10A to 10C are conceptual diagrams for explaining a method for forming a lower electrode by a method according to a modification of the first embodiment. [Diagram 5] FIG. 4 shows a bottom electrode formed on a substrate by a method according to a second embodiment of the present invention. [Figure 6] 5A to 5C are conceptual diagrams for explaining a method for forming a lower electrode by a method according to a second embodiment of the present invention. [Figure 7] 13A to 13C are conceptual diagrams for explaining a method for forming a lower electrode by a method according to a third embodiment of the present invention. [Figure 8] 13A to 13C are conceptual diagrams for explaining a method for forming a lower electrode by a method according to a modification of the third embodiment. [Figure 9] 2 shows a bottom electrode formed on a substrate by a method according to an embodiment of the present invention; [Figure 10] FIG. 13 is a diagram showing a state in which a TiN thin film and a SiN thin film are laminated on a substrate provided with a trench by a method according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. These embodiments are provided merely to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention. In describing the present invention, the same reference numerals are used for the same components, and the drawings may be partially exaggerated in size to describe the embodiments of the present invention, and the same numerals in the drawings indicate the same components.

[0021] FIG. 1 is a conceptual diagram showing a capacitor having electrodes formed by a method for forming a capacitor electrode according to an embodiment of the present invention.

[0022] Referring to FIG. 1, a capacitor 100 may include a substrate 110, a bottom electrode 120 formed on the substrate 110, a dielectric layer 130 formed on the bottom electrode 120, and a top electrode 140 formed on the dielectric layer 130.

[0023] The substrate 110 may be a semiconductor substrate. More specifically, the substrate 110 may be a wafer, or any one of a Si wafer, a GaAs wafer, and a SiGe wafer.

[0024] The dielectric layer 130 is formed on the substrate 110. In this case, the dielectric layer 130 may be formed of a dielectric material including a metal oxide. More specifically, the dielectric layer 130 may be formed of any one of ZrO2, Al2O3, TiO2, TaO2, and HfO2. In addition, the dielectric layer 130 may be formed by an atomic layer deposition (ALD) method or a chemical vapor deposition (CVD) method.

[0025] The lower electrode 120 and the upper electrode 140 are formed by laminating a TiN thin film and a SiN thin film, respectively, and the TiN thin film and the SiN thin film are formed by an atomic layer deposition (ALD) method. At this time, when forming the SiN thin film, a source containing a compound containing multiple Si atoms is used. By using a compound containing multiple Si atoms or a source containing a compound with multiple Si atoms in this way, the deposition rate of the SiN thin film can be improved, and step coverage can be improved.

[0026] Hereinafter, a method for forming a lower electrode on a substrate by the method according to the first embodiment of the present invention will be described with reference to Figures 2 and 3. At this time, since the methods for forming the lower electrode and the upper electrode are similar, the method for forming the lower electrode will be described and the method for forming the upper electrode will be omitted.

[0027] Fig. 2 is a diagram showing a lower electrode formed on a substrate by the method according to the first embodiment of the present invention. Fig. 3 is a conceptual diagram for explaining a method for forming a lower electrode by the method according to the first embodiment of the present invention. In this case, "on" in Fig. 3 may mean blowing gas, and "off" may mean interrupting or ending the blowing of gas.

[0028] 2, the lower electrode 120 may include a TiN thin film 121 and a SiN thin film 122 deposited on the TiN thin film 121. Here, the TiN thin film 121 may be formed by an atomic layer deposition (ALD) method using a source containing titanium (Ti), and the SiN thin film 122 may be formed by an atomic layer deposition (ALD) method using a source containing a compound having a plurality of silicon (Si) atoms.

[0029] Each of the TiN thin film 121 and the SiN thin film 122 is formed in a plurality of layers. At this time, the TiN thin film 121 may be formed in a plurality of layers between the substrate 110 and the SiN thin film 122, or between two layers of the SiN thin film 122. For example, as shown in FIG. 2, the TiN thin film 121 may be formed in three layers between the substrate 110 and the SiN thin film 122, or between two layers of the SiN thin film 122. Here, the TiN thin film 121 in a plurality of layers is formed by repeating an atomic layer deposition (ALD) cycle a plurality of times. In FIG. 2, the TiN thin film 121 deposited by each atomic layer deposition (ALD) cycle is shown as a plurality of layers in order to distinguish them from each other, but the stacked TiN thin films may be integral.

[0030] The SiN thin film 122 is formed between two layers of the TiN thin film 122, and may be formed as a single layer or multiple layers. The number of layers of the SiN thin film 122 may be smaller than the number of layers of the TiN thin film 121.

[0031] The process of forming the lower electrode 120 on the substrate 110 is a process cycle C of forming a TiN thin film 121 and a SiN thin film 122 on the substrate 110 as shown in FIG. p And process cycle C p That is, the process of forming the lower electrode 120 includes a plurality of process cycles C p :C p1 , C p2 , …, C pn-1 , C pn A plurality of process cycles C p :C p1 , C p2 , …, C pn-1 , C pn Each of the process cycles C includes a first cycle C1 for depositing a TiN thin film 121 and a second cycle C2 for depositing a SiN thin film 122. In other words, a plurality of process cycles C p :C p1 , C p2 , …, C pn-1 , C pn Each of the cycles includes a step of forming a TiN thin film 121 and a step of forming a SiN thin film 122. The step of forming the TiN thin film 121 includes a first cycle C1, and the step of forming the SiN thin film 122 includes a second cycle C2.

