KR100578211B1 - Ferroelectric Capacitor Formation Method for Semiconductor Devices - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ferroelectric capacitor of a semiconductor device. In particular, after a large amount of nucleation sites are artificially formed on the surface of a metal lower electrode, a ferroelectric film is deposited to preferentially grow a randomly oriented perovskite nucleus to produce a ferroelectric film. It is the invention which improved the electrical characteristic. To this end, the present invention, in the method of manufacturing a ferroelectric capacitor, forming a randomly oriented metal lower electrode on a semiconductor substrate, electrons, on the surface of the metal lower electrode to generate a randomly oriented perovskite nucleus, Bombarding an ion or atomic group to form a nucleation site on the surface of the metal lower electrode, forming a ferroelectric film on the metal lower electrode on which the nucleation site is formed, and forming an upper electrode on the ferroelectric film A step is made.

Ferroelectric, c-axis orientation, random orientation, nuclear growth site

Description

TECHNICAL FIELD OF THE INVENTION Ferroelectric capacitor formation method of a semiconductor device {FABRICATING METHOD OF FERROELECTRIC CAPACITOR IN SEMICONDUCTOR DEVICE}             

1A to 1L are process cross-sectional views illustrating a capacitor manufacturing process according to an embodiment of the present invention;

* Description of the symbols for the main parts of the drawings *

10 substrate 11 device isolation film

12 gate electrode 13 spacer

14: first interlayer insulating film 15: bit line

16: second interlayer insulating film 17: conductive material for plug

18 barrier film 19 iridium film

20: iridium oxide film 21: platinum film

22: lower electrode 23: third interlayer insulating film

24: deposited ferroelectric film 24 ': crystallized ferroelectric film

25 upper electrode 26 fourth interlayer insulating film

27 metal wiring

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a ferroelectric capacitor of a semiconductor device, and more particularly, to a manufacturing method of improving electrical characteristics of a ferroelectric film by adjusting an orientation characteristic of a ferroelectric film.

The use of ferroelectrics in capacitors in semiconductor memory devices has led to the development of devices capable of using a large-capacity memory while overcoming the limitation of refresh required in DRAM (Dynamic Random Access Memory) devices.

Ferroelectric Random Access Memory (hereinafter referred to as 'FeRAM') using the ferroelectric is a nonvolatile memory device, which has the advantage of storing stored information even when the power is cut off. The operating speed is also comparable to DRAM, and is becoming a popular next-generation memory device.

Ferroelectrics applied to such FeRAM devices include (Bi _x , La _1-x ) ₄ Ti ₃ O ₁₂ (hereinafter BLT) and Bi ₄ Ti ₃ O ₁₂ (hereinafter BTO) SrBi ₂ Ta having a Perovskite structure. ₂ O ₉ (hereinafter SBT), SrBi ₂ (Ta ₂ O ₉ ) (hereinafter SBTN), Ba _x Sr _(1-x) TiO ₃ (hereinafter BST), Pb (Zr, Ti) O ₃ (hereinafter PZT) and The same ferroelectric is mainly used.

These ferroelectrics have hundreds to thousands of dielectric constants at room temperature and have two stable Remnant polarization (Pr) states, so that they are thinned and applied to nonvolatile memory devices.

Non-volatile memory devices using ferroelectrics adjust the direction of polarization in the direction of the electric field to store the digital signals '1' and '0' by the direction of residual polarization remaining when the signal is removed. Hysteresis characteristics are used.

Among the above-described ferroelectric thin films, BLT, BIT, BTO, SBT, SBTN, and PZT thin films have strong anisotropic properties. Therefore, when the anisotropic ferroelectric thin film is deposited on the metal lower electrode by the spin-on method and the appropriate heat treatment is performed in a subsequent process, a c-axis oriented perovskite nucleus is formed on the surface of the ferroelectric thin film. In addition, since a randomly oriented nucleus grows on the surface in contact with the metal lower electrode, a ferroelectric thin film mixed with c-axis orientation and random orientation is produced as a result.

However, most of the ferroelectric thin films tend to be oriented in the c-axis because the above-described heat treatment has a high probability of generating perovskite nuclei oriented in the c-axis. Since the ferroelectric thin film oriented in the c-axis is known to have poor electrical characteristics, there is a need for a method of improving the electrical characteristics of the ferroelectric thin film.

Disclosure of Invention The present invention has been made in view of the above-described problems, and an object thereof is to provide a method of manufacturing a ferroelectric capacitor in which a randomly oriented nucleus in a ferroelectric film is preferentially grown to improve electrical characteristics of the ferroelectric film.

In order to achieve the above object, the present invention provides a method of manufacturing a ferroelectric capacitor, the method comprising: forming a randomly oriented metal lower electrode on a semiconductor substrate, and forming the randomly oriented perovskite nucleus. Bombarding electrons, ions or atomic groups on the surface of the substrate to form nucleation sites on the surface of the metal lower electrode, forming a ferroelectric film on the metal lower electrode on which the nucleation sites are formed, and on the ferroelectric film Forming an upper electrode.

