KR20030000655A - A fabricating method of capacitor - Google Patents

Abstract

PURPOSE: A method for fabricating a capacitor is provided to improve an electrical characteristic and yield by increasing the capacitance of a high dielectric capacitor and by reducing a leakage current. CONSTITUTION: A TiN lower electrode(15) is formed on a substrate(10) which has passed through a predetermined process. A TaN diffusion barrier layer(16b) is formed on the TiN lower electrode. A plasma treatment is performed to densify the TaN diffusion barrier layer. A Ta2O5 dielectric layer(17) is formed on the TaN diffusion barrier layer. An upper electrode(18) is formed on the Ta2O5 dielectric layer.

Description

A fabricating method of capacitor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a semiconductor device, and more particularly, to a method of forming a Ta ₂ O ₅ high dielectric film capacitor having a TaN diffusion barrier layer, in particular, a high dielectric film metal insulator metal (MIM) capacitor.

As the degree of integration increases in FeRAM (Ferroelectric Random Access Memory) devices or 1G DRAM (Dynamic Random Access Memory) class or higher semiconductor devices, capacitors that have high electrode capacity in a narrow space and less influence of leakage current are required. . For this purpose, oxide dielectrics such as BST, PZT, BLT, SBT, and SBTN are used.Noble metals such as Pt, Ru, and Ir, or their oxides, which have excellent electrical properties, are used as electrode materials. I got it.

On the other hand, when using precious metals such as Pt as the lower electrode, there is a problem in securing dielectric properties due to lattice constant mismatch with Perovskite oxide dielectrics such as BST, PZT, BLT, SBT, SBTN, etc. The high dielectric film having a perovskite or bismuth layered structure has a great problem in commercialization as a high dielectric film due to the instability of the material itself.

Accordingly, Ta ₂ O _{5, which} is 3 to 4 times higher than SiON having a dielectric constant of 25 or more and 7 or more, is currently used as a dielectric material of a capacitor in a cell in a high density device of 256M DRAM or more.

However, although Ta ₂ O ₅ has the above high dielectric properties, the following problems appear in the application to the actual capacitor structure. That is, in the subsequent heat treatment process for securing the dielectric constant of Ta ₂ O ₅ , a low dielectric constant film and a low dielectric film are formed through interfacial reaction with the lower electrode, and the total electrode capacity is greatly reduced by the series-connected capacitance structure.

Such a subsequent heat treatment is usually performed in parallel with a high temperature heat treatment such as an O ₂ plasma atmosphere or an ultraviolet-ozone (UV-O ₃ ) low temperature heat treatment and a furnace heat treatment or a rapid thermal process (hereinafter referred to as RTP). As the subsequent heat treatment progresses, the dielectric property of the Ta ₂ O ₅ thin film itself may be improved, but the interface with the lower thin film, for example, the lower electrode, is degraded. Therefore, the total electrode capacitance is reduced and leakage current is increased.

Thus, relatively within Although the use of oxidation resistance and excellent heat resistance TiN, etc. as a lower electrode material, since the situation does not completely inhibit the reaction between the lower electrode when proceeding the current phase, sikimyeo suppress the interface reaction to maximize the dielectric constant of Ta ₂ O ₅ Research continues to make this happen.

In particular, in order to suppress the interfacial reaction between the lower electrode and the Ta ₂ O ₅ dielectric layer, a metal electrode such as TiN or Ru having a high melting point is inevitably used as the lower electrode in the giga class or higher integrated memory device.

The present invention is to solve the problems of the prior art as described above, by using a TaN diffusion barrier film with the same Ta ₂ O ₅ source material on the TiN lower electrode to increase the interfacial adhesion, nano-crystalline (Nano-crystalline) The TaN diffusion barrier that has a compact structure and excellent heat resistance and oxidation resistance can effectively prevent oxidation of the lower electrode by oxygen diffusion, and Ta ₂ O having a TaN diffusion barrier that can increase the electrode capacity by reducing leakage current. to provide a unique conductive film capacitor _5, the method for forming it is an object.

