KR19980065708A - Manufacturing method of capacitor with ferroelectric film - Google Patents

Abstract

A method of manufacturing a capacitor having a ferroelectric film is disclosed. The method comprises the steps of forming a first conductive layer on a semiconductor substrate, forming an interlayer insulating film having a BC plug on the first conductive layer, and forming a three-component nitride, an oxygen diffusion barrier, and platinum diffusion on the entire surface of the resultant. And forming a ferroelectric film on the entire surface of the resultant product on which the platinum electrode is formed. Therefore, the electrode of the ferroelectric capacitor which is excellent in oxidation resistance and small in leakage current can be formed.

Description

Manufacturing method of capacitor with ferroelectric film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a capacitor having a ferroelectric film.

As semiconductor memory devices become more integrated, the cell area is also decreasing. The decrease in cell capacitance caused by the decrease of the cell area not only reduces the readability of the memory cell, increases the soft error rate, but also makes it difficult to operate the device at low voltage, resulting in excessive power consumption during device operation. do. Therefore, it is required to secure sufficient cell capacitance such that the operating characteristics of the memory cell are not degraded.

As a method for increasing the capacitance of a memory cell in a limited cell area, a method of thinning a dielectric film, a method of increasing an effective area of a capacitor, and a method of using a material having a high dielectric constant as a dielectric film may be used. Among these methods, when the thickness of the dielectric film is reduced to 100 μm or less, the reliability of the device is degraded due to the Fowler-Nodheim current, which makes it difficult to apply to a large-capacity memory device. In addition, the method of three-dimensional structure of the capacitor is accompanied by a complicated process for producing a three-dimensional capacitor, there is a disadvantage that can not increase the manufacturing cost. Accordingly, recently, a third method, a method of forming a dielectric film using a dielectric having a high dielectric constant (hereinafter referred to as a ferroelectric) has been proposed.

On the other hand, in order to use the ferroelectric as a dielectric film of a capacitor, an electrode material is important, and as an electrode material of a ferroelectric capacitor, precious metals such as platinum (Pt), ruthenium (Ru), and iridium (Ir), which are oxidation resistant and highly conductive, , Conductive oxides such as iridium oxide (IrO ₂ ) or ruthenium oxide (RuO ₂ ) have been studied. Platinum, which is widely used as an electrode of ferroelectric capacitors because of its excellent oxidation resistance, requires a barrier layer to prevent it because of its strong reaction property with polycrystalline silicon.

1 to 3 are process flowcharts for explaining a method of manufacturing a capacitor having a conventional ferroelectric film.

1 illustrates a process of forming the first conductive layer 10, the barrier layer 30, and the second conductive layer 40. First, a polycrystal doped with a first conductive layer 10, for example, an impurity on a semiconductor substrate. Silicon is formed to a predetermined thickness, and an interlayer insulating film 20 having a BC plug 15 filled with a predetermined conductive material is formed on the first conductive layer 10. Subsequently, a barrier layer 30 such as titanium nitride (TiN) is formed on the entire surface of the resultant, and a second thickness of the second conductive layer 40 such as platinum to be used as the first electrode of the capacitor is formed on the barrier layer 30. do.

FIG. 2 illustrates an etching process of the second conductive layer and the barrier layer. First, a photoresist pattern is formed on the second conductive layer through a process such as photoresist coating, mask exposure, and development. Is applied as an etch mask to sequentially pattern the second conductive layer and the barrier layer to form a patterned second conductive layer, that is, a first electrode 40 'of the capacitor.

3 illustrates a process of forming the dielectric film 50. First, the photoresist pattern is removed, and then a dielectric film 50, for example, a ferroelectric is formed on the entire surface of the resultant. The capacitor is then completed by forming the second electrode of the capacitor in a conventional manner.

Since the platinum electrode 40 'has a strong property of passing oxygen at a high temperature, when the ferroelectric film is sputtered, oxygen diffuses through the grain boundary of platinum to titanium nitride, which is a barrier layer, to the barrier. Titanium oxide, which is a low dielectric layer, is formed between the layer 30 and the first conductive layer, causing a decrease in the dielectric constant, resulting in poor ohmic contact.

In addition, the platinum electrode includes a soft erroe problem due to alpha emission, and has a problem that grain growth is induced at a temperature that forms a dielectric film.

The technical problem to be achieved by the present invention is to provide a method of forming an electrode of a ferroelectric capacitor having excellent oxidation resistance and low leakage current by sequentially forming a three-component nitride, an oxygen diffusion barrier, a platinum barrier, and a platinum electrode on a BC plug. It is.

1 to 3 are process flowcharts for explaining a method of manufacturing a capacitor having a conventional ferroelectric film.

4 to 6 are process flowcharts for explaining a method of manufacturing a capacitor having a ferroelectric film according to the present invention.

7 is a view illustrating a change in contact resistance according to heat treatment.

8A is an Ir / TiN / poly-Si structure and FIG. 8B is an AES depth profile after heat treatment at 700 ° C. in an Ir / TiSiN / poly-Si structure.

9A is a SEM photograph of an Ir / TiN / poly-Si structure.

9B is a view showing a TEM photograph of an Ir / TiSiN / poly-Si structure.

