SG174652A1

SG174652A1 - Composition of sputtering target, sputtering target, and method of producing the same

Info

Publication number: SG174652A1
Application number: SG2010022671A
Authority: SG
Inventors: Sabine Schneider-Betz; xiang yu Bai; Andreas Herzog; Oskar Roidl; Martin Schlott
Original assignee: Heraeus Gmbh W C
Priority date: 2010-03-31
Filing date: 2010-03-31
Publication date: 2011-10-28
Also published as: DE102010054148A1; CN102206804A; JP2011214151A; KR20110109825A

Abstract

COMPOSITION OF SPUTTERING TARGET, SPUTTERING TARGET,AND METHOD OF PRODUCING THE SAMEAbstractComposition of a sputtering target comprising a matrixmaterial comprising a first oxide and a metallic component,wherein the oxide has a high refractive index. The first oxideis selected from a group of oxides consisting of titanium oxidein any oxide modification, niobium oxide in any oxidemodification, vanadium oxide in any oxide modification, yttriumoxide in any oxide modification, molybdenum oxide in any oxidemodification, zirconium oxide in any oxide modification,tantalum oxide in any oxide modification, tungsten oxide in anyoxide modification and hafnium oxide in any oxide modification,or a mixture thereof. The composition further comprises a secondoxide in the Lanthanide series in any oxide modification, orscandium oxide in any oxide modification or lanthanum oxide inany oxide modification. The matrix material further comprisespores. Use of the sputtering target is for high power densitysputtering.

Description

COMPOSITION OF SPUTTERING TARGET, SPUTTERING TARGET,

AND METHOD OF PRODUCING THE SAME

FIELD OF THE INVENTION

The present invention broadly relates to a sputtering target, and particularly relates to a sputtering target that comprises oxides with high refractive index, useful for high power density sputtering. The invention further relates to the composition of the sputtering target and a method of producing the sputtering target.

BACKGROUND OF INVENTION

Sputtering invelves ions being accelerated towards a target (referred to as a sputtering target); and upon striking the sputtering target, the momentum of the ions is transferred to the sputtering target, causing the dislodgement of atoms or molecules from the sputtering target’s surface. These dislodged atoms or molecules then deposit themselves onto a desired surface or substrate. Sputtering is a technique generally used in coating surfaces, especially for thin film coating.

A sputtering target made from different materials generally determines the characteristics of the coating. For example, to achieve an anti-reflection coating often required in several optical applications, oxides with a high index of refraction are used to enhance the properties of a layer system as described in patent publications such as JP 2009-042278 2A (Hoya Corp), KR 1020040074298 A (LG Electronics Inc.) and EP 210396521 (Asahi Glass Company).

The sputtering targets comprise a metal-oxide component (for example, TiQ;) and are usually produced by using a powder- metallurgical process.

During the sputtering process, deposition rate correlates with the amount of power density applied. In order to maximize deposition rate, high power density 1s generally used. However, at increasing power density, the sputtering targets comprising oxide tend to crack due to thermal stress and upon further increasing power, fatal defects such as partially chipping (breakages) may occur. This would result in having a user stop the process in order to change the target. Cracking and chipping of the sputtering target is a limiting factor to achieve a high deposition rate and limits the target lifetime.

A patent, European Patent No. EP 0 852 266 Bl issued to

Asahi Glass Ceramics Co., Ltd. discloses a sputtering target for use in forming a transparent thin oxide film having a high refractive index. The sputtering target comprises a target material which is formed by plasma spraying.

Another prior art, PCT Publication No. WO 2007/141003 Al published on 13 December 2007, discloses plasma spraying of a granulated mixture of TiO, and Nb:0s onto the base of a sputtering target.

Yet another prior art, PCT Publication No. WO 2005/090631

Al published on 29 September 2005, discloses a method to reduce thermal stresses in a sputtering target comprising indium—-tin- oxide during target manufacturing and during sputtering by the introduction of pores. The target material is applied on a target holder by using a spray process, more specifically by thermal spraying, plasma spraying, high velocity oxygen fuel spraying or electric are spraying. The pores are introduced into the target material during the spray process. Porosity is an inherent characteristic of sprayed materials.