[0032] For ease of explanation, the following describes a plurality of process cycles C performed in sequence. p :C p1 , C p2 , …, C pn-1 , C pn For the first process cycle C p1 , 2nd process cycle C p2 , the (n-1)th process cycle C pn-1 , nth process cycle C pn Here, "n" may be the final process cycle. The final number (n) may vary depending on the target number of executions of the process cycle, which may vary depending on the target thickness of the bottom electrode 120 to be manufactured.

[0033] Process cycle C for forming the lower electrode 120 of the capacitor p The method includes a step of spraying a source containing titanium (Ti) and a reactant containing nitrogen (N) to form a TiN thin film, and a step of spraying a source containing silicon (Si) and a reactant containing nitrogen to form a SiN thin film, in which at least one of the source containing titanium (Ti) and the source containing silicon (Si) is sprayed multiple times.

[0034] Here, spraying at least one of the titanium (Ti)-containing source and the silicon (Si)-containing source multiple times means spraying the titanium (Ti)-containing source continuously in a pulse shape. When the titanium (Ti)-containing source is sprayed continuously in a pulse shape, there are cases where purge gas or other types of gas are not sprayed between the continuous sprays. In this case, spraying the source continuously may mean, for example, spraying the titanium (Ti)-containing source and spraying the purge gas in the order of titanium (Ti) source → titanium (Ti) source → titanium (Ti) source → ... → purge gas.

[0035] Spraying the source containing silicon (Si) multiple times means spraying the source containing silicon (Si) continuously in a pulse shape. When spraying the source containing silicon (Si) continuously in a pulse shape, there are cases where purge gas or other types of gas are not sprayed between the successive sprays. In this case, spraying the source continuously may mean spraying the silicon (Si) source → silicon (Si) source → silicon (Si) source → ... → purge gas when spraying the source containing silicon (Si) and spraying the purge gas.

[0036] Based on Figure 3, the process cycle C p Here, we will explain in more detail about the first process cycle C p1 This will be explained using the following example.

[0037] Referring to FIG. 3, the first process cycle C p1 includes a first cycle C1 for depositing a TiN thin film 121 and a second cycle C2 for depositing a SiN thin film 122. At this time, the first cycle C1 is carried out prior to the second cycle C2.

[0038] The first cycle C1 may include a step of spraying a first source containing Ti, a step of spraying a purge gas (first purge), a step of spraying a reactant, and a step of spraying a purge gas after stopping the spraying of the reactant (second purge). For example, a gas containing TiCl4 can be used as the first source containing Ti. And, a gas containing N, for example, a gas containing NH3 can be used as the reactant. And, Ar gas can be used as the purge gas. By the atomic layer deposition (ALD) method using such a first cycle C1, a TiN atomic layer, i.e., a TiN thin film 121 is deposited and formed.

[0039] Thus, the first cycle C1 for depositing the TiN thin film 121 is sometimes named the "TiN deposition cycle."

[0040] The second cycle C2 may include a step of spraying a second source containing a compound having a plurality of Si atoms, a step of spraying a purge gas (first purge), a step of spraying a reactant, and a step of spraying a purge gas after stopping the spraying of the reactant (second purge). At this time, a precursor containing a compound having a plurality of Si atoms and Cl atoms can be used as the second source. The second source may be liquid or gaseous.

[0041] For example, a precursor containing a Si2Cl6 (Hexachlorodisilane: HCDS) compound can be used as the second source. At this time, the Si2Cl6 (HCDS) compound contained in the second source contains a Si atom and a Cl atom, and the Si atom is multiple, i.e., two. Needless to say, as the second source, in addition to the above-mentioned precursor containing Si2Cl6 (HCDS), a precursor containing at least one of monochlorosilane (MCS: SiH3Cl), dichlorosilane (DCS: SiH2Cl2), trichlorosilane (TCS: SiHCl3), and hexachlorodisilane (HCDS: Si2Cl6) can be used.

[0042] The reactant and purge gas may be the same as those used in the first cycle C1. That is, the reactant may be a gas containing nitrogen (N), for example, a gas containing NH3, and the purge gas may be argon (Ar) gas. By the atomic layer deposition (ALD) method in the second cycle C2, a SiN atomic layer, i.e., a SiN thin film 122, is deposited.

[0043] Thus, the second cycle C2 for depositing the SiN thin film 122 may be named the "SiN deposition cycle."

[0044] Thus, in the embodiment, a precursor containing a compound having a plurality of Si atoms, for example, a precursor containing at least one compound selected from the group consisting of Si2Cl6 (HCDS), monochlorosilane (MCS:SiH3Cl), dichlorosilane (DCS:SiH2Cl2), trichlorosilane (TCS:SiHCl3), and hexachlorodisilane (HCDS:Si2Cl6), is used as the second source for depositing the SiN thin film 122. This makes it possible to improve the rate at which the SiN thin film 122 is deposited. That is, compared to the conventional case in which SiH4 (silane) gas is used as the source, the deposition rate of the SiN thin film 122 is improved when the second source as in the embodiment is used.

