JP3127831B2 - Sputtering target for high dielectric film formation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target for forming a high dielectric film for forming a thin film for a capacitor such as a semiconductor memory, and more particularly to a large and high density sputtering target for forming a high dielectric film. It is.

[0002]

2. Description of the Related Art In general, a composite oxide of Ba and Ti (hereinafter referred to as a BaTi composite oxide), Sr and Ti
Composite oxide (hereinafter, referred to as SrTi composite oxide) and a composite oxide of Ba, Sr, and Ti (hereinafter, BaSi
Sputtering target for forming a high dielectric film having a perovskite structure composed of Ti composite oxide)
It is known to use as a sputtering target for forming a thin film for a capacitor used in a semiconductor memory or the like.

In order to manufacture a sputtering target for forming a high dielectric film having a perovskite structure composed of the BaTi composite oxide, first, a BaCO ₃ powder and a TiO ₂ powder as raw material powders are mixed in a predetermined ratio and put into a ball mill. And the resulting mixed powder is placed in a MgO crucible, and in an air atmosphere, at a temperature of 1200 to 1350 ° C.,
It is fired under the condition of holding for 10 to 10 hours, and pulverized by a ball mill to produce a BaTi composite oxide powder. The obtained BaTi composite oxide powder is further subjected to firing and pulverization under the above conditions twice or more, and then the pressure is set to 150 k.
g / cm ² , temperature: 1200-1350 ° C., 0.5-3
Hot press under the condition of holding time. The sintered body of the hot-pressed BaTi composite oxide is machined and finished to a predetermined target shape.

In order to manufacture a sputtering target for forming a high dielectric film having a perovskite structure made of the SrTi composite oxide, a raw material powder of SrCO ₃
The powder and the TiO ₂ powder are blended in a predetermined ratio, put in a ball mill and mixed, and the obtained mixed powder is put in a MgO crucible, in an air atmosphere, at a temperature of 1200 to 1350 ° C.
The SrTi composite oxide powder is prepared by firing under the condition of holding for 3 to 10 hours and pulverizing with a ball mill. The obtained SrTi composite oxide powder was repeatedly fired and pulverized under the above conditions twice or more, and then subjected to a pressure of 150.
kg / cm ² , temperature: 1200-1350 ° C., 0.5-
Hot pressing is performed for 3 hours. The sintered body made of the hot-pressed SrTi composite oxide is machined and finished to a predetermined target shape.

Further, in order to manufacture a sputtering target for forming a high dielectric film having a perovskite structure composed of the BaSrTi composite oxide, the raw material powder Sr
CO ₃ powder, BaCO ₃ powder and TiO ₂ powder are blended in a predetermined ratio, put in a ball mill and mixed, and the obtained mixed powder is put in a MgO crucible.
Baking is performed at 1200 to 1350 ° C. for 3 to 10 hours, and the mixture is pulverized with a ball mill to produce a BaSrTi composite oxide powder. The obtained BaSrTi composite oxide powder is further subjected to baking and pulverization under the above-mentioned conditions twice or more, and then conditions of pressure: 150 kg / cm ² , temperature: 1200 to 1350 ° C., and holding for 0.5 to 3 hours. Hot press. The hot pressed BaSr
The sintered body made of the Ti composite oxide is machined and finished in a predetermined target shape.

In recent years, in order to mass-produce semiconductor memories and reduce costs, sputtering is performed at a high output using a sputtering target for forming a high-dielectric-constant film, which is larger and more dense than before, to form a film over a wide area at high speed. To form a high dielectric film in a short time. However, the diameter of a conventional large and high-density sputtering target for forming a high-dielectric film is about 300 mm, and a larger diameter: a large and high-density sputtering target for forming a high-dielectric film having a diameter of about 400 mm is used. Deposition rate: 1
00 angstroms / min. When the high-speed sputtering film formation is performed, the target surface may peel off in a scale-like manner, or the entire target may be broken.

[0007] As a sputtering target for forming a large, high-density, high-dielectric-constant film that does not crack even when subjected to high-speed sputtering film formation under such severe conditions, Na, Ca,.
90 ppm of unavoidable impurities such as Al, Si and Fe
A large and high-density sputtering target for forming a high dielectric film, which has been reduced as follows, has been proposed (JP-A-7-34).
No. 44). It is said that a large-sized, high-density sputtering target for forming a high-dielectric film in which the unavoidable impurities are reduced to 90 ppm or less does not crack during sputtering even if the sputtering target is as large as 500 mm in diameter.

[0008]

However, at present, in order to increase the productivity of the semiconductor memory, the diameter is 500 mm.
Large and high-density sputtering targets for forming high-dielectric films over 500 mm are required. Cracks were generated in the inside and it was not practical, and did not lead to improvement in productivity.

[0009]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of conducting research to develop a large and high-density sputtering target for forming a high dielectric film with a diameter exceeding 500 mm, which does not cause cracking and peeling even when high-speed sputtering film formation is performed with high power, a) It is understood that the Si component has the greatest influence on the cracks and peeling during high-speed sputtering film formation among the inevitable impurities, and the diameter at which cracking and peeling do not occur even when high-speed sputtering film formation is performed by applying high power. : 500
In order to obtain a large-sized, high-density sputtering target for forming a high-dielectric film having a size exceeding 1 mm, the content of Si contained therein must be 25 ppm or more. It has been discovered that if the Si contained in the sputtering target for forming a body film exceeds 70 ppm, the strength of the sputtering target for forming a high dielectric film is lowered, which is not preferable.