Spraying of ceramic targets is just applied to produce tubular sputtering targets. It is not used for planar targets within the industry.

Application of spray deposition to planar targets does not work for the necessary thickness of 6-10 mm due to the high stress in the coating and consecutive warping of the backing plate. This will result in severe cracking of the target.

Yet another patent, US Patent No. 5,480,532 issued to

Leybold Materials, discloses a sputtering target consisting of a matrix of indium oxide and tin oxide and a metallic phase consisting of at least one of indium or tin. This target has a density of >96% and a high fracture toughness.

Therefore, there is a need for a sputtering target and a method of producing the same to address any one of the problems mentioned above.

SUMMARY OF INVENTION

The present invention is a composition comprising a matrix material comprising a first oxide, and a metallic component, wherein the oxide has a high refractive index, and wherein the first oxide is selected from a group of oxides consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yttrium oxide in any oxide modification, molybdenum oxide in any oxide modification, zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification and hafnium oxide in any oxide modification, or a mixture thereof.

In the composition, the metallic component may be selected from a group consisting of Ti, Wb, V, Y, Mo, Zr, Ta, W and Hf, or a mixture thereof.

The composition may further comprise a second oxide in the

Lanthanide series in any oxide modification, or scandium oxide in any oxide modification or lanthanum oxide in any oxide modification. The second oxide is selected from a group consisting

B of cerium oxide in any oxide modification, dipraseodymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide modification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, ytterbium oxide in any oxide modification, lutetium oxide in any oxide modification, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or the mixture thereof. The second oxide or the mixture thereof may be in a range of 0.1 and 50 wt% or 5-20 wt%. in the composition, the metallic component may be uniformly spread in a microscale within the matrix material. The metallic component may be in a range between 2-20 wt% or 4-6 wt% of the matrix material.

The present invention is also a sputtering target comprising the composition as described above. The sputtering target may further comprise pores, wherein the sputtering target has a density of 70-95%.

Further, the present invention is a sputtering target comprising a microstructure of a matrix material, comprising a first oxide, with pores, wherein the first oxide is selected from a group of oxides consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yttrium oxide in any oxide medification, molybdenum oxide in any oxide modification,

zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification and hafnium oxide in any oxide modification, or a mixture thereof. The sputtering target may further comprise a metallic component, wherein the metallic component is selected from a group consisting of Ti, Nb, V, Y, Mo, Zr, Ta, W and Hf, or a mixture thereof.

The sputtering target may further comprise a second oxide in the Lanthanide series in any oxide modification, or scandium oxide in any oxide modification or lanthanum oxide in any oxide modification. In the sputtering target the second oxide may be selected from a group consisting of cerium oxide in any oxide modification, dipraseodymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide medification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, ytterbium oxide in any oxide modification, futetium oxide in any oxide modification, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or the mixture thereof.

The sputtering target may have a density of 70-95%. The pores may be spread separated within the matrix material of the sputtering target.

The present invention is also a method for producing a sputtering target comprising the composition as described above, the method comprising the steps of dry mixing metal oxide powder with metal powder and shaping the mixture by hot pressing or

HIPing. The metal powder may be 5-20 wt%. The metal oxide powder and the metal powder may have particle sizes in the range between 1-150 pm. The mixture may be shaped at temperatures between 600 — 1400°C.

Further, the present invention is a method for producing a sputtering target comprising a composition as described above, the method comprising the steps of mixing metal oxide powder with metal powder in a slurry, spraying dry, shaping the mixture by pressing and sintering in inert atmosphere or vacuum. The slurry may comprise a solvent which is water or any alcohol.

The present invention is also a method for producing a sputtering target comprising a composition as described above, the method comprising the steps of mixing metal oxide powder or a mixture of several metal oxides powder in a slurry, spraying dry, shaping the mixture by pressing and sintering in inert atmosphere or vacuum. The slurry may comprise a solvent which is water or any alcohol.