[0045] This may be because the gas made of a SiH4 compound (a Si monoatomic compound) which is a conventional source contains one Si atom, whereas the second source used in the embodiment contains a Si compound containing multiple Si atoms. That is, this may be because a compound containing multiple Si atoms, for example, a Si2Cl6 (HCDS) compound, has higher reactivity than a Si monoatomic compound, SiH4.

[0046] Furthermore, by increasing the deposition rate of the SiN thin film 122 as in the embodiment, the time required to deposit the lower electrode 120 to a target thickness can be reduced compared to the conventional method.

[0047] In an embodiment, in carrying out the first cycle C1 and the second cycle C2 as described above, one process cycle C p The number of times T1 of the first cycle C1 is adjusted to be greater than the number of times T2 of the second cycle C2. That is, the number of times T1 of the first cycle C1 is adjusted to be a plurality of times, and the number of times T2 of the second cycle C2 is adjusted to be smaller than the number of times T1 of the first cycle C1. In this case, the number of times T2 of the second cycle C2 may be adjusted to be a plurality of times according to the number of times T1 of the first cycle C1. In addition, when each of the first and second cycles C1 and C2 is adjusted to be a plurality of times, the first cycle C1 is continuously performed a plurality of times, and then the second cycle C2 is continuously performed a plurality of times.

[0048] In this case, the ratio (T1:T2) of the number of times T1 the first cycle C1 is performed to the number of times T2 the second cycle C2 is performed is adjusted to be 1:1 to 4:1 (T1:T2=1:1 to 4:1). More preferably, the ratio (T1:T2) of the number of times T1 the first cycle C1 is performed to the number of times T2 the second cycle C2 is performed is adjusted to be 3:1 to 4:1 (T1:T2=3:1 to 4:1).

[0049] As described above, the first cycle C1 may be named a “TiN deposition cycle,” and the second cycle C2 may be named a “SiN deposition cycle.” Therefore, the ratio (T1:T2) of the number of times T1 the first cycle C1 is performed to the number of times T2 the second cycle C2 is performed can be explained as the ratio (T1:T2) of the number of times T1 the TiN deposition cycle C1 is performed to the number of times T2 the SiN deposition cycle C2 is performed.

[0050] Also, the TiN deposition cycle may be named a “TiN thin film formation step”, and the SiN deposition cycle may be named a “SiN thin film formation step”. For this reason, it can be explained that the ratio (T1:T2) of the number of times the TiN thin film formation step is performed to the number of times T2 the SiN thin film formation step is performed is adjusted to 1:1 to 4:1, and more preferably, adjusted to 3:1 to 4:1.

[0051] In the following, for ease of explanation, the ratio (T1:T2) of the number of times the first cycle C1 is performed to the number of times T2 the second cycle C2 is performed will be abbreviated as the ratio (T1:T2) of the number of times the first and second cycles are performed.

[0052] For a more detailed explanation, a case where the ratio (T1:T2) of the number of times the first and second cycles are performed is 3:1 will be described with reference to FIG. 3. Referring to FIG. 3, a plurality of process cycles C p :C p1 , C p2 , …, C pn-1 , C pn Each of the cycles C1 and C2 may include a first and a second cycle, and in this case, the ratio (T1:T2) of the number of times the first and second cycles are performed may be 3:1.

[0053] More specifically, multiple process cycles C p :C p1 , C p2 , …, C pn-1 , C pnEach of the first process cycles C1 and C2 may include three first cycles C1 and one second cycle C2, as shown in FIG. p1 Taking the above as an example, the first cycle C1 is performed three times in succession. Therefore, three layers of TiN thin film 121 are deposited continuously on the substrate 110 as shown in FIG. 2. After three first cycles C1 are completed, the second cycle C2 is performed once. Therefore, a single layer of SiN thin film 122 is deposited on the TiN thin film 121. Then, as described above, after the first cycle C1 is performed three times in succession, the second cycle C2 is performed once, so the ratio (T1:T2) of the number of times the first and second cycles are performed is 3:1.

[0054] In this way, the first process cycle C p1 When the second cycle C2 is completed, the second process cycle C p2 At this time, the first process cycle C p1 The second process cycle C is carried out in the same ratio as the ratio of the number of times the first and second cycles were carried out (T1:T2 ratio). p2 It is preferable to carry out the second process cycle C. p2 When carrying out the above, the ratio of the number of times the first and second cycles are carried out (T1:T2) is set to 3:1.

[0055] Second process cycle C p2 When the second cycle C2 is completed, the next process cycle C is carried out in the same manner. p3 , …, C pn-1 , C pn At this time, as shown in FIG. 3, the process cycle is carried out until the target number of cycles (n) to be carried out.

[0056] FIG. 4 is a conceptual diagram for explaining a method for forming a lower electrode by a method according to a modification of the first embodiment.

