Study of pulsed RF DPN process parameters for 65 nm node MOSFET gate dielectrics

Abstract

In order to understand how N2plasma 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 N2plasma and the SiOxNyfilm 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.

Improved Poly Gate Engineering for 65 nm Low Power CMOS Technology

“…8,9 Before twin well implants for n-and p-wells, we performed a conventional shallow trench isolation ͑STI͒ process on the logic devices and 6T-SRAM. Then, an effective oxide thickness of ϳ19 Å ultrathin gate dielectric was grown by pulsed radio-frequency ͑rf͒ decoupled plasma nitridation ͑DPN͒ 10,11 and by low pressure chemical vapor deposition ͑LPCVD͒ with 1000 Å after DPN using in situ poly deposition. In this study, two different poly depositions with ϳ1000 Å thickness are named Poly A and B, where Poly B is the deposition process.…”