Also, the present invention is a method for producing a sputtering target comprising the steps of mixing metal oxide powder with carbon/graphite, treating the mixture thermally or alternatively treating the mixture thermally in hydrogen or carbon monoxide until a metal phase forms, shaping the mixture and sintering. In this method, the mixing may be dry mixing or mixing in a slurry. The slurry may comprise a solvent which is water or any alcohol.

Further, the present invention is a method for preducing a sputtering target comprising the steps of adding pore forming agents to metal oxide powder, shaping by pressing, thermally degrading and sintering. The degrading step and the sintering step may be performed in ambient atmosphere.

The present invention is also a method for producing a sputtering target comprising a composition as described above, the method comprising the steps of adding pore forming agents to metal oxide powder and metal powder, shaping by pressing, thermally degrading and sintering. The metal oxide powder may be an oxide selected from a group consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yttrium oxide in any oxide modification, molybdenum oxide in any oxide modification, zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification, hafnium oxide in any oxide modification, cerium oxide in any oxide modification, dipraseodymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide modification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, ytterbium oxide in any oxide modification, lutetium oxide in any oxide modificatien, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or a mixture thereof.

The present invention further relates to a use of a sputtering target as described above for DC/RF sputtering of high-refractive-index layers.

The present invention also relates to a use of a sputtering target as described above for high power density sputtering, wherein the power density applied is at least 10% higher than the power density which can be applied to a related metal oxide target with a density of more than 95% without showing cracks and defects.

DETAILED DESCRIPTION

Example embodiments of the present invention provide a composition comprising a matrix material containing an oxide or a mixture of several different oxides. The oxide is preferably an oxide with a high refractive index. The oxide may be selected from a group consisting of titanium oxide in any oxide modification (e.g., TiO), niobium oxide in any oxide modification (e.g., Nb,Os) , vanadium oxide in any oxide modification {e.g., V20s5) , yhtrium oxide in any oxide modification (e.g., Y,03), molybdenum oxide in any oxide modification {e.qg., MoOs) , zirconium oxide in any oxide modification (e.g., 2r05) , tantalum oxide in any oxide modification (e.qg., Taz0s5) , tungsten oxide in any oxide modification (e.g., WO3) and hafnium oxide in any oxide modification (e.g., HIO;).

The example embodiments of the composition may further comprise a metallic component or peres, or the combination of a metallic component and pores.

In the example embodiments comprising the oxide or the mixture of several different oxides and the metallic component, the metallic component is preferably pure metal powders. ~ Preferably, the metallic component is homogeneously distributed within the oxide/metal matrix in a microscale. The metallic component may be one or more metals selected from a group consisting of titanium (Ti}, niobium (Nb), vanadium (VV), yttrium (Y), molybdenum (Mo), zirconium (Zr), tantalum (Ta}, tungsten (W) and hafnium (Hf).

The quantity of the metallic component may be in the range between 2-20 wt%, 2-15 wt%, 2-10 wt%, 2-6 wt%, 4-20 wt%, 4-15 wt%, or 4-10 wt%. More preferably, the quantity of the metallic component may be in the range between 4-6 wt%.

In the example embodiments comprising the oxide or the mixture of several different oxides and the pores, the composition may have a density of 70-95%, preferably 80-95%.

In the example embodiments comprising the oxide or the mixture of several different oxides, and the combination of the metallic component and the pores, pore forming agents may be used in producing the pores. The pore forming agents may be thermally degradable, for example, polystyrene. The pores may also be introduced by adjusting the sintering parameters (for instance, as in Example 2). The pores are preferably spread separated within the oxide/metal matrix.

Further example embodiments of the present invention provide a composition comprising a matrix material containing a first oxide or a mixture of first oxides and a second oxide or a mixture of second oxides. The first and second oxides are preferably oxides, having high refractive indexes. The first oxide may be selected from a group consisting of titanium oxide in any oxide modification (e.g., TiQ;), niobium oxide in any oxide medification (e.g., Nby;0O;), vanadium oxide in any oxide modification (e.qg., V,0s) , yttrium oxide in any oxide modification {e.g., Y.01) , molybdenum oxide in any oxide modification (e.qg., MoQ3) , zirconium oxide in any oxide modification (e.g., ZrQ,) , tantalum oxide in any oxide modification {e.g., Ta,0s) , tungsten oxide in any oxide modification (e.g., W03} and hafnium oxide in any oxide modification (e.qg., HEO;}.

