Sputtering target of sintered Sb—Te-based alloy

Abstract

SbTe-based alloy sintered sputtering target having a Sb content of 10 to 60 at %, a Te content of 20 to 60 at %, and remainder being one or more types of elements selected from Ag, In, and Ge and unavoidable impurities, wherein an average grain size of oxides is 0.5 m or less. An object of this invention is to improve the texture of the SbTe-based alloy sintered sputtering target in order to prevent the generation of arcing during sputtering and improve the thermal stability of the sputtered film.

Claims

1. A SbTe-based alloy sintered sputtering target, wherein: the target has a composition consisting of Sb in a content of 10 to 60 at %, Te in a content of 20 to 60 at %, oxygen in an average content in the target of 1500 to 2500 wtppm, one or more elements selected from the group consisting of Ag, In, and Ge, one or more oxides of Mg, Al, Si, Ti, Zr, Nb, Hf, and Ta in an amount of 2 to 5 mol %, and unavoidable impurities; the target comprises oxide grains; an average size of the oxide grains is 0.5 m or less; a number of the oxide grains having a size of 1 m or more is 0.5% or less relative to a total number of the oxide grains; and a maximum size of the oxide grains is 1.5 m or less.

2. A SbTe-based alloy sintered sputtering target, wherein: the target has a composition consisting of Sb in a content of 10 to 60 at %, Te in a content of 20 to 60 at %, one or more elements selected from the group consisting of Ag, In, and Ge, one or more elements selected from the group consisting of Ga, Ti, Au, Pt, Pd, Bi, B, C, Mo, and Si in an amount of 30 at % or less, oxygen in an average content in the target of 1500 to 2500 wtppm, and unavoidable impurities; the target comprises oxide grains; an average size of the oxide grains is 0.5 m or less; a number of the oxide grains having a size of 1 m or more is 0.5% or less relative to a total number of the oxide grains; and a maximum size of the oxide grains is 1.5 m or less.

3. The SbTe-based alloy sintered sputtering target according to claim 2, wherein a maximum content of oxygen in the target is 3500 ppm or less.

4. The SbTe-based alloy sintered sputtering target according to claim 2, wherein a concentration difference of oxygen in the target is 2000 wtppm or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an explanatory diagram showing a case where an SEM (scanning electron microscope) is used for measuring the maximum grain size, the number of grains having a size exceeding 1 m, and the total number of grains of four locations in the cross section of the target in the visual field.

DETAILED DESCRIPTION

(2) The SbTe-based alloy sintered sputtering target of the present invention is configured from a sputtering target having a Sb content of 10 to 60 at %, a Te content of 20 to 60 at %, and remainder being one or more types of elements selected from Ag, In, and Ge and unavoidable impurities. The contents of the foregoing components; specifically, the Sb content, the Te content and the content of one or more types of elements selected from Ag, In, and Ge, show the preferred materials and component composition (including the compositional range) for use as a phase change recording material; that is, a medium for recording information by utilizing phase transformation.

(3) In order to finely disperse oxides in the SbTe-based alloy sintered sputtering target, preferably the maximum grain size of the oxides is 1.5 m or less, the average grain size of the oxides is 0.5 m or less, and the number of oxide grains having a size of 1 m or more is 1.5% or less, more preferably 0.5% or less, relative to the total number of oxide grains. These values may be arbitrarily controlled in correspondence with the mode of using the SbTe-based alloy sintered sputtering target. Based on the above, it is possible to obtain a SbTe-based alloy sintered sputtering target having fine oxide grains dispersed therein and which generates minimal arcing.

(4) With regard to the number of oxide grains having a size of 1 m or more being 1.5% or less, more preferably 0.5% or less, relative to the total number of oxide grains, a case in a specific visual field is anticipated, but this can be measured according to the following method. Specifically, an SEM (scanning electron microscope) is used for observing a 2000 visual field of the cross section of the target. In this visual field, the maximum grain size, the number of grains having a size exceeding 1 m, and the total number of grains are measured. Note that the grain size is measured as the diameter of a circle in which the maximum diameter of the grain is used in defining a circle. Furthermore, in order to evaluate the deviation in the target, as shown in FIG. 1, four locations of the cross section are measured in a similar manner, and the average value of these four locations is calculated.

(5) Moreover, the present invention may further contain, as accessory components, one or more types of elements selected from Ga, Ti, Au, Pt, Pd, Bi, B, C, Mo, and Si in an amount of 30 at % or less. These components also show the preferred materials and component composition (including the compositional range) for use as a phase change recording material; that is, a medium for recording information by utilizing phase transformation. In this case also, the accessory components may be arbitrarily selected in accordance with the mode of using the thin film made from a phase change recording material.

