The purity of semiconductor tantalum target material is generally required to be above 3N(99.99%), such as 4N5 (99.995%) or 5N(99.999%)0, so the purity of high purity tantalum ingot used is above 4N (99.99%). In this embodiment, 4N5 (99.995%) tantalum ingot A is preferred. The high purity tantalum ingot A can be a cylinder with a diameter of 140mm ~ 160mm and a height of 85mm ~ 105mm, and its size is determined according to the preset size of the target material produced.
Compared with the prior art, the technical scheme has the following advantages: The preheated high purity tantalum ingot is forged at least twice, and after each forging, the high purity tantalum ingot is heat treated; The high purity tantalum ingot after the last heat treatment is extruded to form tantalum plate; The tantalum plate is processed hot, and the tantalum target blank is formed with compact structure, fine and uniform grains and no stratification phenomenon, which can meet the grain requirements and crystal direction requirements of tantalum target for semiconductor sputtering.
The temperature of each forging for at least two forging sessions is 500°C ~ 1000°C, the forging time is 10min ~ 20min, and the deformation rate is 50% ~ 80%. The original coarse dendritic grains and cylindrical grains are broken into fine grains, and the original segregation, porosity, porosity and slag inclusion in high purity tantalum ingots are compacted and welded. The structure becomes more compact and the plasticity and mechanical properties of high purity tantalum ingots are improved. By controlling the temperature and time of heat treatment after each forging, recrystallized grains after each forging are made to homogenize the grain structure after each forging.
Die extrusion under 500°C ~ 1000°C, the extrusion Angle of the die is 30 degrees ~ 70 degrees, the deformation rate generated by the extrusion of the die is 50% ~ 80%, can accurately control the molding size accuracy of tantalum board, can also obtain the grain size of 30 μm ~ 150 μm, Q00) dominant grain tantalum board, The dominant proportion is 20 % ~ 50 %. Preparation is made for producing tantalum target material conforming to the requirements of plastic deformation process. Hot processing of the tantalum board material, the temperature of the hot processing is 940°C ~ 960°C, and insulation 115min ~ 125min, can eliminate the residual stress inside the tantalum board after extrusion, stabilize the size, reduce the hardness and brittleness of tantalum board material, increase its plasticity, reduce the deformation and crack tendency in the subsequent process, The size of the extruded grains can be further reduced and the reduced grains can be further homogenized.