The second oxide may be selected from a group consisting of cerium oxide in any oxide modification {e.g., CeO), dipraseodymium oxide in any oxide modification (e.g., Pr.0;3), praseodymium oxide in any oxide modification (e.g., Pro0;), neodymium oxide in any oxide modification (e.g., Nd,0s) , samarium oxide in any oxide modification (e.g., SmC;), europium oxide in any oxide modification (e.g., Eu:0;), gadolinium oxide in any oxide modification (e.g., GdO;), terbium oxide in any oxide modification {(e.g., Thy03), dysprosium oxide in any oxide modification {e.g., Py203) , holmium oxide in any oxide modification (e.g., HosCa) , erbium oxide in any oxide modification (e.g... Er;03} , thulium oxide in any oxide modification (e.g., Tm,03) , ytterbium oxide in any oxide modification {e.qg., Yha03) , lutetium oxide in any oxide modification {e.qg., Lus03) , scandium oxide in any oxide modification (e.g., 8cy03) and lanthanum oxide in any oxide modification {e.g., Lay03). The quantity of the second oxide may be in the range between 0-50 wt%, 0-30 wt3¥, 0-20 wt%, 1-50 wt%, 1-30 wt%, 1-20 wt%, 10-50 wt%, or 10-30 wt%. More preferably, the quantity of the second oxide may be in the range between 5- 20 wt%.

The example embodiments of the composition may further comprise a metallic component or pores, or the combination of a metallic component and pores.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxides, and the metallic component, the metallic component is preferably pure metal powders. Preferably, the metallic component 1s homogeneously distributed within the oxide/metal matrix in a microscale. The metallic component may be one or more metals selected from a group consisting of titanium (Ti), nickbium (Wb), vanadium (V), yttrium (Y), molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W) and hafnium (Hf).

The quantity of the metallic component may be in the range between 2-20 wt%, 2-15 wt%, 2-10 wt%, 2-6 wt%, 4-20 wt%, 4-15 wt%, or 4-10 wt%. More preferably, the guantity of the metallic component may be in the range between 4-6 wt$%.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxldes, and the pores, the composition may have a density of 70-95%, preferably 80-95%.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxides, and the combination of the metallic component and pores, pore forming agents may be used in producing the pores. The pore forming agents may be thermally degradable, for example, polystyrene. The pores may also be introduced, for instance, according to Example 2. The pores are preferably spread separated within the oxide/metal matrix.

Example embodiments of the present invention provide a sputtering target comprising a composition comprising a matrix material containing an oxide or a mixture of several different oxides. The oxide is preferably an oxide with a high refractive 16 index. The oxide may be selected from a group consisting of titanium oxide in any oxide modification ({(e.g., Ti0;), niobium oxide in any oxide modification (e.g., Nb:0s}, vanadium oxide in any oxide modification {(e.g., V:0;), vitrium oxide in any oxide modification (e.g., Yo03) , molybdenum oxide in any oxide modification (e.g., MoQs), zirconium oxide in any oxide modification (e.g... Z2rQz), tantalum oxide in any oxide modification (e.g., Tax0s) , tungsten oxide in any oxide modification (e.g., WO3) and hafnium oxide in any oxide modification (e.g., BIfO:).

The example embodiments of the sputtering target may further comprise a metallic component or pores, or the combination of a metallic component and pores.

In the example embodiments comprising the oxide or the mixture of several different oxides and the metallic component, the metallic component is preferably pure metal powders.

Preferably, the metallic component is homogeneously distributed within the oxide/metal matrix in a micrescale. The metallic component may be one or more metals selected from a group consisting of titanium (Ti), niobium (Nb), vanadium (V), yetrium (YY), molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W) and hafnium (Hf).

In the example embodiments comprising the oxide or the mixture of several different oxides and the pores, the sputtering target may have a density of 70-95%, preferably 80- 95%.

