Active matrix display device having multiple gate electrode portions
First Claim
Patent Images
1. An active matrix type display device comprising at least a thin film transistor including:
- a semiconductor island including;
a source region, a drain region, and at least a first channel forming region, a second channel forming region, and a third channel forming region, each being formed between the source region and the drain region;
a gate insulating film; and
a gate electrode, adjacent to the semiconductor island and having the gate insulating film between said semiconductor island and said gate electrode, wherein the gate electrode is divided into at least a first gate electrode portion, a second gate electrode portion and a third gate electrode portion, wherein the first gate electrode portion is formed over the first channel forming region and the closest to the drain region, the first channel forming region being the closest to the drain region, wherein the first gate electrode has the narrowest width so that the first channel forming region has the shortest channel length, wherein the third gate electrode portion is formed over the third channel forming region and the closest to the source region thereby the third channel forming region being defined the closest to the source region, wherein the third gate electrode portion has the widest width so that the third channel forming region has the longest channel length, wherein a current flows from the source region to the drain region through each of the first, second and third channel forming regions in a channel length direction.
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Abstract
In a thin-film transistor of multi-gate structure, the width of a channel forming region 108 closest to a drain region 102 is made the narrowest. This prevents a transistor structure closest to the drain region from first deteriorating. Further, the channel length at the vicinity of a center of an active layer is intentionally widened, so that the amount of current flowing through the vicinity of the center of the active layer is decreased and the deteriorating phenomenon due to heat accumulation is prevented. Therefore, a semiconductor device with a high reliability is realized.
139 Citations
30 Claims
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1. An active matrix type display device comprising at least a thin film transistor including:
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a semiconductor island including;
a source region, a drain region, and at least a first channel forming region, a second channel forming region, and a third channel forming region, each being formed between the source region and the drain region;
a gate insulating film; and
a gate electrode, adjacent to the semiconductor island and having the gate insulating film between said semiconductor island and said gate electrode, wherein the gate electrode is divided into at least a first gate electrode portion, a second gate electrode portion and a third gate electrode portion, wherein the first gate electrode portion is formed over the first channel forming region and the closest to the drain region, the first channel forming region being the closest to the drain region, wherein the first gate electrode has the narrowest width so that the first channel forming region has the shortest channel length, wherein the third gate electrode portion is formed over the third channel forming region and the closest to the source region thereby the third channel forming region being defined the closest to the source region, wherein the third gate electrode portion has the widest width so that the third channel forming region has the longest channel length, wherein a current flows from the source region to the drain region through each of the first, second and third channel forming regions in a channel length direction. - View Dependent Claims (2, 3, 4, 5)
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6. An active matrix type display device comprising at least a thin film transistor including:
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a semiconductor island with a serpentine shape, said semiconductor island including;
a source region, a drain region, and at least a first channel forming region, a second channel forming region an d a third channel forming region, each being formed between the source region and the drain region;
a gate insulating film; and
a gate electrode adjacent to the serpentine shaped semiconductor island the gate insulating film between said semiconductor island and said gate electrode, wherein the gate electrode has at least a first gate electrode portion, a second gate electrode portion and a third gate electrode portion, wherein the first gate electrode portion is formed over the first channel forming region and the closest to the drain region thereby the first channel forming region being defined the closest to the drain region, wherein the first gate electrode has the narrowest width so that the first channel forming region has the shortest channel length, wherein the third gate electrode portion is formed over the third channel forming region and the closest to the source region thereby the third channel forming region being defined the closest to the source region, wherein the third gate electrode portion has the widest width so that the third channel forming region has the longest channel length, wherein a current flows from the source region to the drain region through each of the first, second and third channel forming regions in a channel length direction. - View Dependent Claims (7, 8, 9, 10)
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11. An active matrix type display device comprising:
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a driving circuit portion; and
a pixel matrix circuit portion, said pixel matrix circuit portion including at least a pixel thin film transistor, said pixel thin film transistor comprising;
a semiconductor island including;
a source region, a drain region, and at least a first channel forming region, a second channel forming region and a third channel forming region, each being formed between the source region and the drain region;
a gate insulating film; and