1A to 1E are cross-sectional views illustrating a capacitor formation process according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: substrate

11: impurity junction layer

12: interlayer insulating film

13: plug

14: barrier film

15 TiN lower electrode

16b: TaN diffusion barrier

17: Ta ₂ O ₅ dielectric film

18 TiN upper electrode

In order to achieve the above object, the present invention, the first step of forming a TiN lower electrode on a substrate is completed a predetermined process; Forming a TaN diffusion barrier layer on the TiN lower electrode; Performing a plasma treatment to densify the TaN diffusion barrier film; Forming a Ta ₂ O ₅ dielectric layer on the TaN diffusion barrier layer; And a fifth step of forming an upper electrode on the Ta ₂ O ₅ dielectric layer.

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

First, the characteristics of TaN, which is a technical background of the present invention, will be described with reference to Table 1 below through comparison with TiN.

TiN TaN Melting point (℃) 3000 3400 Work function value (eV) 5.1 5.4 Grain size (Å) Tens to hundreds 30 to 40 Specific resistance value (uΩcm) Dozens To 200 Crystal structure NaCl NaCl Lattice parameter 4.33 4.24

As shown in Table 1, TaN film is a high melting point compared to the TiN film, the work function value is also large, the Ta ₂ O ₅ and the source material is the same, is used as the dielectric film - can be formed in situ and, Ta ₂ O Excellent leakage current characteristics at the interface in contact with ₅ . In addition, the nanocrystals having a grain size of about 30 GPa to 40 GPa can be effectively prevented from diffusion due to oxygen or the like due to the very dense crystal structure. Accordingly, the present invention uses TaN as a diffusion barrier between the TiN lower electrode and the Ta ₂ O ₅ dielectric layer to improve leakage current characteristics and electrode capacity by utilizing TaN as described above.

1A to 1E are cross-sectional views illustrating a capacitor forming process according to an embodiment of the present invention.

First, as shown in FIG. 1A, a capacitor TiN lower electrode 15 is formed on a structure in which a predetermined process is completed.

Specifically, an impurity junction layer 11 such as a source / drain is formed in the substrate 10 through ion implantation, and then a gate electrode (not shown) is formed, and then the planarized interlayer insulating film is formed over the entire structure. (12) and then selectively etch the interlayer insulating film 12 to expose the upper part of the impurity bonding layer 11 for storage contact, and then recessed inside the contact using polysilicon or the like. The plug 13 is formed. Subsequently, after forming the barrier layer 14 such as Ti, TiN, TiSi ₂ , and then depositing TiN, which is a lower electrode material, a planarization process such as chemical mechanical polishing (hereinafter referred to as CMP) is performed. The TiN lower electrode 15 is formed by removing the interlayer insulating film 12 or another insulating film on the interlayer insulating film 12.

Next, as shown in FIG. 1B, a thin TaN diffusion barrier layer 16a having a thickness of 10 μs to 50 μs is formed on the TiN lower electrode 15.

Hereinafter, the formation process of the TaN diffusion barrier layer 16a will be described in detail. The formation of the TaN diffusion barrier layer 16a includes PDEAT (Pentakis Diethyl Amino Tantalum), that is, Ta (N (C ₂ H ₅ ) ₂ ) ₅ as a source material. When the metal organic chemical vapor deposition method (hereinafter referred to as MOCVD) or atomic layer deposition (hereinafter referred to as ALD) is used, the reactivity is described as an example of using MOCVD. After injecting Ta (N (C ₂ H ₅ ) ₂ ) ₅ into the chamber using a small amount of inert gas such as He, Ne, Ar, or Xe as a carrier gas, the TaN diffusion barrier layer 16a was reacted with NH _{3 as} a reaction gas. ). At this time, the temperature in the chamber is kept at a low temperature of 200 ° C to 400 ° C, and the TaN diffusion barrier film 16a has an amorphous structure.

