In high power impulse magnetron sputtering (HiPIMS) operation, there are basically two goals: a high ionized flux fraction of the sputtered target material and a high deposition rate. In this work, it is demonstrated that the former always comes at the cost of the latter. This makes a choice necessary, referred to as the HiPIMS compromise. It is here proposed that this compromise is most easily made by varying the discharge current amplitude, which opens up for optimization of additionally four external process parameters: the pulse length, the working gas pressure, the magnetic field strength, and the degree of magnetic unbalance to achieve the optimum combination of the ionized flux fraction and the deposition rate. As a figure of merit, useful for comparing different discharges, $(1-{\beta }_{\mathrm{t}})$ is identified, which is the fraction of ionized sputtered material that escapes back-attraction toward the cathode target. It is shown that a discharge with a higher value of $(1-{\beta }_{\mathrm{t}})$ always can be arranged to give better combinations of ionization and deposition rate than a discharge with a lower $(1-{\beta }_{\mathrm{t}})$. Maximization of $(1-{\beta }_{\mathrm{t}})$ is carried out empirically, based on data from two discharges with Ti targets in Ar working gas. These discharges were first modeled in order to convert measured plasma parameters to values of $(1-{\beta }_{\mathrm{t}})$. The combined effects of varying the different process parameters were then analyzed using a process flow chart model. The effect of varying the degree of unbalance in the studied range was small. For the remaining three parameters, it is found that optimum is achieved by minimizing the magnetic field strength, minimizing the working gas pressure, and minimizing the pulse length as far as compatible with the requirement to ignite and maintain a stable discharge.

中文翻译：

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HiPIMS放电的优化：脉冲功率，脉冲长度，气压和磁场强度的选择

在高功率脉冲磁控溅射（HiPIMS）操作中，基本上有两个目标：溅射靶材料的高电离通量分数和高沉积速率。在这项工作中，证明了前者总是以后者为代价的。这使选择成为必要，这被称为HiPIMS折衷方案。在此建议，通过改变放电电流幅度最容易做出这种折衷，这为优化另外四个外部过程参数打开了机会：脉冲长度，工作气体压力，磁场强度和磁不平衡度以实现离子通量分数和沉积速率的最佳组合。作为优点，对于比较不同的放电非常有用，$（\mathrm{1个}-{\beta }_{\mathrm{Ť}}）$标识为“离子化溅射材料的一部分”，该部分溅射材料逃逸回吸引向阴极靶。结果表明，具有较高值的​​放电$（\mathrm{1个}-{\beta }_{\mathrm{Ť}}）$ 总是可以安排得比低放电的电离和沉积速率更好的组合 $（\mathrm{1个}-{\beta }_{\mathrm{Ť}}）$。最大化$（\mathrm{1个}-{\beta }_{\mathrm{Ť}}）$基于Ar工作气体中两次以Ti为靶的放电所产生的数据，根据经验进行分析。首先对这些放电建模，以便将测得的血浆参数转换为$（\mathrm{1个}-{\beta }_{\mathrm{Ť}}）$。然后使用过程流程图模型分析改变不同过程参数的综合效果。在研究范围内改变不平衡程度的影响很小。对于其余的三个参数，发现通过使磁场强度最小，工作气体压力最小以及脉冲长度最小，从而达到与点燃和保持稳定放电的要求相称的最佳效果。