In the example embodiments comprising the oxide or the mixture of several different oxides and the combination of the metallic component and pores, pore forming agents may be used 1% in producing the pores. The pore forming agents may be thermally degradable, for example, polystyrene. The pores may also be introduced, for instance, according to Example 2. The pores are preferably spread separated within the oxide/metal matrix.

Yet further example embodiments provide a sputtering target comprising a composition comprising a matrix material containing a first oxide or a mixture of first oxides and a second oxide or a mixture of second oxides. The first and second oxides are preferably oxides, having high refractive indexes. The first oxide may be selected from a group consisting of titanium oxide in any oxide modification (e.g.,

TiQ,), niobium oxide in any oxide modification (e.g., Nbx0s5}, vanadium oxide in any oxide modification (e.g., V;0s), yttrium oxide in any oxide modification (e.g., Y:0:), molybdenum oxide in any oxide modification (e.g., MoO;), zirconium oxide in any oxide modification (e.g., 2r0,), tantalum oxide in any oxide modification (e.g., Ta,0s) , tungsten oxide in any oxide modification f{(e.g., WOj3) and hafnium oxide in any oxide modification (e.g., HfG,).

The second oxide may be selected from a group consisting of cerium oxide in any oxide modification (e.g., CeO;), diprasecodymium oxide in any oxide modification (e.g., Pr:03}, praseodymium oxide in any oxide modification (e.g., PrO:}, neodymium oxide in any oxide modification (e.g., Nd)0s}, samarium oxide in any oxide modification (e.g., S8my0;), europium oxide in any oxide modification (e.g., Eux03), gadolinium oxide in any oxide modification (e.g., GdO;), terbium oxide in any oxide modification (e.g., Thy03), dysprosium oxide in any oxide modification {(e.qg., Dy-0a) , holmium oxide in any oxide modification (e.qg., Ho03) erbium oxide in any oxide modification (e.g., Er:0s), thulium oxide in any oxide modification (e.g., Tmp03)}, ytterbium oxide in any oxide modification (e.qg., Yb,03) , lutetium oxide in any oxide modification (e.qg., Lu,03) , scandium oxide in any oxide modification (e.g., Scy0;) and lanthanum oxide in any oxide modification {(e.g., Lay03). The quantity of the second oxide may be in the range between 0-50 wt%, 0-30 wt%, 0-20 wt%, 1-50 wt$, 1-30 wt%, 1-20 wt%, 10-50 wt%, or 10-30 wt%. More preferably, the quantity of the second oxide may be in the range between 5- 20 wts.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxides, and the metallic component, the metallic component is preferably pure metal powders. Preferably, the metallic component is homogeneously distributed within the oxide/metal matrix in a microscale. The metallic component may be one or more metals selected from a group consisting of titanium (Ti), niobium (Nb} , vanadium (VV), yttrium (YY), molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W) and hafnium (HE).

The quantity of the metallic component may be in the range between 2-20 wt%, 2-15 wt%, 2-10 wt%, 2-6 wt%, 4-20 wt%, 4-15 wt%, or 4-10 wt%. More preferably, the quantity of the metallic component may be in the range between 4-6 wt.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxides, and the pores, the composition may have a density of 70-95%, preferably 80-95%.

In the example embodiments comprising the first oxide or the mixture of first oxides, the second oxide or the mixture of second oxides, and the combination of the metallic component and pores, pore forming agents may be preferably used in producing the pores. The pore forming agents may be thermally degradable, for example, polystyrene. The pores may also be introduced, for instance, according to Example 2. The pores are preferably spread separated within the oxide/metal matrix.

In the embodiments described above, the susceptibility of the sputtering target to crack is reduced or eliminated.

A sputtering target having pores and/or metal that is used for sputtering at higher power densities allows the deposition rate to be maximized throughout the whole target lifetime.

Further, the tendency of the target showing cracks and fatal defects like breakages is shifted to higher power densities or even avoided.

Various methods may be used to produce a sputtering target having pores and/or metal.

EXAMPLE 1

Method of producing a sputtering target in accordance with example embodiments of the present invention, may comprise the following steps of: . dry mixing metal oxide powder with metal powder, and . shaping the mixture by hot pressing or HIPing.

