KR20170016090A

KR20170016090A - Metal sputtering target and method for manufacturing the same

Info

Publication number: KR20170016090A
Application number: KR1020150109415A
Authority: KR
Inventors: 김동욱; 홍길수; 양승호; 윤원규
Original assignee: 희성금속 주식회사
Priority date: 2015-08-03
Filing date: 2015-08-03
Publication date: 2017-02-13

Abstract

The present invention relates to a recycling sputtering target and a method of manufacturing the same, wherein the recycling sputtering target comprises a complex body in which a coarsening layer exists with a minimum thickness.

Description

Technical Field [0001] The present invention relates to a recycling sputtering target,

The present invention relates to a sputtering target used for forming a thin film of a semiconductor device and a method of manufacturing the same.

The sputtering target is used for forming a thin film in the production of a semiconductor device. When about 30% of the sputtering target is consumed in the thin film forming process, protrusions are formed at the boundary defined by the erosion and around the periphery.

If the sputtering operation is continued with the sputtering target in which the erosion or the selenium is generated, the formation of particles is increased, which causes deterioration of the physical properties of the thin film. Therefore, when the sputtering target is consumed by about 30% in general, there is a problem that the sputtering target is discarded and its use efficiency is very low.

In order to increase the efficiency of use of the sputtering target, there has been proposed a technique of separating a sintered body portion from a sputtering target (sputtering waste target) that has been used, filling a new sintered body with new powder, and then pressing and sintering the sputtering target to recycle the sputtering target have. However, in the sputtering target obtained by the above technique, crystal grains are coarsened at a portion (boundary surface) where the new powder and the sintered body are combined, and a thick crystal grain coordination layer is formed in the inside thereof. When a thin film is formed with a recycled sputtering target having such a thick crystal grain coarse layer, the deposition rate and uniformity of the thin film are lowered, resulting in a limit in obtaining a thin film having excellent physical properties.

Korean Patent Publication No. 2007-0106402

In order to solve the above problems, it is an object of the present invention to provide a recycling sputtering target capable of forming a thin film having excellent physical properties.

It is another object of the present invention to provide a method of manufacturing the recycling sputtering target.

In order to achieve the above object, the present invention provides a recycling sputtering target comprising a composite, wherein the composite is a sintered body obtained from a sputtering waste target and having a consumable part; A powder sintered layer formed by filling raw material powder on one surface of the sintered body in which the consumable part exists; And a crystal grain coarse crystal layer existing between the sintered body and the powder sintered layer, wherein the crystal grain coarse crystal layer has a thickness of 500 mu m or less.

(A) removing the backing plate from the sputtering waste target to obtain a sintered body having a consumable part; (b) filling a raw material powder on one surface of the sintered body in which the consumable part is present and pressurizing the isotropic pressure to produce a compact; And (c) pressurizing and sintering the compact to produce a composite. The present invention also provides a method for producing a recycled sputtering target.

Since the recycled sputtering target of the present invention includes a composite having a crystal grain coarsening layer of 500 탆 or less in thickness, a thin film having excellent physical properties can be formed when the thin film is formed.

In addition, the present invention includes a composite in which the thickness of the crystal grain boundary layer is minimized to 500 μm or less since the sintered body separated from the sputtering waste target is filled with a new powder and then subjected to cold isostatic pressing and pressure sintering to produce a recycled sputtering target And a sputtering target.

1 is a cross-sectional view showing a recycling sputtering target of the present invention.
2 is a flow chart showing a method of manufacturing the recycling sputtering target of the present invention.
3 and 4 are reference views for explaining Experimental Example 1 of the present invention.

Hereinafter, the present invention will be described.

1. Recycling Sputtering target

The recycling sputtering target of the present invention includes a composite in which the thickness of the crystal grain coarsening layer is minimized, and will be described in detail with reference to FIG.

The recycled sputtering target of the present invention comprises a composite 10 and the composite 10 includes a sintered body 11, a powder sintered layer 12 and a crystal grain coarsening layer 13.

