KR20090033556A - Method of forming metal oxide - Google Patents

Abstract

A metal oxidation film deposition method is provided that the effect that the reliability and satisfaction to the semiconductor device become maximized can be brought. A metal oxidation film deposition method comprises the steps of: a step for absorbing the organometallic source in the surface of substrate it supplies the organometallic source(S1); a step for purging the organometallic source which is not absorbed(S2); a step for injecting plasma(S3); a step forming the metal oxide layer on the surface of substrate(S5); a step purging the oxygen inclusion source, which does not form the metal oxide layer the organometallic source and reaction by-product(S6).

Description

{Method of forming metal oxide}

The present invention relates to a method for depositing a thin film by an atomic layer deposition (ALD) method using a metal organic (MO) source, and more particularly to a metal oxide film deposition method for suppressing the generation of impurities and interfaces.

Silicon oxide film (SiO ₂ ) and silicon nitride film (SiNx) used in semiconductor devices have been used as gate oxide films and capacitor dielectric films for a long time due to their excellent thermal stability, insulation, dielectric property, and chemical resistance. However, since the dielectric constants of the silicon oxide film and the silicon nitride film are relatively low at 3.5 and 7.0, respectively, the thickness of the film must be made very thin in order to secure sufficient capacitance as the size of the semiconductor device is reduced. However, a problem arises in that the leakage current increases exponentially as the thickness of the silicon oxide film and the silicon nitride film decreases, and thus the silicon oxide film and the silicon nitride film cannot be used in a semiconductor device of high density.

As semiconductor devices have been highly integrated, scaling of gate oxide films has also been required. Even though the thickness thereof becomes thin due to scaling, it is required to maintain excellent electrical characteristics. In the case of the gate oxide film in the next 65nm class generation, a thickness of 10 to 15 mA is required. In this case, the silicon oxide film has a high leakage current of 1 A / cm ² or more, which causes deterioration of device performance.

In order to solve this problem, as a high-k material (high-k material) that can replace the silicon oxide film and silicon nitride film, tantalum oxide film (Ta ₂ O ₅ ), aluminum oxide film (Al ₂ O ₃ ), yttrium oxide film (Y ₂ A method using O ₃ ), a lanthanum oxide film (La ₂ O ₃ ), a titanium oxide film (TiO ₂ ), a zirconium oxide film (ZrO ₂ ), a hafnium oxide film (HfO ₂ ), and a ferroelectric BST has been proposed. In order to use the high-k material as a gate oxide film, it is necessary to deposit very thin and precisely, and to use as a capacitor dielectric film, an excellent step coverage is required.

However, advance deposition techniques such as chemical vapor deposition (CVD) cannot meet the demand for progressive thin films, and are capable of precisely controlling the thickness and content of ultra thin films or depositing reproducibly with uniformity of content throughout the film. There is a limit to this. Although the CVD scheme may be modified to provide a conformal film with advanced step coverage, CVD processes often require high process temperatures and result in incorporation of high impurity concentrations.

To meet the demand for advanced thin films, high dielectric constant materials must be deposited in an ALD manner. A typical ALD process is repeated several times with a cycle of supplying and purging the MO source, and supplying and purging the reaction gas for decomposition of the MO source. Since the thickness is controlled by the number of repetitions of the cycle, the thickness of the ultra-thin film can be accurately adjusted. In addition, it is possible to deposit at a lower temperature than the conventional deposition method, and has a high aspect ratio by a self-limiting mechanism by chemical adsorption, which is a process that is highly dependent on chemical adsorption and desorption characteristics on the substrate surface. There is an advantage in that a uniform thin film can be deposited on a pattern or a large area.

However, the ALD method has a disadvantage in that the deposition rate of the thin film is slower than that of the CVD method. In particular, the MO source has a very complex ligand, and impurities are generated when the reaction gas is adsorbed onto the metal ligand. It is easy and therefore unwanted interface is likely to occur. These interfaces and impurities are more problematic because they severely affect the characteristics of the device and are difficult to control.

The problem to be solved by the present invention is to provide a metal oxide film deposition method that suppresses the generation of impurities and interfaces.

Metal oxide film deposition method according to the present invention for solving the above problems, (a) supplying an organometallic source to adsorb the organometallic source on the surface of the substrate; (b) purging the unsorbed organometallic source; (c) supplying an oxygen-containing source to react with metal in the organometallic source adsorbed on the surface of the substrate to form a metal oxide film on the surface of the substrate; And (d) purging the oxygen-containing source, the organometallic source, and the reaction by-product not forming the metal oxide layer, further comprising a plasma injection process between the steps (b) and (c). It is done.

