JPH10310470A - Sputtering target for forming high dielectric film made of barium-strontium-titanium multiple oxide sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sputtering target for forming a high dielectric film less liable to generate particles at the time of sputtering. SOLUTION: This sputtering target for forming a high dielectric film is made of a Ba-Sr-Ti multiple oxide sintered compact and has a texture in which the average grain diameter of Ba-Sr-Ti multiple oxide grains constituting this target is in the range of 1-10 μm. The average surface roughness of the target is equal to or less than the average grain diameter of the multiple oxide grains, preferably <=1/10 of the average grain diameter.

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 used for forming a film for a capacitor in a semiconductor device such as an IC, and more particularly to a Ba having a small particle generation during sputtering. The present invention relates to a sputtering target for forming a high dielectric film made of a composite oxide sintered body of Sr, Ti and Sr.

[0002]

2. Description of the Related Art Generally, Ba, which has a perovskite structure as a film for a capacitor used for a semiconductor element such as an IC, has
It is known to use a high dielectric film made of a composite oxide of Sr and Ti (hereinafter, referred to as a BaSrTi composite oxide). Such a high dielectric film uses a target made of a BaSrTi composite oxide sintered body. It is also known that they are formed by sputtering.

In order to manufacture a sputtering target for forming a high dielectric film made of the BaSrTi composite oxide sintered body, first, BaCO ₃ powder, SrCO ₃ powder and TiO ₂ powder as raw material powders are prepared, and these raw material powders are prepared. Compounded in a predetermined ratio, put into a ball mill and mixed, put the obtained mixed powder into a MgO crucible, in the air atmosphere, temperature:
BaSrTi composite oxide powder can be prepared by firing at 1200 to 1350 ° C. for 3 to 10 hours and pulverizing the obtained fired body with a ball mill.
However, they can also be produced by a hydrothermal synthesis method, and these B
aSrTi composite oxide powder is also commercially available.

The BaSrTi composite oxide powder usually has an average particle size of 6 to 15 μm, and the powder is vacuumed at 1 × 10 ^{−4 to} 5 × 10 ⁻² Torr and loaded at 50.
~ 200 kg / cm ² , temperature: 1250-1350 ° C,
By hot pressing under the condition of holding for 2 to 5 hours,
A BaSrTi composite oxide sintered body having a structure with a density ratio of 97 to 99% and an average particle diameter of about 6 to 15 μm, which is almost the same as that of the raw material powder, can be produced.

[0005] The obtained BaSrTi composite oxide sintered body can be finished into a sputtering target of a predetermined size by grinding the surface with a rotary grindstone.
The surface roughness of the conventional sputtering target thus obtained has an average roughness of 11 μm or more. The obtained target was brazed to a water-cooled copper plate and set in a sputtering target device, and a high-dielectric film made of a BaSrTi composite oxide having a perovskite structure was formed by sputtering by setting the atmosphere on the target side to a vacuum atmosphere. ing.

[0006]

In recent years, in order to mass-produce semiconductor devices and reduce costs, high-speed sputtering is performed by using a large-sized target and performing high-power sputtering in a high-vacuum atmosphere. A high dielectric film is formed in a short time. However, when high-power sputtering is performed in a high-vacuum atmosphere, particles are generated in the obtained thin film, which seriously affects the yield of semiconductor devices.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
We have been studying to develop a sputtering target for forming a high dielectric film that does not generate particles in the thin film during sputtering. Has a major impact on outbreaks,
(A) a sputtering target for forming a high dielectric film formed of a BaSrTi composite oxide sintered body, wherein the target has a structure in which the average particle diameter of the BaSrTi composite oxide particles constituting the target is in the range of 1 to 10 μm; When the average surface roughness has a value equal to or less than the average particle size of the composite oxide particles, the generation of particles during sputtering is significantly reduced. (B) The average particle size of the BaSrTi composite oxide particles is 1 to 3. When the average roughness of the surface of the target having a structure within the range of 10 μm is 1/10 or less of the average particle size of the composite oxide particles, the generation of particles during sputtering is further reduced. The knowledge was obtained.