In these example embodiments, preferably, the metal powder may be 10-20 wt%. This is to achieve a thorough distributicn.

The metal oxide powder and the metal powder have particle sizes preferably in the range between 1-150 pm. Segregation after mixing has to be avoided by careful optimization between particle size, shape and density of the metal and the oxide.

The mixture may be preferably shaped at temperatures between 600 — 1400°C, depending on the oxides used.

EXAMPLE 2

Method of producing a sputtering target in accordance with further example embodiments of the present invention, may comprise the following steps of: . mixing metal oxide powder with metal powder in a slurry, . spraying dry; 25 . shaping the mixture by pressing; and . sintering in inert atmosphere or vacuum.

In these example embodiments, the slurry may comprise a solvent wherein the solvent may be water or any alcohol.

Sputtering targets with different densities may be achieved by varying the sintering parameters (e.g., temperature and time) during the method of producing the sputtering targets. By doing so, sputtering targets having a low density of 70-95%, preferably 80-95% may be produced.

EXAMPLE 3

Method of producing a sputtering target in accordance with further example embodiments of the present invention, may comprise the following steps of: . mixing metal oxide powder or a mixture of several metal oxides powder in a slurry, . spraying dry; . shaping the mixture by pressing; and . sintering in inert atmosphere or vacuum.

Sputtering targets with different densities may be achieved by varying the sintering parameters (e.g., temperature and time) during the method of producing the sputtering targets. By doing

SO, sputtering targets having a low density of 70-95%, preferably 80-25% may be produced.

EXAMPLE 4

Method of producing a sputtering target in accordance with yet further example embodiments of the present invention, may comprise the following steps of: * mixing metal oxide powder with carbon/graphite, . treating the mixture thermally or alternatively treating the mixture thermally in hydrogen or carbon monoxide (CO) until a metal phase forms; . shaping the mixture; and . sintering.

In these embodiments, the mixing step may be dry mixing or mixing in a slurry. The slurry may comprise a solvent wherein the solvent may be water or any alcohol.

EXAMPLE 5

Method of producing a sputtering target in accordance with yet further example embodiments of the present invention, may comprise the following steps of: 10 . adding pore forming agents to metal oxide powder; . shaping by pressing; . thermally degrading; and . sintering.

In these embodiments, the degrading step and the sintering siep may be performed in ambient atmosphere. A porous metal- oxide structure remains.

EXAMPLE 6

Method of producing a sputtering target in accordance with yet further example embodiments of the present invention, may comprise the following steps of: . adding pore forming agents to a mixture of metal oxide powder and metal powder: 25 . shaping by pressing; ° thermally degrading; and . sintering.

In these embodiments, the pores may be introduced by using thermally degradable pore forming agents. A porous metal-oxide-— metal structure remains after the degrading step and the subsequent sintering step.

EXPERIMENTAL RESULTS

Several sputtering trials have been conducted to investigate the susceptibility of different sputtering targets as described in the example embodiments to cracking. Sputtering targets containing standard oxide materials have also been subject to the same trials and compared against the sputtering targets having pores and/or metal. The dimension of each sputtering target is 488 mm x 88 mm x 6 mm.

The sputtering process comprises the following steps of:-

I. Insert sputtering target into sputtering chamber;

II. Ramp up power to 2 W/cm? target area within 30 minutes;

III. Run target at this power level for 1 hour;

IV. Reduce power to 0 kW within 15 minutes;

Vv. Remove target from sputtering chamber;

VI. Visual checking of target’s conditions;

VII. Repeat steps I to VI with step II having the fellowing increased power settings of:- + 3 W/ em, + 4 W/ cm?, + 6 W/cm? ¢ 8 W/cm? ¢ 10 W/cm? ¢ 12 W/cm?, ¢ 14 W/cm?;

VIII.Repeat steps I to VII for each of the sputtering targets containing the fellowing:- + TiO, ¢ TiO, + 2 wt% Ti, + TiO, + 5 wt% Ti, 4 TiO; + 10wt% Nb,Os+ 5S5wt% Ti,

+ Ti02 {low density of 87% / porosity of 13%}; + Nb,0Os; + 5wt% Nb, and + Nb,Os.

