Deposited oxides of silicon are used for a wide variety of purposes in integrated circuit technology; two of the most important being as interlevel dielectrics and for passivation purposes. It is important to characterize oxides deposited by newer techniques like electron cyclotron resonance (ECR), plasma enhanced (PE) chemical vapor deposition (CVD), and sputtering of quartz for these purposes. In this article, we studied ECR oxides and sputtered quartz oxides to correlate their mechanical behavior to the hydrogenous species concentration. Sputtered quartz oxides were chosen as they are not known to have hydrogenous species concentration, and hence would serve as a comparison tool for ECR oxides which are known to have significant H content. Si-rich ECR oxides were found to have significant hydrogenous species content while near-stoichiometric ECR oxides had low bulk H content (as seen from nuclear reaction analyses). The hydrogenous species was identified from Fourier transform infrared spectroscopy to be Si:H. In these oxides, the stress-temperature behavior is directly related to the H content, with oxides high in hydrogenous species concentration ending up more tensile after thermal cycling. Realizing that these oxides are Si-rich, the above observation indicates that these oxides have oxygen vacancies (as opposed to Si interstitials). In order to achieve stable stress-temperature behavior (i.e., linear, and without hysteresis during thermal cycling), these oxides have to be annealed at temperatures greater than 700°C. Sputtered quartz oxides exhibit stable stress-temperature behavior up to 600°C.
ASJC Scopus subject areas
- General Physics and Astronomy