The sintered body 11 included in the composite 10 is obtained from a sputtering waste target, and a consumable portion exists. That is, the sintered body 11 refers to the portion where the backing plate is removed from the used sputtering waste target.

The powder sintered layer 12 included in the composite 10 is formed by filling a raw powder on one surface of a sintered body 11 in which a consumable part exists. At this time, the raw material powder to be filled is not particularly limited, but is preferably the same as the material constituting the sintered body 11. Specifically, the sintered body 11 is made of tantalum (Ta), tungsten (W), molybdenum (Mo), ruthenium (Ru), silver (Ag), gold (Au), silicon (Si) Zirconium (Zr) or the like. In the case where the sintered body 11 is made of at least one of the metals, the raw material powder is made of the same components as those of the metal.

The crystal grain boundary layer 13 included in the composite 10 exists between the sintered body 11 and the powder sintered layer 12. Concretely, the crystal grain coordination layer 13 is present at the interface between the sintered body 11 and the sintered powder layer 12. The thickness of the crystal grain boundary layer 13 is 500 占 퐉 or less (preferably 350 占 퐉 or less), whereby the recycled sputtering target of the present invention can form a thin film having excellent physical properties. Here, the crystal grain boundary layer 13 may be defined as a layer formed of crystals having a crystal grain size of 200% or more of the average grain size formed in the sintered body 11 and the powder sintered layer 12.

The recycling sputtering target of the present invention may further include a backing plate 20 for supporting the composite 10. The backing plate 20 is bonded to the lower portion of the sintered body 11 included in the composite body 10. Due to such a coupling structure, the recycled sputtering target of the present invention has a powder sintered layer 12 included in the composite body 10 It becomes a consumption part consumed in forming a thin film.

2. Recycling Sputtering Target Manufacturing method

The present invention provides a method of manufacturing a recycling sputtering target as described above, which will be described in detail with reference to FIG.

(a) Backing Remove plate

First, the backing plate is removed from the sputtering waste target (the used sputtering target) to obtain a sintered body having a consumable part. The sintered body to be obtained here is not particularly limited, but is preferably a sintered body consumed at 20 wt% or more, preferably 30 to 35 wt%, based on the total weight of the sintered body. The method of removing (debonding) the backing plate is not particularly limited, but it is preferable to use a lathe and a machined M / C.

On the other hand, since impurities such as oxides and carbides may be present in the sintered body obtained, it is preferable that the sintered body is subjected to a washing process. The method of cleaning the sintered body is not particularly limited, but may be a chemical cleaning method such as cleaning with an acid, an alcohol and / or distilled water, an ultrasonic cleaning, a plasma surface cleaning, and a physical cleaning method using a CNC, MCT, A cleaning method, a method of performing a primary cleaning by a physical cleaning method, and a secondary cleaning by a chemical cleaning method.

When the physical cleaning method is applied, it is preferable to process the surface of the sintered body to within about 1 mm to remove impurities. Further, specific examples of the chemical cleaning method include a method in which a sintered body is put into nitric acid or aqua regia and then kept at room temperature or 100 ° C for about 1 hour, and then the system is subjected to one or more repetitions, followed by final washing with an organic solvent.

b) Cold Isotropic pressure Cold Isostatic Pressing (CIP)

A raw material powder is filled in one surface of the sintered body in which the consumable part is present, and the compact is pressed by cold isostatic pressing. Specifically, the sintered body is charged with the face having the consumable part facing upward, the raw powder is filled on the sintered body, the mold is closed with the upper mold punch, and a uniform pressure is applied to the molded body. Since the one-directional contraction occurs not in the isotropic shrinkage when cold isotropic pressing is performed using the metal mold, the present invention has a high molding density, a strong bonding force between the raw powder and the sintered body, It is possible to produce a molded article in which the thickness of the coarsening layer is minimized.

