KR100293722B1 - Capacitor manufacturing method having BST dielectric film formed from liquid organometallic raw material - Google Patents

Abstract

The present invention can improve the properties of the (Ba, Sr) TiO ₃ thin film used as the dielectric film of the capacitor, and can be formed of a liquid organic metal raw material which can be subjected to a thin film formation process at a relatively low temperature. Sr) TiO ₃ ) A method for manufacturing a capacitor having a dielectric film, wherein Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) ₂ and Ti (C ₆ H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ ) ₂ were used as the source, and a (Ba, Sr) TiO ₃ thin film was formed at a temperature of 350 ° C. to 500 ° C. It is characterized by forming.

Description

Capacitor manufacturing method having BST dielectric film formed from liquid organometallic raw material

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of semiconductor device manufacturing, and more particularly, to a method of manufacturing a capacitor having a biesti ((Ba, Sr) TiO ₃ ) dielectric film formed of a liquid organometallic raw material.

As the degree of integration of semiconductor devices increases, the lower electrode of the capacitor is formed in the form of a storage node in a device having a small cell size, such as a giga bit dynamic random access memory (DRAM), and a simple stack. In order to achieve a structure, an increase in area and a sufficient capacitance are used, and dielectric films such as SrTiO ₃ and (Ba, Sr) TiO ₃ are used.

In order to form a simple laminated structure, it is necessary to deposit a dielectric film by a metal organic chemical vapor deposition (MOCVD) method having excellent step coverage, and to suppress the oxidation and reaction between the lower electrode and the polysilicon plug. There is a need for a technique for depositing a dielectric film at low temperature for thermal stability of the diffusion barrier.

In general, (Ba, Sr) TiO ₃ dielectric film formation is performed by Ba (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₁₀ H ₂₂ O ₅ ), Ba (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₉₎ H ₂₃ N ₃ ), Sr (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₁₀ H ₂₂ O ₅ ), Ba (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₉ H ₂₃ N ₃ ), Ti (OC ₃ H ₇ ) ₂ (C ₁₁ H ₁₉ O ₂ ) ₂ , which is deposited at a substrate temperature of 400 ° C. to 500 ° C. in order to provide excellent step coverage.

However, the thickness and composition uniformity of the thin film formed on the substrate are not good under the deposition conditions using the organometallic raw materials as described above, and a 0.2 μm sized bump is generated on the surface and thus cannot be applied to the actual device. There are disadvantages. This phenomenon occurs because the reactivity and degradability between Ba, Sr, and Ti organometallic raw materials on the gas phase and the substrate are different, and there is a problem in that the characteristics cannot be improved under various conditions such as pressure and temperature. .

The present invention devised to solve the above problems can improve the characteristics of the (Ba, Sr) TiO ₃ thin film used as the dielectric film of the capacitor, and the liquid organic metal that can be fixed to form the film at a relatively low temperature SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a capacitor having a bis ((Ba, Sr) TiO ₃ ) dielectric film formed of a raw material.

1 to 5 are cross-sectional views of a capacitor manufacturing process of a semiconductor device according to an embodiment of the present invention.

6A is a SEM photograph showing a BST thin film surface formed according to the prior art.

Figure 6b is a SEM photograph showing the surface of the BST thin film formed in accordance with an embodiment of the present invention

* Explanation of reference numerals for the main parts of the drawings

1: semiconductor substrate 2: insulating film

3: polysilicon plug 4: Ti film

5: TiN film 6: upper electrode

7: (Ba, Sr) TiO ₃ film 8: upper electrode

10: Antioxidation pattern

According to another aspect of the present invention, there is provided a method of manufacturing a capacitor of a semiconductor device, the method comprising: forming a lower electrode of a capacitor; Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) _2, and Ti (C ₆ H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ ) ₂ , which are liquid organic metal raw materials, are formed on the lower electrode. A second step of forming a (Ba, Sr) TiO ₃ thin film by metal organic chemical vapor deposition (MOCVD) using as a source; And a third step of forming an upper electrode on the (Ba, Sr) TiO ₃ thin film.

