Display apparatus having an oxide semiconductor
A display apparatus may include at least one switching thin film transistor and a driving thin film transistor, which are disposed on a device substrate. The driving thin film transistor may include a driving semiconductor pattern made of an oxide semiconductor. A light-blocking pattern may be disposed between the device substrate and the driving semiconductor pattern. The light-blocking pattern may be disposed close to the driving semiconductor pattern. Thus, in the display apparatus, a current variation value according to a voltage applied to the driving gate electrode of the driving thin film transistor may be reduced, without changing the characteristics of the switching thin film transistor. Thereby, in the display apparatus, the occurrence of a spot in low grayscale may be prevented.
1 . A display apparatus, comprising:
a first separation insulating layer on a device substrate;
a first switching thin film transistor on the device substrate in a pixel area for displaying an image, the first switching thin film transistor including a first semiconductor pattern between the device substrate and the first separation insulating layer and a first gate electrode on the first semiconductor pattern;
a second switching thin film transistor on the first separation insulating layer in the pixel area, the second switching thin film transistor including a second semiconductor pattern made of a material different from the first semiconductor pattern, the second switching thin film transistor including a second gate electrode disposed above the second semiconductor pattern;
a driving thin film transistor on the first separation insulating layer in the pixel area, the driving thin film transistor including a driving semiconductor pattern made of a same material as the second semiconductor pattern, the driving thin film transistor including a driving gate electrode disposed above the driving semiconductor pattern;
a first light-blocking pattern between the device substrate and the first separation insulating layer in the pixel area, the first light-blocking pattern overlapping with the second semiconductor pattern without any metal layer being interposed between the first light-blocking pattern and the second semiconductor pattern; and
a second light-blocking pattern disposed above the first separation insulating layer in the pixel area, the second light-blocking pattern overlapping with the driving semiconductor pattern,
wherein the second light-blocking pattern includes a conductive material,
wherein a distance between the second light-blocking pattern and the driving semiconductor pattern is smaller than a distance between the first light-blocking pattern and the second semiconductor pattern,
wherein the first light-blocking pattern in the pixel area is disposed between a first gate insulating layer positioned below the first gate electrode and a first interlayer insulating layer that covers the first gate electrode, the first light-blocking pattern being placed below the first interlayer insulating layer,
wherein the second light-blocking pattern is disposed on the first interlayer insulating layer, and
wherein a distance between the second light-blocking pattern and the driving semiconductor pattern is less than a distance between the second gate electrode and the second semiconductor pattern and is less than a distance between the driving gate electrode and the driving semiconductor pattern.
2 . The display apparatus according to claim 1 , wherein the first semiconductor pattern includes silicon, and the second semiconductor pattern and the driving semiconductor pattern include an oxide semiconductor.
3 . The display apparatus according to claim 1 , wherein the first light-blocking pattern includes a material different from the second light-blocking pattern.
4 . The display apparatus according to claim 3 , wherein the first light-blocking pattern includes a same material as the first gate electrode of the first switching thin film transistor.
5 . The display apparatus according to claim 1 , further comprising a second separation insulating layer between the second light-blocking pattern and the driving semiconductor pattern,
wherein the second separation insulating layer extends between the first separation insulating layer and the second semiconductor pattern.
6 . The display apparatus according to claim 5 , wherein the second separation insulating layer has a thickness thinner than the first separation insulating layer.
7 . The display apparatus according to claim 5 , wherein the second separation insulating layer includes a same material as the first separation insulating layer.
8 . The display apparatus according to claim 7 , wherein the first separation insulating layer and the second separation insulating layer are an inorganic insulating layer made of silicon oxide.
9 . A display apparatus, comprising:
a first switching thin film transistor on a device substrate in a pixel area for displaying an image, the first switching thin film transistor including a first semiconductor pattern, a first gate electrode, a first source electrode and a first drain electrode;
a first gate insulating layer on the device substrate, the first gate insulating layer between the first semiconductor pattern and the first gate electrode;
a first separation insulating layer on the first gate insulating layer, the first separation insulating layer between the first gate electrode and the first source electrode and between the first gate electrode and the first drain electrode;
a second switching thin film transistor on the first separation insulating layer in the pixel area, the second switching thin film transistor including a second semiconductor pattern, a second gate electrode, a second source electrode and a second drain electrode;
a first light-blocking pattern between the first gate insulating layer and the first separation insulating layer in the pixel area, the first light-blocking pattern overlapping with the second semiconductor pattern without any metal layer being interposed between the first light-blocking pattern and the second semiconductor pattern;
a driving thin film transistor disposed in the pixel area and being spaced apart from the first switching thin film transistor and the second switching thin film transistor, the driving thin film transistor including a driving semiconductor pattern, a driving gate electrode, a driving source electrode and a driving drain electrode;
a second light-blocking pattern on the first separation insulating layer in the pixel area, the second light-blocking pattern including a conductive material and overlapping with the driving semiconductor pattern;
a second separation insulating layer between the second light-blocking pattern and the driving semiconductor pattern, the second separation insulating layer extending between the first separation insulating layer and the second semiconductor pattern; and
a second gate insulating layer between the driving semiconductor pattern and the driving gate electrode, the second gate insulating layer extending between the second semiconductor pattern and the second gate electrode,
wherein a first capacitance between the second light-blocking pattern and the driving semiconductor pattern is larger than a second capacitance between the driving semiconductor pattern and the driving gate electrode,
wherein the first light-blocking pattern in the pixel area is disposed between the first gate insulating layer positioned below the first gate electrode and a first interlayer insulating layer that covers the first gate electrode, the first light-blocking pattern being placed below the first interlayer insulating layer,
wherein the second light-blocking pattern is disposed on the first interlayer insulating layer, and
wherein a distance between the second light-blocking pattern and the driving semiconductor pattern is less than a distance between the second gate electrode and the second semiconductor pattern and is less than a distance between the driving gate electrode and the driving semiconductor pattern.
10 . The display apparatus according to claim 9 , wherein a capacitance between the second semiconductor pattern and the second gate electrode is same as the second capacitance.
11 . The display apparatus according to claim 9 , wherein the second light-blocking pattern is electrically connected to the driving source electrode.
12 . The display apparatus according to claim 9 , further comprising a storage capacitor being spaced apart from the first switching thin film transistor, the second switching thin film transistor and the driving thin film transistor,
wherein the storage capacitor includes a capacitor lower electrode and a capacitor upper electrode, which are stacked on the first separation insulating layer.
13 . The display apparatus according to claim 12 , wherein the capacitor lower electrode includes a same material as the second light-blocking pattern,
wherein the capacitor upper electrode includes a same material as the driving gate electrode, and
wherein the second separation insulating layer and the second gate insulating layer extend between the capacitor lower electrode and the capacitor upper electrode.
14 . The display apparatus according to claim 1 , wherein a thickness of a second separation insulating layer disposed between the second light-blocking pattern and the driving semiconductor pattern is thinner than a thickness of a second gate insulating layer disposed between the second gate electrode and the second semiconductor pattern and between the driving gate electrode and the driving semiconductor pattern.
15 . The display apparatus according to claim 1 , wherein a distance between the driving gate electrode and the second light-blocking pattern is smaller than a distance between the second gate electrode and the first light-blocking pattern.
16 . The display apparatus according to claim 1 , wherein the second light-blocking pattern corresponds to a lowest metal layer between the driving thin film transistor and the device substrate.