KR20150124391A - Material for sputtering target - Google Patents

Abstract

Provided is a material for a sputtering target which controls a sputtering rate. An aspect ratio of the crystalline structure for a sputtered surface of the material for the sputtering target is three or more.

Description

{MATERIAL FOR SPUTTERING TARGET}

The present invention relates to a sputtering target material, and more particularly to a sputtering target material containing molybdenum.

Conventionally, a sputtering target material is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-45066 (Patent Document 1), Japanese Patent Application Laid-Open No. 2007-113033 (Patent Document 2), Japanese Patent Laid-Open Publication No. 2013-32597 (Patent Document 3), Japanese Patent No. 4945037 (Patent Document 4), Japanese Patent Application Laid-Open No. 2000-234167 (Patent Document 5), Japanese Patent Laid-Open Publication No. 2013-154403 (Patent Document 6) Open Publication No. 2010-535943 (Patent Document 7), and Japanese Patent Laid-Open Publication No. 2014-12893 (Patent Document 8).

Japanese Patent Application Laid-Open No. 2000-45066 Japanese Patent Laid-Open No. 2007-113033 Japanese Patent Application Laid-Open No. 2013-32597 Japanese Patent No. 4945037 Japanese Patent Application Laid-Open No. 2000-234167 Japanese Patent Application Laid-Open No. 2013-154403 Japanese Patent Publication No. 2010-535943 Japanese Patent Application Laid-Open No. 2014-12893

Patent Document 1 discloses a molybdenum-based target that generates little abnormal discharge and particles. Also disclosed is an invention related to a molybdenum target having low particle generation even when the grain size is fine.

Patent Document 2 discloses that sintering is performed after pressure sintering with molybdenum. (110) plane is specified to improve the pressure sintering, the relative density and the mechanical properties of the Mo powder.

Patent Document 3 discloses a sputtering target of Al, Cu, Ti, Ni, Cr, Co and Ta using a cold spray method.

Patent Document 4 discloses a target of tungsten.

Patent Document 5 discloses a target of molybdenum. It is disclosed that the tissue causing recrystallization suppresses arcing.

Patent Document 6 discloses that a sputtering target is produced by slant rolling. Sloping rolling is required and the ratio of particles per unit volume of bcc metal oriented within 15 占 of // ND of bcc metal is more than 20.4%.

Patent Documents 7 and 8 disclose targets for sputtering in which the uniformity of 100 texture and 111 texture with respect to the plate thickness direction in bcc metal is improved.

Patent Document 6-8 discloses a bcc metal. In order to obtain uniformity of a structure with respect to a high-melting-point metal, a special machining method such as a slope rolling method is applied. This inclined rolling method is applicable to metals with good processability. In this patent document, there is a description of Ta and Nb with relatively good workability as the bcc metal, but W and Mo which are particularly poor in workability are not described even with a high melting point metal. In fact, when the slant rolling method is applied to W and Mo, a layered crack is generated from a small allowable deformation, and machining is impossible.

In the prior art, there is no suggestion about the adjustment of the sputtering rate at all.

An object of the present invention is to provide a sputtering target material capable of adjusting a sputtering rate.

In the sputtering target material according to one embodiment of the present invention, the aspect ratio of the crystal structure of the surface to be sputtered is 3 or more.

It is possible to provide a sputtering target material capable of adjusting the sputtering rate.

1 is an enlarged view of a TD surface produced according to an embodiment (condition A);
Fig. 2 is an enlarged view of a TD surface produced according to a comparative example (condition B); Fig.
3 is a graph showing the results of XRD in a molybdenum powder (Fsss Fisher method: particle diameter 5 mu m).

[Description of Embodiments of the Present Invention]

First, an embodiment of the present invention will be described.

In the sputtering target material according to one embodiment of the present invention, the aspect ratio of the crystal structure of the surface to be sputtered is 3 or more.

It is impossible to control the sputtering rate in the molybdenum plate target having the body-centered cubic lattice structure that has been present to date. By controlling the crystal structure, a molybdenum target with low consumption of the target can be obtained. By reducing the consumption by the sputter, the target lifetime can be prolonged. Also, the film thickness controllability is improved with respect to the recent demand for thinning. That is, it is suitable for applications other than those in which a high sputtering rate is required.

As a conventional method, there has been a technique for increasing the sputter rate in a random orientation without performing orientation control, such as a sinter target and a heat treatment target. In addition, although the sputtering rate is made a little slower by performing some degree of tissue control, the present invention is to provide a material having a low sputtering rate by controlling the residual strain.