[0057] In the first embodiment described above, the second source is sprayed once in the second cycle C2. However, the present invention is not limited to this, and the second source may be sprayed multiple times, for example, twice, as in the modified embodiment shown in FIG. 4. In other words, the second cycle C2 according to the modified embodiment of the first embodiment may be performed in the order of "first spraying of the second source-second spraying of the second source-spraying of the purge gas-spraying of the reactant-spraying of the purge gas". In this case, the second spraying of the second source may be performed with a time lag after the first spraying of the second source. In other words, the second source is sprayed in a pulsed manner. It is preferable to adjust the total amount of the amount sprayed during the first spraying of the second source and the amount sprayed during the second spraying of the second source to be the target spraying amount of the second source to be sprayed in one second cycle C2.

[0058] In the above example, the second source is sprayed twice. However, the second source may be sprayed more than twice, or after the final spray of the second source, the sequence of "spraying purge gas - spraying reactant - spraying purge gas" may be performed.

[0059] Fig. 5 is a diagram showing a lower electrode formed on a substrate by a method according to a second embodiment of the present invention, and Fig. 6 is a conceptual diagram for explaining a method for forming a lower electrode by a method according to a second embodiment of the present invention.

[0060] In the above-described first embodiment, a precursor containing a compound having a plurality of Si atoms, for example, a precursor containing a Si2Cl6(HCDS) compound, is used as a source for depositing the SiN thin film 122. That is, the SiN thin film 122 according to the first embodiment is a thin film deposited using a second source containing a compound having a plurality of Si atoms.

[0061] However, the present invention is not limited thereto, and the SiN thin film 123 may be deposited using a source (hereinafter, a third source) that contains Si atoms and is different from the second source. In this case, the second cycle C2 for depositing the SiN thin film 122 using the second source and the cycle for depositing the SiN thin film 123 using the third source are performed as separate cycles. For this reason, the cycle for depositing the SiN thin film 123 using the third source is named the third cycle C3.

[0062] Referring to FIG. 5, the bottom electrode 120 may comprise a TiN thin film 121 and SiN thin films 122, 123 deposited on the TiN thin film 121.

[0063] At this time, a part of the SiN thin films 122 and 123 is the thin film 123 formed by the third cycle C3, and the remaining part is the thin film 122 formed by the second cycle C2. Here, the third source used in the third cycle C3 may contain a Si monoatomic compound. More specifically, the third source may be a gas containing silicon (Si) and hydrogen (H), for example, silane (SiH4) gas. Therefore, a part of the SiN thin films 122 and 123 is the thin film 123 formed using the third source which is made of a SiH4 compound which is a Si monoatomic compound or a gas containing a SiH4 compound, and the remaining part is the thin film 122 formed using the second source which contains a gas containing a compound with multiple Si atoms, for example, a Si2Cl6 (HCDS) compound precursor.

[0064] The lower electrode 120 may be provided such that the number of layers of the SiN thin films 122 and 123 formed by the second and third cycles C2 and C3 is even smaller than the number of layers of the TiN thin film 121.

[0065] Referring to FIG. 6, process cycle C according to the second embodiment p :C p1 , C p2 , …, C pn-1 , Cpn includes a first cycle C1 for depositing a TiN thin film 121, and second and third cycles C2, C3 for depositing SiN thin films 122, 123.

[0066] Here, the first and second cycles C2, C3 are similar to those in the first embodiment described above, and therefore a description thereof will be omitted.

[0067] The third cycle C3 may include a step of spraying a third source which is a gas containing a Si monoatomic compound, a step of spraying a purge gas (first purge), a step of spraying a reactant, and a step of spraying a purge gas after interrupting the spraying of the reactant (second purge).

[0068] Here, as described above, a gas containing Si and H, i.e., SiH4 (silane) gas, can be used as the third source. Also, the reactant and purge gas can be the same gases as those used in the first and second cycles C1 and C2. That is, a gas containing N, e.g., a gas containing NH3, can be used as the reactant, and Ar gas can be used as the purge gas. By the atomic layer deposition (ALD) method in such a third cycle C3, a SiN atomic layer, i.e., a SiN thin film 123, is deposited.

[0069] Process cycle C including first to third cycles C1 to C3 p :C p1 , C p2 , …, C pn-1 , C pnIn carrying out the above steps, similarly to the first embodiment, the first cycle C1 is carried out first to deposit the TiN thin film 121, and then the second and third cycles C2 and C3 are carried out to deposit the SiN thin films 122 and 123. At this time, when depositing the SiN thin films 122 and 123, the third cycle C3 is carried out first, and then the second cycle C2 is carried out. In other words, after the SiN thin film 123 is deposited using a third source containing SiH4 (silane), the SiN thin film 122 is deposited using a second source containing a compound having multiple Si atoms. That is, in the third embodiment, the process cycle C is carried out in the order of "first cycle C1-third cycle C3-second cycle C2". p Do the following.

[0070] In addition, when the second and third cycles C2 and C3 are performed, the ratio (T2:T3) of the number of times T2 the second cycle C2 is performed to the number of times T3 the third cycle C3 is performed is adjusted to be 1:3 to 3:1 (T2:T3=1:3 to 3:1).

