Process for producing and using a W—Ni sputtering target

Abstract

A process for producing a W—Ni sputtering target includes providing the sputtering target with 45 to 75 wt % W and a remainder of Ni and common impurities. The sputtering target contains a Ni(W) phase, a W phase and no or less than 10% by area on average of intermetallic phases measured at a target material cross section.

Claims

1. A process of using a sputtering target, the process comprising the following steps: using a sputtering target having from 45 to 75% by weight of W, a balance of Ni and normal impurities, a Ni(W) phase, a W phase and no or less than 10% by area on average of intermetallic phases measured at a target material cross section, for deposition of an electrochromic layer; and producing the sputtering target by at least compacting a powder mixture of W powder and Ni powder by application of pressure, heat or pressure and heat to provide a resulting blank, and cooling the resulting blank at a cooling rate of greater than 30 K/min at least in a temperature range of from 900 to 750° C.

2. A process of using of a sputtering target, the process comprising the following steps: using a sputtering target having from 45 to 75% by weight of W, a balance of Ni and normal impurities, a Ni(W) phase, a W phase and no or less than 10% by area on average of intermetallic phases measured at a target material cross section, for deposition of solar absorber layers, protective layers against high-temperature oxidation or diffusion barrier layers; and producing the sputtering target by at least compacting a powder mixture of W powder and Ni powder by application of pressure, heat or pressure and heat to provide a resulting blank, and cooling the resulting blank at a cooling rate of greater than 30 K/min at least in a temperature range of from 900 to 750° C.

3. A process for producing a W—Ni sputtering target using a powder-metallurgical route, the method comprising the following steps: carrying out a compacting step in which a powder mixture of W powder and Ni powder is compacted by application of pressure, heat or pressure and heat to give a resulting blank; and carrying out a cooling step in which the resulting blank is cooled at a cooling rate of greater than 30 K/min at least in a temperature range of from 900 to 750° C.

4. The process for producing a W—Ni sputtering target according to claim 3, which further comprises effecting the compacting step by sintering at temperatures of from 1100 to 1450° C.

5. The process for producing a W—Ni sputtering target according to claim 3, which further comprises performing a thermomechanical or thermal treatment of the blank between the compacting step and the cooling step.

6. The process for producing a W—Ni sputtering target according to claim 5, which further comprises performing the thermomechanical or thermal treatment at temperatures in a range of from 970 to 1450° C.

7. The process for producing a W—Ni sputtering target according to claim 5, wherein the thermomechanical or thermal treatment includes at least one forging step.

Description

DETAILED DESCRIPTION OF THE EXAMPLES

(1) The examples are summarized in Table 1.

(2) TABLE-US-00001 TABLE 1 Grain Sintering Thermomech. Degree of Area of size of temper- or therm, defor- Den- W W Area of O W Ni ature treatment, mation sity phase phase intermet. Texture of Hardness content Example [wt %] [wt %] [° C.] cooling [%] [%] [%] [μm] phase [%] Ni(W) [HV10] [μg/g] 1* 60 40 1350 Forging, 1300° C., 25 99.7 30 15 7 <110> 344 9 cooling in air 2* 60 40 1350 Forging, 1250° C., 25 99.7 29 14 <5 <110> 331 11 heat treatment at 1000° C. for 1 h, cooling in air 3* 70 30 1350 Forging, 1300° C., 50 99.5 39 19 8 <110> 442 70 cooling in air 4  43 57 1350 None, furnace 0 78 8 18 12 none 163 268 cooling 5  60 40 1200 None, furnace 0 77 30 15 15 none 165 96 cooling 6  60 40 1000 Forging, 1300° C. 25 65 — — — — 74 120 (terminated), furnace cooling *marks examples according to the invention

Example 1

(3) W metal powders having a particle size determined by the Fisher method of 4 μm and Ni metal powders having a particle size measured by the Fisher method of 4.2 μm were used as raw materials. The powders were introduced in a ratio of 60% by weight of W and 40% by weight of Ni into a closed vessel and mixed for 1 hour in a shaker.

(4) A steel mandrel having a diameter of 141 mm was positioned in the middle of a rubber tub which had a diameter of 300 mm and was closed at one end. The powder mixture was introduced into the intermediate space between steel core and rubber wall and the rubber tube was closed at its open end by means of a rubber cap. The closed rubber tube was positioned in a cold isostatic press and pressed at a pressure of 200 MPa to give a green body in the form of a tube having a relative density of 61% and an external diameter of 240 mm.

(5) The green body produced in this way was sintered at a temperature of 1350° C. in an indirect sintering furnace. The relative density after sintering was 95%.

(6) After sintering, the tube was mechanically worked on all sides to give a geometry of 200 mm external diameter, 127 mm internal diameter and 900 mm length.

(7) The tube was subsequently heated and forged on a mandrel at a temperature of 1300° C., giving a tube having a length of 1200 mm, an external diameter of 180 mm and an internal diameter of 120 mm which was cooled in air. A cooling rate of 37 K/min was achieved in the temperature range from 900 to 750° C.

(8) The density after forging was 99.7%, and the hardness of the target material was 344 HV10. An oxygen content of 9 μg/g was measured.