This is because, as a barrier metal for diffusion prevention of Al wiring which is the main main use in recent years, sufficient effect is exhibited in a thin barrier layer. By lowering the sputtering rate with respect to the demand for the thinning, the film thickness controllability and the uniformity can be improved.

By setting the aspect ratio of the crystal structure of the surface to be sputtered to 3 or more, the sputtering rate can be made 400 nm / h or less, whereby a sputtering target having a long target life can be obtained.

Preferably, the material for the sputtering target comprises molybdenum.

Preferably, the material for the sputtering target is molybdenum.

Preferably, when the aspect ratio of the TD surface (plate cross section parallel to the rolling direction) which is the sputtered surface is 3 or more, the sputtering rate becomes 400 nm / h or less. At this time, the average grain size in the plate thickness direction was 50 탆 or less.

Preferably, the Vickers hardness of the surface to be sputtered is Hv200 or more. When the hardness is Hv200 or more, the sputtering rate becomes 400 nm / h or less.

Preferably, the sputtering target material is produced by sintering molybdenum powder, and the purity of the molybdenum powder is 4N (99.99 mass%) or more.

[Detailed Description of Embodiments of the Present Invention]

Specific examples of the embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

(Example)

(1) Manufacturing method

The powder was subjected to hydrostatic pressing using a rubber bag under the conditions of a pressure of 150 to 300 MPa using a molybdenum powder having a particle diameter of 1 to 20 mu m as measured by the Fsss Fisher method. Thereafter, the press-molded article is sintered at a temperature of 1500 DEG C or higher in a hydrogen gas stream to obtain a molybdenum sintered body (specific gravity: 9.7 g / cm3).

The hot rolling of the sintered body was carried out using a two-stage rolling mill in the following manner. And subjected to primary hot rolling at a working rate of 76% such that the plate thickness after rolling was 24 mm. In order to prevent recrystallization coarsening of molybdenum crystal grains due to high temperature heating during hot rolling, the heating temperature in the furnace for initial hot rolling was controlled to 1400 캜 or lower.

Next, the rolled plate after the initial hot rolling was divided into two parts by using a cutter, one was a rolled plate (condition A) for carrying out the rolling pass schedule of the embodiment, the other was a comparative rolled plate Condition B), and hot rolling was performed.

With respect to the condition A, the rolling plate was set to a uniform temperature in a hydrogen atmosphere furnace at a temperature of 900-1150 占 폚, and then a rolled plate of a total thickness of 15 mm was obtained in four passes at a rolling rate of 37.5%.

With respect to the condition B, the rolled plate of the comparative example having a thickness of 15 mm was obtained with a total rolling ratio of 37.5% in five passes in a hydrogen atmosphere heating furnace at a temperature of 1150-1300 占 폚. In both conditions A and B, the processing rate of the hot rolling in the second half was 37.5%, the total rolling ratio from the sintered body was 85%, and the relative density was 99.9%.

Condition A was considered to be highly likely to cause cracking in the cutting process for sampling due to a large residual strain and deformation removal annealing was performed for 15 minutes in a hydrogen heating furnace at a temperature of 600-1000 占 폚 where no recrystallization occurred. Condition B was heat treated at 1000-1300 ° C for 60-120 minutes.

(2) Observation of tissue

Fig. 1 is an enlarged view of a TD surface produced according to the embodiment (condition A). Fig. Fig. 1 shows the metal structure of the TD surface under the condition A of the embodiment. Called as-rolled fibrous structure in which the dimension in the direction parallel to the rolling direction (X direction; longitudinal direction) is about 80 mu m to 300 mu m and the dimension in the vertical direction (Y direction; thickness direction) is about 30 mu m to 100 mu m .

Fig. 2 is an enlarged view of the TD surface produced according to the comparative example (condition B). Fig. The condition B of the comparative example subjected to the heat treatment as usual has a dimension in the direction parallel to the rolling direction (X direction; longitudinal direction) of about 100 m to 150 m, and a dimension in the vertical direction (Y direction; thickness direction) (Fig. 2). Fig.

(3) Relationship between the aspect ratio and the sputter rate

The relationship between the aspect ratio and the sputtering rate in the sample prepared under the condition A of the example and the sample prepared under the condition B of the comparative example was examined.

(3-1) Definition

The sizes of fibrous tissues and equiaxed tissues were calculated by the intercept method. Specifically, the tissue is observed at a magnification of 100 to 200 times using an optical microscope with the long side of the tissue being transversely oriented. The horizontal and vertical lines count the number of points crossing and terminating the grain boundaries of the tissue. The value obtained by dividing the length of the horizontal line by the number of transverse points is taken as the long diameter of the crystal grain. The value obtained by dividing the length of the vertical line by the terminal score is defined as a short diameter. The aspect ratio is a value obtained by dividing the long diameter of the crystal grain by the short diameter.

