JPH09148252A - Sputtering target and sputtering method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering method whereby thin films of various compsn. can be easily formed. SOLUTION: A sputtering target for forming a thin film of a semiconductor element comprises a grounding center electrode 140, two or more insulation layers 10a-10c, each having a concentric shape and specified thickness, mutually different material-made inner target regions 130 which are insulated by these films 10a-10c and have flat surfaces, and outer target regions 120 having two or more concentric target regions having slopes. Thus, thin films of various compsn. can be easily obtained by applying different powers to conical-toroidal sputtering targets and the concentric target regions of the above described target.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target and a sputtering method using the same,
In particular, the present invention relates to a sputtering target capable of easily forming a thin film having various compositions and a sputtering method using the same.

[0002]

2. Description of the Related Art Due to high integration of semiconductor devices, many processes have been introduced in which the materials already used in the semiconductor devices are replaced with new materials or the composition of elements or the like forming the existing thin film is changed. Therefore, it is necessary to change the source gas used in the chemical vapor deposition process or the sputtering target used in the sputtering process.

Chemical Vapor Depositio
n: hereinafter referred to as CVD) is a step of forming a thin film on a semiconductor substrate by utilizing a chemical reaction that occurs after a compound in a gas state is decomposed. Since the CVD process is performed through a reaction of a gas drawn into the reaction chamber from the outside, it is distinguished from other semiconductor processes mainly targeting a substance on a semiconductor substrate. When a CVD process is used to form a thin film, the composition ratio of the deposited thin film can be easily adjusted by variously changing the conditions (temperature, pressure, etc.) of the reaction gas. However, in the CVD process, there is a limit to the development of reaction gas depending on the type of thin film, and the property of reaction gas may cause corrosion of the material before and after deposition.

The sputtering process basically begins by injecting an inert gas, eg, argon, into a vacuum chamber containing electrodes with a high voltage applied across it and then discharging. Argon changes to plasma state by discharge,
Argon ions (Ar +) and the like which compose the plasma are accelerated by an electric field and collide with a minus target.
Due to the exchange of momentum due to the collision, surface atoms of the target material are ejected to the outside, and the ejected atoms are deposited on the substrate to form a thin film.

The sputtering process is usually performed by a direct current discharge type sputtering (DC
), radio-frequency discharge type sputtering (RF sputtering), magnetron sputtering, reactive sputtering (Re
active sputtering). Among the above-mentioned sputtering methods, magnetron sputtering is the most widely used method in the current sputtering process because it enables rapid vapor deposition. In this method, a thin film of a compound is obtained by sputtering a metal target with.

In the case of using a sputtering process to form a thin film having two or more constituent atoms, generally, a composite target or a reactive sputtering in which the composition ratio is determined in advance considering the composition of the thin film. Should be used. However, it is difficult for the two sputtering methods to easily change the composition ratio of the thin film. When argon is used as the plasma generating gas in the sputtering process, the sputtering yield depending on the target material is shown in Table 1 (S. Wolf and RN Tauber, “Silicon Processi
ng "vol 1, 1986 Lattice Press p. 343), different properties are shown for each constituent atom.
Such a characteristic is the power (RF power) applied to the target.
We present the possibility that the composition of the thin film can be easily changed by changing er).

[0007]

[Table 1]

In Table 1, the energies of 100 eV to 2000 eV each represent a sputtering ion (Ar +), and the sputtering yield is defined by the number of surface atoms emitted for one incident ion having a given ion energy. It FIG. 1 is a plan view of a conventional conical-toroidal magnetron sputtering target, particularly showing a sputtering target in which a target material is separated into concentric regions by an insulating layer.

More specifically, the member number 40 is located at the center of the sputtering target, and the central electrode 10a plays a role of a ground for electric power applied to the target. First to make
Insulating layer, 30 is an insulating layer 10a surrounding the central electrode 40
Inner peripheral surface of the inner target region having a flat surface, 10b is a second insulating layer surrounding the outer peripheral surface of the inner target region 30, and 20 is a peripheral surface of the second insulating layer 10b. An outer target region having a surface, 10
Reference character c denotes a third insulating layer that surrounds the outer peripheral surface of the outer target region 20 to insulate it from the outside.

