KR20050020941A - Spattering target - Google Patents

Abstract

PURPOSE: To provide a sputtering target in which since a ratio of Archimedes density(AD) to theoretical density(TD) calculated from lattice constant obtained by X ray diffraction is greater than a prescribed value, generation of nodule is suppressed, particularly specific resistance is greater than a prescribed value, and nodule is further reduced if the lattice constant is not greater than a prescribed value. CONSTITUTION: In a sputtering target formed of sintered oxide containing indium oxide as a principal component, the sputtering target is characterized in that Archimedes density AD(g/cm¬3) of the sintered oxide and theoretical density TD(g/cm¬3) calculated from lattice constant obtained by X ray diffraction have a relation of AD/TD>0.995, wherein the AD and the TD have a relation of AD/TD>0.998, wherein bulk resistance of the sintered oxide is 1.5x10¬-4 §Ùcm or more, wherein the lattice constant is 1.01285 nm or less, and wherein the sintered oxide additionally contains tin oxide.

Description

Sputtering Target {SPATTERING TARGET}

The present invention relates to sputtering targets and has been studied to suppress the generation of nodule.

In general, the sputtering method is known as one of methods for forming a thin film. The sputtering method is a method of obtaining a thin film by sputtering a sputtering target, and since it is easy to enlarge a large area and can form a high performance film efficiently, it is used industrially. Moreover, in recent years, as a method of sputtering, the reactive sputtering method which sputters in reactive gas, the magnetron sputtering method which speeds up thin film formation by providing a magnet on the back surface of a target, etc. are also known.

Among the thin films used in such a sputtering method, an indium tin oxide (composite oxide of In ₂ O ₃ -SnO ₂ , hereinafter referred to as "ITO") film is particularly transparent because of its high visible light transmittance and high conductivity. As a conductive film, it is widely used for a liquid crystal display device, a condensation prevention heating film, an infrared reflecting film, etc. of glass.

For this reason, in order to form a film more efficiently at low cost, improvement of a spatter condition, a spatter apparatus, etc. is performed every day now, and it becomes important whether a device is operated efficiently anyway.

In such ITO sputtering, after a new sputtering target is set, the time until the initial arc (abnormal discharge) disappears and a product can be manufactured is short, and it can be used for a certain period after setting it once. Whether there is (accumulated spatter time: target life) becomes a problem.

The initial arc of the conventional sputtering target is reduced as the target surface is polished and smoothed, so that the surface polishing target having the smoothed surface becomes the mainstream.

In addition, when sputtering is performed continuously, black deposits, called nodules, are formed on the target surface, which causes abnormal discharge or particles to be generated. Therefore, in order to prevent thin film defects, there is a problem that regular nodule removal is required, leading to a decrease in productivity.

For example, techniques for preventing arcing and nodule generation have been developed by keeping the surface roughness of the target within a predetermined range and by setting the density and bulk resistance within a predetermined range (Patent Document 1). Reference). Moreover, the technique which tries to prevent generation | occurrence | production of arcing and a nodule by setting surface roughness to a predetermined range is also developed (refer patent document 2). However, in order to manufacture an ITO sputtering target having such a predetermined surface roughness, after adjusting the thickness by grinding after sintering, three to four polishing steps are required using a gradually fine abrasive grindstone, There have been problems such as increased manufacturing time and cost.

On the other hand, an ITO target has been proposed in which a phase having a diffractive surface having a plane interval in a predetermined range is formed by X-ray diffraction, and an integral intensity of the diffraction peak of the phase in a predetermined range is proposed. (See Patent Document 3) The ITO film having a low specific resistance can be formed even under a condition where the substrate temperature is low.

[Patent Document 1] Japanese Patent No. 2750483

[Patent Document 2] Japanese Patent No. 3152108

[Patent Document 3] Japanese Patent No. 2979648

In the present invention, the density and electrical conductivity of the oxide sintered body are related to the generation of nodules, but in particular, the ratio between the theoretical density TD calculated from the Archimedes density AD (g / cm ³ ) and the lattice constant determined by X-ray diffraction and the generation of the nodules It is a problem to find out that a relationship is shown and to provide the sputtering target which can suppress generation | occurrence | production of a nodule, remarkably improve initial stability, and can manufacture at low cost.

The 1st aspect of this invention which solves the said subject is the grating calculated | required by the Archimedes density AD (g / cm <^3> ) and X-ray diffraction of the said oxide sintered compact in the sputtering target which becomes an oxide sintered compact containing indium oxide as a main component. It is a sputtering target characterized by the theoretical density TD (g / cm < ³ >) calculated from an integer being in the relationship of AD / TD> 0.995.

In such a first aspect, the generation of nodules is suppressed because the ratio between the Archimedes density AD and the theoretical density TD calculated from the lattice constant determined by X-ray diffraction is larger than a predetermined value.

