Chapter 2 Experimental Process and Electrical Parameters Extraction
2.2 Electrical Parameters Extraction
3.1.6 On/Off Current Ratio
Fig.3-39 shows the On/Off current ratio of n-channel FSA-TFTs with in-situ doped gate, undoped gate, and conventional TFTs. The ION is measured at VG=10V and VD=3.0V. IOFF is the value of minimum current at VD=3.0V. The channel width is 10μm. The values of On/Off current ratio are shown in Table 3-6. The ON/OFF current ratio can be increased with scaling down gate length in FSA-TFTs. The value of ON/OFF current ratio is about 107~109 order for FSA-TFTs and 106 order for conventional TFTs. It is found that leakage current can be reduced in FSA-TFTs with scaling down gate-length, but it not the case for the conventional TFTs. This is because of floating body effect for n-channel TFTs which result in larger leakage current at off-state for conventional TFTs. On the other hand, FSA-TFTs can suppress floating-body effect, resulting in a low leakage current.
3.2 Difference between Fully-Salicided and Partially Salicided n-Channel
TFTs with In-situ Poly- Si Gate
Fig.3-40 and Fig.3-41 exhibit transfer characteristics of n-channel FSA-TFTs with in-situ gate and partially Ni-salicided TFTs with in-situ gate. The partially Ni-salicided TFTs are formed suing thin 15 nm Ni-layer. Devices dimensions are W/L=10μm/10μm and W/L=10μm/0.8μm, respectively. Fig.3-42 and Fig.3-43 exhibit transfer characteristics for n-channel partially Ni-salicided TFTs with in-situ doped gate with W/L=10μm/10μm and W/L=10μm/0.8μm at RTA 500oC for 60 seconds and RTA 550oC for 30 seconds, respectively.
Fig.3-44 exhibits threshold voltage roll-off of n-channel FSA-TFTs with in-situ gate with RTA 500oC for 60s, partially Ni-salicided TFTs with in-situ gate witch RTA 550oC for 30s, and partially Ni-salicided TFTs with in-situ gate witch RTA 500oC for 60s. The values of VTH
roll-off are shown in Table 3-7. For long channel devices, uncompleted silicidation will occur as temperature of RTA is not high enough. This partially salicided TFTs have negative shift of VTH than FSA-TFTs. But, for short channel devices, all of VTH closed to each others. Specially, partially salicided TFTs with RTA 550oC for 30 seconds have the smallest VTH roll-off among these devices. The electrical characteristics of the partially salicided TFTs with RTA 550oC for 30 seconds are also better than partially sallicided TFTs with RTA 500oC for 60 seconds.
The reason for these improvements can be attributed to that thin Ni-layer make S/D lateral diffusion less than thick Ni-layer at high temperature. Hence, there is no large leakage current found in partially salicided TFTs with RTA 550oC for 30 seconds.
3.3 Basic Characteristics of p-Channel FAS-TFTs With Undoped Poly- Si Gate
In this section, the basic characteristics of p-channel FSA-TFTs will be explained. At first, the transfer characteristics of FSA-TFTs with undoped gate and conventional TFTs are compared in 3.3.1. In addition, the output characteristics of FSA-TFTs with undoped gate and conventional TFTs are compared in 3.3.2. The parasitic resistance of FSA-TFTs with undoped
gate and conventional TFTs are compared in 3.3.3. Finally, the ON/OFF current ratio of FSA-TFTs with undoped gate and conventional TFTs are compared in 3.3.4.
3.3.1 Transfer Characteristics
Fig.3-45 and Fig.3-46 display the ID-VG transfer characteristics of conventional TFTs with W/L=10μm/10μm and W/L=10μm/0.8μm, respectively. Moreover, these figures show two different treatment steps for p-channel. Obviously, conventional TFTs with NH3 plasma treatment have better subthreshold swing, and higher ON/OFF current ratio. In addition, they have more stable VTH than conventional TFTs without NH3 plasma treatment.
