| AVS 60th International Symposium and Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM-ThA |
| Session: | Materials and Process for Advanced Interconnects II |
| Presenter: | K.H. Lee, Samsung Electronics, Republic of Korea |
| Authors: | K.H. Lee, Samsung Electronics, Republic of Korea S.W. Kim, Samsung Electronics, Republic of Korea K.S. Lee, Samsung Electronics, Republic of Korea T.H. Kim, Samsung Electronics, Republic of Korea S.S. Lee, Samsung Electronics, Republic of Korea S.H. Kim, Samsung Electronics, Republic of Korea J.H. Won, Samsung Electronics, Republic of Korea |
| Correspondent: | Click to Email |
With the continuous scaling down of integrated circuits, the diameter of a contact plug decreases. This causes an increase of contact plug resistance, which is not desirable for high-speed transistor operation. Since metal Tungsten (W) has good filling capability and electrical properties, it has been widely used in semiconductor device area such as gate, metal contact, and via. Tungsten deposition process consists of two steps of nucleation which is for seed layer and bulk step that is for contact filling by CVD process. B2H6 based W nucleation layer technology has been widely used to realize low resistive W film. [1,2]
In this study, the effects of W-nucleation layer using a B2H6 gas as a reducing agent of WF6 gas on electrical properties of W-contact in sub 2x nm flash devices was investigated. CVD-W films using CVD reaction of WF6 and H2 gas were deposited on different thickness of nucleation layer. The resistivity of CVD-W film was not changed as thickness of nucleation layer increase because the thickness of nucleation layer is too thin to affect resistivity of CVD-W film. In order to decrease resistivity of CVD-W film, B2H6 treatment was carried out after nucleation process. It caused decrease of resistivity as B2H6 treatment cycle increased grain growth due to increase of grain size resulted from additional Boron atom. WF6 reacts with absorbed boron preferentially causing a formation of β –W phase of amorphous phase W film which decelerates the nucleation with α -phase W film formed by H2 reaction, which result in larger size grains and low resistive W film as B2H6 post-treatment cycle increases.
In addition, the resistivity of CVD-W deposited on three different thickness nucleation layers is not variable, which means the final grain size of CVD-W film is similar. The contact resistance increases (~12 %) when W nucleation cycle increases from x to x+4 cycles. In general, contact resistance on gate is associated with the resistivity of the total film stack related to final grain size. However, this result reveals that the resistivity of W nucleation layer also affects the contact resistance of CVD-W film although the resistivity of bulk-W film is dominant factor to define a contact resistance.
[ 1] A. Buerke et al., Material Research Society AMC XXI, p239 (2006).
[2] S. Smith et al., Microelectronic Engineering82, 261 (2005).