According to a second aspect of the present invention, in the first aspect, the AD and the TD have a relationship of AD / TD> 0.998, and is a sputtering target.

In this second aspect, the ratio of the theoretical density TD calculated from the lattice constant determined by the Archimedes density AD and the X-ray diffraction is greater than 0.998, so that the nodule is further suppressed.

According to a third aspect of the present invention, in the first or second aspect, a bulk resistance of the oxide sintered body is 1.5 × 10 ⁻⁴ Ω · cm or more, which is a sputtering target.

In this third aspect, the nodule is further suppressed because the bulk resistance is larger than the predetermined value.

In a fourth aspect of the present invention, in any one of the first to third aspects, the grating constant is 1.01285 nm or less, which is a sputtering target.

In this fourth aspect, the generation of nodules is further suppressed because the lattice constant is smaller than a predetermined value.

A 5th aspect of this invention is a sputtering target characterized by the said lattice constant in any one of 1st-4 which is 1.01280 nm or less.

In the fifth aspect, generation of nodules is further suppressed because the lattice constant is 1.01280 nm or less.

The sixth aspect of the present invention is the sputtering target according to any one of the first to fifth aspects, wherein the oxide sinter further contains tin oxide.

In the sixth aspect, generation of nodules is suppressed because the oxide sintered body is an ITO target containing tin oxide.

In the present invention, the Archimedes density AD (g / cm ³ ) refers to the density measured by the substitution method, that is, the Archimedes method, with respect to the actual oxide sintered body, and in the present invention, measured using water at room temperature. On the other hand, the theoretical density TD (g / cm ³ ) is calculated from the lattice constant determined by X-ray diffraction, for example, oxygen deficiency in (O _{o 905} Sn _o . ₀₉₅ ) ₂ O ₃ of _{iron manganese light} structure. It is calculated on the assumption that there is no lattice defect. Specifically, for example, the lattice constant is calculated by performing refinement calculation using diffraction peak data on the planes (622), (662), (840), (761), (844), and (864). Can be.

In the present invention, AD / TD> 0.995, preferably AD / TD> 0.998. In order to obtain an oxide sintered body having such a density ratio, it is necessary to sinter in an atmosphere as high as possible in the partial pressure of oxygen in the manufacturing process illustrated later, but the density ratio is a kind of raw powder, a particle diameter, and a press pressure of the raw powder. It can be changed by various conditions, such as the sintering atmosphere and sintering temperature. In any case, it is possible to judge whether or not the nodule is suppressed by measuring the density by the Archimedes method and calculating the theoretical density by X-ray diffraction after production anyway.

Moreover, in the sputtering target of this invention, it is preferable that the bulk resistance of an oxide sintered compact is 1.5 * 10 <^{-4> (} ohm) * cm or more. In other words, as the bulk resistance increases, the nodule is suppressed. On the other hand, as described above, the bulk resistance tends to decrease as the sintering is carried out in an atmosphere of high oxygen partial pressure, so the bulk resistance needs to be an additional index. In addition, the smaller the bulk resistance, the less preferable it is when sputtering with a DC magnetron.

It is also known that the larger the oxygen concentration in the oxide sintered body, the lower the lattice constant, and therefore, the lattice constant is smaller than a predetermined value. That is, in the present invention, it is desired that the lattice constant is 1.01285 nm or less, preferably 1.01280 nm or less, whereby the generation of nodules is further suppressed.

Here, an example of the manufacturing method of the sputtering target by this invention is demonstrated to a ceramic target as an example.

First, the powder used as a raw material is mixed at a desired blending ratio, and is molded and fired using various conventionally known wet or dry methods.

As a dry method, a cold press method, a hot press method, etc. are mentioned. In the cold press method, a mixed powder is filled into a molding die to produce a molded product, which is calcined and sintered in an air atmosphere or an oxygen atmosphere. In the hot press method, the mixed powder is directly sintered in a mold.

As the wet method, for example, it is preferable to use a filtration molding method (see Japanese Patent Laid-Open No. 11-286002). This filtration molding method is a filtration type mold which is a water-insoluble material for depressurizing and draining water from a ceramic raw material slurry to obtain a molded body. The filtration mold has a mold for molding having one or more water draining holes and a mold for molding. And a molding frame which is sandwiched from the upper surface side through a filter having a water permeability and a sealing material for sealing the filter, and wherein the molding lower frame, the molding frame, the actual material, and the filter are disassembled, respectively. And a slurry made of mixed powder, ion-exchanged water and an organic additive using a filtration type mold that is assembled so that the water in the slurry can be drained under reduced pressure only on the filter face side thereof, and the slurry is filtered. After pouring into a mold, and dehydrating and draining moisture in the slurry only at the filter face side, a molded article was produced, and after drying and degreasing the obtained ceramic molded article, Firing at high temperature.

