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Insight into the removal and reapplication of small inhibitor molecules during area-selective atomic layer deposition of SiO2
Journal of Vacuum Science & Technology A ( IF 2.9 ) Pub Date : 2020-12-04 , DOI: 10.1116/6.0000652
Marc J. M. Merkx 1 , Rick G. J. Jongen 1 , Alfredo Mameli 1 , Paul C. Lemaire 2 , Kashish Sharma 2 , Dennis M. Hausmann 2 , Wilhelmus M. M. Kessels 1 , Adriaan J. M. Mackus 1
Affiliation  

As the semiconductor industry progresses toward more complex multilayered devices with ever smaller features, accurately aligning these layers with respect to each other has become a bottleneck in the advancement to smaller transistor nodes. To avoid alignment issues, area-selective atomic layer deposition (ALD) can be employed to deposit material in a self-aligned fashion. Previously, we demonstrated area-selective ALD of SiO2 using three-step (i.e., ABC-type) ALD cycles comprising an acetylacetone (Hacac) dose (step A), a bis(diethylamino)silane precursor dose (step B), and an O2 plasma exposure (step C). In this work, the mechanisms of the removal and reapplication of the inhibitor molecules during area-selective ALD were studied, with the aim of enhancing the selectivity of the process. In situ infrared spectroscopy shows that the O2 plasma exposure does not completely remove the adsorbed Hacac species (i.e., acac adsorbates) at the end of the cycle. The persisting species were found to contain fragments of Hacac molecules, which hinder subsequent inhibitor adsorption in the next ALD cycle, and thereby contribute to a loss in selectivity. Alternatively, it was found that an H2 plasma is able to completely remove all acac species from the surface. An improvement in selectivity was achieved by using a four-step ALD cycle that includes an H2 plasma step, allowing the nucleation delay to be prolonged from 18 ± 2 to 30 ± 3 ALD cycles. As a result, 2.7 ± 0.3 nm SiO2 can be deposited with a selectivity of 0.9, whereas only 1.6 ± 0.2 nm can be achieved without the H2 plasma step. This work shows that the addition of a dedicated inhibitor removal step before the reapplication of the inhibitors can significantly improve the selectivity.

中文翻译:

洞悉SiO2区域选择性原子层沉积过程中小抑制剂分子的去除和重新应用

随着半导体工业向具有更小特征的更复杂的多层器件发展,使这些层相对于彼此精确对准已经成为向较小的晶体管节点发展的瓶颈。为了避免对准问题,可以采用区域选择性原子层沉积(ALD)以自对准的方式沉积材料。之前,我们使用三步(ABC型)ALD循环演示了SiO 2的区域选择性ALD循环,包括乙酰丙酮(Hacac)剂量(步骤A),双(二乙基氨基)硅烷前体剂量(步骤B)和O 2等离子体暴露(步骤C)。在这项工作中,研究了在区域选择性ALD过程中抑制剂分子的去除和再施加机理,目的是提高工艺的选择性。原位红外光谱显示,在循环结束时,暴露于O 2的等离子体并未完全去除吸附的Hacac物质(即acac被吸附物)。发现该持久存在的物种包含Hacac分子的片段,这阻碍了随后的抑制剂在下一个ALD循环中的吸附,从而导致选择性的损失。另外,发现H 2等离子体能够从表面完全清除所有acac物质。通过使用包括H 2等离子体步骤的四步ALD循环,可以提高选择性,从而将成核延迟从18±2延长到30±3 ALD循环。结果,可以以0.9的选择性沉积2.7±0.3nm的SiO 2,而没有H 2等离子体步骤仅可以实现1.6±0.2nm 。这项工作表明,在重新使用抑制剂之前添加专用的抑制剂去除步骤可以显着提高选择性。
更新日期:2021-01-08
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