(3-2) Preparation of sputtering target test body

Diameter (φ) 75 mm × thickness (T) 2 mm used for evaluating the sputtering rate Each of the sputtering target test specimens was prepared in the following manner. Both of the samples prepared under Condition A of Example and Condition B of Comparative Example were used as material plates. (Φ) of 75 mm and a thickness (T) of 3 mm was prepared by grinding the both surfaces of the material plate [thickness (T) = 15 mm] Mm. A disk having a diameter of 75 mm was polished with a SiC stone using a rotary grinder, and the surface was finished with a sputtering target test piece having a thickness of 2 mm. At this time, in order to unify the sputtering conditions, the surface precision of the sputtering target test object was unified to Ra 3 μm or less.

(3-3) Sputtering conditions

The sputtering rate of the sputtering target specimen prepared in the condition B of the example and the condition B of the comparative example was compared using a small sputtering apparatus (type SH-250-T4) manufactured by ULVAC KABUSHIKI KAISHA. The inside of the apparatus was evacuated to 5 x 10 < ^-5 > Pa or less. The argon gas flow was 0.06 MPa, 6.0 sccm (flow rate of 6.0 dm ³ per minute at 0 DEG C and 1013 hPa) Was sputtered. In order to eliminate the edge effect, a region of about 60 mm in the center portion was sputtered, and a glass-made prepatart was set on the opposite cathode side, and the film thickness sputtered on the preparate was measured to confirm the sputtering rate.

(3-4) Measurement of sputtering film thickness

The sputtering film thickness was measured under the conditions of a full-scale of 12.5 mm, a data length of 4.8 mm, a bait distance of 0.3 mm, and a measurement speed of 1 mm / s using a surface profile measuring device (PGI1200 manufactured by Taylor Hobson) The condition was specified by specifying the LS line and the primary).

(3-5) Evaluation

The results of the sputtering were evaluated in the range of ± 20% from the center of the plate thickness so as to obtain the average information of the sputter.

The values of the sputtering rates of the rolled plates (sputtering target test specimens) produced in Samples 1 to 3 in Table 1 and in Condition B in Sample A and Sample 4 are the values. As shown in Table 1, when the aspect ratio of the crystal grains in the crystal structure is 3 or more, the sputtering rate becomes 400 nm / h or less. In addition, as the aspect ratio increases, the sputtering rate is lowered. That is, the sputtering rate is lowered as the fiber structure becomes stronger.

In addition, this means that when the sputtering rate exceeds 400 nm / h, the consumed amount is 4 mm or more for 10000 h of use time and 8 mm or more for 20000 h, suggesting that the frequency of replacement of the sputtering target is increased.

(4) Vickers hardness and sputter rate

Samples were prepared according to conditions A and B. These samples were subjected to strain relief annealing as a final heat treatment. Specifically, a sample was prepared in which the temperature of the sample was kept constant at 800 占 폚, and the long and short ends of the annealing time were adjusted to change the hardness while maintaining the orientation almost constant. The Vickers hardness of each sample was measured at a load of 10 kg. The sputtering rate of each sample was examined by the method described in "(3) Relationship between aspect ratio and sputtering rate". The results are shown in Table 2.

Samples Nos. 11 and 12 were prepared under condition A, and Sample 13 was prepared under condition B. It was found that the residual amount of strain was correlated with the sputtering rate, and the higher the hardness, the lower the sputtering rate could be suppressed.

(5) plane orientation (222) / (200) and sputter rate

The relationship between the crystal orientation based on the plane orientation (222) / (200) and the sputtering rate was confirmed.

Two types of conditions A and B were used to produce rolled plates. A sample having a thickness of about 15 mm x 10 mm was sampled from each rolled plate for the purpose of irradiating the crystal orientation.

Crystal orientation irradiation (XRD) was performed using a ceramic X-ray tube LFF Cu by PANalytical X-ray diffractometer, Empyrean system manufactured by Parent Company. The crystal orientation was measured by a semiconductor detector under the conditions of 40 kV and 45 mA by an X-ray lens (0.3 DEG) and a plate collimator (0.27 DEG). The slit conditions were a diverging slit of 1/2 ° and a scattering of 1 °. In addition, unless otherwise noted, the XRD measurement angle was 35 ° to 135 ° and the scan speed (time per step) was 10.2 seconds. The evaluation of the measurement results was compared with the standard data by the ICDD database PDF2.

The sputtering rate of each sample was examined by the method described in "(3) Relationship between aspect ratio and sputtering rate".

