A low-temperature and high-quality radical-assisted oxidation process utilizing a remote ultraviolet ozone source for high-performance SiGe/Si MOSFETs

Abstract

By utilizing a remote ultraviolet ozone source, a low-temperature (600-700 • C) radical-assisted oxidation (RAO) process to produce high-quality ultrathin (1.4-3.7 nm) gate oxides was successfully developed for the fabrication of high-performance SiGe/Si metal-oxide-semiconductor field effect transistors (MOSFETs). The oxide grown by this technique showed much improved leakage and breakdown properties, compared with that grown without ozone. The reactive oxygen species in the RAO process seemed to cure the unpaired bonds in oxide networks making them more robust and dense, without an increase in thermal budget. The Si 0.8 Ge 0.2 p-channel MOSFET with a RAO gate oxide exhibited superior device and 1/f noise characteristics to that with a standard higher temperature furnace oxide. This was because of the suppressed Ge-related gate-oxide degradation at the reduced process temperature when the Si-cap layer was thinned to below 2 nm. These suggest that the RAO process is particularly suitable for SiGe/Si MOSFET devices requiring a high-quality and low-temperature oxidation process.

Comprehensive Study and Design of High-k/SiGe Gate Stacks with Interface-Engineering by Ozone Oxidation

“…It has been reported that the Ge-pile up at the IL/SiGe interface would increase the interface state densities. 18,19,30,31 Hence, suppressing the amounts of the Ge atoms accumulating at the IL/SiGe interface is important for the passivation of the D it . Moreover, the amounts of the Ge atoms at the IL/SiGe interface depend not only on the initial atomic fraction of Ge in the SiGe substrate, but also on the thickness of the formed IL.…”

“…To solve these problems, many lowtemperature oxidation processes for interlayer (IL) formation have been explored, such as O plasma 17,18 and ozone oxidation. 19,20 Although ozone oxidation is an important approach to passivate SiGe surface, the influence of the processing conditions on the interfacial and electrical properties of high-k/SiGe gate stacks has not been systematically reported, especially in thin film systems. Actually, clarifying what essentially determines the quality of the SiGe interface during the ozone oxidation processing is indispensable for us to obtain a superior high-k/SiGe interface.…”

Investigate on the Mechanism of HfO2/Si0.7Ge0.3 Interface Passivation Based on Low-Temperature Ozone Oxidation and Si-Cap Methods

“…To control the interface quality, many methods have been extensively explored, such as plasma (N 2 or NH 3 ) nitridation passivation [ 4 , 5 ], sulfur passivation [ 6 ], thermal oxidation [ 7 , 8 ], low-temperature ozone passivation [ 9 , 10 , 11 , 12 ] and Si-cap passivation [ 13 ]. Among them, low-temperature ozone passivation with low thermal budge and Si-cap passivation with excellent properties of interface are considered the most promising passivation methods.…”

Understanding the mechanisms impacting the interface states of ozone-treated high-k/SiGe interfaces

“…The main disadvantage of this method is the trade-off between the interface quality and the scalability of equivalent oxide thickness (EOT). Oxides on SiGe have also been extensively investigated as passivation layers between high-k and SiGe, which are formed by oxidizing SiGe surface via various approaches, such as thermal O 2 oxidation [9][10][11][12][13][14], O plasma [15,16], and ozone [17,18]. Conventional thermal O 2 oxidation are performed at high pressures and temperatures resulting in thick oxides and Ge-rich layers beneath the oxides, which are unsuitable as the passivation layers between high-k and SiGe.…”