[0071] Here, since the second cycle C2 is performed after the third cycle C3, the third cycle C3 may be named a step of forming a first SiN thin film, and the second cycle C2 may be named a step of forming a second SiN thin film. Therefore, when forming a SiN thin film, it can be explained that the ratio (T2:T3) of the number of times T2 of performing the step of forming the second SiN thin film to the number of times T3 of performing the step of forming the first SiN thin film is adjusted to 1:3 to 3:1.

[0072] In performing the first to third cycles C1 to C3, the number of times T2 the second cycle C2 is performed and the number of times T3 the third cycle C3 is performed are summed to obtain a total number of times T 1+2 The ratio of the number of times T1 the first cycle C1 is performed to the number of times T2 2+3 ) is adjusted to 1:1 to 4:1, preferably 3:1 to 4:1.

[0073] For ease of explanation, in the following, the “ratio of the number of times T2 the second cycle C2 is performed to the number of times T3 the third cycle C3 is performed (T2:T3)” will be abbreviated to “the ratio of the number of times the second and third cycles are performed (T2:T3).”

[0074] In addition, "the total number T2 of the second cycle and the total number T3 of the third cycle" 2+3 The ratio of the number of times the first cycle is performed (T1:T 2+3 )" to "Number of times T 2+3 The ratio of the number of TiN deposition cycles T1 to T 2+3 )" and explains it.

[0075] For more specific explanation, based on FIG. 6, the number of times T 2+3 The ratio of the number of TiN deposition cycles T1 to T 2+3 ) is 3:1. Also, the ratio (T2:T3) of the number of times the second and third cycles C2, C3 are performed is 1:1. Therefore, the ratio of the number of times T1 the first cycle C1 is performed: the number of times T2 the second cycle C2 is performed: the number of times T3 the third cycle C3 is performed is T1:T2:T3=6:1:1.

[0076] Multiple process cycles C p :C p1 , C p2 , …, C pn-1 , C pn Each of the first process cycles C1 may include six first cycles C1 and one each of the second and third cycles C2 and C3, as shown in FIG. p1To explain this in more detail using the above as an example, first, the first cycle C1 is performed six times in succession. Therefore, as shown in FIG. 5, six layers of TiN thin films 121 are deposited continuously on the substrate 110. After six first cycles C1 are completed, the third cycle C3 is performed once. That is, atomic layer deposition (ALD) using a third source containing SiH4 (silane) is performed once. Therefore, a single layer of SiN thin film 123 is deposited on the TiN thin film 121.

[0077] When the third cycle C3 is completed, the second cycle C2 is performed once. That is, atomic layer deposition (ALD) is performed once using a second source including a precursor including a compound having a plurality of Si atoms, for example, a Si2Cl6 (HCDS) compound precursor. Thus, a SiN thin film 122 is deposited on the SiN thin film 123 deposited using a third source including SiH4 (silane), using a second source including a Si2Cl6 (HCDS) precursor.

[0078] In this manner, six first cycles C1, one third cycle C3, and one second cycle C2 are sequentially performed, and the next process cycle C is performed in the same manner. p2 , …, C pn-1 , C pn At this time, each process cycle C p2 , …, C pn-1 , C pn When carrying out the above, the ratio of the number of times T1, T2, and T3 of the first to third cycles C1 to C3 is made the same. That is, the ratio (T1:T2:T3) of the number of times T1 of the first cycle C1: the number of times T2 of the second cycle C2: the number of times T3 of the third cycle C3 is adjusted to 6:1:1. That is, in each process cycle C p :C p1 , C p2 , …, C pn-1 , C pn The number of SiN deposition cycles C2 and C3 performed in 2+3 The ratio of the number of TiN deposition cycles T1 to T 2+3The ratio of the number of times the second and third cycles C2 and C3 are performed in each process cycle (T2:T3) is adjusted to 1:1.

[0079] As described above, the first cycle C1 is a cycle for depositing the TiN thin film 122, and the second and third cycles C2, C3 are cycles for depositing the SiN thin films 122, 123. In the second embodiment, the first cycle C1, the third cycle C3, and the second cycle C2 are performed in this order. For this reason, the first cycle C1 may be named the "TiN deposition cycle", the third cycle C3 may be named the "first SiN deposition cycle", and the second cycle C2 may be named the "second SiN deposition cycle".

[0080] FIG. 7 is a conceptual diagram for explaining a method for forming a lower electrode by a method according to a third embodiment of the present invention.

[0081] In the first and second embodiments described above, a plurality of process cycles C p :C p1 , C p2 , …, C pn-1 , C pn However, the present invention is not limited to this, and multiple step cycles C p :C p1 , C p2 , …, C pn-1 , C pn Some of the may be implemented differently.

[0082] That is, the method for forming a lower electrode according to the third embodiment includes a first type TY1 process cycle using a third source as SiH4 gas and a second type TY2 process cycle using a source containing a compound precursor having a plurality of Si atoms, i.e., the second source, when depositing a SiN thin film. The first type TY1 process cycle and the second type TY2 process cycle are alternately performed multiple times.