Fig.3-47 and Fig.3-48 display the ID-VG transfer characteristics of FSA-TFTs with undoped gate with W/L=10μm/10μm at RTA 500oC for 30 seconds and 60 seconds, respectively. In addition, Fig.3-49 and Fig.3-50 show the ID-VG transfer characteristics of FSA-TFTs with undoped gate with W/L=10μm/0.8μm at RTA 500oC for 30 seconds and 60 seconds, respectively. From Fig.45 to Fig.50, all of FSA-TFTs are with channel thickness equal to 50nm and TOX=50nm. The drain voltage bias is 0.5V and 3.0V. Obviously, poly-Si TFTs with fully Ni-salicided process and NH3 plasma treatment have better subthreshold swing, higher ON/OFF current ratio, and more stable VTH than poly-Si TFTs without fully Ni-salicided process and NH3 plasma treatment, and poly-Si TFTs only with fully Ni-salicided process. It is found that these improvements can be attributed to that fully Ni-salicided S/D can passivate the defects of S/D junction, and fully Ni-salicided gate has a high value of COX. In addition, NH3 plasma treatment can also passivate the defects of S/D surface and dielectric interface. Specially, we found that p-channel FSA-TFTs are more sensitive than n-channel FSA-TFTs on parasitic resistance. It is found that FSA-TFTs with RTA 500oC for 60 seconds have better S.S. and lower leakage current than FSA-TFTs with RTA 500oC for 30 seconds.
So, RTA 500oC for 60 seconds is selected for reference.
Fig.3-51 and Fig.3-52 display ID-VG transfer characteristics of p-channel FSA-TFTs with
undoped gate compared with conventional TFTs. The Ni-salicide was formed by RTA at 500oC for 60 seconds. Devices with W/L=10μm/10μm and W/L=10μm/0.8μm have been measured. The drain voltage bias is 0.5V and 3.0V. The extracted values of VTH, S.S., and ON/OFF current ratio are shown in Table 3-8 (a) and (b). It is found that FSA-TFTs with NH3
plasma treatment have stable VTH, better S.S., and higher ON/OFF current ratio. Similar to the n-channel, p-channel with fully Ni-salicided S/D with passivated defects of S/D junction can achieve a lower leakage current about 10-13 ~10-14 than conventional TFTs only with NH3
plasma.
Fig.3-53 and Fig.3-54 display field-effect mobility of p-channel FSA-TFTs with undoped gate compared with conventional TFTs. The Ni-salicide was formed by RTA at 500oC for 60 seconds. Devices with W/L=10μm/10μm and W/L=10μm/0.8μm have been measured. The drain voltage bias is 0.5V. The values of field-effect mobility are shown in Table 3-8 (a). We find that both long-channel and short-channel of FSA-TFTs have higher mobility than conventional TFTs. This improved mobility is due to that FSA-TFTs have a high COX in long-channel and reduced parasitic resistance in short-channel.
Fig.3-55 and Fig.3-56 display field-effect mobility of devise with W/L=10μm/10μm and W/L=10μm/0.8μm, with undoped gate and conventional TFTs, respectively. The Ni-salicide was formed at RTA 500oC for 60 seconds. It is found that FSA-TFTs with W/L=10μm/10μm and W/L=10μm/0.8μm have the same order of magnitude of mobility; however, conventional TFTs have a significant reduction of mobility in short channel devices. This is due to the reduced parasitic resistance of FSA-TFTs in the short channel regime. This trend is the same as n-channel FSA-TFTs.
Fig.3-57 displays threshold voltage roll-off for p-channel FSA-TFTs with undoped gate, and conventional TFTs. The Ni-salicide was formed by RTA at 500oC for 60 seconds. The width is 10μm, and VD=0.5V. The values of VTH roll off are shown in Table 3-9 (a). Fig.3-58 displays S.S. roll-off of p-channel FSA-TFTs with undoped gate, and conventional TFTs. The
Ni-salicide was formed by RTA at 500oC for 60 seconds. The width is 10μm, and VD=0.5V.
The values of S.S. roll off are shown in Table 3-9 (b). From Fig.3-57 and Fig.3-58, we found that threshold voltage roll-off has the same trend as S.S. roll-off. Moreover, FSA-TFTs have less VTH roll-off and S.S. than conventional TFTs. This implies that the trend of VTH roll-off is affected by the trend of S.S. roll-off.