The results of the XRD and the sputtering were evaluated in the range of ± 20% from the center of the plate thickness so as to obtain the average information of the sputter. The results are shown in Table 3.

Samples Nos. 21 to 24 were prepared under condition A, and samples Nos. 25 and 26 were prepared under condition B. The ratio of the reflection intensity on each diffraction plane was determined as a crystal orientation index. When the relationship between the (222) / (200) intensity ratio and the sputtering rate was examined, the sputtering rate tended to decrease with an increase in the intensity ratio (Table 3). This tendency was found to be different in the condition A of the example and the condition B of the comparative example, and the result of the sputtering rate of the fibrous textural plate (sample No. 21-24) was low.

The sputtering rate in the condition B of the comparative example exceeded 400 nm / h. For example, the sputtering rate 420 nm / h corresponds to the G5 (fifth generation) sputtering target life equivalent to the input power under actual use conditions. On the other hand, when the sputtering rate is about 370 nm / h, which is indicated by the condition A in the embodiment, the effect of lifetime extension in inverse proportion to the sputtering rate can be obtained. When the sputtering rate is 400 nm / h or less, the sputtering target has a long sputtering target life, and a long-life sputtering target that has not been obtained so far can be obtained.

As for the crystal orientation, the (222) / (200) intensity ratio did not exceed 50% (0.5).

Generally, the powder represents a random orientation. 3 is a graph showing the results of XRD in molybdenum powder. The crystal orientation was 37% of the powder (Fig. 3; (6278 cps = (37.4%) of 2351 cps / (200) of (222)), the processed tissue of the example of Table 3 did not exceed 35%. The molybdenum sintered body also shows 37%.

(6) Half width and sputter rate

The half width (FWHM) of the (222) diffraction plane of the sample prepared under Condition A and the sample prepared under Condition B was determined using profile pits by High Score Plus software of an XRD apparatus. The sputtering rate of each sample was examined by the method described in "(3) Relationship between aspect ratio and sputtering rate". The results are shown in Table 4.

As a result of these samples, as shown in Table 4, it was found that the sputtering rate strongly correlated with the Full Width Half Maximum of (222) reflection.

Samples Nos. 31 and 32 were prepared under condition A, and sample 33 was prepared under condition B. If FWHM is small, deformation is released and the sputtering rate is considered to be high. In the rolling conditions of the examples, the FWHM did not exceed 0.5 even when the rolling rate was increased.

Table 5 shows examples of XRD in the sample prepared under Condition A of the example. Diffraction intensity in powder "refers to the diffraction intensity in the Mo powder," Examples of practical range "means that the intensity of X-ray diffraction [(200) in the rolled plate produced under Condition A is 100 Is a relative value in the case of "

In addition, not only the targets made of molybdenum but also the targets having the molybdenum alloy target and the body-centered cubic structure including molybdenum showed the same tendencies as Tables 1 to 5.

The material for the sputtering target has a crystal orientation ratio 222/200 of the crystal faces 222 and 200 obtained by X-ray diffraction of the surface to be sputtered of 0.08 or more and less than 0.35 and has a body-centered cubic lattice structure.

Preferably, the material for the sputtering target comprises molybdenum.

Preferably, the material for the sputtering target is made of molybdenum.

Preferably, the half-width of the peak of the crystal plane 222 obtained by X-ray diffraction of the surface to be sputtered is 0.29 or more and 0.5 or less.

Preferably, the Vickers hardness of the surface to be sputtered is Hv200 or more.

Preferably, the crystal structure of the surface to be sputtered has an aspect ratio of 3 or more.

The method for producing a sputtering target material comprising molybdenum having a crystal orientation ratio (222) / (200) of crystal planes (222) and (200) of 0.08 or more and less than 0.35 obtained by X-ray diffraction of a surface to be sputtered, A step of producing a sintered body by using a powder having an average particle diameter of 5 탆 or more and sintering at a temperature of 1500 캜 to 2000 캜, a step of hot rolling the sintered body, and a step of performing a final heat treatment after hot rolling, Is 85%, the heating temperature is 1000-1150 占 폚, and the final heat treatment temperature is 800-1000 占 폚.

The present invention can be used in the field of a sputtering target.

Claims (4)

Wherein the aspect ratio of the crystal structure of the surface to be sputtered is 3 or more. The method according to claim 1,
A material for sputtering targets, comprising molybdenum. 3. The method of claim 2,
A material for sputtering target comprising molybdenum. 4. The method according to any one of claims 1 to 3,
Wherein the Vickers hardness of the surface to be sputtered is Hv200 or more.

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