JP5249560B2 - SnO2-based sputtering target - Google Patents

Description

The present invention relates to a SnO ₂ -based sputtering target. Specifically, in various applications such as a flat panel display, a touch panel, and a solar cell, various films such as a transparent electrode, antistatic, electromagnetic shielding, gas barrier, and heat ray reflection. The present invention relates to a SnO ₂ -based sputtering target used for ensuring the function.

In recent years, SnO ₂ -based thin films have been used in a wide range of applications such as flat panel displays, touch panels, and solar cells. This SnO ₂ -based thin film is industrially mainly manufactured by a spray method or a CVD method. However, these methods are not suitable for making the film thickness uniform over a large area, and it is difficult to control the film formation process. Therefore, there is a need for a new production method that does not have these drawbacks.

On the other hand, production of SnO ₂ -based thin films by a sputtering method has also been attempted, and a SnO ₂ —Sb ₂ O ₃ target to which Sb ₂ O ₃ is added in order to lower the specific resistance of the target is exclusively used as a sputtering target. Has been put to practical use. However, the conventional SnO ₂ based sintered body target tends to generate many particles due to film peeling from the peripheral structure of the sputter cathode when the amount of film adhesion increases as the integrated power increases. It is also known that when these particles adhere to a thin film, the performance of the thin film is deteriorated and can cause thin film defects. For this reason, there is a need for a SnO ₂ -based sputtering target with little film peeling from surrounding structures during sputtering.

For example, the following materials have been proposed as SnO ₂ —Sb ₂ O ₃ -based materials. A sintered body sintered at 1450 ° C. or more, comprising Nb or Nb and Ta of 20% by mass or less in terms of oxide, 10 ppm or less of Sb ₂ O ₃ as an inevitable impurity, and the remaining SnO _2. It is known (see, for example, Patent Document 1). Also includes _Sb 2 _{O 3} of 10.2 wt%, _SnO 2 _-Sb 2 _{O 3} sintered body is known sintered at 820 ° C. or less (e.g., see Patent Document 2). Moreover, a tin oxide-first antimony oxide sintered compact target sintered at 800 ° C. containing ₃ to 10% by mass of Sb ₂ O ₃ and the balance consisting of SnO ₂ and inevitable impurities is known (for example, (See Patent Document 3). Further, a tin-antimony oxide sintered body target sintered at 1500 ° C. composed of 6% by mass of antimony oxide, 5 to 20% by mass of zinc oxide, and the remaining SnO ₂ is known (for example, (See Patent Document 4). However, in any of these documents, it is composed of a sintered body containing Sb ₂ O ₃ exceeding 10 ppm and less than 1% by mass, and the film stress of the sputtered film is small in absolute value. No knowledge about SnO ₂ -based sputtering target with little film peeling from the object is shown.

Japanese Patent No. 3957917 Japanese Patent No. 3662168 Japanese Patent No. 3710021 JP 2003-73819 A

Summary of the Invention

The present inventors have now in SnO ₂ based sputtering target, by identifying less than 1 wt% over the 10ppm of _Sb 2 _{O 3} amount, the resulting SnO ₂ based sintered body when used as a sputtering target It was found that a sputtered film having a small film stress in absolute value was obtained, and that film peeling from the peripheral structure of the sputtered cathode was small during sputtering.

Accordingly, an object of the present invention is to contain Sb ₂ O ₃ in excess of 10 ppm and less than 1% by mass, in which the film stress of the sputtered film is small in absolute value, and the film peeling from the peripheral structure of the sputter cathode is small during sputtering. and to provide a SnO ₂ based sintered body target made of a sintered body made of.

That is, the SnO ₂ -based sputtering target according to the present invention has Sb ₂ O ₃ exceeding 10 ppm and less than 1% by mass, Ta ₂ O ₅ and / or Nb ₂ O ₅ having a total mass of 20% by mass or less, and the balance The sintered body is composed of SnO ₂ and inevitable impurities.

Detailed description of the invention

SnO ₂ based sputtering target according SnO ₂ based sputtering target present invention, the _Sb 2 _{O 3} of less than 1 wt% beyond 10 ppm, total mass 20% by mass or less, _Ta 2 _{O 5} is preferably from 1 to 20 mass% and and / or _Nb 2 _{O 5,} a sintered body consisting of SnO ₂ and unavoidable impurities as a balance. When such a SnO ₂ based sintered body is used as a sputtering target, a sputtered film having a small film stress in absolute value can be obtained, and film peeling from the peripheral structure of the sputtered cathode can be reduced during sputtering.

According to a preferred embodiment of the present invention, the content of _Sb 2 _{O 3} is preferably a 11～9000Ppm, more preferably 100～6000Ppm, more preferably from 300～2000Ppm. In sputtering using a sputtering target made of a sintered body within this composition range, the film stress of the sputtered film obtained is made smaller in absolute value, and the film is peeled off from the peripheral structure of the sputter cathode during sputtering. Can be less.

