(380e) Ion-Enhanced Plasma Etching of Metal Oxides in Chlorine Based Plasmas
AIChE Annual Meeting
2005
2005 Annual Meeting
Materials Engineering and Sciences Division
Thin Film Processing
Wednesday, November 2, 2005 - 1:42pm to 2:00pm
The development of plasma etching chemistries is necessary to pattern new gate dielectric materials, such as hafnium based oxides, for sub-65nm complementary metal oxide semiconductor (CMOS) devices. An electron cyclotron resonance high density plasma reactor is used in this work to study the etching of metal oxides and their corresponding metals in chlorine based chemistries. The plasma density, electron temperature, and gas phase species are characterized by a Langmuir probe, an optical emission spectrometer, and a quadrupole mass spectrometer. The etching of Al2O3, SiO2, and HfO2 was first studied in Cl2 and BCl3 plasmas, to allow for studies of the etching of hafnium aluminate, Hf1-x-yAlxOy, and hafnium silicate, Hf1-x-ySixOy, with well controlled and varying compositions of Al and Si in HfO2. The dominant etch products of Al and Hf metals in Cl2 and BCl3 plasmas were metal chlorides and metal boron-oxy-chlorides, respectively. These results enabled the assessment of the effect of metal-oxygen bond strength on the surface etching reactions, as well as the oxygen removal mechanism in the etching of metal oxides. The etch rates of hafnium aluminates were found to increase with the square root of ion energy, and the surface chlorination was enhanced with increasing ion energy, demonstrating that the etching reaction is limited by the momentum transfer from the ions to the film surface. The etching selectivity of Hf1-x-yAlxOy and Hf1-x-ySixOy to Si in Cl2 and BCl3 plasmas will be presented, with a focus on the effect of increasing concentrations of Al and Si, and how the etch rates compare to the etching of Al2O3, SiO2, and HfO2 individually. Finally, the application of a generalized model, developed for the etching of ZrO2 and HfO2, to the etching of Hf1-x-yAlxOy and Hf1-x-ySixOy in chlorine based plasmas will be discussed.