Effects Of The Magnetic Field Unbalance Coefficient On Deposition Process Of Magnetron Sputtered Cr Coating

By changing the magnetic induction intensity of magnets in magnetrons, we had obtained seven magnetic field configurations which have different unbalance coefficient. We measured magnetic induction intensity on the target surface by Model 6010 Hall Effect Gauss/Tesla-Meter, and we had known about the distribution of magnetic field on the target surface. By analyzing the rectangular planar magnetron, we defined the unbalance coefficient of magnetic field, and calculated the unbalance coefficients of different magnetrons in our experiment. The chromium coatings were deposited on M42 high speed steels and Si wafers using different magnetrons, these coatings had been deposited at different substrate-placed position. We took two technics which have the different deposition times were 60 minutes and 180 minutes, respectively. The other deposition parameters are same. The microstructures of the coatings were analyzed by SEM, AFM and XRD. The thickness of the coatings were measured using a ball crater device and SEM, the hardness of the coatings were measured using a Vickers microhardness tester, the resistivity of coatings were measured using four-point probe method. The effects of unbalance coefficient of magnetic field on properties and microstructures of the coatings were investigated, and the mechanisms about these effects were also discussed in this paper.The investigative results indicated that the precondition is forming a closed magnetic field like a racetrack on target surface in magnetron sputtering system, and when the distribution of magnetic field on the target surface is uneven, maybe induce unstable microstructures of coatings, and reduce the hardness of coatings. The effects of magnetic field unbalance coefficient on deposition rates and microstructures of the coatings are great. With the increasing of magnetic field unbalance coefficient, the thickness of coatings are increased, deposition rates of magnetron sputtered coatings are quickened, and the grain size of coatings are decreased. The increase of magnetic field unbalance coefficient is propitious to deposited continuous coatings. When the distribution of magnetic field on the target surface is symmetrical, with the decreasing of magnetic field unbalance coefficient, the microhardness of coatings are decreased, and microstructures of the coatings became amorphous state from crystalline. The essential reason creating the effects of magnetic field unbalance coefficient on properties and microstructures of the coatings is the dissimilitude of plasma body density with the different magnetic field unbalance coefficient, which induces the dissimilitude of deposition particle density and bombardment of the ion. This dissimilitude was caused by the distribution of magnetic field in the working chamber of magnetron sputtering system.