Light-emitting device

Abstract

To provide a semiconductor device the parasitic capacitance of which is small, or provide a semiconductor device the power consumption of which is small.SOLUTION: Provided is a semiconductor device having a transistor and a capacitive element. The transistor includes a first electrical conductor, a first insulator on the first electrical conductor, a semiconductor having a region that overlaps the first electrical conductor via the first insulator, a second insulator on the semiconductor, a second electrical conductor having a region that overlaps the semiconductor via the second insulator, and a third and a fourth electrical conductor having a region that adjoins the upper surface of the semiconductor. The capacitive element includes the same layer as the first electrical conductor and the same layer as the third and fourth electrical conductors.SELECTED DRAWING: Figure 1

Claims

1. A light-emitting device comprising a pixel having a first transistor, a second transistor, a third transistor, a light-emitting element, a capacitive element, a first wiring, a second wiring, and a third wiring, The gate of the first transistor is always in contact with either the source or the drain of the second transistor. The gate of the first transistor is always in electrical contact with one electrode of the capacitive element. The source and drain of the first transistor are always in electrical contact with the light-emitting element. The source and drain of the first transistor are always in electrical contact with the source and drain of the third transistor. The source and drain of the first transistor are always in electrical contact with the other electrode of the capacitive element. The source and drain of the first transistor are always in electrical contact with the first wiring. The source and drain of the second transistor are always in electrical contact with the second wiring. The source and drain of the third transistor are always in electrical contact with the third wiring. The first transistor described above is The first gate electrode and The first insulator on the first gate electrode, The oxide semiconductor on the first insulator, The second insulator on the oxide semiconductor, The second gate electrode on the second insulator, The third insulator on the second gate electrode, The fourth insulator on the third insulator, A source electrode having a region in contact with the oxide semiconductor, The drain electrode has a region in contact with the oxide semiconductor, The fourth insulator is provided on the source electrode, The fourth insulator is provided on the drain electrode, The third insulator has a region that contacts the upper surface of the second gate electrode, The third insulator has a region that is in contact with the side surface of the second gate electrode, The third insulator has a region that is in contact with the second insulator. The third insulator has a region that is in contact with the upper surface of the oxide semiconductor, The third insulator has a region that is in contact with the side surface of the oxide semiconductor, The third insulator has a region that is in contact with the source electrode, The third insulator has a region that is in contact with the drain electrode, The third insulator has a region that is in contact with the first insulator. The fourth insulator has a region that is in contact with the source electrode, The fourth insulator has a region that is in contact with the drain electrode, The oxide semiconductor has a first region that overlaps with the second insulator and overlaps with the second gate electrode. The oxide semiconductor has a second region that overlaps with the second insulator and does not overlap with the second gate electrode. The oxide semiconductor has a third region that does not overlap with the second insulator and does not overlap with the second gate electrode. The third region has a region with a smaller film thickness than the second region. The second gate electrode comprises a first layer and a second layer on the first layer. In the channel length direction, the first layer has a region that protrudes from the end of the second layer. The first gate electrode has a third layer and a fourth layer on the third layer, The third layer has titanium, The fourth layer has copper, In the channel length direction, both ends of the second insulator are located inward from both ends of the first gate electrode. In the channel length direction, the length of the portion of the first gate electrode that overlaps with the oxide semiconductor is greater than the length of the portion of the second gate electrode that overlaps with the oxide semiconductor. A first electrode is provided, which is on the same layer as the first electrode and made of the same material. A second electrode is provided, which is on the same layer as the source electrode and the drain electrode and is made of the same material. The fourth insulator is provided on the second electrode, The third insulator has a region that is in contact with the second electrode, The fourth insulator has a region that is in contact with the second electrode, The first electrode has a region that overlaps with the second electrode via the first insulator and the third insulator. The first electrode and the second electrode function as electrodes for the capacitive element. The first insulator and the third insulator function as dielectrics for the capacitive element in a light-emitting device.

2. In Claim 1, In the channel length direction, the cross-section of the end of the first layer has a tapered shape. In the channel length direction, the cross-section of the end of the second layer has a tapered shape. In the channel length direction, the cross-section of the end of the third layer has a tapered shape. In the channel length direction, the cross-section of the end of the fourth layer has a tapered shape. A light-emitting device in which the cross-section of the end of the second insulator has a tapered shape in the channel length direction.

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