(6) Moreover, since these elements are also elements that form oxides in the same manner as Ag, In, and Ge, these elements can be included in the SbTe-based alloy sintered sputtering target as grains of oxides of one or more types of elements selected from Ga, Ti, Au, Pt, Pd, Bi, B, C, Mo, and Si. In this case also, in order to refine the oxide grains, preferably the average grain size is 0.5 m or less, the maximum grain size of oxides is 1.5 m or less, and the number of oxide grains having a size of 1 m or more is 0.5% or less relative to the total number of oxide grains.

(7) In the target of the present invention, the average content of oxygen is preferably 1500 to 2500 wtppm. While the existence of oxygen improves the thermal stability of sputtering deposition on the one hand, it also generates grains of oxides formed from constituent elements and oxygen in the target. Furthermore, these oxide grains may become the cause of abnormal discharge. Accordingly, the oxygen content is preferably set to be within the foregoing range. Moreover, there may be a concentration difference in the oxygen content in the target depending on the location. In locations where there is much oxygen, the oxygen content may reach 3500 ppm. Since a concentration difference is undesirable in terms of the uniformity of the sputtered film, the oxygen content is desirably 2000 wtppm or less.

(8) When measuring oxygen, four arbitrary locations of the cross section of the target (same locations shown in FIG. 1) are measured, and the average oxygen concentration of the four locations, the maximum oxygen concentration among the four locations, and the maximum difference among the respective oxygen concentrations of the four locations are calculated and identified, respectively, and used as the average content, maximum content and concentration difference of oxygen. Oxygen may be analyzed by using the analyzer manufactured by LECO, which is often used in the fields of analyzing carbon, sulfur, oxygen, nitrogen and hydrogen.

(9) Furthermore, the present invention may further contain oxides of one or more types of elements selected from Mg, Al, Si, Ti, Cu, Y, Zr, Nb, Hf, Ta, Ce, and Cd in an amount of 0.1 to 5 mol %. The existence of oxygen improves the thermal stability of sputtering deposition. Nevertheless, since the excessive existence of oxygen tends to generate abnormal discharge, the amount of oxides is desirably 5 mol % or less. Moreover, if the amount of oxides is less than 0.1 mol %, there is no effect of adding oxides and, therefore, the amount of oxides is set to be within the foregoing range. It is also preferable to finely disperse these oxides, and preferably the average grain size is 0.5 m or less, the maximum grain size of oxides is 1.5 m or less, and the number of oxide grains having a size of 1 m or more is 0.5% or less relative to the total number of oxide grains.

(10) A preferable example of producing the SbTe-based alloy is now explained. Foremost, a SbTe-based alloy powder obtained by weighing the raw material shots of the respective constituent elements and controlling the grain size to inhibit excessive oxidation (normally the grain size is controlled to be 5 mm or less), and pulverizing the raw material shots using a jet mill or the like is used. Next, these powders are subject to vacuum melting in a vacuumed (normally vacuumed to 8.510.sup.3 Pa or less) melting furnace at 950 C. for 10 minutes. Subsequently, gas atomization is performed using high purity Ar gas with the target level being a grain size of roughly 20 m.

(11) Jet mill pulverization is performed in order to refine and uniformly disperse the oxides in the powders. Consequently, a raw material powder normally having an average grain size of 2 m, a maximum crystal grain size of 5 m, and an oxygen content of 1500 to 2800 wtppm is obtained. The obtained raw material powder is hot pressed. The hot press conditions for preparing a target via sintering are normally a vacuum, rate of temperature increase: 5 to 10 C./minute, end-point temperature: 400 to 600 C., and pressure: 200 to 400 kgf/cm.sup.2.

(12) Conditions of the foregoing jet mill pulverization and hot press are set, and the SbTe-based alloy sintered sputtering target of the present invention is produced according to the conditions of the present invention so that the average grain size of oxides is 0.5 m or less, the number of oxide grains having a size of 1 m or more or more is 0.5% or less relative to the total number of oxide grains, and the average grain size is 2 to 5 m. Furthermore, the SbTe-based alloy sintered sputtering target is produced so that the average content of oxygen is 1500 to 2500 wtppm. The foregoing conditions of the target are essential conditions for preferably inhibiting the generation of particles, abnormal discharge (arcing) and nodules, as well as the generation of cracks or fractures of the target during sputtering. As a result of sputtering a target comprising these conditions, it is possible to form a more uniform film in comparison to conventional technologies.