[0083] First, the process cycle of the first type TY1 and the process cycle of the second type TY2 will be described.

[0084] The process cycle of the first type TY1 includes a first cycle C1 and a third cycle C2. That is, the process cycle of the first type TY1 includes a first cycle C1 for depositing a TiN thin film and a third cycle C3 for depositing a SiN thin film using a third source including SiH4. At this time, the ratio (T1:T3) of the number of times T1 the first cycle C1 is performed to the number of times T3 the third cycle C3 is performed is adjusted to be 1:1 to 4:1, preferably 3:1 to 4:1. That is, the ratio (T1:T3) of the number of times the first and third cycles are performed may be 1:1 to 4:1, preferably 1:1 to 4:1.

[0085] The second type TY2 process cycle includes a first cycle C1 and a second cycle C2. That is, the second type TY2 process cycle includes a first cycle C1 for depositing a TiN thin film and a second cycle C2 for depositing a SiN thin film using a second source containing a compound precursor having a plurality of Si atoms. In this case, the ratio (T1:T2) of the number of times the first and second cycles are performed may be 1:1 to 4:1, preferably 3:1 to 4:1.

[0086] Then, the process cycle of the first type TY1 and the process cycle of the second type TY2 are alternately repeated a plurality of times. p1 is the process cycle of the first type TY1. Therefore, as shown in FIG. 7, the first process cycle C p1 is carried out as the first type TY1, and the second process cycle C p2 is carried out as the second type TY2, and the third process cycle C p3 was carried out as the first type TY1, and the fourth process cycle C p4 is carried out as the second type TY2, and the (n-1)th process cycle C pn-1 is carried out as the first type TY1, and the n-th process cycle Cpn may be implemented as a second type TY2.

[0087] FIG. 8 is a conceptual diagram for explaining a method for forming a lower electrode by a method according to a modification of the third embodiment.

[0088] In the above-described third embodiment, the second cycle C2 in which the second source is sprayed and the third cycle C3 in which the third source is sprayed are performed in different process cycles.

[0089] However, the present invention is not limited thereto, and the second source and the third source may be sprayed simultaneously as in the modified embodiment shown in FIG. 8. That is, the second cycle C2 according to the modified embodiment of the third embodiment may be performed in the order of "spraying the second and third sources-spraying the purge gas-spraying the reactant-spraying the purge gas" as shown in FIG. 8. In this case, the second source and the third source may be stored separately and sprayed toward the substrate 110 simultaneously. Needless to say, the present invention is not limited thereto, and the second source and the third source may be mixed and stored, and the mixed gas may be sprayed toward the substrate 110.

[0090] In the above-mentioned first to third embodiments and modified embodiments, when depositing a SiN thin film, the second source containing a compound precursor having a plurality of Si atoms is used alone, or the second source is used in combination with a third source containing SiH4 (silane). However, the present invention is not limited to this, and a SiN thin film may be deposited using only a third source containing SiH4 (silane) without using a second source.

[0091] In such a case, process cycle C pcan be described as including a first cycle C1 for depositing a TiN thin film 121 and a third cycle C3 for depositing a SiN thin film using a third source including SiH4 (silane). In this case, the process cycle may not include the second cycle C2.

[0092] At this time, the third source spraying in the third cycle C3 may be performed multiple times, for example, twice. That is, the third cycle C3 may be performed in the order of "first spraying of the third source-second spraying of the third source-spraying of the purge gas-spraying of the reactant-spraying of the purge gas". At this time, the second spraying of the third source may be performed after the first spraying of the third source with a time lag. In other words, the third source is sprayed in a pulsed manner. It is preferable to adjust the total amount of the amount sprayed in the first spraying of the third source and the amount sprayed in the second spraying of the third source to be the target spraying amount of the third source to be sprayed in one third cycle C3.

[0093] FIG. 9 shows a bottom electrode formed on a substrate by a method according to an embodiment of the present invention.

[0094] In the above description, a description has been given of forming the lower electrode 120 for a capacitor on a flat substrate 110. However, the present invention is not limited thereto, and as shown in FIG 9, a capacitor may be manufactured by forming the lower electrode 120 on a substrate 110 having a trench 111 by the method according to the embodiment.

[0095] When the method according to the embodiment is used to form the lower electrode 120 on the substrate 110 having the trench 111, the step coverage is improved compared to the conventional method. That is, the thickness of the lower electrode deposited on the inner surface surrounding the trench 111, the thickness of the lower electrode deposited on the bottom surface, and the thickness of the lower electrode deposited on the upper surface outside the trench in the lower electrode 120 formed on the substrate 110 having the trench 111 are more uniform than the conventional method.

[0096] Another way to express step coverage (%) is the thickness of the deposition (TH t ) on the bottom surface of the trench 111 (TH t That is, the step coverage (%) may be calculated as a ratio of the thickness (TH b ) is defined as the thickness (TH t ) (see Equation 1).