As next shown in Figure 1c, the TaN using a bar, NH ₃ gas plasma treatment in order to achieve a crystallized structure densified by a diffusion barrier (16a) is carried out under 200 ℃ to 400 ℃ temperature. Therefore, a dense TaN diffusion barrier film is formed as shown by reference numeral 16b.

Next, as shown in FIG. 1D, a Ta ₂ O ₅ dielectric film 17 having a thickness of 100 μs to 120 μs is formed on the TaN diffusion barrier 16b.

The Ta ₂ O ₅ dielectric film 17 is formed in substantially the same manner as the formation of the TaN diffusion barrier film 16b, using ALD or MOCVD using Ta (N (C ₂ H ₅ ) ₂ ) ₅ source material. The method using MOCVD will be described in detail as an example.

First, a first Ta ₂ O ₅ film having a thickness of 50 kPa to 60 kPa is formed on the TaN diffusion barrier layer 16b, and then a low temperature heat treatment is performed at a temperature of 200 ° C. to 400 ° C. for densification of the first Ta ₂ O ₅ film. To form a second Ta ₂ O ₅ film having a thickness of 50 kPa to 60 kPa.

The first and second Ta ₂ O ₅ film is formed by transporting the source gas into the chamber using an inert gas such as He, Ne, Ar, or Xe, and then reacting with O _{2 as} a reaction gas. It is carried out while maintaining a temperature of 200 ℃ to 400 ℃.

On the other hand, the heat treatment, O₂And N₂In the gas atmosphere Dense Ta by performing for 30 to 150 seconds₂O₅The dielectric film 17 may be formed.

Meanwhile, since the TaN diffusion barrier layer 16b and the Ta ₂ O ₅ dielectric layer 17 are made of the same source material, the TaN diffusion barrier layer 16b and the Ta ₂ O ₅ dielectric layer 17 are formed by an in-situ process in the same chamber. Not only can it be prevented, but also contains the same constituent elements, so that the adhesion between the two layers is quite excellent.

Next, as shown in FIG. 1E, the upper electrode 18, such as TiN, having a thickness of 400 μm to 1000 μm is formed on the Ta ₂ O ₅ dielectric layer 17. The formation process of the TiN upper electrode 17 is as follows. same.

First, a first TiN film having a thickness of 200 μs to 500 μs is formed on the Ta ₂ O ₅ dielectric layer 17 by using chemical vapor deposition (CVD). A second TiN film having a thickness of 200 mV to 500 mV is formed on the TiN film by using physical vapor deposition (PVD), and the formation of the first TiN film by CVD forms TiCl ₄ and NH ₃ . By carrying out the source gas at a temperature of 500 ° C. to 700 ° C., a capacitor including the TiN upper electrode 18 / Ta ₂ O ₅ dielectric film 17 / TaN diffusion barrier film 16b / TiN lower electrode 15 is completed. .

According to the present invention as described above, by using a TaN film as a diffusion barrier against oxygen between TiN and a dielectric film Ta ₂ O ₅ , oxidation prevention of the TiN lower electrode can be effectively prevented by the densified crystal structure of TaN, which leads to leakage current. It is possible to reduce the temperature, and to increase the total electrode capacity by performing a higher temperature heat treatment in the Ta ₂ O ₅ film forming process, which is a dielectric film, thereby increasing the Ta ₂ , a dielectric film at a level capable of maintaining the same electrode flux as before. The thickness of O ₅ can be adjusted upward, and the breakdown voltage of Ta ₂ O ₅ can be increased through the examples.

Meanwhile, in one embodiment of the present invention, a cylindrical capacitor structure is shown as an example, but the capacitor of the present invention may be applied to all capacitor structures such as concave or stacked types as well as the cylindrical type.

Although the technical spirit of the present invention has been described in detail according to a preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

According to the present invention, in the method of forming a capacitor, an increase in electrode capacity and a decrease in leakage current of the high-k dielectric capacitor can be achieved, and thus, an excellent effect of ultimately improving the electrical characteristics and yield of the device can be expected.

