JPH0451409A - Ito sintered body - Google Patents

Abstract

PURPOSE:To effectively suppress generation of an abnormal electric discharging phenomenon by constituting the body of indium, tin and oxygen, and by determining relative density, tin composition in a linear analysis of an electron beam micro-analyzer and a surface resistance value to specified values respectively. CONSTITUTION:An ITO sintered body is substantially constituted of indium, tin and oxygen. Its relative density is 80% or more, tin composition in a linear analysis of an electron probe micro analyzer (EPMA) is within 0.8 to 1.2 times of mean composition and a surface resistance value is 1mOMEGA/cm<2> or less. For example, after sufficient blending of In2O3 powder and SnO2 powder, homogenizing process is performed. By using the processed powder, sintering under pressure (hot press or hot hydrostatic press) is conducted. By making the ITO sintered body of high density, dispersing tin homogeneously and enhancing electric conductivity of the sintered body, accumulation of electric charges is prevented and an abnormal electric discharging phenomenon is effectively suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sputtering target used for producing a transparent conductive film, that is, an ITO sintered body.

(Prior Art) As a transparent conductive film obtained by sputtering, so-called ITO, which is made of indium, tin, and oxygen, is attracting attention as a promising film because of its low specific resistance value.

(Problems to be Solved by the Invention) Conventionally, when sputtering is performed using a TTO target, the plasma state becomes unstable due to an abnormal discharge phenomenon that occurs during film formation, and stable film formation cannot be performed, resulting in sputtering. It is known that the structure of the film deteriorates and the characteristic values of the film deteriorate.

In addition, if an ITO target is used for a long time under conditions where abnormal discharge phenomena occur frequently, a degraded layer will form on the target surface (so-called blackening), which will slow down the film formation rate and reduce productivity. There is also the problem of doing so.

Therefore, an object of the present invention is to provide an ITO sintered body that can eliminate the above-described problems related to sputtering of an ITO target and can effectively suppress the occurrence of abnormal discharge phenomena.

(Means for Achieving the Object) The TO sintered body of the present invention consists essentially of indium, tin, and oxygen, has a relative density of 80% or more, and is analyzed by electron beam microanalyzer (EPMA). The tin composition is within the range of 0.8 to 1.2 times the average composition, and the surface resistance value is 1 mΩ/cnr or less.

The abnormal discharge phenomenon during sputtering is caused by secondary electrons being emitted from the target when argon ions collide with the target, and positive charges accumulating within the target. The present invention prevents the accumulation of charges by making the ITO sintered body high in density as described above, dispersing tin uniformly, and making the sintered body have good electric type conductivity. As a result, we succeeded in effectively suppressing abnormal discharge phenomena.

ITO Sintered Body The TTO sintered body of the present invention consists essentially of indium, tin, and oxygen, and is of the InJ)3-3nL type. The composition itself is the same as that of a known ITO sintered body, and generally the average composition of tin is 4 to 12% by weight, and the average composition of indium is in the range of 70 to 78% by weight.

In the IT○ sintered body of the present invention, first, the relative density is 80
% or more, preferably in the range of 8596 or more. If this relative density is lower than 80%,
There are some parts where the density is quite low, forming parts where electric charges are likely to accumulate locally, making it easy to generate abnormal discharge.

In addition, in the present invention, the range of variation in tin composition in line analysis with an electron beam microanalyzer is 0.
．． It is also important that it be within the range of 8 to 1.2 times. For example, if the variation in the tin composition in the above-mentioned line analysis falls outside the above-mentioned range, it means that there is a portion where the amount of tin is concentrated and considerably large. In areas where a large amount of tin is concentrated, the conductivity is low,
As a result, electric charges tend to accumulate (and abnormal discharges tend to occur).In the present invention, tin is uniformly dispersed throughout the sintered body, and there are no areas where tin is locally concentrated. Therefore, local charge accumulation can be effectively avoided, and abnormal discharge can be effectively suppressed.

Furthermore, according to the present invention, the surface resistance value of the sintered body is 1 mΩ.
/ cnr or less. This surface resistance value is 1mΩ/
If it is larger than crd, the sintered body itself tends to accumulate charge, making it difficult to effectively suppress abnormal discharge.

Manufacture of TTO sintered body A TTO sintered body having the above-mentioned composition and physical properties can be manufactured by the following two methods.

The first method is In2(L) with an average particle size of 0.1 μm or less.
After thoroughly mixing the + powder and 5n02 powder with an average particle size of 1 μm or less, heat the mixture at 1350°C or higher, preferably at 14°C.
Homogenization treatment is carried out at a temperature of 00 to 1500°C, and the treated powder is sintered under pressure at a temperature of 500 to 1000°C (hot press or hot isostatic pressing).
This is the way to do it. A particularly important step in this first method is the homogenization treatment step, and by performing the homogenization treatment in the above temperature range, agglomeration of 5n02 is effectively prevented, and the variation in tin composition in the line analysis mentioned above is prevented. can be adjusted within a certain range.