(13) In particular, the cause of generation of particles is largely affected by the size of oxide grains contained in the SbTe-based alloy target and the oxygen concentration in the SbTe-based alloy target. The foregoing conditions of the target yield an effect of being able to considerably inhibit the generation of arcing and particles. Moreover, by reducing the grain size of the oxides contained in the target, the eroded surface of the target can be kept smooth even after the erosion, and there is an advantage in being able to also inhibit the particles that are generated in conventional technologies as a result of redeposits becoming attached to the irregularities on the eroded surface and then growing into nodules, and consequently collapsing.

(14) Moreover, the SbTe-based alloy sintered sputtering target of the present invention may contain, as accessory components, one or more types of elements selected from Ga, Ti, Au, Pt, Pd, Bi, B, C, Mo, and Si. These accessory components are preferably added to the raw material at the stage of gas atomization. Moreover, the present invention may contain oxides of one or more types of elements selected from Mg, Al, Si, Ti, Cu, Y, Zr, Nb, Hf, Ta, Ce, and Cd. These oxides are preferably added to the raw material at the stage after the jet mill pulverization.

(15) Moreover, as a result of increasing the purity of the SbTe-based alloy sintered sputtering target, impurities other than the main component and oxygen or additive accessory components will become the source of abnormal discharge (arcing). In the present invention, the main component desirably has a purity of 4N or higher. Consequently, it will be possible to effectively prevent arcing caused by impurities, and inhibit the generation of particles caused by arcing. The purity of the main component is more preferably 5N or higher.

EXAMPLES

(16) The Examples of the present invention are now explained. Note that these Examples are merely exemplifications, and the present invention is not limited to these Examples. In other words, the present invention covers all modes or modifications other than those described in the Examples within the scope of the technical concept of this invention.

Example 1-1

(17) As shown in Table 1, the respective raw material shots of Te, Sb, and Ge having a purity of 99.999% (5N) excluding gas components were weighed to attain Ge: 9.5 at %, Sb: 55.1 at %, and Te: 35.4 at %. The raw materials were selected to have a grain size of 5 mm or less with the intention of preventing oxidation. Next, these powders were subject to high frequency melting in a melting furnace, which was vacuumed to have a vacuum degree of 8.510.sup.3 Pa or less, at 950 C. for 10 minutes. After the melting process, gas atomization was performed using high purity Ar gas with the target level being a grain size of 20 m.

(18) Jet mill pulverization was performed in order to refine and uniformly disperse the oxides in the powders. Consequently, a raw material powder having an average grain size of 2 m, a maximum crystal grain size of 5 m, and an oxygen content of 2000 wtppm was obtained. The obtained raw material powder was sintered via hot pressing (vacuum, rate of temperature increase: 5 C./minute, end-point temperature: 570 C., pressure: 200 kgf/cm.sup.2).

(19) As a result of subjecting the thus obtained target to the foregoing evaluation, the average value of the oxygen concentration was 2000 ppm, the maximum concentration was 3000 ppm, and the difference in the oxygen concentration was 1200 ppm. As the oxides, Sb.sub.2O.sub.3, GeO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.2 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 53 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-2

(20) A sintered target was prepared based on the same production conditions as Example 1-1 using the composition shown in Table 1. With the obtained target, the average oxygen concentration was 1600 ppm, the maximum value of the oxygen concentration was 2500 ppm, and the difference in the oxygen concentration was 1300 ppm. As the oxides, Sb.sub.2O.sub.3, GeO.sub.2 were recognized. Moreover, the average grain size of the oxides was 0.1 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%. As a result of sputtering the thus obtained target, the number of particles generated was 37 particles and fewer than the number of particles of Example 1-1, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-3

(21) As shown in Table 1, other than adding In, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 1800 ppm, the maximum concentration was 2000 ppm, and the difference in the oxygen concentration was 1500 ppm. As the oxides, GeO.sub.2, TeO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.3 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.1%.

(22) Moreover, the number of particles generated during sputtering was 80 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-4

(23) As shown in Table 1, other than adding In in substitute for Ge, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2500 ppm, the maximum concentration was 3500 ppm, and the difference in the oxygen concentration was 2000 ppm. As the oxides, In.sub.2O.sub.3, Sb.sub.2O.sub.3, TeO.sub.2 were recognized. The average grain size of the oxides was 0.1 m, the maximum grain size was 1.3 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%.

(24) Moreover, the number of particles generated during sputtering was 66 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-5

(25) As shown in Table 1, other than changing the composition ratio to Ge: 70.5, Sb: 10.5, and Te: 19.0, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 1600 ppm, the maximum concentration was 3000 ppm, and the difference in the oxygen concentration was 1000 ppm. As the oxides, GeO.sub.2 was recognized. The average grain size of the oxides was 0.1 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%.

(26) Moreover, the number of particles generated during sputtering was 61 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-6

(27) As shown in Table 1, other than adding Ag in substitute for Ge, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2000 ppm, the maximum concentration was 3500 ppm, and the difference in the oxygen concentration was 500 ppm. As the oxides, Ag.sub.2O, Sb.sub.2O.sub.3, TeO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%.