Density [%] is defined as the ratio between the apparent density [g/cm®] and theoretical bulk density [g/cm’}, that is:

Density [%] = apparent density [g/cm’] theoretical bulk density [g/cm’] :

The density of a target is related to its porosity. More specifically, a target with a higher percentage density would have a lower porosity.

Table I shows the experimental results. For the results, the definitions of crack attributes are as follow in Table II, where x is the number of cracks per cm® and y is the crack length in cm:-

Table IT

From the experimental results, it can be observed that usage of the sputtering targets containing Ti0Z + 2 wt% Ti,

Ti0Z + 5 wt% Ti, Ti02+ 10wt% Nb205+ 5wt% Ti, TiO2 (low density of 87% / porosity of 13%), and Nb;Os + 5wt% Nb for DC/RF sputtering of high-refractive~index layers at a power density which is at least 10% higher than the power density which can be achieved with TiQ, (the pure metal-oxide).

In conclusion, sputtering targets containing oxides, metallic component and/or pores for DC/RF sputtering of high- refractive-index layers at a high power density have improved sputtering performances over sputtering targets containing only pure metal oxides.

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Claims

WHAT IS CLAIMED IS

1. A composition for use in a sputtering target for sputtering at a power density which is at least 10% higher than the power density which can be applied to a metal oxide target with a density of more than 95% without showing cracks and defects, the composition comprising a matrix material comprising the metal oxide selected from a group of oxides consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yvitrium oxide in any oxide modification, molybdenum oxide in any oxide modification, zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification and hafnium oxide in any oxide modification, or a mixture thereof; and a metallic component homogenously spread in a microscale within the matrix material.

2. The composition as claimed in claim 1, wherein the metallic component is selected from a group consisting of Ti, Nb, V, ¥, Mo, Zr, Ta, W and Ef, or a mixture thereof.

3. The composition as claimed in claim 1 or 2, further comprising a second oxide in the Lanthanide series in any oxide modification, or scandium oxide in any oxide modification or lanthanum oxide in any oxide modification.

4. The composition as claimed in claim 3, wherein the second oxide is selected from a group consisting of cerium oxide in any oxide modification, dipraseodymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide modification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, vtterbium oxide in any oxide modification, lutetium oxide in any oxide modification, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or the mixture thereof.

5. The composition as claimed in claim 3 or 4, wherein the second oxide or the mixture thereof is in a range of 0.1 and 50 wt%.

6. The composition as claimed in claim 5, wherein the second oxide or the mixture thereof is in a range of 5-20 wt%.

7. The composition as claimed in any one of the preceding claims, wherein the metallic component is in a range between 2-20 wt% of the matrix material.

8. The composition as claimed in any one of the preceding claims, wherein the metallic component is in a range between 4-6 wt% of the matrix material.

9. A sputtering target comprising a composition as claimed in any one of claims 1-8.

10. The sputtering target as claimed in claim 9, further comprises pores, wherein the sputtering target has a density of 70-95%.

11. A sputtering target for sputtering at a power density which is at least 10% higher than the power density which can be applied to a metal oxide target with a density of more than 85% without showing cracks and defects, the sputtering target comprising a microstructure of a matrix material having pores, wherein the matrix material comprises the metal oxide selected from a group of : oxides consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yttrium oxide in any oxide modification, molybdenum oxide in any oxide modification, zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification and hafnium oxide in any oxide modification, or a mixture thereof.

12. The sputtering target as claimed in c¢laim 11, {further comprising a metallic component, wherein the metallic component is selected from a group consisting of Ti, Nb, V, Y, Mo, Zr, Ta, W and Hf, or a mixture thereof.

13. The sputtering target as claimed in claim 11 or 12, further comprising a second oxide in the Lanthanide series in any oxide modification, or scandium oxide in any oxide modification or lanthanum oxide in any oxide modification.

14. The sputtering target as claimed in claim 13, wherein the second oxide is selected from a group consisting of cerium oxide in any oxide modification, diprasecdymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide modification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, yvtterbium oxide in any oxide modification, lutetium oxide in any oxide modification, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or the mixture thereof.

