JPS63161161A - Target made al-si alloy and its production - Google Patents

Abstract

PURPOSE:To manufacture a target stably forming a thin electrode film having uniform Si concentration, by subjecting a molten Al-Si alloy to rapid solidification so as to restrict the precipitation of primary-crystal silicon practically within the grain boundaries and inhibit the precipitation of the above in the crystalline grains. CONSTITUTION:An Al-Si alloy (Al -0.5-2wt.% Si, Al-Si-Ti, Al-Si-Cu, etc.) is heated and melted in a refractory crucible free from contamination. The resulting molten alloy is poured into a mold 2 placed on the water surface of a water tank 1, on which cooling water is sprayed through a spray nozzle 4 to carry out rapid solidification..As a result, an ingot in which the precipita tion of prymary-crystal silicon is restricted practically within the grain bounda ries and the precipitation of primary-crystal silicon in the crystalline grains is inhibited can be obtained. Moreover, since there are cases where the precipita tion of Si in the crystalline grains occurs in part in the vicinity of the ingot surface, the part is eliminated. By finish-working this ingot into a target, target forming a wiring film in which Si is uniformly distributed can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The alloy to which the present invention is directed is
81, Aj-! 9l-TI SA No 81-Cm
, A-8l-All, Al-81-TI-Cu, etc. are useful for preventing Si/Xo diffusion at the An-81 contact part of the formed wiring part. Therefore, a wiring film with uniform distribution of SIO is required. In order to improve the quality of the Aj-Si wiring film, small amounts of additive elements are additionally included as necessary. For example, TI is added to prevent a phenomenon called electromigration phenomenon. Here, electromigration is the phenomenon in which gold particles become electronless due to the interaction between metal atoms and electrons when the optical density exceeds m. It moves in the direction of movement and generates atomic vacancies in its wake, and when the atomic vacancies are generated, the current density becomes even larger, the temperature rises, the growth of S Fengzi is accelerated, and eventually the wire breaks. It is a phenomenon that leads to

On the other hand, hillocks occur where metal moves and accumulates, resulting in short circuits between adjacent wires. As a countermeasure against electromicresimin, it has been proposed to add T1 of 001 Hiroshi Shigei or higher. In addition, for various reasons,
Additional elements have been incorporated into AJ-81 alloys, and the present invention is directed to all alloy systems in which SI precipitation occurs during casting in such AJ-81 alloys.

According to the present invention, the An-Sl thread alloy, which has been melted and rapidly solidified, is poured into a non-fouling refractory crucible, such as a high-purity aluminum crucible, and subjected to resistance heating, - It is heated and melted by frequency heating or the like. It is sufficient to set the heating temperature to a temperature equal to or higher than the alloying point; however, when a poorly soluble additive element such as Tl is contained, the higher the temperature, the more the solubility thereof increases, which is preferable. 1 from the points of failure of ingredients, crucible material, electricity cost, etc.
The current limit is about 500°C. When adding a hardly soluble element, the distribution state of solute atoms becomes -N as the temperature increases.
The molten Jj in the casting target is homogenized and rapidly solidified from that state. Since the uniformity of Ti particles is also improved, in the present invention, the heating temperature is maintained at 1200° C. or higher, preferably 1500° C. or higher to form a homogeneous solution.

If the heel-soluble element is not contained, a homogeneous solution is obtained in the molten metal including Si, so the holding temperature of the solution is not a particular problem. Use is preferred.

For example, 5NAl ingot is used as the M raw material.

As the STM material, it is convenient to use single crystal broken material, single crystal porcelain, or polycrystalline material. As the raw material, chips from an electron beam ingot are suitable. Other additives also apply.

The solution is allowed to rapidly solidify at a rate sufficient to substantially prevent precipitation of primary crystals of 81 into the grains.

The most common method of rapid solidification is casting into water-cooled molds. FIG. 1 shows an example of a casting apparatus that can be used in conjunction with the present invention.

In a water tank 1, a target casting mold 2 is placed on a support stand 5 on the water surface. The bottom surface of the mold 2 is in contact with water over the entire portion where the target 5 is to be formed. As an example of cooling means for cooling the bottom surface of the mold 2, a spray nozzle 4 is provided at the bottom of the water tank 1, and sprays cooling water onto the mold bottom plate. The water in the tank is drained into the drain. In addition, in order to use water effectively, water can also be circulated through an appropriate cooling device.

The mold 2 may be placed partially submerged in water so that its side walls are partially submerged in water. Although one spray nozzle is shown at the bottom of the tank, a plurality of spray nozzles may be installed at the bottom of the tank.

The mold 2 may be made of any material that has heat resistance, heat stress resistance, and non-reactivity with M, but Mo or TZM is preferably used.

Since the solidification rate of the cast ingot is slow near the top surface, some SI may precipitate into the crystal grains, making the 81 distribution uneven, but in that case, the corresponding part can be removed by machining. do. In any case, the resulting ingot is finished into a target.

