Usually the sputtering target has a polycrystalline structure, and the crystal grain size can be on the order of micrometers to millimeters. The smaller the grain size, the larger the grain boundary area and the greater the impact on performance. For the same sputtering target, the sputtering rate of the target with fine grains is faster than that of the target with coarse grains; while the thickness distribution of the sputtered film deposited by the target with smaller grain size difference (uniform distribution) Evenly. According to research findings, if the grain size of the titanium target is controlled below 100um and the change of the grain size is kept within 20%, the quality of the sputtered film can be greatly improved.
Three basic methods for sputtering target grain size testing
• Comparison method: The comparison method does not need to calculate the grain and intercept moment. Compared with the standard series of rating charts, there is generally a certain deviation (±0.5 grade) when evaluating the grain size by the comparison method. The reproducibility and reproducibility of the evaluation value is usually ±1 level.
• Area method: The area method is to calculate the number of grains in a known area, and use the number of grains per unit area to determine the number of grain size levels. As a function of the calculated grain size in the accuracy of this method, an accuracy of ±0.25 level can be achieved through reasonable counting. The measurement result of the area method is unbiased, and the reproducibility is less than ±0.5 grade. The key to the grain size of the area method is the count of grains that are clearly divided by the grain interface
• Cut-off point method: The cut-off point number is to calculate the cut-off point number of the intersecting part of the test line segment (or grid) of known length and the grain interface. The number of cut-off points per unit length is used to determine the grain size level. The accuracy of the intercept method is a function of the calculated number of intercepts or intercepts, and an accuracy of ±0.25 can be achieved through effective statistical results. The measurement results of the intercept method are unbiased, and the reproducibility and reproducibility are less than ±0.5 level. For the same level of accuracy, the intercept method does not require precise calibration of the intercept point or intercept number, so it is faster than the area method.
Specific case analysis of metallographic diagram of sputtering target grain size
• Determine the magnification of the photo
First measure the size of the microphotograph, choose one of length or width, and then measure the actual length or width of the sample
Magnification=picture distance/actual distance
• Find out the number of grain size levels
After calculating the magnification, the number of grain size levels can be determined. First, calculate the number of crystal grains in the sample.
The number of grains = the number of complete grains + 0.5 times the partial grains. The grain boundaries of the intact grains are all observable.
Secondly, calculate the actual area, actual area = picture length/magnification rate x width/magnification rate
According to the calculation formula in the ASTM standard: N=2 (n-1) where N refers to the number of crystal grains per square inch under a magnification of 100 times, and n refers to the number of crystal grain levels. The value of N can be obtained after unit conversion. Finally, the number of grain levels n can be calculated.
• Calculate the average grain diameter
Average grain diameter = actual length of the sample / number of grains in the intercepted part
Actual length=Cut length/magnification
The above describes the effect of the sputtering target's grain size on the performance of the target. Let's briefly talk about the process. The crystal orientation requires the performance of the sputtering target. During sputtering, the target atoms are easy to follow the direction of the hexagonal packing of atoms. Sputtering, therefore, in order to achieve a high sputtering rate, the sputtering rate can be increased by changing the crystalline structure of the target. Different materials have different crystalline structures, so different molding methods and heat treatment methods should be used.Xinkang New Material Co., Ltd.
exports to the world and has the world's leading heat treatment technology. It has been pre-hardened to 45-48HRC and 29-33HRC before leaving the factory. The advanced sputtering target production quality control system of Material Co., Ltd. reduces the time and risk of heat treatment for customers.