Here, the central electrode 40 is made of stainless steel so as to serve as a ground for electric power applied to the inner target region 30 and the outer target region 20. In addition, the outer target region 2
0 and the inner target region 30 correspond to the second insulating layer 10
Since they are separated by b, different powers can be applied to the outer target region 20 and the inner target region 30, respectively. Generally, the outer target region 2
0 and the inner target region 30 are made of the same material.
Therefore, when it is desired to form a thin film having two or more kinds of elemental compositions, a composite target having a desired composition ratio may be ordered and used in advance for the inner and outer targets, or the thin film may be formed. A method using a reactive sputtering process depending on a material is mainly adopted.

However, according to the above method, the deposited thin film, for example, TiSi _2.4 , GeSi, TiN, etc., shows only a composition in which the ratio between constituent atoms is constant, so that it is difficult to change the composition ratio of the thin film in various ways.

[0012]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a sputtering target which can easily form thin films having various compositions in thin film formation of semiconductor devices. Another object of the present invention is to provide a sputtering method capable of easily forming thin films having various compositions by using the target.

[0013]

In order to achieve the above-mentioned object, the present invention provides a sputtering target for forming a thin film of a semiconductor device, wherein a center electrode for ground and a predetermined thickness concentric with the center electrode are provided. And two or more insulating layers formed in a toroidal shape, and substances having different components that are respectively insulated by the two or more insulating layers,
A conical-toroidal sputtering target is provided, wherein the plurality of inner target regions have a flat surface and the plurality of outer target regions comprise two or more concentric target regions having inclined surfaces. .

In order to achieve the above other object, the present invention provides
A step of injecting an inert gas into a vacuum chamber including electrodes to which a high voltage is applied to both ends, a step of discharging the inert gas into a plasma state, and a cation forming the plasma are mixed. And a step of applying different electric powers to the respective constituent regions of a sputtering target having two or more concentric target regions made of different components to collide with the concentric target regions. To do.

The two or more concentric targets may be composed of only two inner and outer target regions, and the inner target may be germanium and the outer target may be silicon and may be sputtered. Also,
In the method for forming a thin film of a semiconductor device using the conical-toroidal sputtering target, a reactive gas may be injected to perform sputtering as a reactive sputtering process.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a cross-sectional view showing a sputtering target according to an embodiment of the present invention, and in particular, a sputtering target in which two target materials are separated into regions by an insulating layer.

Specifically, the member number 140 is located at the center of the sputtering target, and serves as a ground for the electric power applied to the target. 110a is a concentric region having a predetermined thickness centered on the center electrode 140. A first insulating layer 130, an outer peripheral surface of an insulating layer 110a surrounding the central electrode 140, an inner target region having a flat surface, and a second insulating layer 110b surrounding an outer peripheral surface of the inner target region 130. Layer, 120 is the second
An outer target region 110c that surrounds the outer peripheral surface of the insulating layer 110b and has an inclined surface, and 110c is the outer target region 1
A third insulating layer is shown, which surrounds the outer peripheral surface of 20 and insulates it from the outside.

Here, the central electrode 140 is made of stainless steel so as to serve as a ground for electric power applied to the inner target region 130 and the outer target region 120. In addition, the outer target region 120 and the inner target region 130 may be the second target region.
Since they are separated by the insulating layer 110b, different powers may be applied to the outer target region 120 and the inner target region 130, respectively.

In the present embodiment, the outer target region 12
0 and the inner target region 130 are made of different materials. Therefore, by adjusting the power applied to the inner and outer target regions of the sputtering target, thin films having various compositions can be easily obtained. FIG. 3 is a cross-sectional view of the sputtering target shown in FIG. 2, in which the outer target region 120 is an inclined surface and the inner target region 130 is a flat upper surface, and erosion due to sputtering occurs. .

