TWI406963B - Tin oxide sputtering target - Google Patents

Abstract

This invention provides an SnO2-based sinter target which has a reduced absolute value of the stress of a sputtered film and causes no significant film separation from a peripheral structure of a sputter cathode. The SnO2-based sputtering target is formed of a sinter comprising more than 10 ppm and less than 1% by mass of Sb2O3 and not more than 20% by mass in total of Ta2O5 and/or Nb2O5 with the balance consisting of SnO2 and unavoidable impurities.

Description

Tin dioxide sputtering target

The present invention relates to a tin dioxide (SnO ₂ )-based sputtering target, and particularly to various applications such as a flat panel display, a touch panel, and a solar cell, in order to secure a transparent electrode, charge prevention, electromagnetic wave shielding, and gas barrier A tin dioxide sputtering target used for various film functions such as heat line reflection.

In recent years, tin dioxide-based sputtering films have been used in a wide range of applications such as flat panel displays, touch panels, and solar cells. In the mainstream of the industry, the tin dioxide-based sputtering film is produced by a spray method or a chemical vapor deposition (CVD) method. However, the two methods are not suitable for equalizing the film thickness over a large area, and it is difficult to control the film forming process, and the film formation may cause high temperature or may generate a chlorine-based gas belonging to a pollutant. Pursue new manufacturing methods without these shortcomings.

On the other hand, attempts have been made to produce a tin dioxide-based sputtering film by sputtering, and a target of SnO ₂ -Sb ₂ O ₃ in which Sb ₂ O ₃ is added to reduce the specific resistance is used as a sputtering target to be manufactured. The industry has been put into practical use. However, the conventional tin oxide-based sintered body target increases the amount of film adhesion as the integrated electric power increases, and the particles caused by the peeling of the film from the peripheral structure of the sputter cathode frequently occur. It is also known that the adhesion of the particles to the film deteriorates the properties of the film and may become a cause of film defects. Therefore, a tin dioxide-based sputtering target in which a film is rarely peeled off from a peripheral structure at the time of a sputtering process is pursued.

In the SnO ₂ -Sb ₂ O ₃ system, a sintered body which is sintered at 1450 ° C or higher is known, and the sintered body is Nb or Nb which is 20% by mass or less in total of oxides. Ta, and unavoidable impurities are composed of Sb ₂ O ₃ of 10 ppm or less, and the remaining percentage of Sn ₂ O ₂ (for example, refer to Japanese Patent No. 3957917). Further, a sintered SnO ₂ -Sb ₂ O ₃ sintered at 820 ° C or lower containing 10.2% by mass of Sb ₂ O ₃ is also known (for example, refer to Japanese Patent No. 3662168). Further, it is also known that Sb ₂ O ₃ is contained in an amount of 3 to 10% by mass, and the remaining percentage is a tin oxide-yttria sintered body target which is sintered by 800 ° C and composed of SnO ₂ and unavoidable impurities (for example, , refer to Japanese Patent No. 3710021). Further, a tin-bismuth oxide sintered body target composed of 6% by mass of cerium oxide, and 5 to 20% by mass of zinc oxide, and the remaining percentage of SnO ₂ sintered at 1500 ° C is known (for example, Japanese Patent Laid-Open Publication No. 2003-73819). However, in any of these documents, the composition of the sintered body containing Sb ₂ O ₃ containing more than 10 ppm and less than 1% by mass, the absolute film stress of the sputter film is small, and the film is rarely splashed during the sputtering process. There is no discussion of the knowledge of the tin-plated sputtering target of the peripheral structure of the plated cathode.

The present inventors have obtained an insight into the tin dioxide sputtering target that the amount of Sb ₂ O ₃ added is more than 10 ppm and less than 1% by mass, and the obtained SnO ₂ sintered body is used as a sputtering target. A sputter film having a small absolute value of the film stress is obtained, and the film is rarely peeled off from the peripheral structure of the sputter cathode during the sputtering process.