(9) In a measurement of the texture, a preferential orientation in the <110> direction in the Ni(W) phase was found. The area of the W phase was 30% and its average grain size was 15 μm. The proportions by area of intermetallic phase were 7%.

Example 2

(10) A tube was produced by a method analogous to Example 1.

(11) The tube was subsequently forged on a mandrel at a temperature of 1250° C., giving a tube having a length of 1200 mm, an external diameter of 180 mm and an internal diameter of 120 mm. A heat treatment at 1000° C. for one hour was subsequently carried out, followed by cooling in air. A cooling rate of 58 K/min was achieved in the temperature range from 900 to 750° C.

(12) The density was then 99.7% and the hardness of the target material was 331 HV10. An oxygen content of 11 μg/g was measured.

(13) In a measurement of the texture, a preferential orientation in the <110> direction was found in the Ni(W) phase. The area of the W phase was 29% and its average grain size was 14 μm. The proportions by area of intermetallic phase were <5%, i.e. no proportions of intermetallic phase could be measured by means of XRD.

Example 3

(14) A tube was produced by a method analogous to Examples 1 and 2, but W and Ni powders were used in a ratio of 70% by weight of W and 30% by weight of Ni.

(15) The tube was subsequently forged on a mandrel at a temperature of 1300° C., giving a tube having a length of 1200 mm, an external diameter of 180 mm and an internal diameter of 120 mm, and this was cooled in air. A cooling rate of 34 K/min was achieved in the temperature range from 900 to 750° C.

(16) The density was then 99.5% and the hardness of the target material was 442 HV10. An oxygen content of 70 μg/g was measured.

(17) In a measurement of the texture, a preferential orientation in the <110> direction in the Ni(W) phase was found. The area of the W phase was 39% and its average size was 19 μm. The proportions by area of intermetallic phase were 8%.

Example 4

(18) A tube was produced by a method analogous to Examples 1 to 3, but W and Ni powders were used in a ratio of 43% by weight of W and 57% by weight of Ni. No thermomechanical or thermal treatment was carried out. After sintering, the product was cooled in the furnace, with a cooling rate of about 10 K/min being achieved in the temperature range from 900 to 750° C. The density after sintering was 78% and the hardness of the target material was 163 HV10. The low hardness value is due to the low density. An oxygen content of 268 μg/g was measured.

(19) The area of the W phase was 8% and its average grain size was 18 μm. The proportions by area of intermetallic phase were 12%.

Example 5

(20) A tube was produced by a method analogous to Examples 1 and 2, but sintering was carried out at a temperature of 1200° C. No thermomechanical or thermal treatment was carried out. After sintering, the product was cooled in the furnace, with a cooling rate of about 10 K/min being achieved in the temperature range from 900 to 750° C. The density after sintering was 77% and the hardness of the target material was 165 HV10. The low hardness value is due to the low density. An oxygen content of 96 μg/g was measured.

(21) The area of the W phase was 30% and its average size was 15 μm. The proportions by area of intermetallic phase were 15%.

Example 6

(22) A tube was produced by a method analogous to Examples 1 and 2, but sintering was carried out at a temperature of 1000° C. After sintering, the product was cooled in the furnace, with a cooling rate of about 10 K/min being achieved in the temperature range from 900 to 750° C. The density after sintering was 77% and the hardness of the target material was 74 HV10. An oxygen content of 120 μg/g was measured. An attempt was subsequently made to forge the tube on a mandrel at 1300° C., but the experiment was stopped since the target material failed mechanically. No values for texture and proportions of phases and grain sizes could be determined.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(23) FIG. 1: Phase diagram of the Ni—W system (source: ASM International's Binary Alloy Phase Diagrams, Second Edition), composition range according to the invention marked.

(24) FIG. 2: Microstructure of a W—Ni sputtering target which is not according to the invention and contains 60% by weight of W, 40% by weight of Ni, etched using a solution composed of 85 ml of 25% strength NH.sub.4OH+5 ml of H.sub.2O.sub.2. Proportion by area of intermetallic phase 11.7%, proportion by area of W phase 29.2%, balance Ni(W).

(25) FIG. 3: Microstructure of a W—Ni sputtering target according to the invention containing 60% by weight of W, 40% by weight of Ni, etched using a solution composed of 85 ml of 25% strength NH.sub.4OH+5 ml of H.sub.2O.sub.2. No measurable proportion by area of intermetallic phase, proportion by area of W phase 29.5%, balance Ni(W).

(26) FIG. 4: X-ray diffraction pattern of a sample of a W—Ni sputtering target which is not according to the invention, proportions of intermetallic phase (Ni.sub.4W) greater than 10% (area).

(27) FIG. 5: X-ray diffraction pattern of a sample of a W—Ni sputtering target according to the invention, no proportions of intermetallic phase (Ni.sub.4W) detectable.

(28) For the evaluation of the diffraction patterns shown, the JCPDS cards 03-065-2673 (Ni.sub.4W), 00-004-0806 (W) and 03-065-4828 (Ni.sub.17W.sub.3, corresponding to Ni(W), W-saturated Ni mixed crystal) were used.