Explanation of symbols for the main parts of the drawings

10 ... 1st conductive layer 15 ... BC plug

20 ... interlayer insulation film 30 ... barrier layer

33 First barrier layer 34 Oxygen diffusion barrier

35.Platinum diffusion barrier 40.2nd conductive layer

40 '... platinum electrode 50 ... ferroelectric film

In order to achieve the above object, the present invention provides a method for forming a first conductive layer on a semiconductor substrate, forming an interlayer insulating film having a BC plug on the first conductive layer, and forming a three-component nitride and oxygen diffusion on the entire surface of the resultant. And forming a platinum electrode through the prevention film and the platinum diffusion prevention film, and forming a ferroelectric film on the entire surface of the resultant product on which the platinum electrode is formed.

Hereinafter, with reference to the accompanying drawings will be described the present invention.

The core of the present invention is to form an electrode of a ferroelectric film capacitor having excellent oxidation resistance and a small leakage current by sequentially forming a three-component nitride, an oxygen diffusion barrier, a platinum diffusion barrier, and a platinum electrode on a BC plug.

4 to 5 are process flowcharts for explaining a method of manufacturing a capacitor having a ferroelectric film according to the present invention.

FIG. 4 illustrates a process of forming the first conductive layer 10, the first barrier layer 33, the oxygen diffusion barrier layer 34, the platinum diffusion barrier layer 35, and the second conductive layer 40. On the semiconductor substrate, a first conductive layer 10, for example, polycrystalline silicon doped with impurities, is formed to a predetermined thickness, and the BC plug 15 filled with a predetermined conductive material on the first conductive layer 10, for example, Si, W, Ir , An interlayer insulating film 20 having a combination of one or more materials selected from the group of IrSix, Ru, and RuSix is formed. Subsequently, the first barrier layer 33 composed of three-component nitrides on the entire surface of the resultant material, for example, amorphous Ti-Si-N, or Ta-Si-N, or Ti-Al-N, or Ta-, having excellent oxidation resistance. Al-N is formed to a predetermined thickness, and on the first barrier layer 33, a combination of one or more materials selected from the group of oxygen diffusion barrier films 34 such as Ru, Ir, Rh, Os and platinum diffusion barrier film 35 For example, each of RuOx, IrOx, RhOx, OsOx, and a combination of one or more materials selected from the group to form a predetermined thickness, respectively. Subsequently, a predetermined thickness is formed on the platinum diffusion barrier film 35, for example, a second conductive layer 40 to be used as the first electrode of the capacitor.

5 illustrates an etching process of the second conductive layer, the platinum diffusion barrier, the oxygen diffusion barrier, and the first barrier layer. First, photoresist coating, mask exposure, and development are performed on the second conductive layer. After the photoresist pattern is formed, the pattern is applied as an etch mask to sequentially pattern the second conductive layer, the platinum diffusion barrier film, the oxygen diffusion barrier film, and the first barrier layer to form a patterned second conductive layer, that is, a capacitor. The first electrode 40 'is formed.

FIG. 6 illustrates a process of forming the dielectric film 50. First, the photoresist pattern is removed, and then the dielectric film 50, such as Ta ₂ 0 ₅ , SiO ₂ , SiN ₃ , SrTiO ₃ (STO), (Ba, Sr) TiO ₃ (BST), PbZrTiO ₃ (PZT), SrBi ₂ Ta209 (SBT), (Pb, La) (Zr, Ti) O ₃ , Bi ₄ Ti ₃ O ₁₂ , and the like, are formed to a predetermined thickness. The capacitor is then completed by forming the second electrode of the capacitor in a conventional manner.

As described above, Ir can easily form Ir oxide in an oxidizing atmosphere as compared with Pt, thereby stuffing the Ir grain boundary to prevent oxygen diffusion, thereby reducing the degree of oxidation of the barrier layer. When TiN is used as the barrier of the Ir electrode as shown in FIG. 7, even though a small amount of oxygen enters, TiN is oxidized to cause TiO _x N, resulting in a large contact resistance. This can be confirmed from the AES depth profile of the film heat-treated in the Ir / TiN / poly-Si structure of FIG. 8 (a). Ir prevents oxidation to some extent but diffuses a lot of oxygen throughout the thin film. We can confirm that it is. However, when amorphous Ti-Si-N having excellent oxidation resistance instead of TiN is used, the increase in contact resistance is very small even when a small amount of oxygen enters. This can be confirmed from the AES depth profile of the film heat-treated in the Ir / TiSiN / poly-Si structure of FIG. 8 (b). Ir almost prevents oxidation and traces of oxygen diffuse only at the interface of Ir / Ti-Si-N. We can confirm that it is. When the storage node is formed, the side of the barrier layer is exposed. When oxygen diffuses from the side and reaches the Si plug during the deposition of the ferroelectric film or during the heat treatment, the contact resistance increases.

In the case of TiN, since the structure is a columnar structure as shown in FIG. 9 (a), oxygen easily diffuses through the grain boundary to reach the Si plug and the contact resistance increases. However, since Ti-Si-N is amorphous as shown in FIG. 9 (b), oxygen does not penetrate into the grain boundary, so oxygen does not penetrate inside even if only the surface is oxidized, and oxygen in the sidewalls enters to increase contact resistance. I can solve it.

Claims (1)

Forming a first conductive layer on the semiconductor substrate; Forming an interlayer insulating film having a BC plug on the first conductive layer; Forming a platinum electrode having a three-component nitride, an oxygen diffusion barrier, and a platinum diffusion barrier on the entire surface of the resultant; And forming a ferroelectric film on an entire surface of the resultant product in which the platinum electrode is formed.