JP2001115257A - Manufacturing method for sputtering target material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially advantageous method of manufacturing for a titanium target material minimal in the occurrence of particles at film deposition. SOLUTION: Titanium is used as a stock, and plastic working is applied to the titanium under the conditions of >=5% draft and >=100%/s working rate. The average size of titanium crystal grains in the resultant sputtering target is <=4 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a sputtering target material, and more particularly, to a method for manufacturing a sputtering target material.
The present invention relates to a method for manufacturing a sputtering target material made of titanium. Hereinafter, in this specification, a sputtering target material is simply referred to as a target material.

[0002]

2. Description of the Related Art The quality of a thin film formed on a substrate by sputtering is affected by the roughness of the target material surface at the time of sputtering. When a protrusion having a certain size or more protrudes from the surface, abnormal discharge called micro arcing is likely to occur at the protrusion. When abnormal discharge occurs, giant particles scatter from the surface of the target material and adhere to the substrate, causing troubles such as uneven thickness of a thin film and short circuit of a semiconductor thin film circuit. Such giant particles are usually called particles or splats (hereinafter collectively referred to as particles).

The surface roughness of the target material has a correlation with the crystal grain size of the target material, and can be reduced by reducing the crystal grain size. Therefore,
By reducing the crystal grain size inside the target material, generation of particles can be prevented and a high-quality thin film can be formed.

[0004] Japanese Patent Application Laid-Open No. 11-50244 discloses that titanium is composed of titanium and has an average crystal grain size of 0.1-5.
A target material of μm has been proposed by the present applicant. This target material is manufactured by hydrogenating titanium, performing plastic working in a β-phase or (α + β) -phase crystal structure, and then performing dehydrogenation and heat treatment. Production methods involving hydrogenation and dehydrogenation are not necessarily industrially advantageous. Therefore, an industrially advantageous production method is desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an industrially advantageous method for producing a titanium target material with less generation of particles during film formation. is there.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that the conditions of plastic working employed in the production of a target material, specifically, the crystal grains can be reduced by simply selecting the working speed. And found that the above object can be easily achieved.

The present invention has been completed on the basis of the above-mentioned findings, and the gist of the present invention is that titanium
% And a processing speed of 100% / second or more.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, titanium is used as a material. Titanium is usually
A titanium ingot obtained by melting and casting a sponge-like titanium by a method such as vacuum metallurgy is used. In the present invention, the purity is from 99.99 to 99.99.
High purity titanium of 99% by weight (4N to 6N) is preferably used.

In the present invention, similarly to the known manufacturing method, plastic working is performed at a working ratio of 5% or more to adjust the crystal orientation content ratio. Plastic working refers to processing in which deformation such as rolling is applied to a material, and the deformation rate of the material at that time (rate of decrease in thickness)
Is called the processing rate. In the present invention, the upper limit of the working ratio is usually 90%.

The most important feature of the present invention is that the processing speed is 100%.
/ S / sec or more.
That is, the processing speed used when manufacturing the target material by plastic working is usually less than 100% / second, for example, about 20% / second, and the greatest feature of the present invention is higher than the conventional method. The point is that the adopted processing speed is adopted. By adopting such a processing speed, the heat treatment usually provided after the plastic working can be omitted, and the crystal grain can be adjusted (miniaturized) by the plastic working itself.

That is, the target material obtained by the manufacturing method of the present invention has an average particle size of titanium crystal grains of 4 μm or less and particles generated in a titanium thin film formed by sputtering, as shown in Examples described later. Has few features. The above processing speed is preferably 500
% / Sec or more, more preferably 1,000% / sec or more, and the upper limit is usually 10,000% / sec.

Preferably, the high-speed plastic working is performed a plurality of times. That is, it is preferable to perform the high-speed processing two or more times with intervening plastic working by pressurization from different directions (for example, the X-axis and Y-axis directions). For example, when a round bar-shaped material is used, high-speed plastic working (eg, forging) for widening with a low-speed plastic working (swing working plastic working) for stretching by pressing in the circumferential direction is applied. 2
Do more than once. In general, it is difficult to perform swaging-like plastic working at a high speed, and usually, it is performed at a low speed as described above.

Usually, the low-speed plastic working is performed by a hydraulic press,
The high-speed plastic working is performed by a hammer press.
In the case of a hammer press, the processing speed can be easily adjusted by changing the falling height of the iron hammer. The maximum number of high-speed plastic working is not particularly limited, but is usually 3 to 5 times.

In the present invention, the necessary performance as a target material is given to the material by the high-speed plastic working as described above. Therefore, the above-mentioned working rate (5% or more) is necessary for high-speed plastic working, and the working rate for low-speed plastic working can be arbitrarily selected.

In high-speed plastic working, the temperature of the raw material is increased by self-heating, but the temperature of the raw material (titanium) during the plastic working is preferably maintained at 400 ° C. or lower. When the raw material temperature exceeds 400 ° C., rapid crystal growth occurs, and it is difficult to obtain fine grains.

The average grain size of the crystal grains of the target material obtained by the production method of the present invention is usually 4 μm or less, preferably 2 μm or less.
μm or less, and the lower limit of warpage is usually 0.1 μm.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Examples 1 to 6 and Comparative Examples 1 to 5 As materials, diameter 150 mm, length 150 mm, purity 9
A round rod-shaped titanium ingot of 9.995% by weight was used. Then, first, the plastic working of (a) to (d) shown in the following table was performed as a set three times continuously. Next, following the above-described plastic working, plastic working (forging) for “spreading” is performed at a processing speed of 20% / sec to adjust the shape.
A 410 × 20 target material was obtained.

[0019]

[Table 1]

A hydraulic press was used for the low-speed plastic working for "stretching", and a hammer press was used for the high-speed plastic working for "spreading". The temperature of the material during the plastic working was about 300 ° C. due to self-heating.

(1) Measurement of average grain size of crystal grains: after polishing the surface of the above-mentioned target material with sandpaper, etching with hydrofluoric nitric acid, making a mirror surface by electrolytic polishing, and further etching with hydrofluoric nitric acid. The grain boundaries were exposed and photographed at 800 times magnification with an optical microscope. Then, the average particle size was measured by the quadrature method. Table 2 shows the results.

(2) Measurement of particles: A disk having a diameter of 250 mm and a thickness of 12 mm was cut out from the above-mentioned target material and set in a sputtering apparatus.
Gas pressure: 10 mmTorr, gas ratio: Ar / N2 = 1
/ 1, thickness: 50 nm, a TiN film was formed on a 6-inch silicon wafer. After the completion of the sputtering, the number of particles in the thin film formed on the silicon wafer was measured. To measure the number of particles, use a laser type particle counter (TENCOR)
Product "SF-642" manufactured by INSTRUMENTS
0 "), the number of particles having a diameter of 0.3 μm or more was measured. The average number of particles of 12 silicon wafers per particle was defined as the number of particles.

[0023]

[Table 2]

[0024]

According to the present invention described above, an industrially advantageous method for producing a titanium target material with less generation of particles during film formation is provided, and the industrial value of the present invention is remarkable.

Claims (4)

[Claims] 1. A method for producing a sputtering target material, wherein titanium is used as a raw material and plastic working of titanium is performed under conditions of a processing rate of 5% or more and a processing speed of 100% / sec or more. 2. The method according to claim 1, wherein the plastic working is performed a plurality of times. 3. The production method according to claim 1, wherein the temperature of the titanium during the plastic working is maintained at 400 ° C. or less. 4. The method according to claim 1, wherein an average particle size of the obtained titanium crystal grains of the sputtering target is 4 μm or less.