According to a preferred 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 within this composition range, it is possible to produce a sintered body by a cold press method or a casting method that can produce a relatively large sintered body, and at a high temperature of 1300 ° C. or higher. Sintering can be performed under conditions.

  According to a preferred embodiment of the present invention, the sputtering target according to the present invention is preferably composed of a sintered body sintered at 1300 ° C. or more, more preferably 1350 to 1650 ° C., further preferably 1500 to 1650 ° C. is there. The sintered body sintered in this temperature range has sufficiently undergone liquid phase sintering, and can be a sintered body having a high sintering density.

  According to a preferred embodiment of the present invention, the sputtering target according to the present invention is preferably composed of a sintered body having a relative density of 60% or more, more preferably 75% or more, and further preferably 95% or more. . In this relative density range, the film formation rate during sputtering can be increased, the period of use of the target can be increased, and arcing during sputtering can be reduced. Further, when the sintered density is increased, bubbles in the sintered body can be reduced.

  According to a preferred aspect of the present invention, when the sputtering target according to the present invention is used for sputtering, it is preferable to obtain a sputtered film having an absolute value of film stress of 1050 MPa or less, more preferably 1000 MPa or less. Within the range of the film stress value, there is little film peeling from the peripheral structure of the sputter cathode, and generation of particles due to film peeling can be suppressed.

Manufacturing method of SnO ₂ based sputtering target according to the production method the present invention SnO ₂ based sputtering target is not particularly limited, can be performed in accordance with preferred embodiments set forth below. That is, according to a preferred embodiment of the present invention, first, SnO ₂ is the main component, Sb ₂ O ₃ is contained in excess of 10 ppm and less than 1% by mass, and Ta ₂ O ₅ and / or Nb ₂ O ₅ is contained in a total mass of 20 An unsintered molded body containing not more than mass% is prepared. In the present invention, the unsintered molded body may be formed by any method as long as the raw material powder containing the above composition is molded. For example, SnO ₂ powder, Sb ₂ O ₃ powder, Ta _The raw material powder can be prepared by mixing ₂ O ₅ powder and Nb ₂ O ₅ powder at a blending ratio that satisfies the above composition, and then forming the raw material powder.

  According to a preferred embodiment of the present invention, it is preferable that the green compact formed from the raw material powder is easily given a predetermined shape by adding a binder to the raw material powder. Such a binder is not limited as long as it is a known binder that disappears or scatters by heating, and an aqueous polyvinyl alcohol solution or the like can be used. Although the method of drying and heating is not limited, it is preferable to first dry at 50 to 130 ° C. for 5 to 30 hours, and then degrease by heating at 500 to 800 ° C. for 6 to 24 hours.

According to a preferred embodiment of the present invention, the green compact prepared as described above is preferably sintered at 1300 ° C. or more, more preferably 1350 to 1650 ° C., further preferably 1500 to 1650 ° C. It is. By carrying out sintering in this temperature range, liquid phase sintering can proceed sufficiently to increase the sintering density, and further, the melting of SnO ₂ can be prevented and the sintered body having a desired shape can be obtained. Fabrication can be facilitated.

  According to a preferred embodiment of the present invention, the sintering is preferably performed for 2 to 20 hours, more preferably 3 to 12 hours, and further preferably 4 to 8 hours. Within this range, it is possible to sufficiently sinter while suppressing power consumption and ensuring high productivity.

  According to a preferred embodiment of the present invention, the sintering is preferably performed in an oxygen-containing atmosphere in order to ensure a high sintering density, for example, in an oxygen-pressurized atmosphere, an oxygen atmosphere, or an air atmosphere. It can be carried out.

Examples 1-37
(1) Production of sputtering target First, the following four kinds of raw material powders were prepared.
SnO ₂ powder: purity 99.99% (4N), average particle size 0.7 to 1.1 μm, specific surface area 2.0 to 2.7 m ² / g
Ta ₂ O ₅ powder: purity 99.9% (3N), average particle size 0.6 to 0.8 μm, specific surface area 2.0 to 3.1 m ² / g
Nb ₂ O ₅ powder: purity 99.9% (3N), average particle size 0.6-1.0 μm, specific surface area 2.1-2.7 m ² / g
Sb ₂ O ₃ powder: purity 99.9% (3N), average particle size 0.6-1.0 μm,
For each example, the above four types of raw material powders were weighed and mixed for 21 hours in a dry ball mill. A polyvinyl alcohol aqueous solution was added to the mixed powder, and after sufficiently mixing, the mixture was filled in a 400 × 800 mm mold and press-molded at a pressure of 800 kgf / cm ² . The molded body was dried at 80 ° C. for 12 hours. This dried body was baked for 8 hours at the baking temperature shown in Table 1 in an oxygen atmosphere to obtain a sintered body. At this time, the temperature rising rate was controlled to 400 ° C./hour and the temperature decreasing rate was controlled to 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 SnO ₂ -based sputtering target. In addition, the processed milled end of the sintered body is pulverized using a mortar, hydrolyzed by adding the pulverized powder, a mixed acid of nitric acid and hydrochloric acid, and ultrapure water to a Teflon (registered trademark) container, and then a constant solution. It was. Measurement of each element of Ta, Nb, and Sb in the obtained constant solution was performed by ICP mass spectrometry using an ICP mass spectrometer (4500 manufactured by Agilent). Table 1 shows the oxide conversion values.