3.3.2 Output Characteristics
Fig.3-59 and Fig.3-60 display ID-VD output characteristics of p-channel FSA-TFTs with undoped gate and conventional TFTs with W/L=10μm/10μm. The Ni-salicide was formed by RTA at 500oC for 60 seconds. VG-VTH was set at -5.0V, -6.0V, -7.0V, -8.0V, -9.0V and VG-VTH=-2.0V, -3.0V, -4.0V, -5.0V, -6.0V, respectively.
Fig.3-61 and Fig.3-62 display ID-VD output characteristics between p-channel FSA-TFTs with undoped gate conventional TFTs with W/L=10μm/0.8μm. The Ni-salicide was formed by RTA at 500oC for 60 seconds. They are measured at VG-VTH=-5.0V, -5.5V, -6.0V, -6.5V, -7.0V and VG-VTH=-3.5V, -4.0V, -4.5V, -5.0V, -5.5V, respectively. It is found that ID-VD
output characteristics of p-channel FSA-TFTs are smooth at saturation region. This is because that p-channel FSA-TFTs is not easy to produce impact ionization, which makes p-channel FSA-TFTs have lower floating-body effect than conventional TFTs. In addition, FSA-TFTs have lower parasitic resistance than conventional TFTs, so FSA-TFTs have higher drive current than conventional TFTs.
3.3.3 Extraction of Parasitic Resistance
Fig.3-63 and Fig.3-64 show the parasitic resistance RP of FSA-TFTs with undoped gate and in-situ gate, respectively. They are extracted by plotting the on state resistance (Ron) versus gate length. The channel width is 10μm, and the drain voltage is 0.5V. The RP of FSA-TFTs with undoped gate is about 0.39 kΩ. Fig.3-38 shows the parasitic resistance RP of
conventional TFTs, and the RP of conventional-TFTs is about 8.80 kΩ. It is found that FSA-TFTs have lower value of RP than conventional TFTs. This result is due to the reduced parasitic resistance of S/D by Ni-salicided process.
3.3.4 On/Off Current Ratio
Fig.3-65 displays the On/Off current ratio of p-channel FSA-TFTs with undoped gate and conventional TFTs. The ION is measured at VG=15V and VD=3.0V. IOFF is the minimum current at VD=3.0V. The channel width is 10μm. The values of ON/OFF current ratio are shown in Table 3-10. The ON/OFF current ratio is increased with scaled down gate length in FSA-TFTs and conventional TFTs. The value of ON/OFF current ratio is about 107~109 for FSA-TFTs and conventional TFTs. But FSA-TFTs still have higher value of ON/OFF current ratio than conventional TFTs. This is because of FSA-TFTs have higher ON current than conventional TFTs. Moreover, p-channel TFTs have larger parasitic resistance and lower intensity of electric field at drain side than n-channel TFTs, therefore both p-channel FSA-TFTs and conventional TFTs have almost the same order of leakage current. This can explain ON/OFF current ratio of FSA-TFTs has the same trend as conventional TFTs. This result is different from that in n-channel FSA-TFTs.
Table 3-1 Summary of VTH, S.S. and ON/OFF current ratio characteristics of FSA-TFTs and conventional TFTs with W/L=10μm/10μm and W/L=10μm/0.8μm.
VTH (V)
TFTs
1.85 0.35 783.13 591.75 1.25E6 1.54E6
FSA-TFTs with undoped gate (RTA 500oC,30s)
1.69 1.17 370.82 280.51 4.78E7 6.16E8
FSA-TFTs with undoped gate (RTA 500oC,60s)
1.50 1.09 361.99 261.84 4.93E7 6.51E8
FSA-TFTs with in-situ gate (RTA 500oC,30s)
1.70 0.88 473.88 301.66 3.75E7 6.33E8
FSA-TFTs with in-situ gate (RTA 500oC,60s)
1.38 0.71 388.37 282.50 6.20E7 1.58E9
Table 3-2 Summary of VTH and μFE characteristics of FSA-TFTs and conventional TFTs with W/L=10μm/10μm and W/L=10μm/0.8μm.