Accordingly, it is an object of the present invention to provide an Sb ₂ O ₃ containing less than 10 ppm and less than 1% by mass of the absolute film stress of the sputter film which is rarely peeled off from the peripheral structure of the sputter cathode during the sputtering process. The formed sintered body is composed of a tin dioxide sputtering target.

In other words, the tin oxide-based sputtering target of the present invention is composed of a sintered body having more than 10 ppm and less than 1% by mass of Sb ₂ O ₃ and a total mass of 20% by mass or less of Ta. ₂ O ₅ and / or Nb ₂ O ₅ , and the remaining percentage of SnO ₂ and unavoidable impurities.

Tin dioxide sputtering target

The tin dioxide-based sputtering target of the present invention is composed of a sintered body, and the sintered body is composed of more than 10 ppm and less than 1% by mass of Sb ₂ O ₃ and a total mass of 20% by mass or less, preferably 1 to 20% by mass of Ta ₂ O ₅ and/or Nb ₂ O ₅ , and the remaining percentage of SnO ₂ and unavoidable impurities. When such a tin dioxide-based sputtering target is used as a sputtering target, a sputtering film having a small absolute value of film stress can be obtained, and the film is rarely peeled off from the peripheral structure of the sputtering cathode during the sputtering process.

According to an embodiment of the present invention, the content of Sb ₂ O ₃ is preferably from 11 to 9000 ppm, more preferably from 100 to 6,000 ppm, still more preferably from 300 to 2,000 ppm. By using a sputtering process composed of a sputtering target composed of a sintered body in the composition range, the absolute film stress of the obtained sputtering film can be made small, and the film is rarely sputtered from the periphery of the sputtering cathode. The structure is peeled off.

According to the embodiment of the present invention, the content of Ta ₂ O ₅ is preferably 0 to 15% by mass, and the content of Nb ₂ O ₅ is preferably 0 to 15% by mass. By using the raw material mixed powder in the composition range, a sintered body can be produced by a cold press method or a casting method in which a large sintered body can be produced, and sintering can be performed at a high temperature of 1300 ° C or higher.

According to an embodiment of the present invention, the sputtering target of the present invention is preferably composed of a sintered body sintered at 1300 ° C, more preferably 1350 to 1650 ° C, still more preferably 1500 to 1650 ° C. The sintered body sintered in this temperature range can be sufficiently sintered in the liquid phase, that is, it can be a sintered body having a high sintered density.

According to an embodiment of the present invention, the sputtering target of the present invention is preferably composed of a sintered body having a relative density of 60% or more, more preferably 75% or more, still more preferably 95% or more. The range of the relative density, the film formation speed during the sputtering process is very fast, and the target period of use of the target is long, and the arc during the sputtering process can also be reduced. Further, when the sintered density is increased, bubbles or the like inside the sintered body can be reduced.

According to the embodiment of the present invention, when the sputtering target of the present invention is used for the sputtering treatment, it is preferable to obtain a sputtering film having an absolute value of the film stress of 1050 MPa or less, more preferably 1000 MPa or less. Within the range of the film stress value, the film is rarely peeled off from the peripheral structure of the sputtering cathode, and the occurrence of particles caused by film peeling can be suppressed.

Method for producing tin dioxide sputtering target

In the present invention, the method for producing the tin oxide-based sputtering target is not particularly limited, but may be carried out in the following manner. That is, according to the embodiment of the present invention, first, an unsintered molded body is prepared, which contains tin dioxide as a main component and contains more than 10 ppm and less than 1% by mass of Sb ₂ O ₃ , and also contains a total mass. It is 20 mass% or less of Ta ₂ O ₅ and/or Nb ₂ O ₅ . In the present invention, the unsintered molded body may be formed by any method if it is formed by molding the raw material powder containing the above composition. For example, SnO ₂ powder or Sb ₂ O may be blended in a ratio matching the above composition. ₃ powder, Ta ₂ O ₅ powder, and Nb ₂ O ₅ powder were mixed to prepare a raw material powder, and the raw material powder was molded to be produced.

