Study of pulsed RF DPN process parameters for 65 nm node MOSFET gate dielectrics
- PDF / 75,070 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 35 Downloads / 306 Views
D2.10.1
Study of pulsed RF DPN process parameters for 65 nm node MOSFET gate dielectrics A. Rothschilda, P. A. Krausb, T.C. Chuab, F. Nourib, F.N. Cubaynesc, A. Velosoa, S. Mertensa, L. Dated, R. Schreutelkampd, M. Schaekersa a
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium Applied Materials Inc., 974 E. Arques Ave, Sunnyvale, CA 94086, USA c Philips Research Leuven, Kapeldreef 75, B-3001 Leuven, Belgium d Applied Materials Belgium, Kapeldreef 75-BAT C1, 3001 Leuven, Belgium b
ABSTRACT In order to understand how N2 plasma conditions impact on the incorporation of nitrogen species into a thin SiO2 (1.4 nm), tuning of some pulsed RF (pRF) Decoupled Plasma Nitridation (DPN) process parameters was performed: duty cycle (DC) or on-time per period, frequency (f), process time (t) and some cross-combinations (DC*f, DC*t, DC*f*t). The N2 plasma and the SiOxNy film were characterized using Langmuir probe analysis (LP) and Delay to Reoxidation (D2R) techniques, respectively. Correlations are established between ion density and electron temperature and the resultant nitrogen concentration and parasitic physical thickness increase. The LP results indicate that while DC impacts the ion density and energy, the frequency has no impact to first order. This is consistent with the physical characteristics of the film. From the combination of DC*f*t, the importance of the off-time portion of the pulse was revealed. With the help of a modified pulsed RF DPN generator, allowing a decrease of the frequency down to 2 kHz, a 5% improvement of the drive current for pMOS transistors was obtained.
INTRODUCTION Balancing between gate leakage current, device performance and gate dielectric reliability is a major challenge when using oxynitrides (SiOxNy) as gate dielectric layer in advanced MOSFET technology. Compared to furnace nitridation, plasma nitridation techniques − Remote Plasma Nitridation (RPN) [1], Continuous-Wave DPN (CW-DPN) [2-3] and pulsed-RF DPN (pRFDPN) [4-7] − have demonstrated reduction in Equivalent Oxide Thickness (EOT) and gate leakage current (Jg) by incorporating a higher concentration of nitrogen atoms into the dielectric film. However, nitrogen incorporation leads typically to channel mobility degradation and threshold voltage shift (Vt), especially for pMOSFET devices. Although improvements of the plasma nitridation techniques have alleviated these problems, control of the incorporation of nitrogen remains a challenge in order to meet the ITRS specifications for the 65 nm technology node. Pulsed plasmas are of growing interest in different plasma-processing applications and accurate measurements of the key plasma parameters for pulsed N2 plasmas − including ion density and electron temperature − are desired. Among the techniques used for plasma characterization [6, 8-10], Langmuir probe measurements are frequently used. In this paper, we report the plasma characterization with LP of two specific pulsed DPN process parameters (duty cycle and frequency) and its impact on physical characteristics. In addition, the impact
Data Loading...