VTH (V) L=10μm
VTH (V) L=0.8μm
μFE (Max.) (cm2/V-s)
L=10μm
μFE (Max.) (cm2/V-s) L=0.8μm
Conventional TFTs
1.85 0.35 29.32 22.44
FSA-TFTs with undoped gate (RTA 500oC,60s)
1.50 1.09 34.81 31.56
FSA-TFTs with in-situ gate (RTA 500oC,60s)
1.38 0.71 32.05 30.98
Table 3-3 Summary of VTH versus drain bias VDS characteristics of FSA-TFTs and conventional TFTs. VD= 0.5V, 1.0V, 3.0V, 5.0V, 7.0V.
VTH (V) VD=0.5V
VTH (V) VD=1.0V
VTH (V) VD=3.0V
VTH (V) VD=5.0V
VTH (V) VD=7.0V
Conventional
TFTs
0.52 0.43 0.30 -0.42 -1.96
FSA-TFTs with undoped gate (RTA 500oC,60s)
1.06 0.99 0.89 0.36 -0.49
FSA-TFTs with in-situ gate (RTA 500oC,60s)
0.59 0.51 0.37 -0.11 -1.04
Table 3-4 Summary of VTH roll-off characteristics of FSA-TFTs and conventional TFTs.
VTH (V) L=10μm
VTH (V) L=8μm
VTH (V) L=5μm
VTH (V) L=3μm
VTH (V) L=2μm
VTH (V) L=1μm
VTH (V) L=0.8μm
Conventional TFTs
1.85 1.68 1.63 1.35 1.12 0.53 0.35
FSA-TFTs with undoped gate (RTA 500oC,30s)
1.69 1.64 1.63 1.62 1.54 1.37 1.17
FSA-TFTs with undoped gate (RTA 500oC,60s)
1.50 1.50 1.47 1.44 1.33 1.18 1.09
FSA-TFTs with in-situ gate (RTA 500oC,30s)
1.70 1.70 1.64 1.60 1.52 1.16 0.88
FSA-TFTs with in-situ gate (RTA 500oC,60s)
1.38 1.35 1.32 1.25 1.10 0.83 0.71
Table 3-5 Summary of subthreshold swing roll-off characteristics of FSA-TFTs and
Conventional TFTs
783.13 738.64 746.52 720.19 710.35 620.04 591.75
FSA-TFTs with undoped gate (RTA 500oC,30s)
370.82 359.22 347.25 343.30 341.76 293.65 280.51
FSA-TFTs with undoped gate (RTA 500oC,60s)
361.99 341.30 331.42 324.94 318.24 318.24 261.84
FSA-TFTs with in-situ gate (RTA 500oC,30s)
473.88 438.05 409.34 399.92 397.25 332.65 301.66
FSA-TFTs with in-situ gate (RTA 500oC,60s)
388.37 371.34 356.46 342.28 342.21 300.11 282.50
Table 3-6 Summary of ON/OFF current ratio characteristics of FSA-TFTs and conventional TFTs.
ION/IOFF
ratio L=10μm
ION/IOFF
ratio L=8μm
ION/IOFF
ratio L=5μm
ION/IOFF
ratio L=3μm
ION/IOFF
ratio L=2μm
ION/IOFF
ratio L=1μm
ION/IOFF
ratio L=0.8μm Conventional
TFTs
1.25E6 1.48E6 1.42E6 3.69E6 1.72E6 1.90E6 1.54E6
FSA-TFTs withundoped gate (RTA 500oC,60s)
4.93E7 5.93E7 1.01E8 1.64E8 2.53E8 4.48E8 6.51E8
FSA-TFTs with in-situ gate (RTA 500oC,60s)
6.20E7 9.42E7 1.60E8 2.99E8 4.99E8 1.38E9 1.58E9
Table 3-7 Summary of VTH roll-off characteristics of FSA-TFTs and partially salicided TFTs.