According to the embodiment of the present invention, in the molded body of the unsintered body of the raw material powder, it is preferable to add an adhesive to the raw material powder so as to easily impart a specific shape. Such an adhesive is not limited as long as it is a known adhesive which is lost by heating or even splashed, and a polyvinyl alcohol aqueous solution or the like can be used. The method of drying and heating is not limited, and it is preferred to carry out drying at 50 to 130 ° C for 5 to 30 minutes, followed by heating at 500 to 800 ° C for 6 to 24 hours for degreasing.

According to the embodiment of the present invention, it is preferable that the unsintered molded body prepared by the above process is sintered at 1300 ° C, more preferably 1350 to 1650 ° C, still more preferably 1500 to 1650 ° C. By sintering in this temperature range, liquid phase sintering can be sufficiently performed to increase the sintered density, and it is possible to prevent the dissolution of tin dioxide so that the sintered body of a desired shape can be easily produced.

According to an embodiment of the present invention, the sintering is preferably carried out for 2 to 20 hours, more preferably 3 to 12 hours, and even more preferably 4 to 8 hours. In this range, it is possible to suppress the power consumption and sufficiently perform the sintering while ensuring high productivity.

According to the embodiment of the present invention, in order to secure a high sintered density, sintering is preferably carried out in an oxygen-containing atmosphere, for example, in an oxygen-pressurized atmosphere, an oxygen atmosphere, or an atmospheric atmosphere.

[Examples]

Example 1~37

(1) Production of sputtering target

First, prepare the following four kinds of raw material powders.

SnO ₂ powder: purity 99.99% (4N), average particle size 0.7~1.1μm, specific surface area 2.0~2.7m ² /g

Ta ₂ O ₅ powder: purity 99.9% (3N), average particle diameter 0.6~0.8μm, specific surface area 2.0~3.1m ² /g

Nb ₂ O ₅ powder: purity 99.9% (3N), average particle size 0.6~1.0μm, specific surface area 2.1~2.7m ² /g

Sb ₂ O ₃ powder: purity 99.9% (3N), average particle size 0.6~1.0μm

For each of the examples, the above four kinds of raw material powders were separately weighed, and then mixed by a dry ball mill for 21 hours. An aqueous polyvinyl alcohol solution was added to the mixed powder, and after sufficiently mixing, it was packed in a mold having a size of 400 × 800 mm, and compression-molded at a pressure of 800 kgf/cm ² . The formed body was dried at 80 ° C for 12 hours. The dried body was fired in an oxygen atmosphere at a firing temperature shown in Table 1 for 12 hours to obtain a sintered body. At this time, the temperature increase rate was controlled at 400 ° C / hour, and the temperature drop rate was controlled at 100 ° C / hour. The obtained sintered body was machined into a size of 152.4 mm in diameter and 5 mm in thickness to obtain a tin dioxide sputtering target. In addition, the processed end material of the sintered body is pulverized with a peony powder, and after adding the powder of the powder, a mixed acid of hydrochloric acid hydrochloric acid, and ultrapure water to hydrolyze in a container made of Teflon (registered trademark), As a fixed solution. The elements of Ta, Nb, and Sb in the obtained fixed solution were measured by ICP mass spectrometry using an ICP (Inductively Coupled Plasma) mass spectrometer (Model 4500 manufactured by Agilent Co., Ltd.). The oxide conversion values are shown in Table 1.

(2) Evaluation

Various evaluation tests shown below were performed for the obtained sputtering target.

Assessment 1: Determination of relative density

The relative density of each sputter target was measured by the Archimedes method. At this time, the density of each raw material was set to SnO ₂ : 6.95 g/cm ³ , Ta ₂ O ₅ : 8.74 g/cm ³ , and Nb ₂ O ₅ : 4.47 g/cm ³ , and the weighted average density was calculated, and the weighted average was calculated. The density was set to 100%, and the relative density was calculated. The results are as described in Table 1.

Evaluation 2: Evaluation of the film stress of the sputter film

The sputtering target metal obtained in Examples 1 to 37 was adhered to a backing plate made of oxygen-free copper. Then, each of the sputter targets adhered to the metal was sputter-plated by a DC power source under the sputtering conditions shown below, and the film was sputter-deposited on the germanium wafer.

