SEMICONDUCTOR APPLICATIONS

Link From Titanium Target Orientation to Titanium/Titanium Nitride/Aluminum Thin Film Orientations

Chi-Fung Lo, Shailesh Kulkarni, Rajan Mathew, Paul S. Gilman, and Hidemasa Tamura
Praxair Materials Research, Orangeburg, NY, USA

Executive Summary

By controlling the grain orientation of Ti targets, the correlation of orientation between the targets and the sequentially deposited Ti films, TiN films and Al films was established. In this study, two 12 inch diameter Ti targets, one had strong (103) orientation, ~58%, and another was more random in the grain orientation. The results revealed that, the grain orientations of the sequentially deposited Ti, TiN and Al films were similar between the (103) and the randomly oriented target depositions, indicating that the target orientation has no significant effect on the film orientation for the Ti/TiN/Al film formations.

Extended Abstract

The (111) is the desired orientation for the aluminum multilevel metal interconnect used in the CMOS devices. This orientation contributes a better reliability to the interconnects. Previous studies showed that the aluminum thin film orientation was dominated by the orientation of the underlying Ti or TiN thin film layers. Strong (002) in Ti or (111) in TiN contributes a strong (111) in aluminum. All these studies correlated the deposition parameters and thin film properties. The current study, however, tries to understand if the titanium target structure, especially the grain orientation, may influence the development of Ti and TiN thin film orientations, which further affect the orientation of the Al film. In this study, two 12" diameter Ti targets with different orientations, one was dominated by (103), another was randomly oriented, on the sputtering surface were manufactured by controlling the target forming process. The two targets together with one 12" diameter Al-0.5Cu target were then sputtered using an Enduraä sputtering machine to form Ti(400Å), Ti(400Å)/TiN(1000Å) and Ti(400Å)/ TiN(1000Å)/Al (5000Å) films. The sputtering parameters for the film depositions are listed in Table 1. The X-ray diffraction results, Figures 1 and 2, reveal that both the two targets form the (002) dominant Ti films. In addition, the subsequently deposited TiN and Al films have near 100% in the (111) orientation. It is concluded that the deposited Ti/TiN/Al film orientations is independent of the Ti target orientation.

Table 1. The Sputtering Parameters for Film Depositions
Ti- 400Å: 3.0 kw, 16 sec, 20°C, 50 sccm Ar, 2.6 mT

TiN-1000Å:

6.5 kw, 59 sec, 20°C, 82 sccm N2/10 sccmAr, 3.67 mT

Al/0.5%Cu-5000Å:

10.6 kw, 32 sec, 300°C, 18C/15H Ar, 2.0mT



Figure 1:
The orientation of the (103) oriented Ti target and the sequentially deposited Ti/TiN/Al films.



Figure 2:
The orientation of randomly oriented Ti target and the sequentially deposited Ti/TiN/Al films.

   
 

CCH Process
CCH Do Aluminum Alloys
CCH Do and Do* Ti
Co and Ni
Ta and Cu

Thin Films Application Lab
Bonding Technology
Novellus Inova™ Tool
Endura™ & Centura™ Systems
RE-Al PLUS": Sputter Targets
Technical Papers  
  1. Reduction of TiN Nodule Density Through Optimization of Cathode and Process Variables
  2. Effect of Oxygen Content on Particle Generation in TiN Reactive Sputtering
  3. Link From Titanium Target Orientation to Titanium/Titanium Nitride/Aluminum Thin Film Orientations
  4. Technical Papers Available in PDF