TW593718B - Sputtering target for forming optical recording protective film and manufacturing method for the same - Google Patents

Abstract

The present invention is to provide a sputtering target for forming optical recording protective film comprising Zns and SiO2, wherein the surface roughness (Ra) of the sputtering target after sputtering is < 2.4.

Description

593718 Case No. 89106792 Rev. V. Description of the Invention (1) Background of the Invention The present invention relates to a sputtering target for forming a optical recording protective film and a method for manufacturing the same. More specifically, it uses a fine Si 02 material. Powder, sintered at high temperature, excellent radon strength, and dust or particles rarely occur during sputtering. As a result, it can withstand long-term use of a sputtering target for forming a light recording protective film and a method for manufacturing the same. An optical recording medium that records and erases information by using a light beam on a thin film such as Ge-Sb-Te or Ag-In-Sb-Te to perform reversible phase transformation. The protective film is provided on both sides. The basic structure of the reflective film is the other side of the substrate. The protective film used here, as described in JP 6 3-2 7 6 7 2 or JP 4-3 6 1 6 4, is known to consist of ZnS and SiO 2 by sputtering. A dielectric thin film is formed. A dielectric thin film composed of ZnS and Si 02 has a refractive index within a predetermined range and a low thermal conductivity, and has various characteristics required for a protective film such as laser light that does not absorb light, so it is widely used as a protective film . In order to form this ZnS -Si 02 series protective film, thin film technology can be used. Sputtering method has become the mainstream. For this sputtering target, a high-purity zinc sulfide powder is proposed. 20 mol% was uniformly mixed, and the obtained mixed powder was pressurized and then calcined (Japanese Patent Application Laid-Open No. 6-6 65 7 25). The main characteristics required by this splash target can be exemplified: even if the power during the splash is large, it will not crack, and dust (particles) will not occur. When the sputtering target is cracked or when dust is generated from the sputtering target, maintenance such as replacement of the sputtering target is often necessary, which impairs the productivity of optical recording media such as optical discs.

O: \ 63 \ 63763.ptc Page 4 593718 _Case No. 89106792_ Year Month Day__ V. Explanation of the invention (2) The frequency of replacement will increase, which is economically disadvantageous. In Japanese Patent Application Laid-Open Nos. 10-8 1 9 54 and Japanese Patent Application Laid-Open Nos. 10-8 1 960, a method for preventing generation of dust (particles) of a sputtering target has been proposed. In these methods, attention is paid to the crystalline structure of zinc sulfide, but it cannot sufficiently prevent the generation of dust from the sputtering target, and it cannot effectively prevent cracking. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sputtering target for forming a light-recording protective film that can withstand long-term use, and a method for manufacturing the same that has excellent strength and does not generate dust or particles during sputtering. As a result of research by the inventors, it has been found that in order to prevent the occurrence of dust, it is important to have a smooth target on the surface after sputtering. A finer material is used as the Si 02 raw material powder, and it has a high density and is fired at a high temperature. After sputtering under the conditions, a sputtering target with a smooth and high-strength surface can also be obtained, which can achieve the above purpose. The present invention is based on the above knowledge, and therefore provides a sputtering target for forming an optical recording protective film including Z n S and Si 02, which is characterized in that the surface roughness (Ra) after the sputtering is less than 2.4. In addition, the present invention provides a method for manufacturing a sputtering target for forming an optical recording protective film. The mixed powder obtained by mixing the Z nS raw material powder S i 02 raw material powder is pressurized and fired, and is characterized by: The average particle size of Si 02 after the formation is 2 # m or less, and the above firing is performed under an inert gas environment at 1 200 ° C or more. Brief Description of Drawings Figure 1 is a scanning electron microscope photograph (500 times) of the surface of a sputtering target after sputtering in Example 1.

O: \ 63 \ 63763.ptc Page 5 593718 _Case No. 89106792_ Year Month Day__ V. Description of the invention (3) Figure 2 is a scanning type of the surface of the sputtering target after sputtering in Example 1 Electron micrograph (500 times). FIG. 3 is a scanning electron microscope photograph (500 times) of the surface of a sputtering target after sputtering in Comparative Example 1. FIG. FIG. 4 is a scanning electron microscope photograph (500 times) of the surface of a sputtering target after sputtering in Comparative Example 2. FIG. FIG. 5 is a scanning electron microscope photograph (500 times) of the surface of a sputtering target after sputtering in Comparative Example 3. FIG. Fig. 6 is a graph showing the relationship between the average particle diameter of Si02 raw material powder, the surface roughness (Ra) after sputtering and the number of good pieces. Fig. 7 is a graph showing the relationship between the surface roughness (Ra) after sputtering and the number of good products. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below. The sputtering target (hereinafter referred to simply as a sputtering target) for forming the optical recording protective film of the present invention includes ZnS and SiO2, and contains 10 to 30 mol% of SiO2 relative to ZnS. The sputtering target of the present invention has a surface roughness (Ra) of less than 2.4 after sputtering. If the surface roughness (Ra) exceeds 2.4, it may become the size of dust and cause the formation of pellets. Due to the pellets, the dust is easily scattered from the surface during sputtering. The sputter target of the present invention should preferably have a flexural strength of 8.5 kg f / mm2 or less. If the flexural strength of 8.5 kgf / m m2 or more, the power at the time of money mining is very large, and it may be generated when the key is dry Cracked. Next, the manufacturing method of this invention is demonstrated. In the present invention, the average particle diameter after firing is 2 # m or less