(28) Moreover, the number of particles generated during sputtering was 75 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-7

(29) As shown in Table 1, other than adding Bi, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2300 ppm, the maximum concentration was 3400 ppm, and the difference in the oxygen concentration was 1700 ppm. As the oxides, Bi.sub.2O.sub.3, GeO.sub.2, TeO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.2 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%.

(30) Moreover, the number of particles generated during sputtering was 79 particles and fewer than the target level of 100 particles, and favorable results were obtained. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Example 1-8

(31) As shown in Table 1, other than substituting a part of Ge with Ga, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 1900 ppm, the maximum concentration was 2600 ppm, and the difference in the oxygen concentration was 800 ppm. The average grain size of the oxides was 0.2 m, the maximum grain size was 0.9 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%. Moreover, the number of particles generated during sputtering was 48 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 1-9

(32) As shown in Table 1, Sb: 20.0 at %, Te: 55.0 at %, Ge: 15.0 at %, and Si: 10.0 at % were used as the raw materials, and a sintered target was prepared based on the same conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 1700 ppm, the maximum concentration was 2000 ppm, and the difference in the oxygen concentration was 900 ppm. As the oxides, TeO.sub.2, SiO.sub.2 were recognized. The average grain size of the oxides was 0.1 m, the maximum grain size was 1.0 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%.

(33) Moreover, the number of particles generated during sputtering was 31 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 1-10

(34) As shown in Table 1, Sb: 18.9 at %, Te: 47.2 at %, Ge: 18.9 at %, and C: 15.0 at % were used as the raw materials, and a sintered target was prepared based on the same conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2200 ppm, the maximum concentration was 3200 ppm, and the difference in the oxygen concentration was 1000 ppm. As the oxides, GeO.sub.2, TeO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%.

(35) Moreover, the number of particles generated during sputtering was 52 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 1-11

(36) As shown in Table 1, Sb: 18.9 at %, Te: 47.2 at %, Ge: 18.9 at %, and B: 15.0 at % were used as the raw materials, and a sintered target was prepared based on the same conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2100 ppm, the maximum concentration was 2900 ppm, and, the difference in the oxygen concentration was 900 ppm. As the oxides, GeO.sub.2, TeO.sub.2 were recognized. The average grain size of the oxides was 0.3 m, the maximum grain size was 1.4 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%.

(37) Moreover, the number of particles generated during sputtering was 68 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 1-12

(38) As shown in Table 1, Sb: 60.0 at %, Te: 22.0 at %, Ge: 10.0 at %, and Ti: 8.0 at % were used as the raw materials, and a sintered target was prepared based on the same conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 2400 ppm, the maximum concentration was 3600 ppm, and the difference in the oxygen concentration was 1500 ppm. As the oxides, Sb.sub.2O.sub.3, TiO.sub.2 were recognized. The average grain size of the oxides was 0.3 m, the maximum grain size was 1.5 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%.

(39) Moreover, the number of particles generated during sputtering was 54 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 1-13

(40) As shown in Table 1, Sb: 60.0 at %, Te: 22.0 at %, Ge: 10.0 at %, and Mo: 8.0 at % were used as the raw materials, and a sintered target was prepared based on the same conditions as Example 1-1. As a result of evaluating the thus obtained target, the average value of the oxygen concentration was 1800 ppm, the maximum concentration was 2700 ppm, and the difference in the oxygen concentration was 1200 ppm. As the oxides, Sb.sub.2O.sub.3, MoO.sub.2 were recognized. The average grain size of the oxides was 0.2 m, the maximum grain size was 1.0 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%.

(41) Moreover, the number of particles generated during sputtering was 65 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Comparative Example 1-1

(42) Other than increasing the oxygen content in the target by leaving the raw material powder in the atmosphere for 6 hours or longer, a sintered target was prepared based on the same production conditions as Example 1-1. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 5000 ppm, the maximum concentration was 10000 ppm, and the difference in the oxygen concentration was 1800 ppm. As the oxides, Sb.sub.2O.sub.3, GeO.sub.2 were recognized.

(43) The average grain size of the oxides was 0.5 m, the maximum grain size was 2.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.6%. Moreover, the number of particles generated during sputtering was 434 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-2

(44) Other than lowering the oxygen content in the target by subjecting the raw material powder to hydrogen reduction treatment, a sintered target was prepared based on the same production conditions as Example 1-2. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 500 ppm, the maximum concentration was 1000 ppm, and the difference in the oxygen concentration was 800 ppm. As the oxides, Sb.sub.2O.sub.3, GeO.sub.2 were recognized.