Cathode: Strong magnetic field electromagnetic circuit

Target/substrate distance: 50mm

Sputtering chamber arrival pressure: <1×10 ^-4 Pa

Substrate temperature: room temperature (no heating)

Introduced gas: argon + oxygen (oxygen concentration 1% by volume)

Introduced gas partial pressure: 0.67Pa

DC applied power: 360W

Film thickness: 500nm

Substrate: Φ4inch×520μm, germanium wafer

With respect to the sputter film obtained in this manner, the radius of curvature was measured using FLX-2320-5 (manufactured by Nippon Techno Co., Ltd.), and the stress was calculated by the following calculation formula. The negative sign of the film stress represents the compressive stress.

σ=Eb ² /{6(1-ν)*rd)

σ: stress

E: Young's modulus of the substrate

b: thickness of the substrate

ν: Poisson's ratio of the substrate

d: film thickness

r: radius of curvature of the substrate after film formation (measured by Newton's method)

As a result, as shown in Table 1, it was found that the sputtering film formed by using the sputtering target which does not have the composition of the present invention has a very low film stress.

Assessment 3: Evaluation of film peeling

The sputtering of the sputtering target obtained in Examples 1 to 37 was evaluated by the sputtering apparatus shown in Fig. 1 in the following manner. In the sputtering apparatus shown in FIG. 1, the processing chamber 1 is provided with a backing plate 3 on which the target 2 is placed, and a substrate holder 4 that is disposed to face the backing plate 3. Then, an earth shield 5 for protecting the sides of the target 2 and the back plate 3 and an anti-adhesion plate 6 for preventing the film from being formed in the processing chamber 1 are further provided in the processing chamber 1.

First, the sputtering target metal is adhered to the backing plate 2 in the processing chamber 1. Then, the target 2 to which the metal adhered was continuously discharged under the conditions shown below. After continuous discharge, the film attached to the substrate holder 4, the grounding barrier 5, and the anti-adhesion plate 6 was observed, and the film was peeled off obviously, and the film was not peeled off.

Cathode: Strong magnetic field electromagnetic circuit

Splash chamber arrival pressure: <1×10 ^-4 Pa

Introduced gas: argon + oxygen (oxygen concentration 1% by volume)

Introduced gas partial pressure: 0.67Pa

DC applied power: 360W

Film thickness: 500nm

Sputtering time: discharge for 30 consecutive hours

Grounding barrier: aluminium (alundum) #60 sandblasted products

Substrate holder: aluminium (alundum) #60 sandblasted product

Anti-adhesion plate: aluminium (alundum) #60 sandblasted product

As a result, as shown in Table 1, it was found that the substrate holder 4, the grounding barrier 5, and the film attached to the adhesion preventing plate 6 shown in Fig. 1 were continuously discharged after the sputtering target having the composition of the present invention was not continuously discharged. No film peeling occurred.

1. . . Processing room

2. . . Target

3. . . Backing plate

4. . . Substrate holder

5. . . Earth shield

6. . . Anti-adhesion board

Fig. 1 is a schematic view of a sputtering apparatus for evaluating film peeling.

1. . . Processing room

2. . . Target

3. . . Backing plate

4. . . Substrate holder

5. . . Earth shield

6. . . Anti-adhesion board

Claims (4)

A tin dioxide sputtering target characterized by being composed of a sintered body of 11 to 9000 ppm of Sb ₂ O ₃ and a total mass of 1 to 20% by mass of Ta ₂ O ₅ and / or Nb ₂ O ₅ , and the remaining percentage of SnO ₂ and unavoidable impurities. The tin dioxide-based sputtering target according to claim 1, wherein the content of Sb ₂ O ₃ is 100 to 6000 ppm. The tin dioxide-based sputtering target according to the first aspect of the invention, wherein the content of Sb ₂ O ₃ is 300 to 2000 ppm. The tin dioxide-based sputtering target according to any one of claims 1 to 3, wherein the content of Ta ₂ O ₅ is 1 to 15% by mass, and the content of Nb ₂ O ₅ is 1 to 1 15% by mass.