Impact of nitrogen depth profiles on the electrical properties of crystalline high-K gate dielectrics

• Published in: Applied surface science Vol. 324; pp. 662 - 668
• Main Authors: Huang, Jhih-Jie, Tsai, Yi-Jen, Tsai, Meng-Chen, Huang, Li-Tien, Lee, Min-Hung, Chen, Miin-Jang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2015
• Subjects: Atomic layer deposition; Capacitance; Crystal structure; Density; Dielectrics; Doping; Gates; High-K gate dielectrics; In-situ atomic layer doping; Oxides; Post-deposition nitridation; Zirconium dioxide; Zirconium oxide; High-K gate dielectrics; Zirconium oxide; Atomic layer deposition; In-situ atomic layer doping; Post-deposition nitridation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.11.009

•The in-situ atomic layer doping of nitrogen and post-deposition nitridation using remote NH3 plasma was used to incorporate nitrogen into the crystalline ZrO2 gate dielectrics at a low temperature..•The impact of nitrogen depth profiles on the electrical properties of crystalline high-K gate oxides was investigated.•The CET was reduced from 1.55nm to 1.13nm and Jg was suppressed up to two orders of magnitude by the post-deposition nitridation.•Post-deposition nitridation contributes to higher nitrogen concentration at the top surface of ZrO2, leading to enhancement of the resistance to oxygen diffusion toward the interface and restrain the IL growth during the thermal treatment.•A low CET of 1.13nm with a suppressed Jg of 1.35×10−5A/cm2 was realized in the crystalline ZrO2 gate oxide treated with the post-deposition nitridation. The electrical characteristics of crystalline ZrO2 gate dielectrics with different nitrogen depth profiles were investigated, which were treated by the in-situ atomic layer doping of nitrogen and post-deposition nitridation processes, respectively, using remote NH3 plasma at a low treatment temperature of 250°C. The crystalline ZrO2 gate dielectric of the tetragonal/cubic phase was formed by post-metallization annealing (PMA) at a low temperature of 450°C, resulting in an increase of the dielectric constant. As compared with the in-situ atomic layer doping of nitrogen, the post-deposition nitrogen process leads to a lower capacitance equivalent thickness of 1.13nm with a low leakage current density of 1.35×10−5A/cm2. The enhanced capacitance density caused by the post-deposition nitrogen treatment may be ascribed to the high nitrogen concentration at the top surface of gate dielectric, giving rise to the suppression of oxygen diffusion from the ambient toward the interface and so a thinner interfacial layer. The result reveals that the nitrogen incorporation at the top surface of gate oxide is favorable to the scaling of crystalline high-K gate dielectrics.