(45) The average grain size of the oxides was 0.6 m, the maximum grain size was 2.4 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.65%. Moreover, the number of particles generated during sputtering was 408 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-3

(46) Other than leaving the raw material powder in the atmosphere for 6 hours or longer and mixing a powder produced based on a standard process, the same production conditions as Example 1-3 were used, and the oxygen content in the target, the maximum oxygen concentration, and the difference in the oxygen concentration all increased. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 4000 ppm, the maximum concentration was 6000 ppm, and the difference in the oxygen concentration was 3500 ppm. As the oxides, GeO.sub.2, TeO.sub.2 were recognized.

(47) The average grain size of the oxides was 0.6 m, the maximum grain size was 2.8 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%. Moreover, the number of particles generated during sputtering was 458 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-4

(48) Other than mixing a powder produced based on a standard process and a powder that was subject to hydrogen reduction treatment, the same production conditions as Example 1-4 were used, and the oxygen content in the target, the maximum oxygen concentration, and the difference in the oxygen concentration all increased. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 3000 ppm, the maximum concentration was 4000 ppm, and the difference in the oxygen concentration was 4000 ppm. As the oxides, In.sub.2O.sub.3, Sb.sub.2O.sub.3, TeO.sub.2 were recognized.

(49) The average grain size of the oxides was 0.1 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.5%. Moreover, the number of particles generated during sputtering was 416 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-5

(50) Other than leaving the raw material powder in the atmosphere for 6 hours or longer, the same production conditions as Example 1-5 were used, and the oxygen content in the target, the maximum oxygen concentration, and the difference in the oxygen concentration all increased. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 3500 ppm, the maximum concentration was 5000 ppm, and the difference in the oxygen concentration was 1800 ppm. As the oxides, GeO.sub.2 was recognized.

(51) The average grain size of the oxides was 0.2 m, the maximum grain size was 1.8 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 314 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-6

(52) Other than leaving the raw material powder in the atmosphere for 6 hours or longer and mixing a powder produced based on a standard process, the same production conditions as Example 1-6 were used, and the oxygen content in the target, the maximum oxygen concentration, and the difference in the oxygen concentration all increased. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 10000 ppm, the maximum concentration was 15000 ppm, and the difference in the oxygen concentration was 8000 ppm. As the oxides, Ag.sub.2O, Sb.sub.2O.sub.3, TeO.sub.2 were recognized.

(53) The average grain size of the oxides was 0.2 m, the maximum grain size was 2.4 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%. Moreover, the number of particles generated during sputtering was 354 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

Comparative Example 1-7

(54) Other than leaving the raw material powder in the atmosphere for 6 hours or longer and mixing a powder produced based on a standard process, the same production conditions as Example 1-7 were used, and the oxygen content in the target, the maximum oxygen concentration, and the difference in the oxygen concentration all increased. As a result of evaluating the thus obtained target, as shown in Table 1, the average value of the oxygen concentration was 6300 ppm, the maximum concentration was 9400 ppm, and the difference in the oxygen concentration was 4000 ppm. As the oxides, Bi.sub.2O.sub.3, Ge.sub.2O.sub.2, TeO.sub.2 were recognized.

(55) The average grain size of the oxides was 0.6 m, the maximum grain size was 2.5 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.6%. Moreover, the number of particles generated during sputtering was 398 particles and considerably greater than the target level of 100 particles. The foregoing results are shown in Table 1. Table 1 also shows the main oxides that existed in the target.

(56) As evident upon comparing the foregoing Examples and Comparative Examples, it can be understood that the generation of particles can be inhibited by attaining a uniform oxygen concentration and refining the oxide grains. It is thereby possible to achieve stable sputtering and yield the effect of improving the uniformity of the sputtered film.

