Molybdenum tubular sputtering targets with uniform grain size and texture
View Patent ↗Molybdenum, sputtering targets and sintering characterized as having no or minimal texture banding or through thickness gradient. The molybdenum sputtering targets having a fine, uniform grain size as well as uniform texture, are high purity and can be micro-alloyed to improved performance. The sputtering targets can be round discs, square, rectangular or tubular and can be sputtered to form thin films on substrates. By using a segment-forming method, the size of the sputtering target can be up to 6 m×5.5 m. The thin films can be used in electronic components such as Thin Film Transistor-Liquid Crystal Displays, Plasma Display Panels, Organic Light Emitting Diodes, Inorganic Light Emitting Diode Displays, Field Emitting Displays, solar cells, sensors, semiconductor devices, and gate device for CMOS (complementary metal oxide semiconductor) with tunable work functions.
1. A method of making a tubular sputtering target comprising:
A) placing molybdenum powder in a mold and pressing the powder at a pressure of from 32 to 40 ksi and sintering the pressed piece at a temperature of from 1785 to 2175° C. to form a billet;
B) removing the center of the billet to form a tubular billet having an inner diameter ID I and an outer diameter OD I ;
C) working the tubular billet to form a worked billet having an inner diameter ID and an outer diameter OD f such that the ratio of OD I to OD f is at least 3:1; and
D) heat treating the tubular billet at a temperature of from 815 to 1375° C.
2. The method target according to claim 1 , wherein the pressing in A) is performed isostatically.
3. The method according to claim 1 , wherein the powder in A) is sintered in hydrogen.
4. The method according to claim 1 , wherein the working in C) comprises extruding the tubular billet at a temperature of from 925 to 1260° C.
5. The method according to claim 1 , wherein the working in C) comprises rotary forging the tubular billet.
6. The method according to claim 1 , wherein after heat treating in D), the sputtering target is completely recrystallized and strain-free.
7. The method according to claim 1 , wherein the sputtering target texture is uniform and 110 parallel to the longitudinal direction and 111 relative to the radial direction.
8. The method according to claim 1 , wherein the heat treatment in D) is carried out at from 1250 to 1375° C.
9. The method according to claim 1 , wherein the heat treatment in D) is carried out at from 815 to 960° C.
10. A tubular-shaped sputtering target comprising molybdenum having a uniform texture, which is a 110 orientation parallel to the longitudinal direction and a 111 orientation relative to the radial direction.