Investigation of etching properties of HfO based high-Kdielectrics using inductively coupled plasma

Abstract

The etching properties of HfO based high dielectric constant (K) films, HfO2, HfON, HfSiO, and HfAlO, were investigated using inductively coupled plasma of Cl2/HBr/CHF3/CF4/O2. The etch rates varied depending on the chemical components in the films. Among HfO2, HfON, HfSiO, and HfAlO, the etch rates of HfSiO increased most significantly with increasing radio frequency bias power. This may be attributed to the ternary network of Hf–Si–O that is different from the binary network of other films of Hf–O, Hf–N, Si–O, and Al–O. The etch rates of HfON were higher than those of HfO2 due to the effect of the high Hf–N etch rates compared to the Hf–O etch rates, whereas the HfAlO etch rates were lower than those of HfO2 due to the effect of the low Al–O etch rates. Etch residues and chemical compositions of HfO based dielectrics were analyzed by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. A significant amount of fluorides existed on the surface after CF4/CHF3 etching whereas only a small amount of chloride and bromide existed after Cl2/HBr etching. The high temperature post-treatment step was effective in reducing the amount of residues.

Selective Etching of High-kDielectric HfO2Films over Si in BCl3-Containing Plasmas without rf Biasing

“…1,2) For the integration of high-k dielectric materials in device fabrication, highly selective etching over underlying Si is indispensable for their removal prior to forming source and drain contacts. Plasma etching of high-k dielectrics has used not only chlorine-based gases such as Cl 2 , 3,4) BCl 3 , [5][6][7][8] BCl 3 / Cl 2 , [5][6][7][8] and Cl 2 /HBr, 9,10) but also fluorine-based gases such as SF 6 , 4) CF 4 , 9,10) and CHF 3 . 10,11) However, the etch selectivity for high-k/Si was not so high (often up to 3 -5), due to the highly volatile halogen compounds of Si, and also to the strong metal-oxygen bonds of high-k dielectrics and less volatile metal-halogen compounds.…”

Modeling of Gate Stack Patterning for Advanced Technology Nodes: A Review

“…Fluorine based chemistries have been shown to reach satisfactory selectivity and etch rates [131], although CF based chemistries form thick fluorocarbon layers, requiring an additional cleaning step after etching, which is not the case for SF chemistries [132]. The thickness of these layers could be reduced by adding hydrogen, which removes carbon from the surface via loosely bound hydrocarbon etch products [133], although even these fewer fluorocarbon residues on the substrate still present a problem [134].…”

Dry Etching of Metal Inserted Poly-Si Stack for Dual High-k and Dual Metal Gate Integration

“…The reasons are as follows: (1) more isotropic SF 6 etching could get the same vertical profile under lower power, which could improve the selectivity to the underlying high-k dielectric. 12 (2) SF 6 gas has a better selectivity to the high-k dielectric due to its lower volatile products HfF x . 13 Fig.…”