Display device, display module, electronic device, and manufacturing method of display device

A display device comprising:

• a first insulating layer;
• a second insulating layer;
• a first conductive layer;
• a second conductive layer;
• a first transistor;
• a second transistor;
• a first light-emitting diode;
• a second light-emitting diode;
• and
• a color conversion layer,
• wherein the first transistor is electrically connected to the first light-emitting diode through the first conductive layer,
• wherein the second transistor is electrically connected to the second light-emitting diode through the second conductive layer,
• wherein the first insulating layer is over the first transistor and the second transistor,
• wherein the first light-emitting diode and the second light-emitting diode are over the first insulating layer,
• wherein the first light-emitting diode comprises a first electrode in contact with the first conductive layer,
• wherein the second light-emitting diode comprises a second electrode in contact with the second conductive layer,
• wherein a top surface of the first electrode and a top surface of the second electrode are level or substantially level with a top surface of the second insulating layer,
• wherein the color conversion layer is over the second light-emitting diode,
• wherein the color conversion layer is configured to convert light emitted from the second light-emitting diode into a light having a longer wavelength,
• wherein the first transistor and the second transistor each comprise a metal oxide layer, and
• wherein the metal oxide layer comprises a channel formation region.

A manufacturing method of a display device, comprising:

• forming a plurality of transistors in a matrix over a first substrate;
• forming a plurality of light-emitting diodes in a matrix over a second substrate;
• forming a first conductor electrically connected to a transistor of the plurality of transistors or a light-emitting diode of the plurality of light-emitting diodes over the first substrate or the second substrate;
• bonding the first substrate and the second substrate so that the transistor and the light-emitting diode are electrically connected to each other through the first conductor;
• exposing a first surface by separating the second substrate;
• and
• forming a color conversion layer over the first surface,
• wherein the color conversion layer overlaps with the light-emitting diode, and
• wherein planarization treatment is performed at least once in formation process of the plurality of transistors.