Claims (18)

In the semiconductor device manufacturing method, A first step of forming a TiN lower electrode on a substrate on which a predetermined process is completed; Forming a TaN diffusion barrier layer on the TiN lower electrode; Performing a plasma treatment to densify the TaN diffusion barrier film; Forming a Ta ₂ O ₅ dielectric layer on the TaN diffusion barrier layer; And A fifth step of forming an upper electrode on the Ta ₂ O ₅ dielectric layer Capacitor formation method comprising a. The method of claim 1, The formation of the TaN diffusion barrier layer in the second step, the method of forming a capacitor, characterized in that using any one of the metal organic chemical vapor deposition method or atomic layer deposition method using a Ta (N (C ₂ H ₅ ) ₂ ) ₅ source material. . The method of claim 2, When forming the TaN diffusion barrier layer of the second step, the capacitor forming method characterized in that using NH ₃ as the reaction gas. The method of claim 2, When the TaN diffusion barrier is formed in the second step, at least one of He, Ne, Ar, or Xe is used as a carrier gas. The method of claim 2, Formation of the TaN diffusion barrier layer of the second step, A capacitor formation method, characterized in that carried out at a temperature of 200 ℃ to 400 ℃. The method of claim 1, The TaN diffusion barrier is a capacitor forming method, characterized in that the thickness of 10 ~ 50Å. The method of claim 1, The plasma treatment of the third step, NH₃Using gas A method of forming a capacitor, characterized in that it is carried out at a temperature of 200 ℃ to 400 ℃. The method of claim 1, Formation of the Ta ₂ O ₅ dielectric film of the fourth step, Forming a first Ta ₂ O ₅ film on the TaN diffusion barrier layer using an organometallic chemical vapor deposition method; A seventh step of heat treatment for densification of the first Ta ₂ O ₅ film; And An eighth step of forming the Ta ₂ O ₅ makreul 2 on the first Ta ₂ O ₅ film using a 1 metal-organic chemical vapor deposition method Capacitor forming method comprising a. The method of claim 8, The Ta ₂ O ₅ film formation of the sixth and eighth steps, the Ta (N (C ₂ H ₅ ) ₂ ) ₅ source material and O ₂ reaction gas, characterized in that the capacitor formation method. The method of claim 9, In the sixth and eighth steps, the Ta ₂ O ₅ film is formed by using at least one of He, Ne, Ar, or Xe as a carrier gas. The method of claim 9, Ta of the sixth and eighth steps₂O₅Membrane formation, A capacitor formation method, characterized in that carried out at a temperature of 200 ℃ to 400 ℃. The method of claim 8, The first and second Ta ₂ O ₅ films have a thickness of 50 kPa to 60 kPa. The method of claim 1, Forming the Ta ₂ O ₅ dielectric film in the fourth step, the method of forming a capacitor, characterized in that the atomic layer deposition method using a Ta (N (C ₂ H ₅ ) ₂ ) ₅ source material. The method of claim 8, The heat treatment of the seventh step, O₂And N₂In the gas atmosphere Capacitor forming method characterized in that for 30 seconds to 150 seconds to maintain a temperature of 200 ℃ to 400 ℃. The method of claim 1, Forming the upper electrode of the fifth step, Forming a first TiN film on the Ta ₂ O ₅ dielectric layer by chemical vapor deposition; And A tenth step of forming a second TiN film on the first TiN film by using physical vapor deposition; Capacitor forming method comprising a. The method of claim 15, In the ninth step, the method of forming a capacitor, characterized in that using TiCl ₄ and NH ₃ as the source gas. The method of claim 15, The ninth step, the capacitor forming method characterized in that carried out at a temperature of 500 ℃ to 700 ℃. The method of claim 15, The first and second TiN films have a thickness of 200 mW to 500 mW.