| 摘要 |
PROBLEM TO BE SOLVED: To reduce particles and sheet resistance value at the time of sputtering and to increase the productivity and yield by controlling the average grain size of the recrystallized crystals in a recrystallized sheet obtd. by subjecting a W/Mo alloy rolled sheet or a W rolling stock to heat treatment to the value equal to or below a specified one. SOLUTION: A W ingot sintered in hydrogen is rolled at about 1300 to 1600 deg.C in such a manner that it is not recrystallized to form into a W sheet. In this way, the W sheet having about 99.9% relative density can be obtd. This sheet is moreover subjected to heat treatment for about 30 min in a furnace heated at about 1700 to 1800 deg.C and is recrystallized. The obtd. recrystallized grains have uniform grain size, and the average grain size thereof is <=100μm. Furthermore, in the containing gas used, the content of oxygen is controlled to 10 ppm, nitrogen to <10 ppm, and the total is controlled to <=100 ppm. By a target for sputtering using this W sheet, the sheet resistance value of the formed W film remarkably reduces. The generating frequency of foreign matters (particles) generated at the time of film formation exceedingly reduces as well.
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