O: \ 63 \ 63763.ptc Page 6 593718 _Case No. 89106792_year month__ V. Description of the invention (4) The material used as Si 02 powder. The above-mentioned average powder diameter after firing forms S i 02 raw material powder below 2 // m, for example: S i 02 raw material such as quartz is crushed to an average particle diameter of 2 // m or less, or agglomerated powder is mixed and crushed Form an average particle size of 2 // m or less. Examples of the agglomerated powder (trade name, manufactured by Japan Corporation) and the like. In addition, as the Z n S raw material powder, an average particle diameter of about 2 to 6 // m is generally used. In the present invention, the Z nS raw material powder and the Si 02 raw material powder are separately mixed with water, and pulverized by bead grinding or the like to form a desired particle diameter. After mixing the two, the mixture is suction-filtered, and then, Dry at a temperature of 4 0 ° C to remove moisture, hydrogen sulfide and sulfur oxides. Next, the mixture of the Zn S raw material powder and the Si 02 raw material powder is pressurized and fired (hot-pressed) under an inert gas atmosphere, preferably under an argon atmosphere. In the present invention, the firing temperature is 1200 ° C or higher, preferably at 1200 to 1300 ° C. The firing temperature is below 1 200 ° C, and it is difficult to fire fine Si 02, and a high-strength sputtering target cannot be obtained. The preferred firing conditions of the present invention are, for example, raising the temperature to 110 ° C in a vacuum, removing sulfur oxides, and finally introducing argon to pressurize and sinter at above 1200 ° C. In this way, the sputtering target of the present invention can be obtained. The sputtering target is as described above, and the surface is smooth and high-strength after being sputtered with a certain partner. Hereinafter, the present invention will be specifically described based on examples and the like. [Example 1] 4.33 kg of ZnS raw material powder having an average particle diameter of 6.3 / zm was mixed with water at 90% by volume ratio. That is, the density of Z n S is 4 g / c c, so Z n S is 1 0 8 3 c c and water 9 7 4 7 c c. Use bead grinding, residence time is 4 in 3 ways

O: \ 63 \ 63763.ptc Page 7 593718-Action 1 89106792_ ^ Month Day Amendment V. Description of the invention (5) &quot; Crushing in a manner known by the knife &apos; In addition, a Si 02 raw material powder (-0X 5 0) having an average particle diameter of 2 · 0 // m was prepared and 0.6 7 kg, and 1,000 cc of water was put into the mixture and stirred thoroughly. Next, the mixed solution in which the Z n S aqueous solution and the Si 02 aqueous solution were mixed was agitated by pellets, stirred, and then allowed to stand, the supernatant was removed, and the mixture was filtered by suction and dried in the air at 400 ° C. Then, the obtained mixed powder was pre-pressurized at 50 kg f / cm2, and then evacuated, and the temperature was raised to 150 ° C at 80 minutes. In addition, argon gas was introduced at a pressure of 1 100 ° C. After reaching 1 250 ° C, pressurize at 300 gf / cm2 for 5 minutes, hold for 60 minutes, and depressurize the furnace for 3 minutes to cool down to obtain a sputtering target. In the target of the obtained sputtering target, Si 02 had an average particle diameter of 2 · 0 # m or less and a density of 3. 67 g / c c. In addition, target evaluation was performed on the surface roughness (Ra), flexural strength, and number of good pieces after sputtering. The results are shown in Table 1. Scanning electron micrographs (500 times and 5000 times) of the sputtering target surface after sputtering are shown in Figs. 1 and 2, respectively. [Comparative Example 1] A sputtering target was obtained in the same manner as in Example 1 except that the Si 02 raw material powder (quartz crushed product) having an average particle diameter of 6 · 2 # m was used. The target density was measured and target evaluation was performed in the same manner as in Example 1. The results are shown in Table 1. FIG. 3 shows a scanning electron microscope photograph (500 times) of the surface of the sputtering target after sputtering. [Comparative Example 2] The ZnS raw material powder with an average particle diameter of 6.3 / zm 4.33 kg and the Si 002 raw material powder with an average particle diameter of 5 8. 7 / m 0.67 kg were mixed by bead milling. The resulting mixed powder was pre-pressurized at 50 k g f / c m2 and ‘evacuated’ for 5 5 minutes.

