Refractory tungsten metals and tungsten alloys have the advantages of high temperature stability, high resistance to electron migration and high electron emission coefficient. High-purity tungsten and tungsten alloy targets are mainly used to fabricate gate electrodes, connection wiring, diffusion barrier layers of semiconductor integrated circuits. They have very high requirements on purity, impurity element content, density, grain size and uniform grain structure of materials. Let’s take a look at the factors influencing the preparation of high-purity tungsten target by Rich Special Material Co.,Ltd.
I. Effect of Sintering Temperature
The forming process of tungsten target embryo is usually made by cold isostatic pressure. The tungsten grain will grow up during sintering. The growth of tungsten grain will fill the gap between the crystal boundaries, thus increasing the density of tungsten target. With the increase of sintering times, the density increase of tungsten target slows down gradually. The main reason is that the quality of tungsten target material has not changed much after several sintering processes. Because most of the voids in the crystal boundary are filled by tungsten crystals, the overall size change rate of tungsten target is very small after each sintering process, which results in limited space for tungsten target density to increase. As sintering proceeds, large tungsten grains are filled into the voids, resulting in a denser target with smaller size.
2. Effect of heat preservation Time
At the same sintering temperature, the compactness of tungsten target material is improved with the increase of sintering time. With the increase of sintering time, the tungsten grain size increases, and with the extension of sintering time, the grain size growth factor slows down gradually. This shows that increasing the sintering time can also improve the performance of tungsten target.
3. Effect of Rolling on Target Performance
In order to improve the density of tungsten target materials and obtain the processing structure of tungsten target materials, medium temperature rolling of tungsten target materials must be carried out below the recrystallization temperature. When the rolling temperature of target blank is high, the fiber structure of target blank is thicker, whereas that of target blank is finer. When the hot rolling yield is above 95%. Although the difference of fiber structure caused by different sintering original grain or rolling temperature will be eliminated, more homogeneous fiber structure will be formed inside the target, so the higher the processing rate of warm rolling, the better the performance of the target.
Post time: May-05-2022