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| 3. |
- Wu, D., et al.
(författare)
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A novel strained Si0.7Ge0.3 surface-channel pMOSFET with an ALD TiN/Al2O3/HfAlOx/Al2O3 gate stack
- 2003
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 24:3, s. 171-173
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Tidskriftsartikel (refereegranskat)abstract
- Proof-of-concept pMOSFETs with a strained-Si0.7Ge0.3 surface-channel deposited by selective epitaxy and a TiN/Al2O3/HfAIO(x)/Al2O3 gate stack grown by atomic layer chemical vapor deposition (ALD) techniques were fabricated. The Si0.7Ge0.3 pMOSFETs exhibited more than 30% higher current drive and peak transconductance than reference Si pMOSFETs with the same gate stack. The effective mobility for the Si reference coincided with the universal hole mobility curve for Si. The presence of a relatively low density of interface states, determined as 3.3x10(11) cm(-2) eV(-1), yielded a subthreshold slope of 75 mV/dec. for the Si reference. For the Si0.7Ge0.3 pMOSFETs, these values were 1.6x10(12) cm(-2) eV(-1) and 110 mV/dec., respectively.
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- Wu, Dongping, et al.
(författare)
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Characterization of high-kappa nanolaminates of HfO2 and Al2O3 used as gate dielectrics in pMOSFETs
- 2004
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Ingår i: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions. - : Springer Science and Business Media LLC. - 155899761X ; , s. 19-24
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Konferensbidrag (refereegranskat)abstract
- In order to combine the merits of both HfO2 and Al2O3 as high-kappa gate dielectrics for CMOS technology, high-kappa nanolaminate structures in the form of either Al2O3/HfO2/Al2O3 or Al2O3/HfAlOx/Al2O3 were implemented in pMOSFETs and electrically and microstructurally charachterized. ALD TiN film was used as the metal gate electrodes for the pMOSFETs. After full transistor-processing including a rapid thermal processing step at 930 T, the HfO2 film in the former nanolaminate was found to be crystallized. In contrast, the HfAlOx layer in the latter nanolaminate remained in the amorphous state. Both types of pMOSFETs exhibited a hysteresis as small as similar to20 mV in C-V characteristics in the bias range of +/- 2 V. They also showed a reduced gate leakage current. The pMOSFET with the Al2O3/HfAlOx/Al2O3 nanolaminate was characterized with a subthreshold slope of 77 mV/decade and a channel hole mobility close to the universal hole mobility curve. The pMOSFET with the Al2O3/HfO2/Al2O3, however, exhibited a subthreshold slope of 100 mV/decade and a similar to30W lower hole mobility than the universal curve.
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| 5. |
- Wu, Donping, et al.
(författare)
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Influence of surface treatment prior to ALD high-kappa dielectrics on the performance of SiGe surface-channel pMOSFETs
- 2004
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 25:5, s. 289-291
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Tidskriftsartikel (refereegranskat)abstract
- Compressively strained Si0.7Ge0.3 surface-channel pMOSFETs with atomic layer deposition (ALD) Al2O3/HfO2/Al2O3 nanolaminate and low-pressure chemical vapor deposition p(+) poly-SiGe gate electrode were fabricated. Surface treatment with either hydrogen fluoride (HF) clean, or HF clean followed by water rinse was performed prior to the ALD processing. The devices with water rinse show a good control of interfacial layer and device reproducibility, while the devices without water rinse lack a clearly observable interfacial layer and show scattered electrical characteristics and distorted mobility curve. A similar to20% increase in hole mobility compared to the Si universal mobility and a similar to0.6-nm-thick continuous interfacial layer are obtained for the pMOSFETs with water rinse.
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| 6. |
- Wu, D., et al.
(författare)
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Structural and electrical characterization of Al2O3/HfO2/Al2O3 on strained SiGe
- 2005
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 49:2, s. 193-197
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Tidskriftsartikel (refereegranskat)abstract
- The interfacial integrity of a gate stack featuring a polycrystalline SiGe gate, an ultrathin Al2O3/HfO2/Al2O3 nano-laminate and a strained-SiGe surface-channel is examined for full transistor fabrication and characterization. The high-K dielectric nano-laminate is prepared by means of atomic layer deposition, and the SiGe channel and gate by chemical vapor deposition. After full transistor-processing including a rapid thermal processing step at 930 degreesC, the 3 nm thick HfO2 film becomes polycrystalline whereas the Al2O3 films about 0.5 nm thick remain in the amorphous state, according to analyses using high-resolution and energy-filtering transmission electron microscopy. No interfacial reaction is observable between the HfO2 film and the SiGe gate or channel, since both interfaces are fiat and the two Al2O3 films remain continuous. Well-behaving gate leakage and capacitance characteristics of the transistors are found. An enhanced channel hole mobility compared to the Si universal curve is obtained.
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| 7. |
- Wu, D., et al.
(författare)
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Ni-salicided CMOS with a poly-SiGe/Al2O3/HfO2/Al2O3 gate stack
- 2005
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 77:1, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- Ni-salicided MOSFETs with a gate stack of ALD Al2O3/HfO2/Al2O3 high-x dielectric and poly-SiGe gate electrode were fabricated. The Si pMOSFETs with an EOT of 1.7 nm showed an expected gate leakage current reduction compared to SiO2 with the same EOT and a mobility around 20% lower than the universal curve. The strained SiGe surface-channel pMOSFETs with the same gate stack showed an enhanced current drive and hole mobility. The Si nMOSFETs, however, exhibited a degraded subthreshold slope and a lower current drive even compared with the Si pMOSFETs. Possible reasons for the degradation of Si nMOSFETs were discussed.
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