O: \ 63 \ 63763.ptc Page 8 593718 __Case No. 89106792_year month __ V. Description of the invention (6) The temperature of the clock is raised to 900 ° C and maintained for 80 minutes. After the pressure system was heated up to 900 ° C, 300 kg f / c m2 was formed in 15 minutes from 15 minutes later. Furnace cooling. After holding at 90 ° C for 80 minutes, the pressure was removed in 2 minutes, and the furnace was cooled 'to obtain a sputtering target. Table 1 shows the results of the dry density measurement and dry evaluation evaluation in the same manner as in Example 1. A scanning electron microscope photograph (500 times) of the surface of the sputtering target after sputtering is shown in FIG. 4. [Comparative Example 3] The ZnS raw material powder with an average particle diameter of 6 · 3 # m 4 · 3 3 g and the Si02 raw material powder with an average particle diameter of 25.1 · 67 kg were mixed by bead milling. After the obtained mixed powder was pre-pressurized at 50 k g f / cm 2, it was evacuated, and the temperature was raised to 100 0 in 90 minutes. (: Hold for 120 minutes. After increasing the temperature to 1000 ° C. under pressure, 300 kgf / cm 2 is formed in 20 minutes from 20 minutes. After holding at 1000 ° C. for 120 minutes, The pressure was removed in 2 minutes, and the furnace was cooled to obtain sputter dryness. The target density was measured and target evaluation was performed in the same manner as in Example 1. The results are shown in Table 1. In addition, the surface of the sputtering target after the sputtering was scanned. A type electron microscope photograph (500 times) is shown in FIG. 5.

O: \ 63 \ 63763.ptc Page 9 593718 _Case No. 89106792_ Year Month and Day_ V. Description of the Invention (7) * 1: &gt; SH ^^ M ^^ Ha ^ TENCOIlp-10-# ^^ 2000 ^ m &gt; ^^ it &gt; t50 // m / se? ^^ 12.5 ^ m '^ _2omg. * 2: The Iridium Tablets 漭 洚 lai a ^ 澉 and 蒎 ^: 婵. Example 1 K) Lj ON Lj K) Lh K) L / \ ZnS average particle size (// m) raw material, target K) U \ oo-as k) K) o Si02 average particle size (// m) 1000 〇1250 1250 Hot pressing temperature (° C) k) Η— * U) § LO SU) Os Target density (g / cc) bo On K) K) o * 4 ^ Surface roughness after sputtering (// m ) Geba evaluated U \ 00 HA 2 flexural strength (kg / mm2) 1500 1000 5000 12000 Number of good products (pieces) tt O: \ 63 \ 63763.ptc Page 10 593718 _Case No. 89106792_year month__ V. Description of the invention (8) It is clear from Table 1 that Example 1 is smoother and has a higher bending strength than that of Comparative Examples 1 to 3 after sputtering. As a result, the number of good products increased rapidly. [Experimental example] A sputtering target was obtained in the same manner as in Example 1 except that the average particle diameter of the Si 02 raw material powder was changed. The relationship between the average particle diameter of this Si 02 raw material powder, the surface roughness (Ra) after the diameter sputtering, and the number of good pieces is shown in FIG. Fig. 7 shows the relationship between the surface roughness (Ra) after sputtering and the number of good products. As can be seen from FIG. 6 and FIG. 7, as the average particle diameter of the Si 02 raw material powder becomes smaller, the surface roughness also becomes smaller, and the number of good pieces increases. As described above, the sputtering target for forming the optical recording protective film of the present invention has excellent strength and is unlikely to generate cracks. In addition, dust or particles are rarely generated during sputtering, and as a result, it can withstand long-term use. According to the manufacturing method of the present invention, it can be obtained that the above sputtering target has productivity.

O: \ 63 \ 63763.ptc Page 11 593718 _Case No. 89106792_ Year Month Day _ Amendment

O: \ 63 \ 63763.ptc Page 12

Claims (1)

593718— ΰ Case No. 89106792 P: Rev. 16 、 Scope of patent application 1——One… ————〗 1 · A sputtering target for optical recording protection film formation, which includes ZnS and Si 02, which is characterized by · • The surface roughness (Ra) after sputtering is less than 2.4. 2. A method for manufacturing a sputtering target for forming an optical recording protective film, the sputtering target comprising ZnS and Si 02, which is a mixture of ZnS raw material powder and Si 02 raw material powder obtained by pressing and firing, It is characterized in that the average particle diameter of S i 02 after firing is 2 // in or less, and the firing is performed under an inert gas environment at 120 ° C or higher. O: \ 63 \ 63763.ptc Page 13