a gate electrode adjacent to the semiconductor island having the gate insulating film therebetween, wherein the gate electrode has a symmetrical structure and is divided into at least a first gate electrode portion, a second gate electrode portion and a third gate electrode portion, wherein the first gate electrode portion is formed over the first channel forming region and the closest to one of the source and drain regions, wherein the third gate electrode portion is formed over the third channel forming region and the closest to the other of the source and drain regions, wherein the second gate electrode portion is formed over the second channel forming region and between the first and third gate electrode portion thereby the second channel forming region being defined between the first and third channel forming regions, wherein the second gate electrode portion has the widest width so that the second channel forming region has the longest channel length, wherein each of the first and third gate electrodes has a same width which is narrower than a width of the second gate electrode portion so that each of the first and third channel forming regions has a same length which is shorter than a width of the second channel forming region, wherein a current flows from the source region to the drain region through each of the first, second and third channel forming regions in a channel length direction, wherein the source region and the drain region are interchanged with each other every time of a charge and a discharge. - View Dependent Claims (12, 13, 14, 15)
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16. An active matrix type display device comprising at least a thin film transistor including:
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a semiconductor island including;
a source region, a drain region, and a channel forming region being formed between the source and drain regions;
a gate insulating film; and
a gate electrode adjacent to the semiconductor island having the gate insulating film therebetween, wherein the gate electrode has two end portions and a center portion formed between the two end portions, each of the end and center portions being located in a channel width direction, wherein the center portion of the gate electrode has the widest width so that a center portion of the channel forming region has the longest channel length, wherein a current flows from the source region to the drain region through the channel forming region in a channel length direction. - View Dependent Claims (17, 18, 19, 20)
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21. An active matrix type display device comprising at least a thin film transistor including:
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a semiconductor island including;
a source region, a drain region, and a channel forming region being formed between the source region and the drain region;
a gate insulating film; and
a gate electrode adjacent to the semiconductor island having the gate insulating film therebetween, wherein the gate electrode has two end portions and a middle portion formed between the two end portions, each of the end and middle portions being located in a channel width direction, wherein the channel forming region has a plurality of slits therein so that a plurality of active regions are defined and electrically connected in parallel to each other, wherein the middle portion of the gate electrode has the widest width so that a middle portion of the channel forming region has the longest channel length, wherein a current flows from the source region to the drain region through the channel forming region in a channel length direction. - View Dependent Claims (22, 23, 24, 25)
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26. An active matrix type display device comprising at least a thin film transistor including:
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a semiconductor island including;
a source region;
a drain region;
at least a first channel forming region, a second channel forming region and a third channel forming region, each being formed between the source and drain regions;
a gate insulating film;
a gate electrode adjacent to the semiconductor island having the gate insulating film therebetween;
wherein the gate electrode is divided into at least a first gate electrode portion, a second gate electrode portion and a third gate electrode portion;
wherein the first gate electrode portion is formed over the first channel forming region and the closest to the drain region thereby the first channel forming region being defined the closest to the drain region;
wherein the first gate electrode portion has the narrowest width so that the first channel forming region has the shortest channel length;
wherein the third gate electrode portion is formed over the third channel forming region and the closest to the source region thereby the third channel forming region being defined the closest to the source region;
wherein the third gate electrode portion has the widest width so that the third channel forming region has the longest channel length;
wherein each of the first, second and third gate electrode portions has two end portions and a middle portion formed between the two end portions, of the end and middle portions being located in a channel width direction;
wherein the middle portion of each of the first, second and third gate electrodes has the widest width so that a middle portion of each of the first, second and third channel forming regions has the longest channel length; and
wherein a current flows from the source region to the drain region through each of the first, second, and third channel forming regions in a channel length direction. - View Dependent Claims (27, 28, 29, 30)
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Specification
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Current AssigneeSemiconductor Energy Laboratory Co., Ltd.
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Original AssigneeSemiconductor Energy Laboratory Co., Ltd.
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InventorsHayakawa, Masahiko, Tsukamoto, Yosuke
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Primary Examiner(s)CARROLL, JAMES J
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Application NumberUS08/970,542Time in Patent Office1,180 DaysField of Search257/401, 257/72, 257/368, 257/57, 257/66, 257/365US Class Current257/401CPC Class CodesG02F 1/1368 in which the switching elem...H01L 27/12 the substrate being other t...H01L 29/42384 for thin film field effect ...H01L 29/78696 characterised by the struct...