Generally, in order to bind raw material powders to the sintered body, raw material powders are more likely to bond with the sintered body than to form a new sintered region (powder sintered layer) due to agglomeration of the raw material powders. Therefore, It is required to control the bonding of the sintered body. If the control of the binding of the raw powder to the sintered body is not controlled, the raw powder is excessively combined with the sintered body which is already forming the crystal, and the abnormal grain is grown at the interface between the raw powder and the sintered body. And a thick crystal grain coordination layer is formed at the interface.

Accordingly, conventionally, a method of controlling the bonding of the raw powder and the sintered body to minimize the formation of the crystal grain coarse layer has been applied, but the method of pressurizing and sintering has been limited to minimize the formation of the crystal grain coarsening layer.

However, according to the present invention, before the pressure sintering, the raw material powder and the sintered body are put into a metal mold, and the compact is subjected to cold isostatic pressing under uniform pressure, so that the combination of the raw material powder and the sintered body is controlled, It is possible to minimize the formation of the crystal grain coarse crystal layer at the boundary surface.

The conditions under which the raw material powder and the sintered compact are pressurized by cold isostatic pressing are not particularly limited, but the pressure is preferably 200 MPa or more (specifically, 180 to 250 MPa) and the time is preferably 30 to 90 minutes.

(c) Pressure sintering

The compact is pressed and sintered to produce a composite. Specifically, the sintered body is put into a sintering furnace having an internal pressure of 5.0 x 10 < ^-4 > At this time, the pressure, temperature and time for pressure sintering are preferably adjusted according to the ingredients of the raw material powder and the sintered body.

(d) Hot Isostatic Pressing (HIP)

Meanwhile, the manufacturing method of the recycling sputtering target of the present invention may further include a step of subjecting the composite to hot isostatic sintering in order to increase the relative density. Specifically, the composite is sintered at a high temperature and a high pressure in the presence of an inert gas (for example, nitrogen, argon, etc.). When the composite is sintered by hot isostatic pressing, the inert gas, which is a pressure medium, maintains equal pressure so that the shape of the composite does not change during the sintering, and the pores existing in the composite due to high temperature and high pressure are minimized to obtain a composite having high density have.

The temperature at which the composite is sintered under hot isostatic pressing is not particularly limited, but it is preferable that the temperature is not higher than the temperature applied during the pressure sintering. If the temperature for hot hydrostatic sintering exceeds the pressure sintering temperature, the grain coarsening may proceed rapidly and the thickness of the grain coarsening layer may become thick. Specifically, the temperature at which the composite is sintered under hot isostatic pressing is preferably 1,400 to 1,900 DEG C, and the pressure and the time are preferably 90 to 200 MPa and 2 to 5 hours, respectively.

According to the present invention, a composite having a relative density of 99.0% or more and a thickness of a crystal grain boundary layer of 500 탆 or less can be obtained by subjecting to hot isostatic pressing.

The composite obtained through the above process may further be subjected to bonding and processing processes known in the art. Specifically, the composite is bonded (bonded) to a backing plate, processed to a required size, and the bead and arc treatment are performed on the backing plate surface. After that, the reclaimed sputtering target is manufactured through the cleaning and packaging process.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example One]

The tungsten sputtering waste target was processed with a CNC lathe to separate the backing plate from the tungsten sintered body in which the consumable parts were present, and then the tungsten sintered body was cleaned.

Next, the tungsten sintered body was placed in a molding die made of SKD material, the tungsten sintered body was filled with tungsten powder, and then a cold isotropic pressure was applied at a pressure of 250 MPa to form a molded body. The tungsten powder used had an oxygen content of 900 ppm, a carbon content of 70 ppm, a particle size of 5 μm and a purity of 99.998 wt%.

Then, the molded body was sintered at a temperature of 1,800 ° C. for 1 hour while applying a pressure of 20 MPa to prepare a tungsten composite having a relative density of 96%.

Finally, a tungsten composite with a relative density of 99.3% was prepared by sintering the tungsten composite by hot isostatic pressing at a temperature of 1,800 ° C under a pressure of 170 MPa for 2 hours.

