Ge diffusion in Ge metal oxide semiconductor with chemical vapor deposition HfO2 dielectric

Abstract

We report a study on Ge diffusion and its impact on the electrical properties of TaN∕HfO2∕Ge metal-oxide-semiconductor (MOS) device. It is found that Ge diffusion depends on the amount of GeO2 formed at the HfO2∕Ge interface and can be retarded by surface nitridation. It is speculated that Ge diffusion is in the form of GeO or Ge-riched HfGeO. Effective suppression of Ge diffusion by NH3 nitridation has resulted in improved electrical properties of TaN∕HfO2∕Ge MOS device, including equivalent oxide thickness (EOT), leakage current, hysteresis, and interface state density. The degradation of leakage current after high temperature post metallization anneal (PMA) is found to be due to Ge diffusion.

HfO2/GeO N /Ge gate stacks with sub-nanometer capacitance equivalent thickness and low interface trap density by in situ NH3 plasma pretreatment

“…Some literature reported that in situ Ge plasma nitridation for ALD high-k thin film deposition can improve the interface quality [9,18,33]. However, there is rare work on fabrication of the Gebased MOS device with sub-nanometer CET by in situ Ge plasma nitridation.…”

“…Nitrogen incorporation into GeO 2 , which causes the formation of GeO x N y , has been used to improve its stability against thermal and wet treatments [16,17]. It was also found that nitridation of Ge surfaces prior to high-k film deposition is effective in suppressing Ge diffusion into high-k film and improving performance of Ge-based devices [18]. The scaled GeO x N y gate dielectrics fabricated by NH 3 plasma pretreatment may be one of the most reasonable solutions for future Ge-MOS devices.…”

Effects of postgate dielectric treatment on germanium-based metal-oxide-semiconductor device by supercritical fluid technology

“…Sequentially, poor interface properties and high gate leakage current will be exhibited in the Ge-MOS device. [3][4][5][6][7] Various pre-gate surface modification techniques, such as surface nitridation or Si passivation, have been developed to improve the quality of gate insulator/Ge interface. 13 It was also reported that high-performance Ge MOSFET could be realized by careful control of interfacial GeO 2 formation.…”

Defect configurations of high-k cations in germanium

“…[43][44][45] In Ge/oxide interfaces (for example, Ge/high-k oxide or Ge/GeO x /high-k oxide), there have also been numerous reports that during volatilization germanium out-diffuses into the oxide in the form of Ge atoms or as GeO molecules. 30,[46][47][48][49][50] This could form lattice vacancies or divacancies (V 2 ) in Ge among other possible defects. It is also anticipated that cations from the oxides will diffuse into Ge.…”