The present invention provides liquid organometallic raw materials Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) ₂ and Ti (C ₆ ), which are liquid organometallic raw materials having similar reactivity and degradability between Ba, Sr and Ti organometallic raw materials. H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ ) ₂ is used as a source, and a (Ba, Sr) TiO ₃ thin film is formed under a temperature condition of 350 ° C. to 500 ° C.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention.

1 to 5 are cross-sectional views of a capacitor manufacturing process of a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG. 1, a contact hole for exposing the semiconductor substrate 1 is formed by selectively removing the insulating film 2 formed on the semiconductor substrate 1, and has a thickness of 500 kV to 3000 kV over the entire structure. A polysilicon film formed by chemical vapor deposition, and then etched the polysilicon film so that the polysilicon film remained only in the contact hole, thereby connecting the polysilicon plug to the lower electrode of the capacitor 1 3) form.

Next, as shown in Fig. 2, a Ti film 4 having a thickness of 100 mW to 1000 mW and a TiN film 5 having a thickness of 200 mW to 2000 mW are deposited on the entire structure, and the TiN film 5 and Ti are deposited. The film 4 is selectively etched to form the diffusion barrier pattern 10.

Next, as shown in FIG. 3, an Ir film having a thickness of 500 kPa to 5000 kPa is formed on the entire structure, and the bottom electrode 6 is formed by selectively etching the Ir film. In this case, the lower electrode 6 is formed to cover sidewalls of the diffusion barrier pattern 10.

Next, as shown in FIG. 4, Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) _2, and Ti (C ₆ H), which are liquid organic metal raw materials, are formed on the lower electrode 6. _{Using 12} O ₂ ) (C ₁₁ H ₁₉ O ₂ ) ₂ as a source, a (Ba, Sr) TiO ₃ thin film 7 having a thickness of 50 Pa to 500 Pa at a temperature of 350 ° C. to 500 ° C. was obtained by MOCVD. Form. Subsequently, plasma treatment using N ₂ O or O ₂ for 1 to 20 minutes at a temperature of 200 ° C. to 500 ° C. removes impurities such as carbon contained in the (Ba, Sr) TiO ₃ thin film 7 and At the same time improves crystallinity.

Next, as shown in FIG. 5, an Ir film having a thickness of 500 mV to 2000 mV is formed on the (Ba, Sr) TiO ₃ thin film 7 as the upper electrode 8. Subsequently, rapid thermal anneal or tubular anneal is performed for 1 to 60 minutes at a temperature of 400 ° C. to 1000 ° C. in a nitrogen, oxygen, N ₂ O or mixed gas atmosphere thereof.

In the above-described embodiment of the present invention, a Ta film, a W film, or a Zr film may be formed in place of the Ti film 4 forming the diffusion barrier pattern 10, and a TaN film may be substituted for the TiN film 5. , WN film, TiSiN film or TaSiN film may be formed. In addition, the lower electrode 6 and the upper electrode 8 may be formed of a Pt or Ru film.

FIG. 6A illustrates Ba (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₁₀ H ₂₂ O ₅ ) and Ba (C ₁₁ H ₁₉ O _{2 as} solid organic metal raw materials, according to a conventional (Ba, Sr) TiO ₃ dielectric film forming method. ) ₂ (C ₉ H ₂₃ N ₃ ), Sr (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₁₀ H ₂₂ O ₅ ), Ba (C ₁₁ H ₁₉ O ₂ ) ₂ (C ₉ H ₂₃ N ₃ ), Ti Scanning electron microscope (SEM) image showing the result of depositing (Ba, Sr) TiO ₃ dielectric film at a substrate temperature of 400 ℃ to 500 ℃ using (OC ₃ H ₇ ) ₂ (C ₁₁ H ₁₉ O ₂ ) ₂ 6b shows Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) ₂ and Ti (C ₆ H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ ) _{2 according} to the present invention. SEM image showing the result of depositing a (Ba, Sr) TiO ₃ thin film at a temperature of 350 ° C. to 500 ° C. Also from a comparison of Figure 6b and 6a, it can be seen that the present invention formed in accordance with (Ba, Sr) (Ba, Sr) becomes better than the uniformity of the TiO ₃ thin film, the surface uniformity of the TiO ₃ thin film formed according to the prior art.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

