Repeated compressive stress increase with 400 [degree]C thermal cycling in tantalum thin films due to increases in the oxygen content
- IBM Research Division, Thomas J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598 (United States)
Stresses which build up in thin films such as tantalum, during thermal processing, can cause major reliability problems in electronic and x-ray optics applications. We demonstrate that 50--200 nm thick sputtered [beta]-Ta thin films undergo repeated compressive stress increases when thermally cycled to 400 [degree]C (at a rate of 10 [degree]C/min) and back in a purified He ambient because of small amounts of oxygen gettered by the tantalum. The oxygen contamination results from the poor quality of the atmospheric seal on the quartz annealing chamber. As-deposited Ta thin films have a compressive stress ranging from [minus]1 to [minus]4 GPa. The compressive stress buildup was monitored [ital in] [ital situ] and was shown to increase [minus]0.5 GPa on average after each thermal cycle for a final value from [minus]6 to [minus]7 GPa after seven cycles. After being cycled thermally seven times any perturbation of the film such as a four-point probe resistivity measurement can cause the film to instantaneously crack in a serpentine pattern, relieving the large compressive stress. Auger electron spectroscopy depth profiling analysis was used to determine that the as-deposited film contained 1 at. % oxygen which increased to 8%--12% after seven thermal cycles with an approximate doubling in resistivity. The [minus]0.5 GPa average compressive stress increase in Ta thin films when cycled to 400 [degree]C is attributed to a 1.3% increase in oxygen concentration leading to a Ta unit cell expansion of 0.6%.
- OSTI ID:
- 6654706
- Journal Information:
- Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Vol. 12:4; ISSN 0734-211X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Stress and stability of sputter deposited A-15 and bcc crystal structure tungsten thin films
Electrical and mechanical properties of ferroelectric thin films laser ablated from a Pb{sub 0.97}Nd{sub 0.02}(Zr{sub 0.55}Ti{sub 0.45})O{sub 3} target
Related Subjects
TANTALUM
THIN FILMS
STRESSES
CRACKING
OXYGEN ADDITIONS
SPUTTERING
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THERMAL CYCLING
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
FILMS
METALS
PYROLYSIS
TEMPERATURE RANGE
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
360103* - Metals & Alloys- Mechanical Properties