KR0150982B1 - Manufacture of semiconductor device - Google Patents

Abstract

A method of manufacturing a semiconductor device capable of depositing a high dielectric thin film at high speed is disclosed. The powder of high dielectric constant oxide is sintered in a vacuum atmosphere or a reducing atmosphere to prepare a target material having a specific resistance value capable of applying DC voltage, and then the target material is deposited on a semiconductor substrate by direct current sputtering to deposit a high dielectric constant. Form a thin film. A deposition rate of about 5 times or more can be obtained compared to the conventional RF method.

Description

Manufacturing method of semiconductor device

1 is a schematic view showing a method for producing a taget by a conventional method.

FIG. 2 is a schematic diagram showing a method for producing a taget by sintering powder of a high dielectric constant oxide in a reducing atmosphere according to a first embodiment of the present invention.

3 is a schematic diagram showing a method for producing a taget by attaching a titanium metal plate to promote a reducing atmosphere according to a second embodiment of the present invention.

4 is a graph showing a change in deposition rate with respect to applied power after RF and DC sputtering are carried out using targets respectively drawn by the conventional method and the method of the present invention.

5 is a cross-sectional view of a capacitor manufactured to investigate the electrical characteristics of the capacitor using the high-k dielectric thin film according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for depositing a high dielectric thin film at high speed.

As the integration of DRAM increases, many methods for increasing capacitance within a limited cell area have been proposed, which can be generally divided into three types. That is, (1) thinning of the dielectric film, (2) increasing the effective area of the capacitor, and (3) using a material having a high dielectric constant.

Among these, the first method is difficult to apply to large-capacity memory devices when the thickness of the dielectric film is reduced to 100 Å or less because the reliability is degraded by the Fowler-Nordheim current.

The second method has a disadvantage in that the process becomes complicated and the process steps are increased in order to manufacture a three-dimensional capacitor.

Therefore, in recent years, attempts have been actively made to planar capacitors using a third method, that is, oxides such as SrTiO ₃ , BaSrTiO ₃ , PZT, and PLZT as dielectric films. .

The high dielectric constant oxide is deposited by a metal organic chemical vapor deposition (hereinafter referred to as MO CVD) method or a sputtering method. However, in the case of the MO CVD method, since the precursor and the process, which are the gaseous raw materials of CVD, have not been completely developed, mass production of high dielectric constant oxides has been attempted by the sputtering method, which is relatively easier than the MO CVD method. .

As a method of injecting such a high dielectric constant oxide into a thin film by a sputtering method, a metal target obtained by alloying each constituent metal is, for example, a direct current discharge method in a reactive atmosphere of argon (Ar) and oxygen (O ₂ ). A method of obtaining a thin film by sputtering, and sintering an oxide having a composition similar to that of the film to be obtained to produce a solid target, followed by a radio-frequency discharge method. There is a method of obtaining a thin film.

The former metal target has the advantage of being able to be deposited at a high speed by sputtering by a relatively simple direct current method. However, since the difference in film composition obtained by the target composition is severe and the activity of the constituent metals (Ba, Sr, Ti, etc.) is strong, it is difficult to produce a uniform alloy target.

On the other hand, in the case of the latter oxide target, a small amount of reaction gas is additionally required, but there is an advantage in that there is almost no difference in composition with the obtained film composition and difficulty in preparing the target. However, the oxide target is generally sputtered by the RF method because of its high electrical resistance, and thus the deposition rate is lowered.

Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device capable of depositing high dielectric constant oxide at a high speed by sputtering.

In order to achieve the above object, the present invention comprises the steps of: sintering the powder of the high dielectric constant oxide in a vacuum atmosphere or a reducing atmosphere to prepare a target material having a specific resistance value capable of applying a DC voltage; And depositing the target material on the semiconductor plate by a direct current sputtering method to form a high dielectric thin film.

The high dielectric constant oxide is preferably any one selected from the group consisting of SrTiO ₃ , Ba _x Sr ₁ -xTiO ₃ , PZT and PLZT.

The reducing atmosphere is preferably an argon or hydrogen gas atmosphere, and in order to enhance the reducing atmosphere, it is preferable that the upper and lower portions of the high dielectric constant oxide powder are further provided with sintered titanium plates.

According to the present invention, a low-resistance oxide target obtained by artificially depleting oxygen by sintering powder of a high dielectric constant oxide in a vacuum atmosphere or a reducing atmosphere enables direct sputtering.

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

In order to explain the present invention more clearly, the conventional method of preparing a taget and the characteristics of the prepared taget are presented as comparative examples, and the method of preparing the taget according to the embodiments of the present invention and the prepared tagage This will be described in comparison with the characteristics of the network.