VTH (V) L=10μm
VTH (V) L=8μm
VTH (V) L=5μm
VTH (V) L=3μm
VTH (V) L=2μm
VTH (V) L=1μm
VTH (V) L=0.8μm
FSA-TFTs with in-situ gate (RTA 500oC,60s)
1.38 1.35 1.32 1.25 1.10 0.83 0.71
Partially NiSi-TFTs with
in-situ gate (RTA 550oC,30s)
0.73 0.61 0.58 0.56 0.52 0.51 0.55
Partially NiSi-TFTs with
in-situ gate (RTA 500oC,60s)
-0.24 -0.52 -0.70 -0.48 -0.30 0.13 0.39
Table 3-8 (a) and (b) Summary of VTH, μFE, S.S. and ON/OFF current ratio characteristics of FSA-TFTs and conventional TFTs with W/L=10μm/10μm and W/L=10μm/0.8μm.
(a) Values of VTH, μFE
VTH (V) L=10μm
VTH (V) L=0.8μm
μFE (Max.) (cm2/V-s)
L=10μm
μFE (Max.) (cm2/V-s) L=0.8μm
Conventional TFTs
-5.86 -3.87 18.92 11.84
FSA-TFTs with undoped gate (RTA 500oC,60s)
-4.94 -3.55 27.57 27.66
(b) Values of S.S. and ON/OFF current ratio
S.S.
(mV/dec) L=10μm
S.S.
(mV/dec) L=0.8μm
ION/IOFF ratio L=10μm
ION/IOFF ratio L=0.8μm
Conventional TFTs
805.12 307.94 1.29E7 1.21E8
FSA-TFTs with undoped gate (RTA 500oC,60s)
639.47 290.74 2.89E7 9.95E8
Table 3-9 (a) and (b) Summary of VTH roll-off and subthreshold swing roll-off characteristics of FSA-TFTs and conventional TFTs.
(a) Values of VTH
Conventional TFTs
-5.86 -5.88 -5.90 -5.57 -5.30 -4.38 -3.87
FSA-TFTs with undoped gate (RTA 500oC,60s)
-4.94 -4.98 -4.93 -4.82 -4.64 -4.12 -3.55
(b) Values of S.S.
Conventional TFTs
805.12 747.40 696.65 653.59 490.93 410.59 307.94
FSA-TFTs with undoped gate (RTA 500oC,60s)
639.47 632.67 563.06 542.43 428.29 359.49 290.74
Table 3-10 Summary of ON/OFF current ratio characteristics of FSA-TFTs and conventional TFTs.
ION/IOFF
ratio L=10μm
ION/IOFF
ratio L=8μm
ION/IOFF
ratio L=5μm
ION/IOFF
ratio L=3μm
ION/IOFF
ratio L=2μm
ION/IOFF
ratio L=1μm
ION/IOFF
ratio L=0.8μm Conventional
TFTs
1.29E7 1.94E7 1.97E7 4.62E7 5.78E7 9.80E7 1.20E8
FSA-TFTs withundoped gate (RTA 500oC,60s)
2.89E7 4.95E7 6.33E7 1.84E8 1.89E8 4.01E8 9.96E8
Fig.3-1 TEM photograph for cross-section of FSA-TFTs.
Fig.3-2 TEM photograph for cross-section of S/D junction.
Conventional TFTs W / L = 10μm / 10μm Channel Thickness = 50 nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current I D (A)
10-13
Conventional TFTs without NH3 plasma Conventional TFTs with NH3 plasma
Fig. 3-3 Transfer characteristics of conventional TFTs with W/L=10μm/10μm, and two different treatment steps for n-channel.
Conventional TFTs W / L = 10μm / 0.8μm Channel Thickness = 50 nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Drain Current I D (A)
10-12
Conventional TFTs without NH3 plasma Conventional TFTs with NH3 plasma
Fig. 3-4 Transfer characteristics of conventional TFTs with W/L=10μm/0.8μm, and two different treatment steps for n-channel.
FSA-TFTs with undoped gate W/L =10μm/10μm Channel Thickness = 50nm Metal RTA 500oC , 30sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
Without NiSi and NH3 plasma With NiSi
With NiSi and NH3 plasma
Fig.3-5 Transfer characteristics of FSA-TFTs with undoped gate, W/L=10μm/10μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 30 seconds.
