Paper PS-TuP3
Etch Characteristics of HfAlO₃ Thin Films in High Density Plasma

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

With the permanent scaling down of complementary metal oxide semiconductor (CMOS) devices, the thickness of the gate oxide is expected to be reduced to less than 1 nm for the 45 nm and 32 nm technology nodes. Continuing to reduce the gate insulator thickness using SiO₂ is problematic as gate leakage current due to direct-tunneling increase.^1-2 One solution to the problem is the replacement of SiO₂ by high-k material. HfAlO₃ have arisen as a promising material for gate oxide replacement due to their high dielectric constant, bandgap, and recrystallization temperature. Therefore, a further on the study of HfAlO₃ thin films is needed.³

In this work, HfAlO₃ thin films were etched in BCl₃/He plasma. The etching characteristics of HfAlO₃ thin films were investigated in terms of etch rates and selectivity as a function of gas mixing ratio, RF power, DC bias voltage, and chamber pressure. The total flow rate of BCl₃/He was fixed at 20 sccm. The other parameters were varied as follows; RF power = 400 ~ 600 W, DC-bias voltage = - 50 ~ - 200 V, process pressure = 1 Pa ~ 3 Pa. The plasma diagnosis was characterized by optical emission spectroscopy (OES) analysis. The chemical reaction on the surface of the etched the HfAlO₃ thin films was investigated with X-ray photoelectron spectroscopy (XPS). Field emission scanning electron microscopy (FE-SEM) was used to investigate the etching profile.

Refernce

¹G. D. Wilk, E. M. Wallace, J. M. Anthony. J. Appl. Phys. 89, 5243 (2001).

²A. I. Kingon, J. I. Maria, S. K. Streiffer, Nature 406, 1032 (2000).

³W. J. Zhu, T. Tamagawa, M. Gibson, T. Kurukawa, and T. P. Ma. IEEE Electron Device Letters 23, 649 (2002).