(57) TABLE-US-00001 TABLE 1 Evaluation of oxygen concentration Average oxygen Maximum oxygen Difference in Composition concentration/ concentration/ oxygen Composition Sb/at % Te/at % Other/at % ppm ppm concentration Example 1-1 GeSbTe 55.1 35.4 Ge(9.5) 2000 3000 1200 Example 1-2 GeSbTe 55.1 35.4 Ge(9.5) 1600 2500 1300 Example 1-3 GeInSbTe 16.1 53.8 Ge(16.0), In(9.1) 1800 2000 1500 Example 1-4 InSbTe 33.5 50.3 In(11.2) 2500 3500 2000 Example 1-5 GeSbTe 10.5 19.0 Ge(70.5) 1600 3000 1000 Example 1-6 AgSbTe 21.1 52.8 Ag(21.1) 2000 3500 500 Example 1-7 BiGeSbTe 10.0 50.0 Bi(9.0), Ge(31) 2300 3400 1700 Example 1-8 GeGaSbTe 55.1 35.4 Ge(6.5), Ga(3.0) 1900 2600 800 Example 1-9 SiGeSbTe 20.0 55.0 Ge(15.0), Si(10.0) 1700 2000 900 Example 1-10 CGeSbTe 18.9 47.2 Ge(18.9), C(15.0) 2200 3200 1000 Example 1-11 BGeSbTe 18.9 47.2 Ge(18.9), B(15.0) 2100 2900 900 Example 1-12 TiGeSbTe 60.0 22.0 Ge(10.0), Ti(8.0) 2400 3600 1500 Example 1-13 GeMoSbTe 60.0 22.0 Ge(10.0), Mo(8.0) 1800 2700 1200 Comparative GeSbTe 54.8 35.7 Ge(9.5) 5000 10000 1800 Example 1-1 Comparative GeSbTe 54.8 35.7 Ge(9.5) 500 1000 800 Example 1-2 Comparative GeInSbTe 16.0 53.5 Ge(15.9), In(9.1) 4000 6000 3500 Example 1-3 Comparative InSbTe 33.5 50.3 In(11.2) 3000 4000 4000 Example 1-4 Comparative GeSbTe 10.5 19.0 Ge(70.5) 3500 5000 1800 Example 1-5 Comparative AgSbTe 21.1 52.8 Ag(21.1) 10000 15000 8000 Example 1-6 Comparative BiGeSbTe 10.0 50.0 Bi(9.0), Ge(31) 6300 9400 4000 Example 1-7 Evaluation of texture Maximum grain Number of grains of Effect Grain size of size of oxides 1 m or larger/Total Number of Oxides oxides (m) (m) number of grains particles Example 1-1 Sb2O3, GeO2 0.2 1.2 0.4 53 Example 1-2 Sb2O3, GeO2 0.1 1.1 0.2 37 Example 1-3 GeO2, TeO2 0.2 1.3 0.1 80 Example 1-4 In2O3, Sb2O3, TeO2 0.1 1.3 0.4 66 Example 1-5 GeO2 0.1 1.1 0.4 61 Example 1-6 Ag2O, Sb2O3, TeO2 0.2 1.1 0.3 75 Example 1-7 Bi2O3, GeO2, TeO2 0.2 1.2 0.3 79 Example 1-8 Sb2O3, GeO2 0.2 0.9 0.2 48 Example 1-9 TeO2, SiO2 0.1 1.0 0.2 31 Example 1-10 GeO2, TeO2 0.2 1.1 0.2 52 Example 1-11 GeO2, TeO2 0.3 1.4 0.4 68 Example 1-12 Sb2O3, TiO2 0.3 1.5 0.3 54 Example 1-13 Sb2O3, MoO2 0.2 1.0 0.2 65 Comparative Sb2O3, GeO2 0.5 2.1 0.6 434 Example 1-1 Comparative Sb2O3, GeO2 0.6 2.4 0.65 408 Example 1-2 Comparative GeO2, TeO2 0.6 2.8 0.2 458 Example 1-3 Comparative In2O3, Sb2O3, TeO2 0.1 1.1 0.5 416 Example 1-4 Comparative GeO2 0.2 1.8 0.4 314 Example 1-5 Comparative Ag2O, Sb2O3, TeO2 0.2 2.4 0.3 354 Example 1-6 Comparative Bi2O3, GeO2, TeO2 0.6 2.5 0.6 398 Example 1-7

Example 2-1

(58) The respective raw material shots of Te, Sb, and Ge having a purity of 99.999% (5N) excluding gas components were weighed to attain Ge: 9.5, Sb: 55.1, and Te: 35.4. The raw materials were selected to have a grain size of 5 mm or less with the intention of preventing oxidation. Next, these powders were subject to high frequency melting in a melting furnace, which was vacuumed to have a vacuum degree of 8.510.sup.3 Pa or less, at 950 C. for 10 minutes. After the melting process, gas atomization was performed using high purity Ar gas with the target level being a grain size of 20 m.

(59) Jet mill pulverization was performed in order to refine and uniformly disperse the oxides in the powders. Consequently, a raw material powder having an average grain size of 2 m, a maximum crystal grain size of 5 m, and an oxygen content of 2000 wtppm was obtained. After adding 5 mol % of SiO.sub.2 to the obtained raw material powder, the raw material powder was sintered via hot pressing (vacuum, rate of temperature increase 5 C./minute, end-point temperature: 570 C., pressure 200 kgf/cm.sup.2).

