Gate oxide : 1000A
Vd = 0.1V Vd = 5V
Field Effect Mobility (cm 2/V-s)
Fig. 3-15 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 40 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0.070
conventional top gate LTPS-TFT (W/L= 2/2um)
conventional top gate LTPS-TFT (W/L= 1.5/1.5um)
conventional top gate LTPS-TFT (W/L= 1.2/1.2um)
20 shots Gate oxide: 1000 Å
0.070
conventional top gate LTPS-TFT (W/L= 2/2um)
conventional top gate LTPS-TFT (W/L= 1.5/1.5um)
conventional top gate LTPS-TFT (W/L= 1.2/1.2um)
20 shots Gate oxide: 1000 Å
Table 3. 2 Measured optimal electrical characteristics of TFTs crystallized with VSGB-LTPS structure and conventional structure in short channel devices. The thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8
Con. top gate device
|Vg-Vth|= 8V and 6V W/L=1.2u/1.2um 10 shots
Gate oxide : 1000A
Fig. 3-16 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.2 μm, in which the thickness of gate oxide
was 1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 1 2 3 4 5 6 7 8
Con. top gate device
|Vg-Vth|= 8V and 6V W/L=1.5u/1.5um 10 shots
Gate oxide : 1000A
Fig. 3-17 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.5 μm, in which the thickness of gate oxide
was 1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 1 2 3 4 5 6 7 8
Con. top gate deviec
|Vg-Vth|= 8V and 6V W/L=2u/2um 10 shots
Gate oxide : 1000A
Fig. 3-18 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 2 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 1 2 3 4 5 6 7 8 9 10
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=3u/3um 10 shots
Gate oxide : 1000A
Fig. 3-19 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 3 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 1 2 3 4 5 6 7 8 9 10
Con. top gate device
|Vg-Vth|= 8V and 6V W/L=5u/5um 10 shots
Gate oxide : 1000A
Fig. 3-20 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 20 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 2 4 6 8 10 12 14 16 18
Con. top gate device
|Vg-Vth|= 8and 6V W/L=20u/20um 10 shots
Gate oxide : 1000A
Fig. 3-21 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 20 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 2 4 6 8 10 12 14 16 18 20 22 24
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=40u/40um 10 shots
Gate oxide : 1000A
Fig. 3-22 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 40 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 10(ie. 90% overlapping).
0 1 2 3 4 5 6 7 8
Con. top gate device
|Vg-Vth|= 8V and 6V W/L=1.2u/1.2um 20 shots
Gate oxide : 1000A
Fig. 3-23 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.2 μm, in which the thickness of gate oxide
was 1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8 Con. top gate device
|Vg-Vth|= 8V and 6V W/L=1.5u/1.5um 20 shots Gate oxide :1000A
Fig. 3-24 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.5 μm, in which the thickness of gate oxide
was 1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8
Con. top gate device
|Vg-Vth|= 8V and 6V W/L=2u/2um 20 shots
Gate oxide : 1000A
Fig. 3-25 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 2 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8 9 10
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=3u/3um 20 shots
Gate oxide : 1000A
Fig. 3-26 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 3 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8 9 10
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=5u/5um 20 shots
Gate oxide : 1000A
Fig. 3-27 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 5 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=20u/20um 20 shots
Gate oxide : 1000A
Fig. 3-28 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 20 μm, in which the thickness of gate oxide was
1000Å. The number of laser shots was 20(ie. 95% overlapping).
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Con. top gate device
|Vg-Vth|= 8Vand 6V W/L=40u/40um 20 shots
Gate oxdie : 1000A
Fig. 3-29 The output characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 40 μm, in which the thickness of gate oxide was 1000Å. The number of laser shots was 20(ie.
95% overlapping).
2/2 1.5/1.5 1.2/1.2 0
100 200 300 400 500 600
VSGB device Con. top gate device 10 shots
Gate oxide : 1000A
Dimension W/L (um/um) Feiled Effect Mobility (cm2 /V-s)
Fig. 3-30 The dependence of field-effect mobility on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate
oxide was 1000Å. The number of laser shots was 10(ie. 90% overlapping).
Fig. 3-31 The dependence of threshold voltage on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate
oxide was 1000Å. The number of laser shots was 10(ie. 90% overlapping).
2/2 1.5/1.5 1.2/1.2
Standard Deviation of Mobility (cm2 /V-s)
Dimension W/L(um/um) VSGB device Con. top gate device 10 shots
Gate oxide : 1000A
Fig. 3-32 The dependences of standard deviation of field-effect mobility and threshold voltage on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate oxide was 1000Å. The number of laser shots was 10(ie. 90%
overlapping). Con. top gate device 20 shots
Gate oxide : 1000A
Dimension W/L (um/um) Feiled Effect Mobility (cm2 /V-s)
Fig. 3-33 The dependence of field-effect mobility on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate
oxide was 1000Å. The number of laser shots was 20(ie. 95% overlapping).
2/2 1.5/1.5 1.2/1.2
14 VSGB device
Con. top gate device 20 shots
Gate oxide : 1000A
Threshold Voltage V th(V)
Dimension W/L(um/um)
Fig. 3-34 The dependence of threshold voltage on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate
oxide was 1000Å. The number of laser shots was 20(ie. 95% overlapping).
2/2 1.5/1.5 1.2/1.2
Standard Deviation of Mobility (cm2 /V-s)
VSGB device Con. top gate device 20 shots
Gate oxide : 1000A
Standard Deviation of Threshold Voltage (V)
Dimension W/L(um/um)
Fig. 3-35 The dependences of standard deviation of field-effect mobility and threshold voltage on the channel length of LTPS TFTs crystallized with VSGB-LTPS and conventional top-gate structures. The thickness of gate oxide was 1000Å. The number of laser shots was 20(ie. 95%
overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 1.2u/1.2um 10 shots
Gate oxide : 500A Vd = 0.1V
Vd = 3V
Fig. 3-36 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.2 μm, in which the thickness of gate oxide
was 500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 1.5u/1.5um 10 shots Gate oxide : 500A
Vd = 0.1V Vd = 3V
Fig. 3-37 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 1.5 μm, in which the thickness of gate oxide
was 500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 2u/2um
Fig. 3-38 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 2 μm, in which the thickness of gate oxide was
500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 3u/3um
10 shots Gate oxide : 500A
Vd = 0.1V Vd = 3V
Field Effect Mobility (cm 2/V-s)
Fig. 3-39 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 3 μm, in which the thickness of gate oxide was
500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 5u/5um
10 shots Gate oxide : 500A
Vd = 0.1V Vd = 3V
Field Effect Mobility (cm 2/V-s)
Fig. 3-40 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 5 μm, in which the thickness of gate oxide was
500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 20u/20um
Fig. 3-41 The typical transfer characteristic of polycrystalline silicon TFTs crystallized using VSGB-LTPS structure with channel length of 20 μm, in which the thickness of gate oxide was
500Å. The number of laser shots was 10(ie. 90% overlapping).
-20 -15 -10 -5 0 5 10 15 20
Drain Current Ids (A)
Gate Voltage Vgs (V) VSGB device
Con. top gate device W/L = 40u/40um