(2) Evaluation About the obtained sputtering target, the various evaluation tests shown below were done.

Evaluation 1: Measurement of relative density The relative density of each sputtering target was measured by the Archimedes method. In this case, each raw material density of ^{_{SnO 2: 6.95g / cm 3,}} Ta 2 O 5: 8.74g / cm 3, Nb 2 O 5: Weighted average density of 4.47 g / cm ³ (theoretical density) The relative density was calculated with the weighted average density as 100%. The results were as shown in Table 1.

Evaluation 2: Evaluation of film stress of sputtered film The sputtering target obtained in Examples 1 to 37 was metal bonded to a backing plate made of oxygen-free copper. Each metal-bonded sputtering target was sputtered on a silicon wafer by sputtering using a DC power source under the sputtering conditions shown below.
Cathode: High magnetic field magnetic circuit Target / substrate distance: 50 mm
Sputtering chamber ultimate pressure: <1 × 10 ⁻⁴ Pa
Substrate temperature: room temperature (no heating)
Introduced gas: Argon + oxygen (oxygen concentration 1 vol%)
Inlet gas partial pressure: 0.67 Pa
DC applied power: 360W
Film thickness: 500nm
Substrate: φ4inch × 525μm Silicon wafer

About the sputtered film thus obtained, the radius of curvature was measured using FLX-2320-5 (manufactured by Toago Technology Co., Ltd.), and the stress was calculated using the following formula. The negative sign of the film stress indicates a compressive stress.
σ = Eb ² / {6 (1-ν) * rd}
σ: Stress E: Young's modulus of substrate b: Substrate thickness ν: Poisson's ratio of substrate d: Film thickness r: Radius of curvature of substrate after film formation (measured by Newton method)

  The results are as shown in Table 1, and it can be seen that all of the sputtered films formed using the sputtering target satisfying the composition of the present invention have low film stress.

Evaluation 3: Evaluation of film peeling was performed using the sputtering target obtained in Evaluation Examples 1 to 37 of film peeling using the sputtering apparatus shown in FIG. The sputtering apparatus shown in FIG. 1 includes a backing plate 3 on which a target 2 is placed in a chamber 1 and a substrate holder 4 provided to face the backing plate 3. In the chamber 1, there are further provided an earth shield 5 that protects the side surfaces of the target 2 and the backing plate 3, and an adhesion-preventing plate 6 that prevents film formation on the chamber 1.

First, each sputtering target was metal bonded to the backing plate 3 in the chamber 1. Then, the metal-bonded target 2 was continuously discharged under the sputtering conditions shown below. After continuous discharge, the film adhering to the substrate holder 4, the earth shield 5, and the deposition preventing plate 6 was observed.
Cathode: Strong magnetic field magnetic circuit Sputtering chamber ultimate pressure: <1 × 10 ⁻⁴ Pa
Introduced gas: Argon + oxygen (oxygen concentration 1 vol%)
Inlet gas partial pressure: 0.67 Pa
DC applied power: 360W
Film thickness: 500nm
Sputtering time: Continuous 30 hr discharge Earth shield: Alundum # 60 blasted product Substrate holder: Alundum # 60 blasted product Adhering plate: Alundum # 60 blasted product

  The results are as shown in Table 1, and after continuous discharge using a sputtering target satisfying the composition of the present invention, the films attached to the substrate holder 4, the earth shield 5 and the deposition preventing plate 6 shown in FIG. It turns out that neither film peeling occurs.

It is a schematic diagram of the sputtering device used for evaluation of film peeling.

Explanation of symbols

1 Chamber 2 Target 3 Backing plate 4 Substrate holder 5 Earth shield 6 Anti-adhesive plate

Claims (5)

Sintering comprising Sb ₂ O ₃ exceeding 10 ppm and less than 1% by mass, Ta ₂ O ₅ and / or Nb ₂ O ₅ having a total mass of 1 to 20% by mass, and SnO ₂ and unavoidable impurities as the balance A SnO ₂ -based sputtering target consisting of a body. The content of Sb ₂ O ₃ is 11～9000Ppm, sputtering target according to claim 1. The content of Sb ₂ O ₃ is 100～6000Ppm, sputtering target according to claim 1. The content of Sb ₂ O ₃ is 300～2000Ppm, sputtering target according to claim 1. 1 to 15 wt% content of ta ₂ O _5, and the content of _Nb 2 _{O 5} is 1 to 15 wt%, the sputtering target according to any one of claims 1 to 4.

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