[0097]

number

[0098] In terms of such step coverage, when the method according to the embodiment is used, the step coverage is further improved compared to the conventional method. That is, when the lower electrode 120 is provided by stacking a TiN thin film and a SiN thin film on the substrate 110 provided with the trench 111, the step coverage is further improved when the SiN thin film is deposited using a gas containing a compound having a plurality of Si atoms, for example, a gas containing a compound Si2Cl6 (HCDS) as a source as in the embodiment, compared to the conventional method of using SiH4 (silane) gas as a source. This is because the gas containing a compound having a plurality of Si atoms, such as Si2Cl6 (HCDS) gas, has higher reactivity than SiH4 (silane) gas, thereby improving the deposition rate of the SiN thin film 122.

[0099] FIG. 10 is a diagram showing a state in which a TiN thin film and a SiN thin film are laminated on a substrate provided with a trench by the method according to the second embodiment of the present invention.

[0100] Here, FIG. 10(a) shows the state where the first cycle C1 and the second cycle C2 of the first process cycle have been carried out, and FIG. 10(b) shows the state where up to the second cycle C2 has been carried out after the first and third cycles C1 and C2 have been completed.

[0101] When forming a lower electrode 120 on a substrate 110 having a trench 111 formed therein to provide a capacitor 100, the step coverage can be more effectively improved by forming the lower electrode 120 according to the second embodiment among the first to third embodiments.

[0102] This will be described in more detail with reference to FIGS. 6 and 10. In order to form the lower electrode 120 on the substrate 110 having the trench 111, first, a first process cycle C p1For this purpose, for example, the first cycle C1 is performed six times in succession as shown in Fig. 6. For this reason, six layers of TiN thin films 121 are deposited in succession on the substrate 110 as shown in Fig. 10(a).

[0103] After six first cycles C1 are completed, a third cycle C3 is performed once. That is, atomic layer deposition (ALD) is performed once using a third source containing SiH4 (silane). As a result, a single layer of SiN thin film 123 (hereinafter referred to as first SiN thin film 123) is deposited on TiN thin film 121. At this time, as shown in FIG. 10(a), the thickness TH of first SiN thin film 123 deposited on the upper surface of TiN thin film 121 outside trench 111 is 100 nm. t-sin1 In comparison, the thickness TH of the first SiN thin film 123 formed on the inner wall surface and bottom surface of the TiN thin film 121 surrounding the trench 111 is s-sin1 , T.H. b-sin1 is even thinner, which may be due to the slower rate at which SiH4 is deposited.

[0104] When the third cycle C3 is completed, the second cycle C2 is performed once. That is, atomic layer deposition (ALD) is performed once using a gas containing a compound precursor having a plurality of Si atoms, for example, a second source containing a Si2Cl6 (HCDS) compound precursor. Thus, a SiN thin film 122 (second SiN thin film 122) is deposited using a second source containing a Si2Cl6 (HCDS) precursor on a first SiN thin film 123 made of a SiH4 compound, which is a Si monoatomic compound, or deposited using a third source containing a SiH4 compound. At this time, the second SiN thin film 122 is formed in a region corresponding to the upper surface of the substrate 110 with a thickness TH t-sin2 In comparison, the thickness TH of the second SiN thin film 122 formed on the inner wall surface and bottom surface surrounding the trench 111 is s-sin2 , T.H. b-sin2 is thicker, which may be due to the slower rate at which SiH4 is deposited.

[0105] This is because the first SiN thin film 123 formed using SiH4 as a source prevents the second SiN thin film 122 formed from a gas containing a compound precursor having multiple Si atoms, for example, a second source containing a Si2Cl6 (HCDS) precursor, from being deposited on its surface. The first SiN thin film 123 is formed relatively thick on the upper surface of the substrate 110 and relatively thin on the inner side and bottom surface inside the trench 111. The larger the film thickness, the greater the force that prevents the deposition of the second SiN thin film 122 may be. In addition, the second source containing a compound precursor having multiple Si atoms can descend more quickly and easily to a deep location inside the trench 111, compared to the SiH4 compound gas containing one Si atom.

[0106] As a result, when the second SiN thin film 122 is deposited on the first SiN thin film 123, the second SiN thin film 122 is deposited on the upper surface of the first SiN thin film 123 with a relatively thin thickness TH t-sin2 Thus, the second SiN thin film 122 can be deposited relatively thickly on the inner side and bottom surface of the first SiN thin film 123 inside the trench 111.

[0107] The first process cycle C1, the third cycle C2, and the second cycle C3 are carried out in this order. p1 As shown in FIG. 10(b), when the above process is completed, the thickness of the thin film formed on the upper surface of the substrate 110 and the thickness of the thin film formed on the inner wall surfaces and bottom surface of the substrate 110 inside the trench 111 are the same or there is only a small difference between them.

[0108] Therefore, when the lower electrode 120 is formed by repeating such a process cycle multiple times, the lower electrode 120 having excellent step coverage can be provided.

[0109] Table 1 shows a summary of the results of calculating the step coverage when the lower electrode 120 is formed on the substrate 110 having the trench 111 by the method according to the comparative example and the first embodiment.

[0110] [Table 1]

[0111] For the experiment, two substrates 110 each having a trench 111 were prepared, and a lower electrode 120 was formed on one substrate 110 by a method according to a comparative example, and a lower electrode 120 was formed on the remaining substrate 110 by a method according to the first embodiment.