In each method, 1300-1600 degreeC is preferable in the case of an ITO target, for example, More preferably, it is 1450-1600 degreeC. After that, machining is carried out for molding and processing to a predetermined dimension to be a target.

Example

Hereinafter, the present invention will be described with reference to Examples, but is not limited thereto.

(Test Items 1 to 5)

The indium oxide powder and the tin oxide powder were mixed at a ratio of In ₂ O ₃ : SnO ₂ = 9O: 1Owt%, and after the addition of the binder, press molding was carried out with a mold of 140 mmφ. The press-molded compacts were naturally dried to degrease the binder, and five kinds of mass products obtained by firing at 0.1 MPa (gauge pressure), firing temperature 1550 ° C. and holding time of 8 hours in an oxygen atmosphere were prepared.

From these board | plate materials, it cut out to diameter 101.6mm, finished the surface with the diamond grindstone # 1000 with the planar grinding mill, and made it the thickness of 5 mm.

The target after grinding was bonded to the copper backing plate with In, and it was set as the target of the test articles 1-5.

(Test Example 1)

The targets of the test products 1 to 5 were attached to the spatter apparatus, and spattering was carried out under the following conditions, and the cumulative occurrence of arcing occurring at the time of spattering was counted with an arcing monitor by Landmark Technology Inc. The results are shown in Table 1.

 Spatter Condition:

  Process pressure (Ar) = 0.4 Pa

Oxygen partial pressure (O ₂ ) = 2.7mPa

Input power = 2W / cm ²

Input integrated power amount = 6OWhr / cm ²

Arcing monitor: μArc Monitor (MAM Genesis) made by Landmark Technology

Arc monitor condition:

  Detection mode: energy

  Arc detection voltage: 10OV

  Mass-Popular Boundaries: 5omJ

  Hard arc minimum time: 100 μs

(Test Example 2)

After each target after spatter was peeled from the backing plate, the lattice constant and density by the X-ray diffraction method, and the density and bulk resistance by the Archimedes method were measured. MXP18 manufactured by McScience Co., Ltd. is used for the X-ray diffraction apparatus, and diffraction peaks on the planes (622), (662), (840), (761), (844) and (864) are calculated for the lattice constant. Refinement calculations were performed using the data. In addition, the bulk resistance was measured by the Hall measuring instrument (Resitest8200 by Toyo Technica). These results were also shown in Table 1 together.

TABLE 1

Test article 1 Test article 2 Test article 3 Test article 4 Test article 5 Lattice constant (nm) 1.01281 1.01259 1.01271 1.01286 1.01301 Density TD by X-ray Diffraction Method (g / cm ³ ) 7.122 7.127 7.124 7.121 7.118 Alchemedes density AD (g / cm ³ ) 7.100 7.111 7.134 7.105 7.069 AD / TD 0.997 0.998 1.001 0.998 0.993 Specific resistance (mΩcm) 0.172 0.159 0.192 0.141 0.123 Cumulative arc recovery 32 25 20 78 103

As a result, when the density ratio is larger than 0.995, preferably larger than 0.998, the nodule is suppressed, so that the cumulative arc number is reduced, and in particular, when the specific resistance is smaller than 0.15 m? · Cm, the arc number is somewhat increased, In addition, it was found that the lattice constant is less than 1.01285, preferably less than 1.01280, so that the number of arcs is slightly reduced.

Since the ratio of the theoretical density TD calculated from the lattice constant determined by Archimedes density AD and X-ray diffraction is larger than the predetermined value, the spattering target of the present invention is suppressed in the generation of nodules, and in particular, the specific resistance is predetermined. If the value is larger than and the lattice constant is less than or equal to the predetermined value, the nodule is further reduced.

Claims (9)

In the sputtering target which consists of an oxide sinter which has an indium oxide as a main component, the theoretical density TD (g / cm) computed from the Archimedes density AD (g / cm <^3> ) of the said oxide sintered compact, and the lattice constant calculated by X-ray diffraction. A sputtering target, wherein cm ³ ) is in a relationship of AD / TD> 0.995. The method of claim 1, And the AD and the TD are in a relationship of AD / TD> 0.998. The method of claim 1, The bulk resistance of the oxide sintered body is 1.5 × 10 ^-4 A sputtering target characterized by being Ω · cm or more. The method of claim 2, The bulk resistance of the said oxide sintered compact is 1.5x10 <^{-4> (} ohm) * cm or more, The sputtering target characterized by the above-mentioned. The method according to any one of claims 1 to 4, Sputtering target, characterized in that the lattice constant is 1.01285nm or less. The method of claim 4, wherein Sputtering target, characterized in that the lattice constant is 1.01280nm. The method according to any one of claims 1 to 4, A sputtering target, wherein the oxide sinter further contains tin oxide. The method of claim 5, A sputtering target, wherein the oxide sinter further contains tin oxide. The method of claim 6, A sputtering target, wherein the oxide sinter further contains tin oxide.