JP4761605B2 - Sputtering target - Google Patents

Description

【表２】

表２から明らかなように、参考例１、実施例１〜３による各Ｍｏ−Ｗターゲットを用いることによって、膜中に混入するパーティクル数が大幅に低減することが分かる。
【００４１】
【発明の効果】
以上説明したように、本発明のスパッタリングターゲットによれば、スパッタ成膜時にスパッタ面で生じる異常放電を抑制することが可能であることから、異常放電に基づくダストの発生、特にスプラッシュ現象に基づく塊状の異物の発生を大幅に低減することができる。従って、半導体素子や液晶表示素子などに代表される電子部品の配線、電極、素子構成膜などとして使用される金属薄膜や化合物薄膜の品質向上を図ることが可能となる。
【図面の簡単な説明】
【図１】 本発明の実施例１によるスパッタリングターゲットのスパッタ面の表面粗さ曲線を示す図である。
【図２】 比較例１によるスパッタリングターゲットのスパッタ面の表面粗さ曲線を示す図である。
【図３】 本発明のスパッタリングターゲットにおけるスパッタ面の表面粗さを測定する際の方法を説明するための図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering coater Getting preparative used in forming various electronic components of the wiring layer, electrode, etc. device structure film.
[0002]
[Prior art]
When manufacturing electronic parts typified by semiconductor elements and liquid crystal display elements, simple elements of various metal elements such as Mo, W, Ta, Ti, Cr, Nd, Ni, Co, Pt, Al, and Cu (single metal) A thin film made of an alloy or a metal compound is used as a wiring, an electrode, an element constituent film, or the like. In order to form a thin film made of such a metal or metal compound, a sputtering method is generally used frequently.
[0003]
For example, in an active matrix type liquid crystal display element using TFTs as switching elements, refractory metal thin films such as Mo—W alloy films and Mo—Ta alloy films are used for various wirings. When such an alloy thin film is used as wiring, an alloy thin film is formed by sputtering using a target obtained by processing an alloy ingot into a target shape or a sintered target obtained by sintering alloy powder into a target shape. ing.
[0004]
[Problems to be solved by the invention]
By the way, the sputtering target as described above is usually used by finishing the sputter surface with a lathe or rotary grinding. In such a conventional finishing process of the sputtered surface, there is a problem that a processing flaw (scratch) is likely to occur on the surface due to the falling off of the grindstone, and that such a flaw adversely affects the quality of the sputtered film.
[0005]
That is, in conventional finishing of the sputtered surface (using a lathe or rotary grinding), scratches (concave defects) with a depth of about 10 μm often occur at intervals of about 50 μm. If the sputter surface of the sputtering target has scratches of about 10 μm at relatively small intervals as described above, in other words, if there are irregularities (projections and scratches) with a narrow interval, abnormalities will occur during sputter deposition. There is a problem that a so-called splash phenomenon is likely to occur in which discharge occurs and the tip of the convex portion falls off as a lump-like foreign matter due to this abnormal discharge. The splash phenomenon causes, for example, massive foreign matters to be mixed into the sputtered film, thereby reducing the manufacturing yield of electronic components such as semiconductor elements and liquid crystal display elements.
[0006]
In addition, the splash phenomenon is not only a massive foreign substance but also a cause of generation of normal-size dust, and normal dust naturally causes a decrease in manufacturing yield of semiconductor elements, liquid crystal display elements, and the like. Therefore, in order to improve the manufacturing yield of electronic parts typified by semiconductor elements and liquid crystal display elements, there is an urgent need to suppress the generation of dust, including massive foreign matters based on the splash phenomenon.
[0007]
In particular, in recent semiconductor elements, a wiring width of 0.3 μm or less, and further 0.18 μm is required in order to achieve a degree of integration such as 64M, 256M, and 1G. It is being advanced. In such a narrowed high-density wiring, for example, even if ultrafine particles having a diameter of about 0.2 μm are mixed, it causes a wiring failure, and therefore, the manufacturing yield of highly integrated semiconductor elements and the like is increased. Therefore, it is necessary to greatly reduce the amount of dust generated. Therefore, there is a strong demand to suppress abnormal discharge that contributes to dust generation.