Additionally, the method may further include a plasma injection process after the step (d), wherein the purge using an inert gas is performed between the steps (b) and (c) and / or after the step (d). It may further comprise a step. At least one gas selected from the group consisting of Ar, N ₂ , Ne, Xe, H _2, and NH ₃ between the steps (b) and (c) and / or after the step (d) May be injected together with the plasma.

The oxygen-containing source is at least one selected from the group consisting of O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , N ₂ O, CH ₃ OH, C ₂ H ₅ OH, and C ₃ H ₇ OH. The plasma may be injected at the same time as the start of step (c) or in the middle of step (c). At least one selected from the group consisting of N ₂ , H ₂ and Ar may be further injected together with the oxygen-containing source.

According to the present invention, a high-k dielectric metal having the effect of reducing leakage current and improving the reliability of a device while maintaining capacitance by depositing a thin film thicker by the ratio of dielectric constant in the MOSFET instead of the conventional silicon oxide film. An oxide film can be deposited.

The ALD method provides the advantages of accurate thickness control and content control, uniformity and reproducibility of the entire film, and unlike the conventional method, plasma is injected to induce deposition between the substrate and the high-k metal oxide film during deposition. The problem caused by the interface and impurities can be solved. By solving this problem, various electrical characteristics of the device may be improved and reproducibility may be guaranteed, thereby maximizing reliability and satisfaction in use of the semiconductor device. Therefore, it is more suitable for highly integrated semiconductor devices.

The present invention can improve the device characteristics by suppressing the generation of interfaces and impurities during oxide deposition, particularly in semiconductor devices. Efficient application of the present invention is possible in the field of manufacturing next-generation nanometer-class semiconductor integrated devices according to the high speed and super integration of transistors, which are the core components of the device.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The embodiments described below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. In the drawings illustrating embodiments of the present invention, like numerals in the drawings refer to like elements.

First, the metal oxide film deposition method according to the present invention can be performed using a thin film deposition apparatus as shown in FIG.

The thin film deposition apparatus 100 of FIG. 1 is for depositing a thin film on a substrate w such as a silicon wafer seated on the wafer block 12 in the reactor 10.

Here, the thin film deposition apparatus 100 includes a reactor 10 through which thin film deposition is performed, and a gas supply device 20 for supplying an organometallic source, a reaction gas, and an inert gas to the reactor 10.

The reactor 10 may include a shower head 11 installed above the shower head in which an organometallic source, a reaction gas and an inert gas are injected, and a wafer block installed below the shower head 11 and on which the substrate w may be seated. 12) and a pumping baffle 13 installed at the outer periphery of the wafer block 12 for smooth and uniform pumping of the organometallic source, the reaction gas, the inert gas and the reaction by-product, and the inert gas at the outer periphery of the shower head 11. And a gas curtain block 14 for injection.

The organometallic source may be supplied into the reactor 10 in a bubbled form by Ar or He, which is an inert gas, and into the reactor 10 through a liquid delivery system (LDS) or a vaporization system. It may be supplied.

A heater 12a is built in the wafer block 12, and the heater 12a heats the substrate w in a range of 100 ° C. to 700 ° C. FIG. The pumping baffle 13 can ensure optimal thickness uniformity and composition of the thin film, and optimize the reaction space.

The gas curtain block 14 injects an inert gas toward the edge of the substrate w to control the compositional change of the edge of the substrate w. In addition, the inner wall of the reactor 10, specifically, the pumping baffle 13 is formed of an organic metal. Minimize contamination by sources.

The thin film deposition apparatus 100 may further include a remote plasma generator or a direct plasma generator (not shown).

2 is a flowchart of a metal oxide film deposition method according to an embodiment of the present invention. 3 is a gas pulsing diagram of a metal oxide film deposition method according to an embodiment of the present invention. A method of depositing a metal oxide film according to the present invention will be described with reference to FIGS. 1 to 3 as follows.

First, the substrate w on which the thin film is to be deposited is loaded into the reactor 10 of the thin film deposition apparatus 100. At this time, the substrate w is loaded while the natural oxide film or the like is removed through DHF cleaning (cleaning using a mixed solution of hydrofluoric acid and deionized water). The temperature of the substrate w is then preheated to a process temperature suitable for film deposition using a heater 12a installed in the reactor 10. At this time, the preheating of the substrate w is performed simultaneously with the exhaust from the reactor 10, and the pressure in the reactor 10 is maintained at 10 Torr or less. When the substrate w is raised to a desired process temperature, thin film deposition is started.