The second method uses the same In2O3 powder as above and 5n02
Thoroughly mix and crush the powder to obtain an average particle size of 0.07 μm.
After improving the sinterability by micronizing the particles as shown below, solution treatment is preferably performed at a temperature of 1000 to 1200°C, press molding is performed using the powder, and then 1350°C or higher, Preferably 1400-1550°
Sintering is performed at a temperature of
In this method, heat treatment is performed at a temperature of 1000 to 1300°C. An important step in this second method is the atomization step, and by performing such a micronization treatment, agglomeration of 5n02 is effectively prevented, and the variation in tin composition in the line analysis mentioned above is kept constant. It is possible to adjust within the range of . Further, the above-mentioned heat treatment step is a treatment performed to reduce the surface resistance value.

The sintered body manufactured by the above method has a relative density, a variation range of tin composition in line analysis using an electron beam microanalyzer, and a surface resistance value within the above-mentioned ranges, which effectively suppresses abnormal discharge. It becomes possible to do so.

The excellent effects of the present invention will be explained with the following example.

(Example) Example 1 Indium oxide (In203) with an average particle size of 0.07 μm
powder and tin oxide (SnO□) powder with an average particle size of 0.5 μm, and the composition ratio was
Both were blended so that O□)+o.

Next, 1% by weight of paraffin wax binder and pure water were added thereto, and then ball mill mixing was performed for 24 hours using 10 mm diameter zirconia balls.

After drying this mixed powder, it was held at 1400°C in the air for 5 hours to homogenize it. Then, after cooling to room temperature,
Filled into a graphite mold and heated at 800°C in vacuum to 0.
Hot press at 2 ton/ci pressure, 75 m
A disc-shaped sintered body (Tagela I-) with a diameter of m and a thickness of 5 mm was obtained.

Table 1 shows the density of the obtained sintered body and the surface resistance value measured by the four-probe method.

In addition, after polishing the cross section of the sintered body described in 1., the beam diameter was 1 μm.
As a result of examining the variation in tin over a length of 50 μm using EPMA line analysis of
．． It varied between 5% by weight. The average tin composition determined by chemical analysis was 7.9% by weight.

Further, using the above sintered body as a sputtering target, continuous sputtering was performed for 16 hours by DC magnetron sputtering, and Table 1 shows the number of abnormal discharges that occurred per minute. In addition, the observation results of the surface state after 16 hours and the rate of change in the film formation rate after 16 hours of sputtering with respect to the film formation rate after 1 hour of sputtering were determined.
They are also shown in Table 1.

Example 2 After adding a binder and pure water to tin solid solution indium oxide powder manufactured from an alloy of indium and tin, 1
Ball mill mixing was performed for 24 hours using zirconia balls with a diameter of 0 mm. The particle size of the obtained powder was measured by the BET method and was found to be 0.05 μm.

After drying this powder, it is granulated to produce 3 ton/cn.
It was press-formed into a disk shape with a diameter of 75 mm and a thickness of 5 mm at a pressure of r, and then heated at 1550 °C in an oxygen atmosphere for 5
It was held for a time and sintered. Then in argon, 1250
A heat treatment was performed at °C for 3 hours to reduce the surface resistance value.

When this sintered body was examined for variations in tin composition in the same manner as in Example 1, the tin composition varied between 7.0% by weight and 8.9% by weight. The average tin composition determined by chemical analysis was 7.9% by weight.

Table 1 also shows the density and surface resistance of the sintered body, and the results of a sputtering test conducted in the same manner as in Example 1.

Comparative Example 1 Powder obtained by blending and mixing in the same manner as in Example ① except that homogenization treatment was not performed was dried and 2 tons
/cnf pressure, then held at 1550'C in an oxygen atmosphere for 5 hours to form a 75+n+n diameter x 5
A disk-shaped sintered body with a thickness of mm was obtained.

Various properties of this sintered body were measured and sputtering tests were conducted in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 Each powder similar to that used in Example 1 was blended with the same composition as in Example 1, mixed for 60 minutes using a ■-blender, and then filled into a graphite mold and heated in a vacuum. 800
Hot pressing was performed at a temperature of 0.2 ton/c&, to obtain a disk-shaped sintered body (target) with a diameter of 75 mm and a thickness of 5 mm.

Various properties of this sintered body were measured and sputtering tests were conducted in the same manner as in Example 1, and the results are shown in Table 1.

(Effects of the Invention) According to the present invention, it is possible to provide an ITO target that has an extremely small number of abnormal discharges during sputtering and does not cause surface blackening even after long-term use.

Claims (1)

[Claims] (1) In an ITO sintered body that consists essentially of indium, tin, and oxygen and has a relative density of 80% or more, the tin composition in line analysis with an electron beam microanalyzer is
An ITO sintered body having a surface resistance value within a range of 0.8 to 1.2 times the average composition and a surface resistance value of 1 mΩ/cm^2 or less.