[0008]
The present invention has been made to cope with such problems, and suppresses abnormal discharge generated on the sputtering surface of the target during sputtering film formation, and on the basis of this, generation of dust, in particular, the formation of massive foreign matters based on the splash phenomenon. It aims at providing the sputtering target which made it possible to reduce generation | occurrence | production.
[0009]
[Means for Solving the Problems]
As described in claim 1, the sputtering target of the present invention comprises a single element of a metal element selected from Mo, W, Ta, Ti, Cr, Nd, Ni, Co, Pt, Al and Cu, or the metal element. A sputtering target comprising an alloy or a compound including a sputtering surface having a surface roughness Ry of 7 μm or more and 10 μm or less, and the width of a recess having a depth of 5 μm or more present on the sputtering surface is a roughness curve. The distance between the local peaks is 70 μm or more.
[0010]
Thus, in the sputtering target of the present invention, the surface roughness of the sputtering surface is set to 10 μm or less in terms of Ry. Such a sputter surface can be obtained with good reproducibility by, for example, finishing the sputter surface by surface grinding when processing the target. By setting the surface roughness of the sputter surface to a maximum height Ry of 10 μm or less, it is possible to suppress the occurrence of abnormal discharge due to relatively large irregularities existing on the sputter surface.
[0011]
Accordingly, it is possible to prevent the splash phenomenon associated with abnormal discharge, and further, the mixing of massive foreign matters into the sputtered film based on the splash phenomenon. In addition, the suppression of abnormal discharge is effective not only for preventing the generation of fine dust (for example, fine particles having a diameter of about 0.2 μm or less), but not limited to massive foreign matters. As a result, the quality of the sputtered film can be greatly improved, and as a result, it is possible to improve the manufacturing yield of electronic parts using such a sputtered film as a wiring film, an electrode, an element constituent film, and the like.
[0012]
In the sputtering target of the present invention, as described in claim 2, the surface roughness of the sputtering surface is preferably 1 μm or less in terms of Ra in addition to the above-mentioned definition of Ry .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, modes for carrying out the present invention will be described.
[0015]
In the sputtering target of the present invention, the surface of the target body, that is, the surface roughness of the sputtering surface is 10 μm or less at the maximum height Ry. Here, the maximum height Ry is based on the provisions of JIS B0601-1994, and is specifically measured by a contact-type surface roughness meter.
[0016]
The sputtering target of the present invention can be applied to various metal materials and compound materials. Examples of the constituent material of the target include a simple metal element selected from Mo, W, Ta, Ti, Cr, Nd, Ni, Co, Pt, Al, and Cu, or an alloy or compound containing the above metal element. .
[0017]
As described above, by setting the surface roughness of the sputter surface to 10 μm or less at the maximum height Ry, it is possible to greatly suppress the entry of foreign matter into the sputtered film. In other words, the generation of foreign matters, particularly the generation of massive foreign matters, in the conventional sputtering target is caused by abnormal discharge due to the presence of relatively large irregularities on the sputtering surface, and the phenomenon that the tip of the convex part falls off due to this abnormal discharge (splash phenomenon) )caused by. Therefore, by removing large irregularities that cause abnormal discharge, it is possible to greatly suppress the occurrence of abnormal discharge and the splash phenomenon associated therewith. Such an effect of suppressing the splash phenomenon can be remarkably obtained by setting the surface roughness of the sputtering surface to 10 μm or less at the maximum height Ry. The maximum height Ry of the sputter surface is more preferably 7 μm or less, and further preferably 3 μm or less.
[0018]
As described above, by setting the surface roughness of the sputtered surface to a maximum height Ry of 10 μm or less, and further 7 μm or less, it is possible to prevent mass foreign matter from being mixed into the sputtered film due to the splash phenomenon. In addition, the suppression of abnormal discharge is effective not only for preventing the generation of fine dust (for example, fine particles having a diameter of about 0.2 μm or less) but also for a bulky foreign material (for example, particles having a diameter of 0.3 μm or more). As a result, the quality of the sputtered film can be greatly improved.