The present invention has been made based on this finding, and (1) has a structure in which the average particle size of the BaSrTi composite oxide particles is in the range of 1 to 10 μm;
And a sputtering target for forming a high dielectric film comprising a BaSrTi composite oxide sintered body having an average surface roughness equal to or less than the average particle size of the composite oxide particles, (2)
In a sputtering target for forming a high dielectric film formed of a sintered body of BaSrTi composite oxide, the target has a structure in which the average particle diameter of BaSrTi composite oxide particles constituting the target is in the range of 1 to 10 μm, and The sputtering target for forming a high dielectric film has an average surface roughness of 1/10 or less of the average particle diameter of the composite oxide particles.

Assuming that the surface roughness of the sputtering target for forming a high dielectric film of the present invention is R and the average particle size of the BaSrTi composite oxide particles in the substrate is D (1 to 10 μm), the high dielectric film of the present invention is The relationship between the surface roughness R of the sputtering target for formation and the average particle diameter D of the BaSrTi composite oxide particles is preferably 0 <R ≦ D,
More preferably, 0 <R ≦ D / 10. Further, assuming that the average of the surface roughness measured at 10 points of the sputtering target for forming a high dielectric film of the present invention is 10 point average roughness Rz, 0 <Rz ≦ D, and further 0 <Rz ≦ D / 1.
A value of 0 represents a more realistic value.

The structure of the sputtering target for forming a high dielectric film according to the present invention is preferably such that the average particle diameter of the BaSrTi composite oxide particles is in the range of 1 to 10 μm. : 1
More preferably, it is within the range of 5 to 5 μm. Since the ordinary sputtering target has BaSrTi composite oxide particles having an average particle diameter in the range of 6 to 15 μm, the structure of the sputtering target for forming a high dielectric film of the present invention is the same as that of the conventional target BaSrTi composite oxide. Although there is a range where the particles overlap the average particle size, the structure is finer than the conventional target.

In the method of manufacturing a sputtering target for forming a high dielectric film according to the present invention, a BaSrTi composite oxide powder having an average particle diameter of 1 to 10 μm is vacuum-heated to 1 × 10 ^{-4 to} 5
× 10 ^-2 Torr, load: 50 to 200 kg / cm ² ,
Temperature: 1250 to 1350 ° C., hot-pressed for 2 to 5 hours to obtain a density ratio of 97 to 99%,
Producing a BaSrTi composite oxide sintered body having an average particle diameter of about the same as the raw material powder: an average particle diameter of 1 to 10 μm;
BaSrT having an average particle size of 1 to 10 μm
The composite oxide sintered body is manufactured by grinding with a normal grindstone to a predetermined size, and then performing chemical mechanical polishing using a diamond slurry obtained by mixing 5 to 30% of hydrochloric acid and hydrogen peroxide solution. can do.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

BaS the average particle diameter as prepared in Example 1 hydrothermal synthesis method consists commercial _{(Ba 0.5, Sr 0. 5)} TiO 3 powder having a 1μm
An rTi composite oxide powder is prepared, and the BaSrTi composite oxide powder is filled into a high-purity graphite mold having an inner diameter of 330 mm, a pressure of 200 kgf / cm ² is applied, and the temperature is maintained at 1250 ° C. for 3 hours. Then, a hot press sintered body having a diameter of 330 mm, a thickness of 7 mm and a density ratio of 99% was produced by vacuum hot pressing. The hot press sintered body is ground by a grindstone to obtain a diameter of 300 mm and a thickness of 5 mm.
Dimensions of 25% hydrochloric acid and hydrogen peroxide solution
The target surface was chemically and mechanically polished using the mixed diamond slurry. At this time, a jig for the polishing machine made of Teflon or Hastelloy was used to suppress metal contamination on the target surface.