FSA-TFTs with undoped gate W/L =10μm/10μm Channel Thickness = 50nm Metal RTA 500oC , 60sec VD = 0.5V, 3.0V
Gate VoltageVG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
Without fully NiSi and NH3 plasma With fully NiSi
With fully NiSi and NH3 plasma
Fig.3-6 Transfer characteristics of FSA-TFTs with undoped gate, W/L=10μm/10μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 60 seconds.
FSA-TFTs with undoped gate W/L =10μm/0.8μm Channel Thickness = 50nm Metal RTA 500oC , 30sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Drain Current ID (A)
10-14
Without NiSi and NH3 plasma With NiSi
With NiSi and NH3 plasma
Fig.3-7 Transfer characteristics of FSA-TFTs with undoped gate, W/L=10μm/0.8μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 30 seconds.
FSA-TFTs with undoped gate W/L =10μm/0.8μm Channel Thickness = 50nm Metal RTA 500oC , 60sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Drain Current ID (A)
10-14
Without fully NiSi and NH3 plasma With fully NiSi
With fully NiSi and NH3 plasma
Fig.3-8 Transfer characteristics of FSA-TFTs with undoped gate, W/L=10μm/0.8μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 60 seconds.
FSA-TFTs with in-situ gate W/L =10μm/10μm Channel Thickness = 50nm Metal RTA 500oC , 30sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
Without NiSi and NH3 plasma With NiSi
With NiSi and NH3 plasma
Fig.3-9 Transfer characteristics of FSA-TFTs with in-situ gate, W/L=10μm/10μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 30 seconds.
FSA-TFTs with in-situ gate W/L =10μm/10μm Channel Thickness = 50nm Metal RTA 500oC , 60sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
Without fully NiSi and NH3 plasma With fully NiSi
With fully NiSi and NH3 plasma
Fig.3-10 Transfer characteristics of FSA-TFTs with in-situ gate, W/L=10μm/10μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 60 seconds.
FSA-TFTs with in-situ gate W/L =10μm/0.8μm Channel Thickness = 50nm Metal RTA 500oC , 30sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Drain Current ID (A)
10-14
Without NiSi and NH3 plasma With NiSi
With NiSi and NH3 plasma
Fig.3-11 Transfer characteristics of FSA-TFTs with in-situ gate, W/L=10μm/0.8μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 30 seconds.
FSA-TFTs with in-situ gate W/L =10μm/0.8μm Channel Thickness = 50nm Metal RTA 500oC , 60sec VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Drain Current ID (A)
10-14
Without fully NiSi and NH3 plasma With fully NiSi
With fully NiSi and NH3 plasma
Fig.3-12 Transfer characteristics of FSA-TFTs with in-situ gate, W/L=10μm/0.8μm, and three different treatment steps for n-channel. Ni-salicide was formed by RTA 500oC for 60 seconds.
With NH3 Treatment W/L =10μm/10μm Channel Thickness = 50nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
FSA-TFTs with undoped gate Conventional TFTs
Fig. 3-13 Transfer characteristics of n-channel FSA-TFTs with undoped gate, and W/L=10μm/10μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
With NH3 Treatment W/L =10μm/0.8μm Channel Thickness = 50nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
FSA-TFTs with undoped gate Conventional TFTs
Fig. 3-14 Transfer characteristics of n-channel FSA-TFTs with undoped gate, and W/L=10μm/0.8μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility W / L = 10μm / 10μm Channel Thickness = 50 nm VD = 0.5V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Field -Effect Mobility μFE (cm2 /V-s)
0
FSA-TFTs with undoped gate Conventional TFTs
Fig.3-15 Field-effect mobility of n-channel FSA-TFTs with undoped gate, and W/L=10μm/10μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility W / L = 10μm / 0.8μm Channel Thickness = 50 nm VD = 0.5V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 Field -Effect Mobility μFE (cm2 /V-s)
0
FSA-TFTs with undoped gate Conventional TFTs
Fig.3-16 Field-effect mobility of n-channel FSA-TFTs with undoped gate, and W/L=10μm/0.8μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility FSA-TFTs with undoped gate Channel Thickness = 50 nm VD = 0.5V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Field -Effect Mobility μFE (cm2 /V-s)
0
Fig.3-17 Comparison of field-effect mobility between W/L=10μm/10μm and W/L=10μm/0.8μm for n-channel FSA-TFTs with undoped gate. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility Conventional TFTs Channel Thickness = 50 nm VD = 0.5V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Field -Effect Mobility μFE (cm2 /V-s)
0
Fig.3-18 Comparison of field-effect mobility between W/L=10μm/10μm and W/L=10μm/0.8μm for n-channel conventional TFTs.