(60) As a result of subjecting the thus obtained target to the foregoing evaluation, the average grain size of the oxides was 0.1 m, the maximum grain size was 1.3 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 42 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-2

(61) Other than not adding SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.1 m, the maximum grain size was 1.0 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%. Moreover, the number of particles generated during sputtering was 59 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-3

(62) Other than adding In, changing the composition ratio to Ge: 16.0, In: 9.1, Sb: 16.1, and Te: 53.8, and adding 3 mol % of SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.5 m, the maximum grain size was 0.8 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.1%. Moreover, the number of particles generated during sputtering was 75 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-4

(63) Other than adding In in substitute for Ge, changing the composition ratio to In: 11.2, Sb: 33.5, and Te: 50.3, and adding 4 mol % of SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.3 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%. Moreover, the number of particles generated during sputtering was 60 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-5

(64) Other than changing the composition ratio to Ge: 70.5, Sb: 10.5, and Te: 19.0 and adding 2 mol % of TiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.45 m, the maximum grain size was 0.5 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 83 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-6

(65) Other than changing the composition ratio to Ag: 21.1, Sb: 21.1, and Te: 52.8 and adding 1 mol % of MgO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.1 m, the maximum grain size was 0.7 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.5%. Moreover, the number of particles generated during sputtering was 61 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-7

(66) Other than adding Al.sub.2O.sub.3 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.1 m, the maximum grain size was 0.6 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%. Moreover, the number of particles generated during sputtering was 64 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-8

(67) Other than adding ZrO.sub.2 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.3 m, the maximum grain size was 0.9 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 73 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-9

(68) Other than adding Nb.sub.2O.sub.5 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.2 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.5%. Moreover, the number of particles generated during sputtering was 79 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-10

(69) Other than adding HfO.sub.2 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.2 m, the maximum grain size was 0.8 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.3%. Moreover, the number of particles generated during sputtering was 62 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-11

(70) Other than adding Ta.sub.2O.sub.5 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.3 m, the maximum grain size was 1.0 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 62 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Example 2-12

(71) Other than adding Nb.sub.2O.sub.5 and Ta.sub.2O.sub.5 at a ratio of 1:1 in substitute for SiO.sub.2, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.3 m, the maximum grain size was 1.0 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. Moreover, the number of particles generated during sputtering was 75 particles and fewer than the target level of 100 particles, and favorable results were obtained.

Comparative Example 2-1

(72) Other than increasing the additive amount of SiO.sub.2 to 6 mol % and additionally increasing the grain size of the oxides, a sintered target was prepared based on the same production conditions as Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.7 m, the maximum grain size was 1.8 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.6%. Moreover, the number of particles generated during sputtering was 382 particles and considerably greater than the target level of 100 particles.

Comparative Example 2-2

(73) Other than not adding SiO.sub.2, a sintered target was prepared based on the same production conditions as Comparative Example 2-1. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.8 m, the maximum grain size was 1.9 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.65%. Moreover, the number of particles generated during sputtering was 429 particles and considerably greater than the target level of 100 particles.

Comparative Example 2-3

(74) Other than reducing the additive amount of SiO.sub.2 to 0.08 mol %, a sintered target was prepared based on the same production conditions as Example 2-3. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.05 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.2%. Moreover, the number of particles generated during sputtering was 74 particles and, while this was lower than the target level of 100 particles or less, the thermal stability of the film could not be obtained.

Example 2-13

(75) Other than selecting the grain size of the raw material powder in order to coarsen the grain size of the oxides, a sintered target was prepared based on the same production conditions as Example 2-4. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 1.0 m, the maximum grain size was 2.5 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.7%. The number of particles generated during sputtering was 124 particles, and the number of particles decreased considerably in comparison to foregoing Comparative Examples 2-1 to 2-3. Nevertheless, in comparison to Examples 2-1 to 2-12, since the number of particles generated during sputtering increased slightly from the target level of 100 particles, it can be understood that it is necessary to control the grain size of the oxides to be added depending on the purpose and use.

Example 2-14

(76) Other than coarsening the grain size of TiO.sub.2 as the additive element by selecting the grain size of the raw material powder, a sintered target was prepared based on the same production conditions as Example 2-5. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.6 m, the maximum grain size was 2.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.4%. The number of particles generated during sputtering was 148 particles, and the number of particles decreased considerably in comparison to foregoing Comparative Examples 2-1 to 2-3. Nevertheless, in comparison to Examples 2-1 to 2-12, since the number of particles generated during sputtering increased slightly from the target level of 100 particles, as with Example 2-13, it can be understood that it is necessary to control the grain size of the oxides to be added depending on the purpose and use.