The present invention has been made based on this finding, and (1) a large-sized, high-density high-dielectric film having a perovskite structure composed of a BaTi composite oxide containing Si: 25 to 70 ppm. (2) Si: a large and high-density sputtering target for forming a high dielectric film having a perovskite structure composed of a SrTi composite oxide containing 25 to 70 ppm; (3) Si: 25 to 70 ppm BaSrTi
A large and high density sputtering target for forming a high dielectric film having a perovskite structure composed of a composite oxide,
It is characterized by the following.

In the present invention, the large and high-density sputtering target for forming a high-dielectric film refers to a target having a diameter of more than 500 mm and a relative density of 95% or more. From the viewpoint of the quality of the resulting high dielectric film, it is preferable that the amount is very small.
If it is less than 5 ppm, cracking and peeling of the target during high power sputtering will increase, while 70 pp
If the content exceeds m, the strength of the target is undesirably reduced. Therefore, the amount of Si contained in the sputtering target for forming a high dielectric film of the present invention is 25%.
に 70 ppm. A more preferred range of the Si content is 30 to 50 ppm.

In the method for producing a sputtering target for forming a high dielectric film according to the present invention, any
i content: A commercially available high-purity Ba carbonate powder having a content of less than 10 ppm, a commercially available high-purity Sr carbonate powder and a commercially available high-purity titanium oxide powder are prepared, and these raw material powders are blended in a predetermined ratio, and Si is further added. And Si content is 25-70p
Except that the components are adjusted to be pm, the production method is the same as that of the conventional production method, and a detailed description thereof will be omitted.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In each case, commercially available high-purity Ba having a Si content of 5 ppm or less.
CO ₃ powder, high-purity SiCO ₃ powder and high-purity TiO
₂ powder were prepared, these high-purity BaCO ₃ powder, high-purity SrCO ₃ powder, and high-purity TiO ₂ powder were blended in such a ratio as to become a high dielectric compound shown in Table 1, and a small amount of Si powder was added. The mixture was placed in a ball mill and mixed, and the obtained mixed powder was baked in the atmosphere at 1100 ° C. for 1 hour to produce a composite oxide containing Si in the amount shown in Table 1.

The composite oxide is pulverized in a ball mill to produce a composite oxide powder having an average particle size of 1 to 5 μm. The obtained composite oxide powder is filled in a graphite mold, and the temperature is increased. : 5 ° C / min, heating temperature: 1300 ° C, pressure: 150 ton / cm ² , holding time: 1 hour, cooling: furnace cooling, diameter: 650m by hot pressing
m, thickness: 6 mm, relative density of 9
A hot-pressed body of 9% or more is produced, and the hot-pressed body is machined to obtain a diameter: 600 mm and a thickness:
Sputtering targets of the present invention (hereinafter, referred to as present invention targets) 1 to 5 and comparative sputtering targets (hereinafter, referred to as comparative targets) 1 to 5 each having a size of 5 mm were produced.

The targets 1 to 5 of the present invention and the comparative targets 1 to 5 were joined to a water-cooled copper plate by In-Sn solder, set in a high-frequency magnetron sputtering apparatus, and an atmosphere gas: a mixed gas of Ar and oxygen (Ar: O = 1
1) Atmospheric pressure: 1 pa, Frequency: 13.56 Mhz, Output: 3 kW, Time: 50 hours, Deposition rate: 250 Å / min, whether or not cracks occurred on the target surface Was observed by silent observation, and the results are shown in Table 1.

[0016]

[Table 1]

[0017]

As can be seen from the results shown in Table 1, high purity BaCO having a Si content of 5 ppm or less was used as the raw material powder.
₃ powder, high-purity SrCO ₃ powder and TiO ₂ powder, and further adding Si to reduce the Si content to 25 to 70 p.
Si content obtained by adjusting to pm: 25 to 70 ppm
It can be seen that none of the targets 1 to 5 of the present invention cause peeling or cracking during sputtering, but the comparative targets 1 to 2 having a Si content of less than 25 ppm are peeled or cracked during sputtering.

However, the comparative targets 3 to 5 containing the Si content exceeding 70 ppm do not cause peeling or cracking at the time of sputtering, but have insufficient strength of the target itself, and are particularly suitable for forming a large high dielectric film. It turns out that it is not preferable as a component composition of a sputtering target. As described above, the sputtering target for forming a high dielectric film of the present invention does not cause separation or cracking at the time of sputtering even if the sputtering target is large and has a high density. It has excellent effects.

Continuation of front page (56) References JP-A-59-199504 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 14/00-14/58 C01G 23/00 C01G 25 / 00-57/00 C04B 35/42-35/51 C01F 11/16 C01B 13/16 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A sputtering target for forming a high dielectric film having a perovskite structure composed of a composite oxide of Ba and Ti, containing 25 to 70 ppm of Si , having a diameter of more than 500 mm and a relative density of 95% or less.
A sputtering target having the above . 2. A sputtering target for forming a high dielectric film having a perovskite structure comprising a composite oxide of Sr and Ti, which contains 25 to 70 ppm of Si , has a diameter of more than 500 mm and a relative density of 95% or less.
A sputtering target having the above . 3. A sputtering target for forming a high dielectric film having a perovskite structure comprising a composite oxide of Ba, Sr and Ti, wherein Si: 25 to 70 pp.
m , diameter: over 500 mm and relative density: 9
A sputtering target having 5% or more .