[ Comparative Example One]

The tungsten powder used in Example 1 was hot pressed and sintered under hot isostatic pressure to prepare a tungsten sintered body. At this time, the hot press was performed under the condition of applying 20 MPa pressure at 1,800 ° C for 3 hours, and the hot isostatic pressing was performed under the condition of applying 170 MPa pressure at 1,800 ° C for 2 hours.

[ Comparative Example 2]

A tungsten composite was prepared in the same manner as in Example 1 except that the cold isostatic pressing was not performed (the tungsten composite was produced through the pressure sintering and the hot-pressing under a hydrostatic pressure sintering process).

[ Experimental Example One]

The crystal grains of the tungsten composites prepared in Example 1 and Comparative Example 2 were confirmed by an optical microscope, and the results are shown in FIG. 3 and FIG. 4, respectively.

The tungsten composite according to Example 1 of the present invention had a thickness of about 320 탆 (see Fig. 3) and a tungsten composite of Comparative Example 2 having a thickness of 880 탆 See Fig. 4).

[ Manufacturing example One]

The tungsten composite of Example 1 was indium-bonded to a 4in backing plate to prepare a recycled tungsten sputtering target.

[ Comparative Manufacturing Example 1 and 2]

A tungsten sputtering target was produced in the same manner as in Production Example 1, except that the tungsten sintered body of Comparative Example 1 and the tungsten composite of Comparative Example 2 were used instead of the tungsten composite of Example 1, respectively.

[ Experimental Example 2]

A tungsten thin film was formed by applying the recycled tungsten sputtering target of Production Example 1 and Comparative Production Example 2 and the tungsten sputtering target of Comparative Production Example 1 to a DC magnetron sputtering apparatus (Model: SME-200E) And a thin film was formed until it was consumed), and physical properties of the formed thin film were evaluated by the following methods, and the results are shown in Table 1 below. At this time, the substrate used for forming the tungsten thin film was a bare wafer, and the temperature of the substrate was room temperature. The film formation power was 2,200 W, and the amount of argon gas was fixed at 75 sccm. Then, a tungsten thin film was formed on the wafer to have a thickness of about 500 Å.

(1) Surface resistance: Measured by Four Point Probe Resistivity Measurement method using Four Point Probe.

(2) Uniformity: After measuring the thickness of the thin film at any five points, the deviation was calculated.

division Sheet resistance (Ω / ㅁ) Uniformity (%) Example 3.0 0.96 Comparative Example 1 3.0 1.02 Comparative Example 2 3.4 1.25

Referring to Table 1, it was confirmed that a thin film having a low sheet resistance and a high uniformity was formed by forming a thin film on the recycled tungsten sputtering target of Production Example 1 of the present invention. This supports the fact that when the thin film is formed into the recycled sputtering target of the present invention comprising a composite having a crystal grain coarse layer thickness of 500 탆 or less, a thin film having excellent physical properties is formed.

Claims

In a recycling sputtering target comprising a composite,
The composite may comprise:
A sintered body obtained from a sputtering waste target, the sintered body having a consumable part;
A powder sintered layer formed by filling raw material powder on one surface of the sintered body in which the consumable part exists; And
And a crystal grain coarse crystal layer existing between the sintered body and the powder sintered layer,
Wherein the thickness of the crystal grain coarse layer is 500 mu m or less.

The method according to claim 1,
Wherein the material constituting the sintered body and the raw material powder are the same component.

The method according to claim 1,
Wherein the crystal grain coordination layer is present at an interface between the sintered body and the sintered powder layer.

The method according to claim 1,
And a backing plate coupled to a lower portion of the sintered body.

(a) removing a backing plate from a sputtering waste target to obtain a sintered body in which a consumable part exists;
(b) filling a raw material powder on one surface of the sintered body in which the consumable part is present and pressurizing the isotropic pressure to produce a compact; And
(c) press-sintering the compact to produce a composite.

6. The method of claim 5,
(d) pressurizing the composite with hot isostatic pressing.

6. The method of claim 5,
Wherein the pressure for cold isostatic pressing is 200 MPa or more and the time is 30 to 90 minutes.