US 7,484,546 B2
Sputtering target for phase-change memory, film for phase change memory formed by using the target, and method for producing the target
Masataka Yahagi, Ibaraki (Japan); Yuichiro Shindo, Ibaraki (Japan); and Hideo Takami, Ibaraki (Japan)
Assigned to Nippon Mining & Metals Co., Ltd., Tokyo (Japan)
Filed on Sep. 21, 2006, as Appl. No. 11/533,945.
Application 11/533945 is a division of application No. 10/504739, granted, now 7,156,964, previously published as PCT/JP02/12739, filed on Dec. 05, 2002.
Claims priority of application No. 2002-047370 (JP), filed on Feb. 25, 2002.
Prior Publication US 2007/0062808 A1, Mar. 22, 2007
Int. Cl. B22D 7/00 (2006.01); B22D 27/00 (2006.01)
U.S. Cl. 164—55.1  [164/76.1] 17 Claims
 
1. A method of manufacturing a sputtering target for use in forming a phase change memory film, comprising the steps of melting and casting a raw material in a vacuum or under a hermetically sealed inert gas atmosphere to form an ingot pulverizing the ingot to form a powder, and hot pressing the powder to form said sputtering target such that the sputtering target is composed from elements of not less than a three component system and one or more principal components selected from a group consisting of stibium, tellurium and selenium, said target has a compositional deviation in relation to an intended composition of ±1.0 at % or less, an average crystal grain size of 50 μm or less and a relative density of 90% or more; said target having a purity, excluding gas components, of 99.995 wt. % or more, and a total amount of carbon, nitrogen, oxygen and sulfur, which are gas components, of 700 ppm or less and said target has an average value of composition Ai (wt %) of respective constituent elements of said target, excluding the one or more principal components, in each of two or more samples (i =2, 3, 4 . . . ) collected from an arbitrary location within said target of A(wt %), |A−Ai|≤0.15.