AVS 45th International Symposium
    Electronic Materials and Processing Division Thursday Sessions
       Session EM+PS-ThM

Paper EM+PS-ThM9
The High Temperature Platinum Etching Using Titanium Layer

Thursday, November 5, 1998, 11:00 am, Room 314/315

Session: Processing of High K Dielectrics for DRAMs
Presenter: H.-W. Kim, Samsung Electronics, Co., Korea
Authors: H.-W. Kim, Samsung Electronics, Co., Korea
B. Ju, Samsung Electronics, Co., Korea
B. Nam, Samsung Electronics, Co., Korea
W. Yoo, Samsung Electronics, Co., Korea
C.J. Kang, Samsung Electronics, Co., Korea
T.-H. Ahn, Samsung Electronics, Co., Korea
J. Moon, Samsung Electronics, Co., Korea
M.Y. Lee, Samsung Electronics, Co., Korea
Correspondent: Click to Email
1. Introduction: It is necessary to use the platinum as a bottom electrode material of the BST capacitor in highly integrated deveces, however, the Pt etching of the fine patterns is difficult due to the inherent non-reactivity of platinum. It is revealed that the Pt etch slope of 80° was attained by O@sub 2@/Cl@sub 2@ chemistry by elevating the substrate temperature up to 160°C. This result is thought to be due to the reaction of O species with Ti layer and analyzed by TEM, XPS and AES. 2. Experimental & Results: As an experimental setup for high temperature etching, the modified chiller using Galden HS260 (B.P.=270°C) was chosen. The oxide 5000Å/ Ti600Å/ Pt 2000Å structure was used and the O@sub 2@/Cl@sub 2@ (O@sub 2@ = 80%) gas was chosen as an etchant combination in MERIE system. The change of the Pt etching profile at 100°C, 130°C, 160°C, respectively was investigated.The Pt etch slope does not depend on the substrate temperature up to the just etch time, the etch slope of the 160°C-sample was about 80° after 100% overetch and the Ti mask was not eroded significantly. It appeared that the titanium mask of 100°C, 130°C samples were eroded considerably, The Pt etching results of 160°C with Ti, TiN and TiO@sub 2@ layer were compared (not shown). TiN and TiO@sub 2@ layer does not help attaining high Pt etch slope even with the thermal heating. From the above result, it is surmised that the change or stabilization of Ti layer through the reaction/diffusion of O atoms during plasma etching plays a major role in attaining the higher Pt etching slope. From the XTEM investigation of the 160°C-etched one, the center of the Ti layer stays crystalline, however, the edge of the Ti layer became amorphous and the oxygen content increased up to more than 50%, by EDX analysis. The XPS analysis of 100-Ti layer showed that the considerable amount of Ti-Ti bond changed to the Ti-O bond during the O@sub 2@/Cl@sub 2@ plasma treatment. The AES analysis confirmed the above phenomena. 3. Conclusions: The etching slope of Pt was improved by the reaction of the mask material with the etching species, not by the reaction of Pt itself. The optimal overetching helps to attain the higher etch slope as long as the Ti mask stays. High temperature processing helped the duration of the titanium mask by activating the reaction of Ti with O-species.