[0019]
The surface roughness of the sputtering surface in the sputtering target of the present invention is preferably 1 μm or less when expressed by the arithmetic average roughness Ra specified in JIS B0601-1994. When the arithmetic average roughness Ra of the sputter surface exceeds 1 μm, a region where the sputtering is selectively performed and a region where the sputter surface is not selectively generated are generated due to the unevenness of the sputter surface, and projections generally called nodules are likely to occur, which causes splash. The arithmetic average roughness Ra of the sputter surface is more preferably 0.8 μm or less, and further preferably 0.4 μm or less. The arithmetic average roughness Ra is measured by a contact type surface roughness meter based on JIS B0601-1994.
[0020]
In addition, since the abnormal discharge described above is likely to occur between adjacent convex portions, the width of the concave portions having a depth of 5 μm or more present on the sputtering surface is preferably set to 70 μm or more as the interval between the local peaks of the roughness curve. . The interval between the local peaks of the roughness curve is based on JIS B0601-1994, and is specifically determined from the roughness curve measured by a contact-type surface roughness meter.
[0021]
Here, the typical example of the roughness curve of the sputtering surface in the sputtering target of this invention is shown in FIG. FIG. 2 is a typical example of the roughness curve of the sputtering surface in the conventional sputtering target. As shown in FIG. 2, when the width of the concave portion having a depth of 5 μm or more is narrow, abnormal discharge tends to occur between the convex portions located at both ends of the concave portion.
[0022]
On the other hand, as shown in FIG. 1, it is possible to prevent abnormal discharge more stably by widening the width of the recess having a depth of 5 μm or more. For this reason, the width of the recess having a depth of 5 μm or more is preferably 70 μm or more as the interval between the local peaks of the roughness curve. Here, the recess having a depth of 5 μm or more is a recess having a depth of 5 μm or more and 10 μm or less because the surface roughness of the sputtering surface is 10 μm or less at the maximum height Ry. In addition, since a shallow recess having a depth of less than 5 μm is unlikely to be a starting point of abnormal discharge, the width of the recess having a depth of 5 μm to 10 μm is defined as 70 μm or more in the present invention.
[0023]
Note that the surface roughness of the sputtering surface defined in the present invention includes the surface roughness of the sputtering surface of the sputtering target, that is, the maximum height Ry, the arithmetic average roughness Ra, and the width of the recess having a depth of 5 μm or more. The value measured by the above method shall be indicated. That is, as shown in FIG. 3, for example, the center part (position 1) of the disk-shaped target, the positions near the outer periphery (positions 2 to 9) on the four straight lines that divide the circumference through the center part, Samples with a length of 10 mm and a width of 10 mm were taken from each position at a distance of 1/2 (positions 10 to 17), and the surface roughness of the sputter surface of these 17 test pieces was measured. Each value is averaged.
[0024]
A sputter surface having a surface roughness as described above, in other words, a smooth sputter surface can be obtained with good reproducibility by applying surface grinding as a finishing process of the sputter surface, for example. That is, first, a target material is produced by a melting method or a powder metallurgy method. After machining this target material to a desired dimension, the sputter surface is finished by surface grinding. The surface grinding of the sputter surface is performed using, for example, a horizontal axis surface grinding machine. According to such surface grinding, it is possible to obtain a sputter surface satisfying each surface roughness specification as described above with good reproducibility.
[0025]
The sputtering target of the present invention comprises, for example, a single metal element selected from Mo, W, Ta, Ti, Cr, Nd, Ni, Co, Pt, Al and Cu, or an alloy or compound containing these metal elements. It is. Although the regulation of the surface roughness is effective for various sputtering targets as described above, it is more effective particularly for a sputtering target having a Vickers hardness of Hv 100 or higher.
[0026]
That is, in the high-hardness sputtering target as described above, when the conventional finishing process as described above is applied to the sputtering surface, such as a lathe or rotary grinding, a deep and narrow scratch (concave part) is narrow. It tends to occur at the pitch, and an abnormal discharge that causes foreign matter is likely to occur. When finishing the sputter surface of such a high-hardness sputtering target, it is possible to more easily obtain a sputter surface that satisfies the surface roughness defined in the present invention by applying the above-described surface grinding. it can.