Referring to steps s1 and 3 of FIG. 2, the organometallic source is supplied into the reactor 10 while the substrate w is loaded inside the reactor 10. The organometallic source is chemically adsorbed on the surface of the substrate w and then physically adsorbed thereon. For example, to form hafnium oxide, HfCl ₄ , Hf (OtBu) ₄ , Hf (N (C ₂ H ₅ ) ₂ ) ₄ , TDMAHf (tetra dimethyl amino hafnium, Hf [N (CH ₃ ) ₂ ] ₄ ), TDEAHf (tetra inert using any one selected from diethyl amino hafnium, Hf [N (C ₂ H ₅ ) ₂ ] ₄ ), and TEMAHf (tetra ethyl methyl amino hafnium, Hf [N (C ₂ H ₅ ) CH ₃ ] ₄ ) It is supplied into the reactor 10 in a bubbled form by the gas Ar or He. Alternatively, the source stock solution may be diluted with a solvent such as n-butyl acetate, n-hexane, tetrahydrofuran, ethylcyclohexane, etc., and then changed into a gaseous state through a liquid feeder or a vaporizer.

Next, referring to steps s2 and 3 of FIG. 2, an inert gas purge gas is supplied into the reactor 10 to physically adsorb the organometallic source not adsorbed to the substrate w in the previous step s1. Remove the organometallic source. This is a step of purging the organometallic source, preferably by supplying an unreactive gas such as Ar or N ₂ . The purge step may be performed by pumping excess gas using a vacuum pump.

Thereafter, referring to steps s3 and 3 of FIG. 2, a plasma injection process peculiar to the present invention is performed. The plasma injection process injects an inert gas such as Ar, N ₂ , Ne, Xe, or H ₂ or a mixed gas such as NH ₃ containing the same together with the plasma, and removes metal from the organometallic source adsorbed onto the substrate (w). It will function to cleanly decompose the ligands.

3 illustrates an example in which plasma injection is started after the purge step S2 is terminated, but if the gas used in the plasma injection process is the same kind as in the previous purge, the purge gas is continuously supplied (that is, the purge state). This step can be performed by turning on the plasma power. Plasma injection may be by a remote plasma method or a direct plasma method according to the specification of the thin film deposition apparatus 100, the plasma applied is a low frequency of 300 ~ 500KHz and / or 13.56MHz ~ 21.12MHz at a power of 50 ~ 2000W It may be a high frequency of.

Next, a purge step of supplying a purge gas to discharge the decomposed ligands is performed (step s4 of FIGS. 2 and 3). This has the effect of removing impurities and ligands that cause interfacial generation from the reactor 10 in advance. 3 shows an example in which purge is started again after the plasma injection step S3 is finished, but if the gas used in the plasma injection process is the same type as in the purge, the plasma power is turned off while the purge gas is continuously supplied. This step can be performed by turning off.

Now to form a metal oxide film, O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , N ₂ O, CH ₃ OH, C ₂ H ₅ OH, and C as in steps s5 and 3 of FIG. 2. ₃ H ₇ the OH at least one of a metal oxide film on the surface of the injected gas is an oxygen containing source, a substrate (w) to the organic metal source in the metal and the reaction adsorbed on the surface of the substrate (w) of which is selected from the group consisting of Form. At least one selected from the group consisting of N ₂ , H ₂ and Ar may be further injected together with the oxygen containing source. Since the oxygen-containing source is adsorbed to the organometallic source from which the ligand is decomposed in the previous step s3, the metal oxide film is effectively formed.

Meanwhile, as shown in FIG. 3, the plasma can be injected into the reactor 10 at the same time as the step S3 at the same time as the injection of the oxygen-containing source. In this case, the plasma injection effect is the activation of the oxygen-containing source. The plasma injection in step s5 may be performed at the same time as the start of the injection of the oxygen-containing source, but may be performed in the middle of the start of the injection of the oxygen-containing source in a predetermined time.

Next, referring to step s6 of FIG. 2, an inert gas purge gas is supplied into the reactor 10 to form an oxygen-containing source that does not form a metal oxide film, an organometallic source, and CO, CO ₂ , Remove reaction by-products such as H ₂ O. This is also carried out as a purge step, preferably by supplying an unreactive gas such as Ar or N ₂ . It may also be carried out by pumping excess gas using a vacuum pump.

The above steps s1 to s6 perform one cycle, and a monolayer of HfO ₂ made of, for example, Hf-O is formed on the surface of the substrate w. Thus, the process consisting of steps s1 to s6 is 1 cycle, and it is determined whether a thin film having a desired thickness is deposited (step s9), and the cycle is repeated until the desired thickness is deposited to deposit a thin film. In this embodiment, two steps in one cycle may be deposited in a high quality thin film by the ALD method through different plasma injection processes (steps s3 and s5). That is, the first is to decompose the complex ligand of the organometallic source by injecting the inert gas with the plasma, and the second is to inject the oxygen-containing gas with the plasma to form the oxide film, thereby suppressing the generation of impurities and interfaces, excellent performance It is to deposit a metal oxide film for a high quality device having a.