15. The sputtering target as claimed in any one of claims 11-14, wherein the sputtering target has a density of 70-95%.

i6. The sputtering target as claimed in any one of claims 11-15, wherein the pores are spread separated within the matrix material.

17. 2 method for producing a sputtering target comprising a composition as claimed in any one of claims 1-8, the method comprising the steps of dry mixing powder of the metal oxide with powder of the metal; and shaping the mixture by hot pressing or EIPing.

18. The method as claimed in claim 17, wherein the metal powder is 5-20 wt%.

19. The method as claimed in claim 17 or 18, wherein the metal oxide powder and the metal powder have particle sizes in the range between 1-150 um.

20. The method as claimed in any one of claim 17-19, wherein the mixture is shaped at temperatures between 600 - 1400°C.

21. A method for producing a sputtering target comprising a composition as claimed in any one of claims 1-8, the method comprising the steps of mixing powder of the metal oxide powder with powder of the metal in a slurry; spraying dry; shaping the mixture by pressing; and sintering in inert atmosphere or vacuum.

22. A method for producing & sputtering target as claimed in any one of claims 11-16, the method comprising the steps of mixing powder of the metal oxide optionally with a mixture of several metal oxides powder in a slurry; spraying dry; shaping the mixture by pressing; and sintering in inert atmosphere or vacuum.

23. A method for producing a sputtering target suitable for sputtering at a power density which is at least 10% higher than the power density which can be applied to a metal oxide target with a density of more than 95% without showing cracks and defects, the method comprising the steps of mixing powder of the metal oxide with carbon/graphite; treating the mixture thermally or alternatively treating the mixture thermally in hydrogen or carbon monoxide until a metal phase forms; shaping the mixture; and sintering.

24. The method as claimed in claim 23, wherein the mixing is dry mixing or mixing in a slurry.

25. The method as claimed in claim 21, 22 or 24, wherein the slurry comprises a solvent which is water or any alcohol.

26. A method for producing a sputtering target suitable for sputtering at a power density which is at least 10% higher than the power density which can be applied to a metal oxide target with a density of more than 95% without showing cracks and defects, the method comprising the steps of adding pore forming agents to powder of the metal oxide; shaping by pressing; thermally degrading; and sintering.

27. The method as claimed in claim 26, wherein the degrading step and the sintering step is performed in ambient atmosphere.

28. A method for producing a sputtering target comprising a composition as claimed in any one of claims 1-8, the method comprising the steps of adding pore forming agents to powder of the metal oxide and powder of the metal; shaping by pressing; thermally degrading; and sintering.

29. The method as claimed in any one of claims 17-28, wherein the metal oxide powder is an oxide selected from a group consisting of titanium oxide in any oxide modification, niobium oxide in any oxide modification, vanadium oxide in any oxide modification, yttrium oxide in any oxide modification, molybdenum oxide in any oxide modification, zirconium oxide in any oxide modification, tantalum oxide in any oxide modification, tungsten oxide in any oxide modification, hafnium oxide in any oxide modification, cerium oxide in any oxide modification, dipraseodymium oxide in any oxide modification, praseodymium oxide in any oxide modification, neodymium oxide in any oxide modification, samarium oxide in any oxide modification, europium oxide in any oxide modification, gadolinium oxide in any oxide modification, terbium oxide in any oxide modification, dysprosium oxide in any oxide modification, holmium oxide in any oxide modification, erbium oxide in any oxide modification, thulium oxide in any oxide modification, ytterbium oxide in any oxide modification, lutetium oxide in any oxide modification, scandium oxide in any oxide modification and lanthanum oxide in any oxide modification, or a mixture thereof.

30. Use of a sputtering target as claimed in any one of claims 9-16 for DC/RF sputtering of high-refractive-index layers.

31. Use of a sputtering target as claimed in any one of claims 9-16 for high power density sputtering, wherein the power density applied 1s at least 10% higher than the power density which can be applied to a related metal oxide target with a density of more than 95% without showing cracks and defects.