In the present invention, in order to preferentially grow randomly oriented nuclei over growth of c-axis oriented nuclei, a large amount of nucleation growth sites were artificially formed on the metal lower electrode surface.

That is, since the metal lower electrode such as platinum (Pt) has a property of randomly oriented itself, a randomly oriented perovskite nucleus is generated at an interface in contact with the metal lower electrode, and in the present invention, a large amount of nuclei are artificially produced. By forming a production site on the surface of the metal lower electrode, the randomly oriented perovskite nucleus is preferentially grown to improve the electrical characteristics of the ferroelectric thin film.

In the present invention, a large amount of nuclear growth sites are grown on the surface of the metal lower electrode by bombarding electrons, ions, radicals, and the like by using plasma on the surface of the metal lower electrode.

Therefore, since defect sites of grains and interfaces are rapidly increased, a large amount of randomly oriented perovskite nuclei could be formed. In addition, magnetron energy was used to accelerate electrons, ions, or atomic groups during bombaedment by the plasma or the like.

Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention.

1A to 1L illustrate a ferroelectric capacitor manufacturing process according to an embodiment of the present invention. The process until the ferroelectric film is deposited in the manufacturing process according to an embodiment of the present invention is similar to the prior art.

It demonstrates with reference to this point.

First, as shown in FIGS. 1A to 1B, an isolation layer 11 for defining an active region and a field region is formed in a predetermined region on the semiconductor substrate 10, and then a spacer ( A gate electrode 12 having 13 is formed.

Next, a first interlayer insulating film 14 is formed on the semiconductor substrate 10 including the gate electrode 12, and the bit line is connected to the semiconductor substrate 10 through the first interlayer insulating film 14. 15).

Next, after the second interlayer insulating film 16 is deposited on the first interlayer insulating film 14 including the bit line 15, the semiconductor layer penetrates through the first interlayer insulating film 14 and the second interlayer insulating film 16. A plug contact hole for exposing the substrate 10 is formed.

Subsequently, a plug conductive material 17 filling the plug contact hole is deposited on the second interlayer insulating film 16. As the plug conductive material 17, polysilicon, tungsten, titanium, or the like may be used.

Next, chemical mechanical polishing (CMP) is performed on the deposited plug conductive material 17 to planarize the surface and recess the plug conductive material into the plug contact hole. .

Subsequently, a barrier metal 18 is deposited on the recessed plug. The barrier metal is to prevent the oxidation source from penetrating and oxidizing the plug in a subsequent high temperature thermal process. In one embodiment of the present invention, titanium nitride (TiN) is used as the barrier metal.

In addition, a process of additionally forming titanium silicide (not shown) may be applied before depositing the titanium nitride film. In this case, the titanium silicide is formed through titanium deposition and heat treatment, and an etching process is performed to remove unreacted titanium after heat treatment. Thus formed barrier metal 18 is shown in Figure 1b.

Next, as shown in FIG. 1C, a process of forming a lower electrode is performed. In an embodiment of the present invention, a lower electrode having a structure in which a platinum film 21, an iridium oxide film 20, and an iridium film 19 is stacked is formed. 22) was used.

As described above, the lower electrode of the capacitor is applied to the stacked structure of platinum film (Pt) / iridium oxide film (IrOx) / iridium film (Ir), which reduces leakage current, prevents diffusion of oxygen or hydrogen, and prevents the upper and lower interlayers. This is to prevent the interdiffusion of materials.

In such a Pt / IrO _x / Ir stacked structure, the iridium film 19 located at the bottom serves to prevent oxygen diffusion, and the iridium oxide film 20 is a diffusion barrier that suppresses mutual diffusion between upper and lower materials. (Diffusion Barrier)

However, the iridium film (Ir) 19 located at the bottom of the stack structure used as the lower electrode 22 has a weak adhesive strength with the second interlayer insulating film 16 thereunder. Therefore, an adhesive layer made of Al ₂ O ₃ or the like may be formed at the interface between the iridium film 19 and the second interlayer insulating film 16.

In an embodiment of the present invention, a structure in which Pt / IrO _x / Ir is stacked as the lower electrode 22 is used. In addition, Pt, Ir, IrOx, Ru, RuOx, RuTiN, W, TiN, and WN may be used. The thickness of the lower electrode 22 is preferably 100 to 5000 kPa.

Next, as shown in FIG. 1D, a hard mask (not shown) such as a titanium nitride film is formed on the lower electrode 22 of the Pt / IrOx / Ir stacked structure, and the lower electrode 22 is formed using a hard mask. Isolate and isolate by bit.

Next, a third interlayer insulating film 23 is deposited on the second interlayer insulating film 16 including the lower electrodes 22 isolated as shown in FIGS. 1E to 1F, and the surface of the lower electrode is planarized. Expose

Next, a process for forming a nucleation site according to an embodiment of the present invention is performed. That is, in one embodiment of the present invention, the platinum film 23 used as the lower electrode has a property of randomly oriented itself.

Therefore, when depositing a ferroelectric film, a randomly oriented perovskite nucleus is generated at the interface with the platinum film 23. In the present invention, by artificially forming a large amount of nucleation sites on the surface of the platinum film, Perovskite nuclei were preferentially grown.

