Reactive high power impulse magnetron sputtering (HiPIMS) of a cobalt cathode in pure argon gas and with different oxygen admixtures was investigated by time-resolved optical emission spectroscopy and time-integrated energy-resolved mass spectrometry. The HiPIMS discharge was operated with a bipolar pulsed power supply capable of providing a large negative voltage with a typical pulse width of 100 micro-s followed by a long positive pulse with a pulse width of about 350 micro-s. The HiPIMS plasma in pure argon is dominated by Co+ ions. With the addition of oxygen, O+ ions become the most prominent positive ion species. Optical emission spectroscopy reveals the presence of Ar I, Co I, O I, and Ar II emission lines. The transition from an Ar+ to a Co+ ion sputtering discharge is inferred from time-resolved OES. The enhanced intensity of excited Ar+* is explained by simultaneous excitation and ionization induced by energetic secondary electrons from the cathode. The intensity of Ar I lines is drastically reduced during HiPIMS. Intensity of near-infrared Ar I lines resumes during the positive pulse indicating an additional heating mechanism.

中文翻译：

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具有钴靶的氩/氧气混合物中单极和双极脉冲磁控管溅射放电的时间分辨光发射光谱

通过时间分辨光学发射光谱法和时间积分能量分辨质谱法研究了在纯氩气和不同氧混合物中钴阴极的反应性高功率脉冲磁控溅射 (HiPIMS)。HiPIMS 放电使用双极脉冲电源进行操作，该电源能够提供典型脉冲宽度为 100 微秒的大负电压，然后是脉冲宽度约为 350 微秒的长正脉冲。纯氩气中的 HiPIMS 等离子体以 Co+ 离子为主。随着氧气的加入，O+ 离子成为最突出的正离子种类。光学发射光谱揭示了 Ar I、Co I、OI 和 Ar II 发射线的存在。从时间分辨 OES 推断从 Ar+ 到 Co+ 离子溅射放电的转变。增强的 Ar+* 强度可以通过来自阴极的高能二次电子引起的同时激发和电离来解释。在 HiPIMS 期间，Ar I 线的强度急剧降低。近红外 Ar I 线的强度在正脉冲期间恢复，表明存在额外的加热机制。