Manufacturing method of thin film transistor and liquid crystal display device
View Patent ↗Etching of a semiconductor layer including a part over a gate wiring and formation of a contact hole for connection between a pixel electrode and a drain electrode are performed by one-time photolithography step and one-time etching step; thus, the number of photolithography steps is reduced. The exposed part of the gate wiring is covered by an insulating layer, and this insulating layer also functions as a spacer for maintaining a space for a liquid crystal layer. By the reduction in the number of photolithography steps, a liquid crystal display device can be provided at lower cost and higher productivity. Using an oxide semiconductor for the semiconductor layer can realize a liquid crystal display device with low power consumption and high reliability.
1. A manufacturing method of a liquid crystal display device, comprising:
forming a plurality of transistors, the formation of the plurality of transistors comprising:
forming gate electrodes and a gate wiring over a substrate by a first photolithography step;
forming a gate insulating layer over the gate electrodes;
forming a semiconductor layer over the gate insulating layer; and
forming source electrodes and drain electrodes over the semiconductor layer by a second photolithography step;
forming a first insulating layer over the source electrodes and the drain electrodes;
forming contact holes by selectively removing first parts of the first insulating layer wherein the first parts overlap with the drain electrodes, and removing a second part of the first insulating layer, a third part of the semiconductor layer, and a fourth part of the gate insulating layer wherein each of the second part, the third part, and the fourth part overlaps with neither the source electrodes nor the drain electrodes, by a third photolithography step, wherein the third photolithography step comprises a step of exposing a part of the gate wiring positioned between the plurality of transistors to divide the semiconductor layer;
forming pixel electrodes over the first insulating layer by a fourth photolithography step, wherein the fourth photolithography step is performed so that the pixel electrodes are electrically disconnected from the exposed gate wiring; and
forming, over the exposed gate wiring, a second insulating layer serving as a spacer maintaining a space that is to be filled with a liquid crystal.
2. The manufacturing method of a liquid crystal display device according to claim 1 , further comprising:
forming a base layer between the substrate and the gate electrodes.
3. The manufacturing method of a liquid crystal display device according to claim 1 , wherein the semiconductor layer includes an oxide semiconductor.
4. The manufacturing method of a liquid crystal display device according to claim 1 , wherein at least one of the gate electrodes, the gate wiring, the source electrodes, and the drain electrodes comprises a material containing copper.
5. The manufacturing method of a liquid crystal display device according to claim 4 , wherein a maximum process temperature after the formation of the gate electrodes, the gate wiring, the source electrodes, or the drain electrodes is 450° C. or lower.
6. The manufacturing method of a liquid crystal display device according to claim 1 , wherein at least one of the gate electrodes, the gate wiring, the source electrodes, and the drain electrodes comprises a material containing aluminum.
7. The manufacturing method of a liquid crystal display device according to claim 6 , wherein a maximum process temperature after the formation of the gate electrodes, the gate wiring, the source electrodes, or the drain electrodes is 380° C. or lower.
8. A manufacturing method of a liquid crystal display device, comprising:
forming a conductive layer;
forming a first insulating layer over the conductive layer;
forming a semiconductor layer over the first insulating layer;
forming a first electrode and a second electrode over the semiconductor layer;
forming a second insulating layer over the first electrode and the second electrode;
removing a first part of the second insulating layer, a second part of the second insulating layer, a third part of the semiconductor layer, and a fourth part of the first insulating layer, so as to form a contact hole at the first part, and to expose a part of the conductive layer;
forming a pixel electrode over the second insulating layer so as to be electrically disconnected from the exposed part of the conductive layer, and to be electrically connected to the first electrode through the contact hole; and
forming a third insulating layer that overlaps with the exposed part of the conductive layer.
9. The manufacturing method of a liquid crystal display device according to claim 8 , further comprising:
forming a base layer under the conductive layer.
10. The manufacturing method of a liquid crystal display device according to claim 8 , wherein the semiconductor layer includes an oxide semiconductor.
11. The manufacturing method of a liquid crystal display device according to claim 8 , wherein at least one of the conductive layer, the first electrode, and the second electrode comprises a material containing copper.
12. The manufacturing method of a liquid crystal display device according to claim 11 , wherein a maximum process temperature after the formation of the first electrode and the second electrode is 450° C. or lower.
13. The manufacturing method of a liquid crystal display device according to claim 8 , wherein at least one of the conductive layer, the first electrode, and the second electrode comprises a material containing aluminum.
14. The manufacturing method of a liquid crystal display device according to claim 13 , wherein a maximum process temperature after the formation of the first electrode and the second electrode is 380° C. or lower.
15. A manufacturing method of a liquid crystal display device, comprising:
forming a conductive layer;
forming a first insulating layer over the conductive layer;
forming a semiconductor layer over the first insulating layer;
forming a first electrode and a second electrode over the semiconductor layer;
forming a second insulating layer over the first electrode and the second electrode;
removing a first part of the second insulating layer, a second part of the second insulating layer, a third part of the semiconductor layer, and a fourth part of the first insulating layer, so as to form a contact hole at the first part, and to expose a part of the conductive layer;
forming a pixel electrode over the second insulating layer so as to be electrically disconnected from the exposed part of the conductive layer, to be electrically connected to the first electrode through the contact hole, and so as not to overlap with a channel formation region of the semiconductor layer; and
forming a third insulating layer that overlaps with the exposed part of the conductive layer.
16. The manufacturing method of a liquid crystal display device according to claim 15 , further comprising:
forming a base layer under the conductive layer.
17. The manufacturing method of a liquid crystal display device according to claim 15 , wherein the semiconductor layer includes an oxide semiconductor.
18. The manufacturing method of a liquid crystal display device according to claim 15 , wherein at least one of the conductive layer, the first electrode, and the second electrode comprises a material containing copper.
19. The manufacturing method of a liquid crystal display device according to claim 18 , wherein a maximum process temperature after the formation of the first electrode and the second electrode is 450° C. or lower.
20. The manufacturing method of a liquid crystal display device according to claim 15 , wherein at least one of the conductive layer, the first electrode, and the second electrode comprises a material containing aluminum.
21. The manufacturing method of a liquid crystal display device according to claim 20 , wherein a maximum process temperature after the formation of the first electrode and the second electrode is 380° C. or lower.