1 is a schematic diagram showing a conventional method for producing a target, and FIG. 2 is a method for producing a target by sintering powder of a high dielectric constant oxide in a reducing atmosphere according to a first embodiment of the present invention. It is a schematic diagram shown. 3 is a schematic diagram showing a method of producing a taget by attaching a titanium metal plate to promote a reducing atmosphere according to a second embodiment of the present invention.

[First Embodiment]

As a high dielectric constant oxide, for example, raw material powders such as SrTiO ₃ , Ba _x Sr ₁ -xTiO ₃ , PZT, and PLZT are compressed to an appropriate pressure to prepare powder. Subsequently, after placing the oxide powder on a holder in a heater, the heater is placed in a vacuum chamber. Next, the target is prepared by sintering the oxide powder at a high temperature of 1,000 ° C. or higher in a vacuum atmosphere or in an argon (Ar) gas atmosphere or in a reducing atmosphere of hydrogen (H ₂ ) gas (see FIG. 2). .

Second Embodiment

After preparing the powder of the high dielectric constant oxide in the same manner as in the first embodiment, a metal plate of about 1 mm thickness is attached to the upper and lower portions of the oxide powder in order to promote a reducing atmosphere. Subsequently, the taget is prepared by sintering the oxide powder having the titanium plate attached thereto at a high temperature of 1,000 ° C. or higher in a vacuum atmosphere or a reducing atmosphere (see FIG. 3). Here, the titanium plate is removed by mechanical processing after sintering the oxide powder.

[Comparative Example]

In the same manner as in the first embodiment, the high-gauge oxide powder is prepared by sintering at high temperature of 1,000 ° C. or higher in the air (see FIG. 1).

The resistivity values of the targets prepared by the comparative example and the methods of the first and second examples are shown in Table 1 below. Here, A represents the target of the comparative example, B represents the target by the method 2 of the first embodiment, and C represents the target by the method 1 or 3 of the first embodiment.

As can be seen in Table 1, the taget C prepared in a hydrogen gas atmosphere or a vacuum atmosphere has the lowest specific resistance value, and although not shown in Table 1, a taget attached to a titanium metal plate is used. It has a resistivity slightly lower than C.

4 shows RF and DC sputtering using 4 inch targets manufactured by the method of 2 and 3 of the comparative example and the first embodiment, and then the deposition rate for the applied power. A graph showing the change in. In the graph, A represents the target of the comparative example, B represents the target by the method ② of the first embodiment, and C represents the target by the method ① or ③ of the first embodiment.

As shown in FIG. 4, only the taget B · C manufactured in the reducing atmosphere is capable of DC sputtering. In the case of the target C, which has the lowest specific resistance, it has a deposition rate of 5 times or more at the same applied power as that of the target A, which is sputtered with RF.

5 is a cross-sectional view of a capacitor manufactured for investigating its electrical characteristics when a high-k dielectric thin film manufactured by high-speed deposition using direct current sputtering is used for the capacitor.

Referring to FIG. 5, an insulation layer is formed by growing silicon dioxide (SiO) having a thickness of 1,000 상 에 on a silicon substrate, and then an 80 Å thick titanium (Ti) layer and a 3,000 Å thick platinum ( The Pt) layer was sputtered in sequence to form the lower electrode of the capacitor. Subsequently, (BaSr) TiO is deposited to a thickness of 1,000 Å on the lower electrode by direct current sputtering to form a high dielectric thin film. Next, a platinum (Pt) layer having a thickness of 3,000 Å is formed on the high dielectric thin film as an upper electrode.

As a result of measuring the relative dielectric constant (εr) and the dielectric loss (tanδ) by using an LCR meter on the capacitor manufactured by the above-described manufacturing method, the following characteristics were excellent as a dielectric thin film of the capacitor.

As described above, according to the present invention, a high-resistance high-k oxide oxide target is obtained by sintering powder of the high-k oxide oxide in a vacuum atmosphere or a reducing atmosphere artificially to deplete oxygen, thereby enabling direct sputtering. do. Therefore, the high dielectric constant thin film can be obtained at a deposition rate of about five times or more than the conventional RF method by the direct current method sputtering.

In addition, when the high-k dielectric thin film obtained by high-speed deposition is adapted to a capacitor, excellent dielectric constant and dielectric loss can be obtained.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical idea of the present invention.

Claims (4)

Sintering the powder of the high dielectric constant oxide in a vacuum atmosphere or a reducing atmosphere to prepare a target material having a specific resistance value capable of applying DC voltage; And depositing the target material on the semiconductor substrate by a direct current sputtering method to form a high dielectric thin film. The method of claim 1, wherein the high dielectric constant oxide is any one selected from the group consisting of SrTiO ₃ , Ba _x Sr ₁ -xTiO ₃ , PZT, and PLZT. The method of claim 1, wherein the reducing atmosphere is an argon or hydrogen gas atmosphere. The method of manufacturing a semiconductor device according to claim 4, further comprising a titanium plate on the upper and lower portions of the high dielectric constant oxide powder.