In one embodiment of the present invention by using a plasma energy (magnetron) or a magnetron (energy) on the surface of the platinum film (Pt) by bombarding (electron), ions (ion), atomic groups (radical), etc. A large amount of nuclear growth sites were grown on the surface of the platinum film (Pt).

When plasma energy is used, the power is 10 to 2000 Watts, and oxidizing gases such as O ₂ , N ₂ , N ₂ O, and H ₂ O ₂ are used as the plasma active gas. In addition, the pressure preferably has a range of 1 mTorr to 30 Torr, and the reaction temperature is set to 100 to 700 ° C.

In the case of forming nucleation sites using magnetron energy, an electric field was used.

Fig. 1G shows this nucleation site formation process.

Next, as shown in FIGS. 1H to 1I, ferroelectric films 24 such as SBT, SBTN, BIT, BLT, and PZT are deposited to a thickness of 80 to 5000 kV using various deposition methods.

As a method of depositing a ferroelectric film, a sputter method, a spin-on method, a liquid source mist chemical deposition (LSMCD) method, a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, and the like are used.

After the ferroelectric film 24 is deposited as described above, a thermal process for crystallization of the ferroelectric film 24 is performed, and FIG. 1I illustrates the ferroelectric film 24 'in the crystallized state.

The heat treatment for crystallization of the ferroelectric film applied in one embodiment of the present invention is carried out by a two-step heat treatment for nucleation and grain growth, the heat treatment for nucleation using rapid heat treatment at a temperature of 200 ~ 500 ℃ and oxidizing atmosphere Heat treatment for grain growth is carried out at a temperature of 600 ~ 1000 ℃, and in an oxidizing atmosphere. During such rapid heat treatment, the thermal ramp up rate is in the range of 35 ° C / sec to 200 ° C / sec.

After the ferroelectric film 24 is deposited as described above and the thermal process is performed, the upper electrode 25 is deposited on the ferroelectric film 24 as shown in FIG. 1J. In the present invention, Pt, Ir, Ru, IrOx, RuOx and the like are used as the upper electrode 25.

Next, as shown in FIG. 1K, the upper electrode 25 is etched and separated through a photolithography process and an etching process, and then a fourth interlayer insulating layer 26 covering the upper electrode 25 is deposited.

Next, as shown in FIG. 1L, the fourth interlayer insulating layer is selectively etched to form a metal contact hole, and then a first metal wiring 27 and metal 1 are formed.

As described above, the present invention is not limited to the above-described embodiments and the accompanying drawings, and the present invention may be variously substituted, modified, and changed without departing from the spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

When the present invention is applied, the electrical characteristics of the ferroelectric capacitor can be improved, so that a reliable and stable capacitor can be obtained and the yield is improved.

Claims (9)

In the method of manufacturing a ferroelectric capacitor, Forming a randomly oriented metal lower electrode on the semiconductor substrate; Bombarding electrons, ions, or atomic groups on the surface of the metal lower electrode using plasma energy to form randomly oriented perovskite nuclei to form nucleation sites on the surface of the metal lower electrode; Forming a ferroelectric film on the metal lower electrode on which nucleation sites are formed; And Forming an upper electrode on the ferroelectric film Ferroelectric capacitor manufacturing method comprising a. delete The method of claim 1, In the method using the plasma energy, Plasma power is a method of producing a ferroelectric capacitor, characterized in that 10 ~ 2000 Watt. The method of claim 1, In the method using the plasma energy, Method for producing a ferroelectric capacitor, characterized in that any one or more of O ₂ , N ₂ , N ₂ O, H ₂ O ₂ is used as the plasma active gas. The method of claim 1, In the method using the plasma energy, Plasma pressure is 1 mTorr ~ 30 Torr, the temperature is 100 ~ 700 ℃ characterized in that the ferroelectric capacitor manufacturing method. In the method of manufacturing a ferroelectric capacitor, Forming a randomly oriented metal lower electrode on the semiconductor substrate; Bombarding electrons, ions, or atomic groups on the surface of the metal lower electrode using magnetron energy to form a randomly oriented perovskite nucleus to form nucleation sites on the surface of the metal lower electrode; Forming a ferroelectric film on the metal lower electrode on which nucleation sites are formed; And Forming an upper electrode on the ferroelectric film Ferroelectric capacitor manufacturing method comprising a. The method of claim 1, Forming the ferroelectric film, A method of manufacturing a ferroelectric capacitor, using any one of BLT, BIT, BTO, SBT, SBTN, and PZT. The method of claim 7, wherein Forming the ferroelectric film, A method of manufacturing a ferroelectric capacitor, comprising using a sputter method, a spin-on method, a liquid source mist chemical deposition (LSMCD) method, a chemical vapor deposition (CVD) method, and an atomic layer deposition (ALD) method. The method of claim 1, Forming the metal lower electrode, Pt, Ir, IrOx, Ru, RuOx, RuTiN, W, TiN, WN using at least any one of the ferroelectric capacitor manufacturing method.

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