Partial-depleted SOI(silicon on insulator) nMOS devices are fabricated with and without silicide technology,respectively.Off-state breakdown characteristics of these devices are presented with and without body contact...Partial-depleted SOI(silicon on insulator) nMOS devices are fabricated with and without silicide technology,respectively.Off-state breakdown characteristics of these devices are presented with and without body contact,respectively.By means of two-dimension(2D) device simulation and measuring junction breakdown of the drain and the body,the difference and limitation of the breakdown characteristics of devices with two technologies are analyzed and explained in details.Based on this,a method is proposed to improve off-state breakdown characteristics of PDSOI nMOS devices.展开更多
Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si...Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.展开更多
For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields ...For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields the derivation of SiOC.This causes a significant degradation of the 4H SiC surface characteristics according to the results of surface composition analysis.As validity,Ni/SiC ohmic contact measurement illustrates a higher specific contact resistance than the normal value by a factor of 2～3.Consequently the MESFET fabricated with this kind of 4H SiC material results in a degraded I V output performance compared with that of normal 4H SiC MESFET.展开更多
Different silicidation processes are employed to form NiSi,and the NiSi/Si interface corresponding to each process is studied by cross-section transmission electron microscopy （XTEM）. With the sputter deposition of ...Different silicidation processes are employed to form NiSi,and the NiSi/Si interface corresponding to each process is studied by cross-section transmission electron microscopy （XTEM）. With the sputter deposition of a nickel thin film,nickel silicidation is realized on undoped and doped （As and B） Si（001） substrates by rapid ther mal processing （RTP）. The formation of NiSi is demonstrated by X-ray diffraction and Raman scattering spectros- copy. The influence of the substrate doping and annealing process （one-step RTP and two-step RTP） on the NiSi! Si interface is investigated. The results show that for one-step RTP the silicidation on As-doped and undoped Si substrates causes a rougher NiSi/Si interface,while the two-step RTP results in a much smoother NiSi/Si interface. High resolution XTEM study shows that axiotaxy along the Si（111） direction forms in all samples, in which specific NiSi planes align with Si（111） planes in the substrate. Axiotaxy with spacing mismatch is also discussed.展开更多
An investigation of Au/Ti/Ni and Au/Ti/Pt ohmic contacts to n-type 4H-SiC and the behavior of metal films on SiC with thermal anneals is reported. Specific contact resistance as low as 2. 765 x 10^-6Ω·cm^2 was a...An investigation of Au/Ti/Ni and Au/Ti/Pt ohmic contacts to n-type 4H-SiC and the behavior of metal films on SiC with thermal anneals is reported. Specific contact resistance as low as 2. 765 x 10^-6Ω·cm^2 was achieved after rapid thermal annealing in N2 for 2min at 950℃. SIMS analysis shows that the formation of Ni silicide after annealing supported a number of carbon atoms＇ outdiffusion from the SiC to form interstitial compound TiC. This process can create abundant C vacancies near the interface. It is the carbon defect layer that enhances the defect-assisted tunneling. The interface band structure within the defect level could make it clear why the metal-SiC contacts become ohmic during annealing.展开更多
We investigate the effects of the surface states on the Schottky contacts in 4H-SiC MESFET. The Ti/Pt/Au gate metal contacts are deposited by electron beam evaporation and patterned by a lift-off process. Based on the...We investigate the effects of the surface states on the Schottky contacts in 4H-SiC MESFET. The Ti/Pt/Au gate metal contacts are deposited by electron beam evaporation and patterned by a lift-off process. Based on thermionic theory,a simple parameter extraction method is developed for determination of the surface states in metal/4H-SiC Schottky contacts. The interface state density and interface capacitance are calculated to be 4. 386 × 10^12 cm^-2 · eV^- 1 and 6. 394 × 10^-6 F/cm^2 ,which are consistent with the device＇s terminal characteristics.展开更多
文摘Partial-depleted SOI(silicon on insulator) nMOS devices are fabricated with and without silicide technology,respectively.Off-state breakdown characteristics of these devices are presented with and without body contact,respectively.By means of two-dimension(2D) device simulation and measuring junction breakdown of the drain and the body,the difference and limitation of the breakdown characteristics of devices with two technologies are analyzed and explained in details.Based on this,a method is proposed to improve off-state breakdown characteristics of PDSOI nMOS devices.
文摘Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.
文摘For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields the derivation of SiOC.This causes a significant degradation of the 4H SiC surface characteristics according to the results of surface composition analysis.As validity,Ni/SiC ohmic contact measurement illustrates a higher specific contact resistance than the normal value by a factor of 2～3.Consequently the MESFET fabricated with this kind of 4H SiC material results in a degraded I V output performance compared with that of normal 4H SiC MESFET.
文摘Different silicidation processes are employed to form NiSi,and the NiSi/Si interface corresponding to each process is studied by cross-section transmission electron microscopy （XTEM）. With the sputter deposition of a nickel thin film,nickel silicidation is realized on undoped and doped （As and B） Si（001） substrates by rapid ther mal processing （RTP）. The formation of NiSi is demonstrated by X-ray diffraction and Raman scattering spectros- copy. The influence of the substrate doping and annealing process （one-step RTP and two-step RTP） on the NiSi! Si interface is investigated. The results show that for one-step RTP the silicidation on As-doped and undoped Si substrates causes a rougher NiSi/Si interface,while the two-step RTP results in a much smoother NiSi/Si interface. High resolution XTEM study shows that axiotaxy along the Si（111） direction forms in all samples, in which specific NiSi planes align with Si（111） planes in the substrate. Axiotaxy with spacing mismatch is also discussed.
文摘An investigation of Au/Ti/Ni and Au/Ti/Pt ohmic contacts to n-type 4H-SiC and the behavior of metal films on SiC with thermal anneals is reported. Specific contact resistance as low as 2. 765 x 10^-6Ω·cm^2 was achieved after rapid thermal annealing in N2 for 2min at 950℃. SIMS analysis shows that the formation of Ni silicide after annealing supported a number of carbon atoms＇ outdiffusion from the SiC to form interstitial compound TiC. This process can create abundant C vacancies near the interface. It is the carbon defect layer that enhances the defect-assisted tunneling. The interface band structure within the defect level could make it clear why the metal-SiC contacts become ohmic during annealing.
文摘We investigate the effects of the surface states on the Schottky contacts in 4H-SiC MESFET. The Ti/Pt/Au gate metal contacts are deposited by electron beam evaporation and patterned by a lift-off process. Based on thermionic theory,a simple parameter extraction method is developed for determination of the surface states in metal/4H-SiC Schottky contacts. The interface state density and interface capacitance are calculated to be 4. 386 × 10^12 cm^-2 · eV^- 1 and 6. 394 × 10^-6 F/cm^2 ,which are consistent with the device＇s terminal characteristics.