4 to 6 are views showing the results of composition analysis of a Si-Ge thin film formed using a Si-Ge target according to an embodiment of the sputtering method of the present invention,
Germanium is used for the inner target region 130 and silicon is used for the outer target region 120, and the composition of the thin film deposited by applying different powers to each other is XPS (X-rsyPho).
2 is a diagram showing the results of analysis by toelectron spectroscopy for each power ratio. The power ratio is defined as (power of outer target) / (power of inner target). The thin film was deposited at a substrate temperature of 400 ° C. and a pressure of 7 m Torr. After the deposition, titanium was deposited on the Si-Ge thin film in connection with an experiment on a gate electrode. , Silicon and germanium. Titanium reacts with the Si-Ge layer after heat treatment, and 60 atomic fraction or more exists on the surface side.

On the other hand, the following Table 2 shows the relative atomic fraction of Ge to Si after completely etching titanium. The relative atomic fraction is 500 Å from the surface of the sample, that is, 400 seconds to 60 seconds on the graphs of FIGS. 4 to 6.
It was measured at 0 seconds.

[0022]

[Table 2]

According to Table 2 above, as the power ratio increases, Ge
It can be seen that the relative atomic fraction (Atomic%) with respect to Si decreases. Therefore, it can be seen that thin films having various compositions can be easily obtained by applying different powers to the outer and inner targets, respectively.

[0024]

As described above, according to the present invention, a central electrode for ground, a plurality of insulators for applying different powers to each target region, and a material having different components separated by the insulators. The conical-toroidal sputtering target is characterized by being composed of two or more concentric target regions each having different composition by applying different power to each target region (for example, Ti _x Si _y. , Ge _x Si _1-x , Ti _x N _y, etc.) can be easily formed.

The present invention is not limited to the above embodiments, and it is obvious that many modifications can be made by a person having ordinary skill in the art within the technical idea of the present invention.

[Brief description of the drawings]

FIG. 1 is a plan view of a conventional sputtering target.

FIG. 2 is a plan view of a sputtering target according to an embodiment of the present invention.

3 is a cross-sectional perspective view of the sputtering target shown in FIG.

FIG. 4 is a drawing showing the results of composition analysis of a Si—Ge thin film formed by an example of the sputtering method of the present invention.

FIG. 5 is a diagram showing a composition analysis result of a Si—Ge thin film formed by an example of the sputtering method of the present invention.

FIG. 6 is a drawing showing the results of composition analysis of a Si—Ge thin film formed by an example of the sputtering method of the present invention.

[Explanation of symbols]

 110a 1st insulating layer 110b 2nd insulating layer 110c 3rd insulating layer 120 Outer target area 130 Inner target area 140 Central electrode

Claims (7)

[Claims] 1. A sputtering target for forming a thin film of a semiconductor device, comprising: a central electrode for ground; and two or more insulating layers formed in a toroidal shape having a predetermined thickness concentric with the central electrode. Two or more concentric shapes, each of which has a different surface, each of which is insulated by the two or more insulating layers, the inner target regions have flat surfaces, and the outer target regions have inclined surfaces. A conical-toroidal sputtering target. 2. The conical-toroidal sputtering target according to claim 1, wherein the two or more concentric target regions are composed of only two inner and outer target regions. 3. The inner target is germanium,
The conical-toroidal sputtering target according to claim 2, wherein each of the outer targets is made of silicon. 4. A step of injecting an inert gas into a vacuum chamber including electrodes to which a high voltage is applied to both ends, a step of discharging the inert gas into a plasma state, and forming the plasma. And applying different electric power to the cations for each constituent region of the sputtering target having two or more concentric target regions having different components to collide with the concentric target regions. And a sputtering method. 5. The sputtering method according to claim 4, wherein the two or more concentric targets are composed of two inner and outer target regions. 6. The sputtering method according to claim 5, wherein the inner target region is made of germanium and the outer target region is made of silicon. 7. The sputtering method according to claim 4, wherein the sputtering is reactive sputtering by further injecting a reactive gas.