[0112] In both the comparative example and the first embodiment, the lower electrode 120 is formed by forming a TiN thin film 121 and a SiN thin film 122 on a substrate 110 by an atomic layer deposition (ALD) method. The comparative example and the first embodiment have the same ratio (T1:T2) of the number of times the first and second cycles are performed, which is 3:1. The comparative example and the first embodiment also use the same first source, purge gas, and reactant used in the first cycle C1 or the deposition of the TiN thin film 121. That is, the comparative example and the first embodiment use TiCl4 gas as the first source, NH3 gas as the reactant, and Ar gas as the purge gas.

[0113] At this time, in the comparative example and the first embodiment, other types of substances were used as the second source used in the second cycle C2 or the deposition of the SiN thin film 122. That is, in the comparative example, SiH4 (silane) gas was used as the second source, and in the first embodiment, a gas containing a Si2Cl6 (HCDS) precursor was used as the second source.

[0114] In the comparative example and the first embodiment, NH3 gas was similarly used as the reactant used in the second cycle C2 or in the deposition of the SiN thin film 122, and Ar gas was similarly used as the purge gas.

[0115] In addition, in the comparative example and the first embodiment, the number of times T1 the first cycle C1 was performed and the number of times T2 the second cycle C2 was performed were set to be the same, and the ratio of the number of times the first and second cycles were performed was set to be the same, 3:1.

[0116] The lower electrode was formed in this manner, and the step coverage was calculated using the following formula 1.

[0117] Referring to Table 1, the step coverage of the lower electrode formed by the method according to the first embodiment is higher than that of the lower electrode formed by the method according to the comparative example. This is because, in the comparative example, the SiN thin film 122 is deposited using SiH4 (silane) gas as a source, whereas in the first embodiment, the SiN thin film 122 is deposited using a gas containing a Si2Cl6 (HCDS) compound as a source, resulting in a deposition rate that is faster than that of the comparative example.

[0118] In the above, the lower electrode 120 of the capacitor is formed by the method according to the embodiment. However, the upper electrode 140 may be formed by the method according to the embodiment, or the lower electrode 120 and the upper electrode 140 may be formed by the method according to the embodiment.

[0119] As described above, in the embodiment, when forming at least one of the lower electrode 120 and the upper electrode 140 of the capacitor 100 by stacking the TiN thin film 121 and the SiN thin film 122, the SiN thin film 122 is deposited using a source containing a compound precursor having a plurality of Si atoms. This makes it possible to improve the deposition rate of the SiN thin film 122 and the step coverage of the thin film. [Industrial Applicability]

[0120] According to an embodiment of the present invention, when a TiN thin film and a SiN thin film are stacked to form at least one of a lower electrode and an upper electrode of a capacitor, the deposition rate of the SiN thin film can be improved and the step coverage of the thin film can be improved.

Claims

1. spraying a source containing titanium (Ti) and a reactant containing nitrogen to form a TiN thin film; A step of spraying a source containing silicon (Si) and a reactant containing nitrogen to form a SiN thin film; Including, A method for forming a capacitor electrode, comprising spraying at least one of the titanium (Ti)-containing source and the silicon (Si)-containing source multiple times.

2. 2. The method for forming a capacitor electrode according to claim 1, wherein the step of forming the TiN thin film and the step of forming the SiN thin film are carried out consecutively.

3. 3. The method of claim 2, wherein the step of forming the TiN thin film is performed more times in succession than the step of forming the SiN thin film.

4. The number of times the step of forming the SiN thin film is performed (T ２ The number of times the step of forming the TiN thin film is performed (T １ ) ratio (T １ :T ２ 3. The method for forming a capacitor electrode according to claim 2, wherein the ratio of the thickness of the electrode to the thickness of the capacitor is adjusted to 1:1 to 4:

1.

5. The silicon (Si)-containing source is a hydrogen (H)-containing silicon (Si) gas or a chlorine (Cl)-containing silicon (Si) precursor; or 2. The method of claim 1, wherein the mixed gas is a mixture of silicon (Si) gas containing hydrogen (H) and a silicon (Si) precursor containing chlorine (Cl).

6. The chlorine (Cl)-containing silicon (Si) precursor is hexachlorodisilane (HCDS:Si ２ C ６ ) or dichlorosilane (DCS: SiH ２ C ２ ) and The hydrogen (H)-containing silicon (Si) gas is silane (SiH ４ 6. The method of claim 5, further comprising:

7. The step of forming the SiN thin film includes: spraying silicon (Si) gas containing hydrogen (H) to form a first SiN thin film; spraying a silicon (Si) precursor containing chlorine (Cl) to form a second SiN thin film; The method for forming a capacitor electrode according to claim 5 , comprising:

8. 8. The method of claim 7, wherein a ratio of the number of times the step of forming the first SiN thin film is performed to the number of times the step of forming the second SiN thin film is performed is adjusted to be 1:3 to 3:

1.

9. 9. The method for forming a capacitor electrode according to claim 1, further comprising the step of blowing a purge gas between the steps of blowing different types of gases.

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