A review of metal-ion-flux-controlled growth of metastable TiAlN by HIPIMS/DCMS co-sputtering
A review of metal-ion-flux-controlled growth of metastable TiAlN by HIPIMS/DCMS co-sputtering
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DOI：
10.1016/j.surfcoat.2014.01.055
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发表时间：
2014-10-25
影响因子：
5.4
通讯作者：
Hultman, L.
中科院分区：
文献类型：
--
作者：
Greczynski, G.;Lu, J.;Hultman, L.
我们回顾了通过混合高功率脉冲和直流磁控共溅射 (HIPIMS/DCMS) 生长亚稳态 Ti1-xAlxN 合金薄膜的结果，该方法使用时域与整个 HIPIMS 脉冲同步或仅在混合 Ar/N-2 放电中的脉冲的富金属部分施加衬底偏压。根据 HIPIMS 提供动力的元素靶材（Ti 或 Al），由于生长表面入射的金属离子通量的电荷和质量差异，观察到明显不同的薄膜生长动力学路径。在 Al-HIPIMS/Ti-DCMS 期间，在 500 摄氏度下进行 Al+ 离子辐照，负衬底偏压 V-s = 60 V 与 HIPIMS 脉冲同步（从而抑制 DCMS 引起的 Ar+ 离子辐照），产生单相 NaCl 结构 Ti1-xAlxN 薄膜（x 30 GPa，x > 0.55）和低应力（0.2-0.8 GPa 压缩）。通过将基底偏压仅与 Al-HIPIMS 脉冲的富含金属离子的部分同步，可以进一步抑制 Ar+ 离子轰击，以利于主要的 Al+ 离子照射。与此形成鲜明对比的是，采用 Ti+/Ti2+ 金属离子辐照和相同的 HIPIMS 同步 V-s 值生长的 Ti-HIPIMS/Al-DCMSTi1-xAlxN 层是两相混合物，即 NaCl 结构 Ti1-xAlxN 加纤锌矿 AlN，表现出低硬度（类似于或等于 18 GPa）和高达 -3.5 GPa 的高压应力。在这两种情况下，薄膜特性均由转移到薄膜表面的每个沉积原子的平均金属离子动量控制。在 Ti-HIPIMS 过程中，生长的薄膜受到双电离 Ti2+ 的强烈通量的影响，而在 Al-HIPIMS 过程中 Al2+ 的照射微不足道。这种不对称性是决定性的，因为即使没有故意偏差，在 Ti-HIPIMS 过程中也很容易超过 w-AlN 沉淀的临界极限 135 eV-amu(1/2)。高 Ti2+ 离子通量主要是由于 Ti 的第二电离势 (IP2) 低于 Ar 的第一电离势 (IP1)。涉及从分段 TiAl 靶材进行亚稳态 Ti1-xAlxN 合金薄膜的 HIPIMS 生长的新结果与上述结论一致。 (C) 2014 Elsevier B.V. 保留所有权利。
We review results on the growth of metastable Ti1-xAlxN alloy films by hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS/DCMS) using the time domain to apply substrate bias either in synchronous with the entire HIPIMS pulse or just the metal-rich portion of the pulse in mixed Ar/N-2 discharges. Depending upon which elemental target, Ti or Al, is powered by HIPIMS, distinctly different film-growth kinetic pathways are observed due to charge and mass differences in the metal-ion fluxes incident at the growth surface. Al+ ion irradiation during Al-HIPIMS/Ti-DCMS at 500 degrees C, with a negative substrate bias V-s = 60 V synchronized to the HIPIMS pulse (thus suppressing Ar+ ion irradiation due to DCMS), leads to single-phase NaCl-structure Ti1-xAlxN films (x 30 GPa with x > 0.55) and low stress (0.2-0.8 GPa compressive). Ar+ ion bombardment can be further suppressed in favor of predominantly Al+ ion irradiation by synchronizing the substrate bias to only the metal-ion-rich portion of the Al-HIPIMS pulse. In distinct contrast Ti-HIPIMS/Al-DCMSTi1-xAlxN layers grown with Ti+/Ti2+ metal ion irradiation and the same HIPIMS-synchronized V-s value, are two-phase mixtures, NaCl-structure Ti1-xAlxN plus wurtzite AlN, exhibiting low hardness (similar or equal to 18 GPa) with high compressive stresses, up to -3.5 GPa. In both cases, film properties are controlled by the average metal-ion momentum per deposited atom transferred to the film surface. During Ti-HIPIMS, the growing film is subjected to an intense flux of doubly-ionized Ti2+, while Al2+ irradiation is insignificant during Al-HIPIMS. This asymmetry is decisive since the critical limit for precipitation of w-AlN, 135 [eV-amu](1/2), is easily exceeded during Ti-HIPIMS, even with no intentional bias. The high Ti2+ ion flux is primarily due to the second ionization potential (IP2) of Ti being lower than the first IP (IP1) of Ar. New results involving the HIPIMS growth of metastable Ti1-xAlxN alloy films from segmented TiAl targets are consistent with the above conclusions. (C) 2014 Elsevier B.V. All rights reserved.