The target 1 of the present invention thus produced
When the average particle size of the structure was measured, the average particle size was 1 μm. Furthermore, the surface of the target 1 of the present invention is
When the 10-point average roughness Rz was measured at 50 μm and the average of five measurements, the 10-point average roughness Rz was 0.1 μm.
After the surface of the obtained target 1 of the present invention was further confirmed by an optical microscope that there was no linear scratch having a width of 2 μm or more over the entire target, the surface was brazed to an oxygen-free copper backing plate. 7.5 mTorr, sputter gas composition: Ar / O ² = 4/1, applied power: high frequency (13.56 MHz) 3000 W (about 4.2 W / cm ² ), film formation rate: 20 nm / min, preliminary Without discharge, a 100 nm film is formed on a 6 inch diameter silicon wafer in a batch mode,
The number of particles of m or more on the wafer was measured, the number of counted particles was plotted on the vertical axis, and the number of deposition batches was plotted on the horizontal axis. This graph is shown in FIG.

[0014] Example 2 average particle diameter produced by hydrothermal synthesis method is commercially available having a _{3μm (Ba 0.5, Sr 0. 5} ) consisting of TiO ₃ powder BaS
An rTi composite oxide powder was prepared, and then subjected to vacuum hot pressing under the same conditions as in Example 1 to obtain a diameter of 330 m.
m, a hot-press sintered body having a thickness of 7 mm and a density ratio of 98% is prepared, and the hot-pressed sintered body is ground by a grindstone to dimensions of 300 mm in diameter and 5 mm in thickness. Was subjected to chemical mechanical polishing of the target surface under the same conditions as in Example 1 to produce a target 2 of the present invention. When the average particle size of the structure of the target 2 of the present invention was measured, the average particle size was 3 μm. Further, when the surface of the target 2 of the present invention was measured for a 10-point average roughness Rz of a reference length of 250 μm and an average of five measurements, the 10-point average roughness Rz was 1.4 μm. The surface of the obtained target 2 of the present invention was further confirmed with an optical microscope that no linear scratches having a width of 2 μm or more were present over the entire target, and this was brazed to an oxygen-free copper backing plate. Under the same conditions as above, a 100 nm-thick film was formed on a silicon wafer having a diameter of 6 inches by a batch method without preliminary discharge, the number of particles of 0.23 μm or more was measured on the wafer, and the number of counted particles was measured. Create a graph with the vertical axis and the number of film formation batches on the horizontal axis,
This graph is shown in FIG.

[0015] Example 3 average particle diameter produced by hydrothermal synthesis method is commercially available with a _{5μm (Ba 0.5, Sr 0. 5} ) consisting of TiO ₃ powder BaS
An rTi composite oxide powder was prepared, and then subjected to vacuum hot pressing under the same conditions as in Example 1 to obtain a diameter of 330 m.
m, a hot press sintered body having a thickness of 7 mm and a density ratio of 97% was prepared, and the hot pressed sintered body was ground by a grindstone to a size of a diameter of 300 mm and a thickness of 5 mm. Under the same conditions as in Example 1, a target 3 of the present invention was produced. When the average particle size of the structure of the target 3 of the present invention was measured, the average particle size was 5 μm. Further, when the surface of the target 3 of the present invention was measured for a 10-point average roughness Rz of a reference length of 250 μm and an average of five measurements, the 10-point average roughness Rz was 3.7 μm. The surface of the obtained target 3 of the present invention was further confirmed with an optical microscope that there was no linear scratch having a width of 2 μm or more over the entire target, and this was brazed to an oxygen-free copper backing plate. Under the same conditions as above, a 100 nm-thick film was formed on a silicon wafer having a diameter of 6 inches by a batch method without preliminary discharge, the number of particles of 0.23 μm or more was measured on the wafer, and the number of counted particles was measured. FIG. 3 shows a graph in which the vertical axis is plotted and the number of film forming batches is plotted on the horizontal axis.