[0027]
For these reasons, the present invention works more effectively on a sputtering target having a Vickers hardness of Hv 100 or higher. Specific examples of the target material having such hardness include a single metal element selected from Mo, W, Ta, Ti, Ni, Co, Al and Cu, or an alloy or silicide containing these metal elements. . In particular, the present invention is particularly effective for a sputtering target made of a high hardness alloy such as a Mo-Ta alloy. Furthermore, it is effective for a target that is difficult to perform lathe processing, which is generally used, such as a large sputtering target having a vertical and horizontal length of 500 mm or more.
[0028]
As described above, the sputtering target of the present invention reduces irregularities (protrusions and scratches) on the sputtered surface that cause abnormal discharge, and the surface roughness of the sputtered surface is 10 μm or less at the maximum height Ry. Ra is set to 1 μm or less, and the width of the recesses having a depth of 5 μm or more is set to 70 μm or more as the interval between the local peaks of the roughness curve. ) Can be stably suppressed from being mixed into the sputtered film. Furthermore, the generation of fine dust (for example, fine particles having a diameter of about 0.2 μm or less) can be suppressed without being limited to massive foreign matters.
[0029]
Therefore, according to the sputtering target of the present invention, it is possible to greatly improve the quality of the sputtered film. Then, a sputtered film formed using the sputtering target of the present invention, that is, a metal thin film or a compound thin film, is used for a wiring film, an electrode, an element constituent film, etc. of an electronic component such as a semiconductor element or a liquid crystal display element. By doing so, it becomes possible to improve the manufacturing yield of electronic components.
[0030]
【Example】
Next, specific examples of the present invention will be described.
[0031]
Reference example 1
Mo powder having an average particle diameter of 2 to 3 μm and W powder having an average particle diameter of 2 to 3 μm were mixed at a mass ratio of 50:50, and after the mixed powder was filled in a carbon mold, the pressure was 29.4 MPa and the heating temperature was 1800. Sintering was performed by hot pressing under the conditions of ° C and heating time of 8 hours. This sintered material (Mo-W alloy material) was rolled and then machined to a desired target size.
[0032]
Next, the sputter surface of the target material (Mo—W alloy material) was finished by a surface grinder. Specifically, the sputter surface is finished using a horizontal axis surface grinder, using an Al ₂ O ₃ ceramic grindstone (grain size # 60), grinding wheel peripheral speed of 1600 m / min, and material feed speed of 10 m / min. It carried out on condition of this.
[0033]
The surface roughness of the sputtered surface that was surface ground under the above conditions was measured with a Form Talysurf S4C contact surface roughness meter manufactured by Taylor-Hobson. FIG. 1 is a surface roughness curve of the sputtering surface of the sputtering target according to the first embodiment. As for the surface roughness of the sputter surface, the maximum height Ry was 4.3 μm, and the arithmetic average roughness Ra was 0.55 μm. Further, there was a recess (scratch) having a depth of about 5 μm, and the width of this recess was about 135 μm.
[0034]
The Mo—W alloy target thus obtained was joined to a copper backing plate using a brazing material, and then set in a sputtering apparatus. Using such a sputtering apparatus, a Mo—W alloy film having a thickness of 0.3 μm was formed on a SiO ₂ substrate. The sputtering conditions were a sputtering pressure of 0.4 Pa, a Kr gas flow rate of 12 sccm, and a substrate temperature of 150 ° C. Sputter deposition was performed on 15 substrates in order, and the number of particles of 0.3 μm or more present in the Mo—W alloy film on each substrate was examined. Table 2 shows the number of particles and the average value of each substrate.
[0035]
Comparative Example 1
A sputtering target (Mo-W alloy target) was produced in the same manner as in Example 1 except that the sputtering surface of the target material (Mo-W alloy material) was surface-finished by a vertical rotary grinder. FIG. 2 is a surface roughness curve of the sputtering surface of the sputtering target according to Comparative Example 1. As for the surface roughness of the sputter surface, the maximum height Ry was 14.2 μm, the arithmetic average roughness Ra was 0.91 μm, and there was a recess (scratch) having a depth of about 14 μm and a width of 66 μm.