With NH3 Treatment W/L =10μm/10μm Channel Thickness = 50nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
FSA-TFTs with in-situ gate Conventional TFTs
Fig.3-19 Transfer characteristics of n-channel FSA-TFTs with in-situ gate, and W/L=10μm/10μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
With NH3 Treatment W/L =10μm/0.8μm Channel Thickness = 50nm VD = 0.5V, 3.0V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Drain Current ID (A)
10-14
FSA-TFTs with in-situ gate Conventional TFTs
Fig.3-20 Transfer characteristics of n-channel FSA-TFTs with in-situ gate, and W/L=10μm/0.8μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility Field -Effect Mobility μFE (cm2 /V-s)
0
FSA-TFTs with in-situ gate Conventional TFTs
Fig. 3-21 Field-effect mobility of n-channel FSA-TFTs with in-situ gate, and W/L=10μm/10μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds. Field -Effect Mobility μFE (cm2 /V-s)
0
FSA-TFTs with in-situ gate Conventional TFTs
Fig. 3-22 Field-effect mobility of n-channel FSA-TFTs with in-situ gate, and W/L=10μm/0.8μm compare with conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds.
Field-Effect Mobility FSA-TFTs with in-situ gate Channel Thickness = 50 nm VD = 0.5V
Gate Voltage VG (V)
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Field -Effect Mobility μFE (cm2 /V-s)
0
Fig. 3-23 Comparison of field-effect mobility between W/L=10μm/10μm and W/L=10μm/0.8μm for n-channel FSA-TFTs with in-situ gate. Ni-salicide was formed by RTA 500oC for 60 seconds. Field -Effect Mobility μFE (cm2 /V-s)
0
Fig. 3-24 Comparison of field-effect mobility between W/L=10μm/10μm and W/L=10μm/0.8μm for n-channel conventional TFTs.
W/L=10μm/0.8μm
Channel Thickness = 50nm VG-VTH =0.5V-2.5V, Step = 0.5V
Drain Voltage VD (V)
0 1 2 3 4 5
Drain Current I D (μΑ)
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
150 FSA-TFTs with in-situ gate FSA-TFTs with undoped gate Conventional TFTs
Fig.3-25 Comparison of output characteristics between n-channel FSA-TFTs with in-situ doped gate, undoped gate, and conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds. W/L=10μm/0.8μm, and VG-VTH=0.5V, 1.0V, 1.5V, 2.0V, 2.5V.
Floating Body Effect
Drain Current ID (A)
10-14
FSA-TFTs with undoped gate Conventional TFTs
Fig.3-26 Comparison of floating-body effect between n-channel FSA-TFTs with undoped gate and conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds. W/L=10μm/0.8μm, and VD=0.5V, 1.0V, 3.0V, 5.0V, 7.0V.
Floating Body Effect
Drain Current ID (A)
10-14
FSA-TFTs with in-situ gate Conventional TFTs
Fig.3-27 Comparison of floating-body effect between n-channel FSA-TFTs with in-situ gate and conventional TFTs. Ni-salicide was formed by RTA 500oC for 60 seconds. W/L=10μm/0.8μm, and VD=0.5V, 1.0V, 3.0V, 5.0V, 7.0V.
Floating Body Effect VTH roll-off W / L=10μm/0.8μm
Channel Thickness=50 nm
Channel Thickness=50 nm