Conventional Example 1 A market having an average particle size of 13 μm produced by a hydrothermal synthesis method
(Ba of sales_0.5, Sr _0.5) TiO_ThreeBa made of powder
A SrTi composite oxide powder was prepared, and the BaSrTi composite oxide was prepared.
Vacuum hot pressing of mixed oxide powder under the same conditions as in Example 1
Has a diameter of 330 mm and a thickness of 7 mm
A hot press sintered body having a density ratio of 94% is produced,
This hot-pressed sintered body has a diameter of 300 mm and a thickness of 5
mm by grinding with a whetstone
Target 1 was produced.

When the average grain size of the structure of the conventional target 1 thus manufactured was measured, the average grain size was 13 m. Further, the surface of the conventional target 1 is set to a reference length of 250.
The 10-point average roughness Rz of μm, the average of five measurements, was measured, and the 10-point average roughness Rz was 11 μm. The obtained conventional target 1 was brazed to an oxygen-free copper backing plate, and a 100-nm-thick film was formed on a 6-inch-diameter silicon wafer by a batch method without preliminary discharge under the same conditions as in Example 1, and 0.23 μm was formed. FIG. 4 shows a graph in which the number of the above particles was measured on the wafer, the number of counted particles was plotted on the vertical axis, and the number of film forming batches was plotted on the horizontal axis.

[0018]

From the results shown in Examples 1 to 3 and Conventional Example 1, in the targets 1 to 3 of the present invention, the number of counted particles decreases as the number of deposition batches increases.
In particular, the target 1 of the present invention having a 10-point average roughness Rz of 0.1 μm in Example 1 has a small number of particles counted irrespective of the number of film forming batches. It can be seen that the number of generated particles can be reduced by performing sputtering outside the pre-discharge period. On the other hand, it can be seen that the number of particles counted in the conventional target 1 does not decrease even when the number of deposition batches increases. Therefore,
The sputtering target of the present invention can reduce the number of particles generated at the time of sputtering by forming a high dielectric film made of a BaSrTi composite oxide having a perovskite structure in a semiconductor element except for at least the preliminary discharge period, It can be seen that the rate of defective products in mass production of semiconductor devices can be reduced.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the number of counted particles and the number of deposition batches in Example 1.

FIG. 2 is a graph showing the relationship between the number of counted particles and the number of deposition batches in Example 2.

FIG. 3 is a graph showing the relationship between the number of counted particles and the number of deposition batches in Example 3.

FIG. 4 is a graph showing the relationship between the number of counted particles and the number of deposition batches in Conventional Example 1.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/822 C04B 35/46 E 27/108 H01L 27/04 C 21/8242 27/10 651 // H01L 21/203 (72 ) Inventor: Akifumi Mishima 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Mitsubishi Materials Corporation

Claims (3)

[Claims] 1. A structure in which the average particle size of the composite oxide particles of Ba, Sr and Ti is in the range of 1 to 10 μm,
And Ba, Sr and Ti, wherein the average roughness of the surface has a value equal to or less than the average particle size of the composite oxide particles.
A sputtering target for forming a high dielectric film comprising a composite oxide sintered body of the above. 2. A structure in which the average particle size of the composite oxide particles of Ba, Sr and Ti is in the range of 1 to 10 μm,
And Ba, Sr, wherein the average roughness of the surface has a value of 1/10 or less of the average particle size of the composite oxide particles.
Target for forming a high dielectric film, comprising a composite oxide sintered body of Ti and Ti. 3. The Ba, Sr, and T according to claim 1, wherein the average roughness of the surface is a 10-point average roughness, which is an average value of an average roughness of 10 surfaces.
A sputtering target for forming a high dielectric film comprising the sintered complex oxide of i.