[0036]
Using this Mo—W alloy target, a Mo—W alloy film having a thickness of 0.3 μm was formed on 15 substrates under the same conditions as in Example 1. Table 2 shows the measurement results of the number of particles of 0.3 μm or more present in the Mo—W alloy film on each substrate.
[0037]
Examples 1-3
The conditions for surface grinding of the sputter surface of the target material (Mo—W alloy material) are as follows: Al ₂ O ₃ series ceramic grindstone (grain size # 60), grindstone peripheral speed 1200 m / min, material feed speed 10 m / min (Example) 1 ), Al ₂ O ₃ series ceramic grindstone (grain size # 60), grinding wheel peripheral speed 1600 m / min, material feed speed 15 m / min (Example 2 ), and Al ₂ O ₃ series ceramic grindstone (grain size # 46), grindstone A sputtering target (Mo—W alloy target) was produced in the same manner as in Reference Example 1 except that the peripheral speed was 1600 m / min and the material feed speed was 10 m / min (Example 3 ).
[0038]
The surface roughness of the sputtering surface of each sputtering target thus obtained was measured in the same manner as in Reference Example 1 . Table 1 shows the value of the surface roughness of each sputtering target. Further, using each of these Mo—W alloy targets, a Mo—W alloy film having a thickness of 0.3 μm was formed on 15 substrates under the same conditions as in Reference Example 1 . Table 2 shows the measurement results of the number of particles of 0.3 μm or more present in the Mo—W alloy film on each substrate.
[0039]
Comparative Example 2
A sputtering target (Mo-W alloy target) was produced in the same manner as in Example 1 except that the sputtering surface of the target material (Mo-W alloy material) was finished by milling. The surface roughness of the sputtering surface of the obtained sputtering target is as shown in Table 1. In addition, using this Mo—W alloy target, a Mo—W alloy film having a thickness of 0.3 μm was formed on 15 substrates under the same conditions as in Example 1. Table 2 shows the measurement results of the number of particles of 0.3 μm or more present in the Mo—W alloy film on each substrate.
[0040]
[Table 1]

[Table 2]

As is clear from Table 2, it can be seen that the number of particles mixed in the film is greatly reduced by using each Mo-W target according to Reference Example 1 and Examples 1 to 3 .
[0041]
【The invention's effect】
As described above, according to the sputtering target of the present invention, it is possible to suppress the abnormal discharge generated on the sputtering surface during the sputtering film formation, so that dust generation based on the abnormal discharge, particularly a lump shape based on the splash phenomenon. The generation of foreign matter can be greatly reduced. Therefore, it is possible to improve the quality of metal thin films and compound thin films used as wiring, electrodes, element constituent films and the like of electronic components typified by semiconductor elements and liquid crystal display elements.
[Brief description of the drawings]
FIG. 1 is a diagram showing a surface roughness curve of a sputtering surface of a sputtering target according to Example 1 of the present invention.
2 is a diagram showing a surface roughness curve of a sputtering surface of a sputtering target according to Comparative Example 1. FIG.
FIG. 3 is a view for explaining a method for measuring the surface roughness of the sputtering surface in the sputtering target of the present invention.

Claims (5)

A sputtering target comprising a single element of a metal element selected from Mo, W, Ta, Ti, Cr, Nd, Ni, Co, Pt, Al and Cu, or an alloy or compound containing the metal element,
The surface roughness is a sputtering surface having a Ry of 7 μm or more and 10 μm or less, and the width of the concave portion having a depth of 5 μm or more existing on the sputtering surface is 70 μm or more as the interval between the local peaks of the roughness curve. Sputtering target. The sputtering target according to claim 1, wherein
The sputtering target is characterized in that the surface roughness of the sputtering surface is further 1 μm or less in terms of Ra. The sputtering target according to claim 1 or 2,
The sputtering target has a surface finished by surface grinding. In the sputtering target according to any one of claims 1 to 3,
The sputtering target is made of a metal material or a compound material having a Vickers hardness of Hv 100 or higher. The sputtering target according to claim 4, wherein
The said target consists of a simple substance of the metal element chosen from Mo, W, Ta, Ti, Ni, Co, Al, and Cu, or the alloy or silicide containing the said metal element.

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