The present invention made as described above is a liquid organometallic raw material Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) ₂ And Ti (C ₆ H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ By using () ₂ as a source to form a (Ba, Sr) TiO ₃ thin film, it is possible to further improve the step coverage and to improve the thickness, uniformity and electrical properties of the thin film. In addition, the clogging phenomenon of the vaporizer generated when a solid raw material is dissolved in an organic solvent and used as a conventional method by using a liquid raw material can be solved. Thus, the reproducibility of the deposition process of (Ba, Sr) TiO ₃ thin film is improved. The reliability and yield can be improved.

Claims (10)

In the capacitor manufacturing method of a semiconductor device, Forming a lower electrode of the capacitor; Ba (C ₁₄ H ₂₅ O ₄ ) ₂ , Sr (C ₁₄ H ₂₅ O ₄ ) _2, and Ti (C ₆ H ₁₂ O ₂ ) (C ₁₁ H ₁₉ O ₂ ) ₂ , which are liquid organic metal raw materials, are formed on the lower electrode. A second step of forming a (Ba, Sr) TiO ₃ thin film by metal organic chemical vapor deposition (MOCVD) using as a source; And And a third step of forming an upper electrode on the (Ba, Sr) TiO ₃ thin film. The method of claim 1, The first step, Selectively etching an insulating film formed on the semiconductor substrate to form a contact hole exposing the semiconductor substrate; Forming a polysilicon film on the entire structure in which the contact hole is completed, and forming a polysilicon plug in the contact hole by etching the polysilicon film over the entire surface; Forming a diffusion barrier pattern connected to the polysilicon plug; And And forming the lower electrode surrounding upper and side surfaces of the diffusion barrier pattern. The method of claim 2, Forming the diffusion barrier pattern, Forming a first diffusion barrier layer using any one of a Ti film, a Ta film, a W film, or a Zr film on the entire structure of the polysilicon plug formation; Forming a second diffusion barrier layer on the first diffusion barrier layer using any one of a TiN layer, a TaN layer, a WN layer, a TiSiN layer, or a TaSiN layer; And And selectively etching the second diffusion barrier layer and the first diffusion barrier layer to form the diffusion barrier pattern. The method of claim 2 or 3, A method for manufacturing a capacitor of a semiconductor device, wherein the (Ba, Sr) TiO ₃ thin film is formed at a temperature of 350 ° C to 500 ° C. The method of claim 4, wherein A method for manufacturing a capacitor of a semiconductor device, wherein the (Ba, Sr) TiO ₃ thin film is formed to a thickness of 50 kV to 500 kV. The method of claim 4, wherein After the second step, The method of manufacturing a capacitor of a semiconductor device further comprising the step of performing a plasma treatment using N ₂ O or O ₂ for 1 to 20 minutes at a temperature of 200 ℃ to 500 ℃. The method of claim 4, wherein After the third step, The method of manufacturing a capacitor of a semiconductor device further comprising the step of heat treatment for 1 minute to 60 minutes at a temperature of 400 ℃ to 1000 ℃ in a mixed gas atmosphere containing oxygen and nitrogen. The method of claim 4, wherein A method for manufacturing a capacitor of a semiconductor device, wherein the lower electrode and the upper electrode are formed of any one of Ir, Pt, and Ru films. The method of claim 8, The lower electrode is formed to a thickness of 500 to 5000 Å, A capacitor manufacturing method for a semiconductor device, wherein the upper electrode is formed to a thickness of 500 kV to 2000 kV. The method of claim 9, The first diffusion barrier is formed to a thickness of 100 Å to 1000 Å, A method for manufacturing a capacitor of a semiconductor device, wherein the second diffusion barrier layer is formed to have a thickness of 200 GPa to 2000 GPa.