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- Yin, X., et al.
(författare)
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Vertical Sandwich Gate-All-Around Field-Effect Transistors with Self-Aligned High-k Metal Gates and Small Effective-Gate-Length Variation
- 2020
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 0741-3106 .- 1558-0563. ; 41:1, s. 8-11
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Tidskriftsartikel (refereegranskat)abstract
- A new type of vertical nanowire (NW)/nanosheet (NS) field-effect transistors (FETs), termed vertical sandwich gate-all-around (GAA) FETs (VSAFETs), is presented in this work. Moreover, an integration flow that is compatible with processes used in the mainstream industry is proposed for the VSAFETs. Si/SiGe epitaxy, isotropic quasi-atomic-layer etching (qALE), and gate replacement were used to fabricate pVSAFETs for the first time. Vertical GAA FETs with self-aligned high-k metal gates and a small effective-gate-length variation were obtained. Isotropic qALE, including Si-selective etching of SiGe, was developed to control the diameter/thickness of the NW/NS channels. NWs with a diameter of 10 nm and NSs with a thickness of 20 nm were successfully fabricated, and good device characteristics were obtained. Finally, the device performance was investigated and is discussed in this work. © 2019 IEEE.
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| 2. |
- Li, C., et al.
(författare)
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Selective digital etching of silicon-germanium using nitric and hydrofluoric acids
- 2020
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society. - 1944-8244 .- 1944-8252. ; 12:42, s. 48170-48178
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Tidskriftsartikel (refereegranskat)abstract
- A digital etching method was proposed to achieve excellent control of etching depth. The digital etching characteristics of p+-Si and Si0.7Ge0.3 using a combination of HNO3 oxidation and buffered oxide etching oxide removal processes were investigated. Experimental results showed that oxidation saturates as time goes on because of low activation energy and its diffusion-limited characteristic. An oxidation model was developed to describe the wet oxidation process with nitric acid. The model was calibrated with experimental data, and the oxidation saturation time, final oxide thickness, and selectivity between Si0.7Ge0.3 and p+-Si were obtained. In Si0.7Ge0.3/p+-Si stacks, the saturated relative etched depth per cycle was 0.5 nm (four monolayers), and variation between experiments was about 4% after saturation. A corrected selectivity calculation formula was also proposed, and the calculated selectivity was 3.7-7.7 for different oxidation times, which was the same as the selectivity obtained from our oxidation model. The proposed model can be used to analyze process variations and repeatability, and it can provide credible guidance for the design of other wet digital etching experiments. © 2020 American Chemical Society.
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