Example 2-15

(77) Other than increasing the hot press temperature by 30 C., a sintered target was prepared based on the same production conditions as Example 2-6. As a result of observing the cross section of the thus obtained target, the average grain size of the oxides was 0.9 m, the maximum grain size was 1.1 m, and the number of grains having a size of 1 m or more relative to the total number of grains was 0.65%. The number of particles generated during sputtering was 116 particles, and the number of particles decreased considerably in comparison to foregoing Comparative Examples 2-1 to 2-3. Nevertheless, in comparison to Examples 2-1 to 2-12, since the number of particles generated during sputtering increased slightly from the target level of 100 particles, as with Example 2-13, it can be understood that it is necessary to control the grain size of the oxides to be added depending on the purpose and use.

(78) The foregoing results are shown in Table 2. As evident upon comparing the foregoing Examples and Comparative Examples, it can be understood that the inclusion of a moderate amount of oxides of one or more types of elements selected from Mg, Al, Si, Ti, Cu, Y, Zr, Nb, Hf, Ta, Ce, and Cd in the SbTe-based alloy sintered target is effective in inhibiting the generation of particles during sputtering and improving the uniformity of the sputtered film. Moreover, the foregoing effects can be further improved by additionally controlling the grain size of the oxides.

(79) TABLE-US-00002 TABLE 2 Composition Additive amount Composition Sb/at % Te/at % Other/at % Added oxide of oxide/mol % Example 2-1 GeSbTe 55.1 35.4 Ge(9.5) SiO2 5 Example 2-2 GeSbTe 55.1 35.4 Ge(9.5) Example 2-3 GeInSbTe 16.1 53.8 Ge(16.0), In(9.1) SiO2 3 Example 2-4 InSbTe 33.5 50.3 In(11.2) SiO2 4 Example 2-5 GeSbTe 10.5 19.0 Ge(70.5) TiO2 2 Example 2-6 AgSbTe 21.1 52.8 Ag(21.1) MgO2 1 Example 2-7 GeSbTe 55.1 35.4 Ge(9.5) Al2O3 5 Example 2-8 GeSbTe 55.1 35.4 Ge(9.5) ZrO2 5 Example 2-9 GeSbTe 55.1 35.4 Ge(9.5) Nb2O5 5 Example 2-10 GeSbTe 55.1 35.4 Ge(9.5) HfO2 5 Example 2-11 GeSbTe 55.1 35.4 Ge(9.5) Ta2O5 5 Example 2-12 GeSbTe 55.1 35.4 Ge(9.5) Nb2O5 + Ta2O5 5(2.5/2.5) Comparative GeSbTe 54.8 35.7 Ge(9.5) SiO2 6 Example 2-1 Comparative GeSbTe 54.8 35.7 Ge(9.5) Example 2-2 Comparative GeInSbTe 16.1 53.8 Ge(15.9), In(9.1) SiO2 0.1 Example 2-3 Example 2-13 InSbTe 33.5 50.3 In(11.2) SiO2 4 Example 2-14 GeSbTe 10.5 19.0 Ge(70.5) TiO2 4 Example 2-15 AgSbTe 21.1 52.8 Ag(21.1) MgO2 2 Evaluation of texture Number of grains of Effect Grain size of Maximum grain size 1 m or larger/Total Number of oxides (m) of oxides (m) number of grains particles Example 2-1 0.1 1.3 0.4 42 Example 2-2 0.1 1.0 0.2 59 Example 2-3 0.5 0.8 0.1 75 Example 2-4 0.3 1.1 0.3 60 Example 2-5 0.45 0.5 0.4 83 Example 2-6 0.1 0.7 0.5 61 Example 2-7 0.1 0.6 0.3 64 Example 2-8 0.3 0.9 0.4 73 Example 2-9 0.2 1.1 0.5 79 Example 2-10 0.2 0.8 0.3 62 Example 2-11 0.3 1.0 0.4 62 Example 2-12 0.3 1.0 0.4 75 Comparative 0.7 1.8 0.6 382 Example 2-1 Comparative 0.8 1.9 0.65 429 Example 2-2 Comparative 0.05 1.1 0.2 74 (no high Example 2-3 tempature stability of film) Example 2-13 1.0 2.5 0.7 124 Example 2-14 0.6 2.1 0.4 148 Example 2-15 0.9 1.1 0.65 116

(80) With the SbTe-based alloy sintered target of the present invention, the characteristics of the SbTe-based alloy can be improved by controlling the oxide grains configuring the target and controlling the oxygen content. In other words, by refining the oxide grains and attaining a uniform oxygen concentration, it is possible to improve the characteristics of the target and achieve stable sputtering. It is thereby possible to prevent the generation of abnormal discharge originating from the oxides, and inhibit the generation of particles caused by arcing. The present invention additionally yields a superior effect of being able to improve the uniformity of the sputtered film. The present invention is extremely effective as a phase change recording material; that is, a medium for recording information by utilizing phase transformation.