Chemical Vapor Deposition of Tungsten and Tungsten Silicides for VLSI/ ULSI Applications

1. Introduction
1.1 Scaling down
1.2 Electrical contacts
1.3 Device reliability
1.4 Contact planarization and design rules

2. The Blanket Tungsten Approach
2.1 Principal steps
2.2 Tungsten adhesion
2.3 Blanket deposition of tungsten
2.4 Etch back of blanket tungsten
2.5 Degree of planarization and the contact diameter
2.6 Blanket tungsten material characterization

3. The Selective Tungsten Approach
3.1 Principal steps
3.2 Types of substrates
3.3 Types of dielectric layers
3.4 Chemistry of selective tungsten
3.5 Mechanisms of selectivity loss
3.6 Electrical characterization

4. Blanket Versus Selective Tungsten
4.1 Feasibility of selective and blanket contact or via fill
4.2 Costs of the contact/via fill process
4.3 World wide status of CVD of tungsten
4.4 Conclusion

5. Tungsten as Interconnect Material
5.1 Weaknesses of aluminum internconnects
5.2 Tungsten interconnects
5.3 Issues of tungsten interconnects

6. The Chemistry of CVD-W and Properties of Tungsten
6.1 CVD tungsten source material
6.2 Experimental deposition rate relations obtained for the H2/WF6 chemistry
6.3 Some properties of tungsten
6.4 Contamination issues in CVD-W

7. The Deposition Equipment
7.1 Hot wall reactors
7.2 Cold wall reactors
7.3 Industrial reactors
7.4 Future reactor developments

8. Miscellaneous
8.1 Tungsten gates
8.2 Selective growth on implanted oxide
8.3 Buried tungsten
8.4 Alternative deposition techniques
8.5 Alternative plug processes

9. Chemical Vapor Deposition of Tungsten Silicide
9.1 Introduction
9.2 WSix for polycide applications
9.3 Silicide deposition methods
9.4 CVD of WSix
9.5 CVD-WSix based on SiH4/WF6 chemistry
9.6 WSix based on SiH2Cl2/WF6 chemistry
9.7 Fluorine content in CVD-WSix films
9.8 Stress in CVD-WSix films
9.9 Step coverage of CVD-WSix films
9.10 Conclusions
References
Author Index
Subject Index
Appendix: Unit Cells of W and WSi2