The rapid solidification method is not limited to water cooling as described above, and may employ methods such as the use of a refrigerant, forced cooling using cold air, spray droplet cooling, and the like. In short, cooling in the atmosphere after casting into a mold is fast enough, and the temperature is sufficiently low to substantially prevent intragranular precipitation of St.
# Any cooling method that can achieve solid velocity can be used.

As will be shown later in the examples, the target thus generated has the following characteristics: (1) In the conventional product, the precipitation of primary silicon can be seen not only at the grain boundaries but also within the grains; The precipitation of crystalline silicon is suppressed, and the precipitated parts of side crystalline silicon are only the substantial grain boundaries, and (0) there is little variation in S concentration due to target parts, that is, the 81 distribution is uniform. There is a noticeable difference between the target and the conventional product.

Since the precipitation of primary Si is confined to the grain boundaries, the uniformity of the 3 distribution throughout the target is greatly improved. By using the target of the present invention, an electrode thin film with a uniform 981 concentration is stabilized. high quality LSI devices,
Contributes to improved reliability and yield, etc.

The present method makes it possible to manufacture such target rays at low cost and simply.

Example 1 and Comparative Example 1 A7-t O weight %S according to the method of the present invention and the conventional method
A target made of I-α05% by weight TI alloy was produced.

In this method, the alloy was melted in an aluminum crucible at 1300 DEG C. and then rapidly solidified into a water-cooled mold as shown in FIG. The conventional method was to cool the material in the atmosphere after casting it into a mold.

The solidified structure of the target obtained in this way was
As shown in the figure. The photo in Figure 2 (conventional method) is 100 mm
An ingot with a size of 200 mm was divided into two pieces, polished with emery paper to #1200, further polished with diamond paste, and then electrolytically etched. The photograph in Figure 3 (rapid cooling method according to the present invention) shows an ingot that was rapidly solidified to a thickness of about 30 mm, cut at half the thickness, and then finally electrolytically etched using the same procedure as above. .

If you compare the two photos, the differences are obvious.

In Figure 2 (conventional), the crystal grains are thick (and the grain boundaries are
1 (Si compound) was significantly precipitated. Many fine grains are also precipitated within the crystal grains. On the other hand, in Fig. 3C (invention), no precipitation of Si within the crystal grains is observed (in the photograph of Fig. 5, black dots are visible within the crystal grains, but this is not precipitation S1, but etching). and photography).

Example 2 and Comparative Example 2 Here, for the purpose of actual measurement of S1 distribution degree, AI-1wt%St-0,5 produced by the rapid solidification method of the present invention
wt% Cu target (product of the present invention) and commercially available A7-1
Regarding the vt%Si target (commercially available product), the 81 content at each part of the target was measured. The results are shown in Figures 4 and 5, respectively.

Figure 4(a) shows the 81 and Co content at each location expressed as the distance from the outer periphery in the outer cross section, and Figure 4(b) shows the distance from the bottom surface in the outer longitudinal cross section. 1. Figure 4(C) shows the St and Cu contents at each location expressed as
Indicates the content.

FIG. 5(a) shows the Si content at each location along one diameter of a commercial product from one end through the center to the other end.

FIG. 5(b) shows the Si content at each location from the center to the outer peripheral edge along the radial line perpendicular to the above.

From the comparison between Figure 4 (product of the present invention) and Figure 5 (commercial product),
It is clear that the target of the present invention is significantly superior to commercial products in terms of uniformity of Si concentration distribution. this is,
This is because segregation of Sl cannot be avoided in commercially available products, and coarse St is locally present in clusters within crystal grains. In the present invention, such coarse S
The precipitates of i do not exist within the grains.

Next, the results of measuring the total Si concentration and the solid solution St concentration of the target at two extreme locations will be shown.

The target of the present invention has a much more uniform total 5ifi degree and solid solution St concentration than commercially available products, which indicates that the precipitated Sl
This means that the uniformity of distribution is good.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of the rapid solidification device used in the present invention, and Fig. 2 is a 200x microscopic photograph showing the metal structure of the l -Si-based target normally solidified by the conventional method. , $3 shows the metallographic structure of the same alloy target as in FIG. 2 which was rapidly solidified by the method of the present invention.
Magnification micrographs, 4(a), 4(b) and 4(c)
) is a concentration distribution graph showing the content of Sl and Cu in each part of the target of the present invention.
Figures t and 5(b) are graphs showing the 81 content distribution of commercially available Targera F. 1: Water tank 2: Mold 3: Support stand 4: Spray nozzle 5: Target 5. τ-・ Fig. 1 ζ

Claims (1)

[Scope of Claims] 1) An Al-Si alloy target characterized in that primary silicon is precipitated substantially only at grain boundaries, and precipitation of primary silicon within crystal grains is suppressed. 2) A method for producing an Al-Si alloy target, which comprises rapidly solidifying a molten AL-Si alloy.