Electronic device and electronic apparatus
View Patent ↗An EL display having high operating performance and reliability is provided. LDD regions 15 a through 15 d of a switching TFT 201 formed in a pixel are formed such that they do not overlap gate electrodes 19 a and 19 b to provide a structure which is primarily intended for the reduction of an off-current. An LDD region 22 of a current control TFT 202 is formed such that it partially overlaps a gate electrode 35 to provide a structure which is primarily intended for the prevention of hot carrier injection and the reduction of an off-current. Appropriate TFT structures are thus provided depending on required functions to improve operational performance and reliability.
1. An EL display device having a pixel portion and a driving circuit portion formed on an insulating surface,
the driver circuit portion comprising:
at least one p-channel type TET having no LDD region,
the pixel portion comprising:
at least two switching TFTs connected to each other in series;
at least one current-control TFT electrically connected to the switching TFT; and
an EL element connected to the current control TFT,
wherein an LDD (lightly-doped-drain) region formed in the switching TFT does not overlap a gate electrode with a gate insulating film interposed therebetween,
wherein an LDD region formed in the current-control TFT partially overlaps a gate electrode with a gate insulating film interposed therebetween.
2. An EL display device according to claim 1 wherein a length of the LDD region overlapping the gate electrode of the current-control TFT is in the range from 1 to 3 μm.
3. An EL display device according to claim 1 wherein an n-type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2 to 10 times higher than that of the LDD region of the switching TFT.
4. An EL display device according to claim 1 wherein an n-type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2×10 16 to 5×10 19 atoms/cm 3 .
5. An EL display device according to claim 1 wherein the EL display device is selected from the group consisting of a video camera, a digital camera, a goggle type display, a navigation system, a sound reproduction device, a note type personal computer, a game machine, a portable information terminal, and an image projection device.
6. An EL display device having a pixel portion and a driving circuit portion formed on an insulating surface,
the driving circuit portion comprising:
at least one p-channel type TFT having no LDD region,
at least one n-channel type TFT having an LDD region entirely overlapping a gate electrode with a gate insulation film interposed therebetween, and
the pixel portion comprising:
at least two switching TFTs connected to each other in series;
at least one current-control TFT electrically connected to the switching TFT, and
an EL element connected to the current control TFT,
wherein an LDD (lightly-doped-drain) region formed in the switching TFT does not overlap a gate electrode with a gate insulating film interposed therebetween,
wherein an LDD region formed in the current-control TFT partially overlaps a gate electrode with a gate insulating film interposed therebetween.
7. An EL display device according to claim 6 wherein a length of the LDD region overlapping the gate electrode of the current-control TFT is in the range from 1 to 3 μm.
8. An EL display device according to claim 6 wherein an n-type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2 to 10 times higher than that of the LDD region of the switching TFT.
9. An EL display device according to claim 6 wherein an n type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2×10 16 to 5×10 19 atoms/cm 3 .
10. An EL display device according to claim 6 wherein the EL display device is selected from the group consisting of a video camera, a digital camera, a goggle type display, a navigation system, a sound reproduction device, a note type personal computer, a game machine, a portable information terminal, and an image projection device.
11. An EL display device having at least one pixel, said pixel comprising:
at least two switching TFTs connected each other in series;
at least one current-control TFT electrically connected to the switching TFT; and
an EL element connected to the current control TFT,
wherein an LDD (lightly-doped-drain) region formed in the switching TFT does not overlaps a gate electrode with a gate insulating film interposed therebetween,
wherein an LDD region formed in the current-control TFT partially overlaps a gate electrode with a gate insulating film interposed therebetween, and
wherein a channel region formed in the current-control TFT is in contact with a source region and the LDD region.
12. An EL display device according to claim 11 wherein an n-type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2×10 16 to 5×10 19 atoms/cm 3 .
13. An EL display device according to claim 11 wherein an n-type impurity element is contained in the LDD region of the switching TFT at a concentration of 1×10 16 to 5×10 18 atoms/cm 3 .
14. An EL display device according to claim 11 wherein the EL display device is selected from the group consisting of a video camera, a digital camera, a goggle type display, a navigation system, a sound reproduction device, a note type personal computer, a game machine, a portable information terminal, and an image projection device.
15. An EL display device having a pixel portion and a driving circuit portion formed on an insulating surface,
the driving circuit portion comprising:
at least one n-channel type TFT having an LDD region partially or entirely overlapping a gate electrode with a gate insulation film interposed, and
the pixel portion comprising:
at least two switching TFTs connected to each other in series;
at least one current-control TFT electrically connected to the switching TFT; and
an EL element connected to the current control TFT,
wherein an LDD (lightly-doped-drain) region formed in the switching TFT does not overlap a gate electrode with a gate insulating film interposed therebetween,
wherein an LDD region formed in the current-control TFT partially overlaps a gate electrode with a gate insulating film interposed therebetween, and
wherein a channel region formed in the current-control TFT is in contact with a source region and the LDD region.
16. An EL display device according to claim 15 wherein an n-type impurity element is contained in the LDD region of the current-control TFT at a concentration of 2×10 16 to 5×10 19 atoms/cm 3 .
17. An EL display device according to claim 15 wherein an n-type impurity element is contained in the LDD region of the switching TFT at a concentration of 1×10 16 to 5×10 18 atoms/cm 3 .
18. An EL display device according to claim 15 wherein the EL display device is selected from the group consisting of a video camera, a digital camera, a goggle type display, a navigation system, a sound reproduction device, a note type personal computer, a game machine, a portable information terminal, and an image projection device.