Since the thin film formed by the above method is prevented from generating impurities and interfaces and is grown into a very dense film having a high step coverage, it may be variously applied in the manufacturing process of the highly integrated semiconductor device. For example, the hafnium oxide film formed by the above method may be constituted by a gate oxide film during MOSFET production. It may also be composed of a capacitor dielectric film at the time of capacitor formation on the substrate.

On the other hand, in the previous embodiment when the thin film is deposited using one organometallic source and an oxygen-containing source for the reaction of the organometallic source, that is, a single metal oxide (for example, HfO ₂ ) Although the deposition process has been described, the multi-component thin film may be formed using a first organometallic source (eg, Hf precursor) and a second organometallic source (eg, Si precursor), and an oxygen-containing source for reacting these organometallic sources. For example, even in the case of depositing HfSiO, a plasma injection step after the injection and purge of the organometallic source will correspond to a modification of the present invention.

4 is a gas pulsing diagram of a metal oxide film deposition method according to another embodiment of the present invention.

The process from steps s1 to s6 described with reference to FIG. 2 is the same, but as shown in FIG. 4, the plasma injection (step s7) peculiar to the present invention after step s6, that is, after the purge step is performed after supplying the oxygen-containing source (step s7). The difference is that it further includes a purge step (step s8) using an inert gas. That is, the process consisting of steps s1 to s8 is one cycle, and it is determined whether a thin film having a desired thickness is deposited (see step s9 of FIG. 2), and the thin film is repeatedly deposited until the desired thickness is reached. In this embodiment, the thin film of good quality can be deposited by the ALD method through the plasma injection process (steps s3, s5, s7) having three roles in one cycle. That is, the first is to decompose the complex ligand of the organometallic source by injecting the inert gas with the plasma, and the second is to inject the oxygen-containing gas with the plasma to form the oxide film, and the third is the inert gas once again. By injecting together with the plasma, the complex ligands of the organometallic source, which may have been left unremoved in the past, are removed, thereby more reliably suppressing the generation of impurities and interfaces, thereby creating a high-quality device having excellent performance.

Plasma injection in step s7 may also inject an inert gas such as Ar, N ₂ , Ne, Xe, H ₂ , or a mixed gas such as NH ₃ containing the same together with the plasma, even if the previous steps (s2 to s6) are performed. It is effective in removing ligands that could not be removed.

Although the detailed description of the present invention has been made, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the present invention. The invention is only defined by the scope of the claims.

1 is a schematic cross-sectional view of a thin film deposition apparatus capable of performing a metal oxide film deposition method according to the present invention.

2 is a flowchart of a metal oxide film deposition method according to an embodiment of the present invention.

3 is a gas pulsing diagram of a metal oxide film deposition method according to an embodiment of the present invention.

4 is a gas pulsing diagram of a metal oxide film deposition method according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10 ... reactor 11 ... showerhead

12 ... wafer block 12a ... heater

13 ... pumping baffle 14 ... gas curtain block

20 ... Gas Supply Unit ... Thin Film Deposition Equipment

Claims (7)

(a) supplying an organometallic source to adsorb the organometallic source on the surface of the substrate; (b) purging the unsorbed organometallic source; (c) supplying an oxygen-containing source to react with metal in the organometallic source adsorbed on the surface of the substrate to form a metal oxide film on the surface of the substrate; And (d) purging the oxygen-containing source, the organometallic source, and the reaction by-products that do not form a metal oxide layer, And a plasma injection process between the steps (b) and (c). The method of claim 1, further comprising a plasma injection process after the step (d). The method of claim 1 or 2, further comprising a purge step using an inert gas after the plasma injection process. The plasma injection process of claim 1 or 2, wherein at least one gas selected from the group consisting of Ar, N ₂ , Ne, Xe, H ₂ and NH ₃ is injected together with the plasma. Metal oxide film deposition method. The method of claim 1, wherein the oxygen-containing source is O ₂ , O ₃ , H ₂ O, H ₂ O ₂ , N ₂ O, CH ₃ OH, C ₂ H ₅ OH, and C ₃ H ₇ OH. Metal oxide film deposition method, characterized in that at least one selected. The method of claim 5, wherein the plasma is injected at the same time as the start of step (c) or in the middle of step (c). The method of claim 5, wherein at least one selected from the group consisting of N ₂ , H _2, and Ar is further injected together with the oxygen-containing source.

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