Display motherboard, preparation method thereof, display substrate and display device

A preparation method of a display motherboard, wherein the display motherboard comprises a plurality of display substrate regions and a cutting region located at a periphery of each of the plurality of display substrate regions;

• the preparation method comprises steps of:
• respectively forming a driving structure layer and a marking structure layer in the plurality of display substrate regions and the cutting region, wherein the marking structure layer comprises a cutting mark layer;
• and
• forming a planarization layer on the driving structure layer and the marking structure layer, wherein the planarization layer covers the marking structure layer;
• wherein the driving structure layer comprises a first source-drain metal layer;
• and the step of respectively forming the driving structure layer and the marking structure layer in the plurality of display substrate regions and the cutting region comprises:
• forming a first insulating layer on a base substrate, forming an active layer on the first insulating layer, forming a second insulating layer covering the active layer, forming a first gate metal layer on the second insulating layer, forming a third insulating layer covering the first gate metal layer, forming a second gate metal layer on the third insulating layer, forming a fourth insulating layer covering the second gate metal layer, and forming the first source-drain metal layer and the cutting mark layer on the fourth insulating layer by the same patterning process;
• wherein the active layer, the first gate metal layer, the second gate metal layer and the first source-drain metal layer are arranged in the display substrate region, and the cutting mark layer is arranged in the cutting region;
• or,
• wherein the driving structure layer comprises a second source-drain metal layer;
• and the step of respectively forming the driving structure layer and the marking structure layer in the plurality of display substrate regions and the cutting region comprises:
• forming a first insulating layer on a base substrate, forming an active layer on the first insulating layer, forming a second insulating layer covering the active layer, forming a first gate metal layer on the second insulating layer, forming a third insulating layer covering the first gate metal layer, forming a second gate metal layer on the third insulating layer, forming a fourth insulating layer covering the second gate metal layer, forming the first source-drain metal layer on the fourth insulating layer, forming a fifth insulating layer covering the first source-drain metal layer, forming a first planarization layer on the fifth insulating layer, and forming the second source-drain metal layer and the cutting mark layer on the first planarization layer by the same patterning process;
• wherein the active layer, the first gate metal layer, the second gate metal layer, the first source-drain metal layer and the second source-drain metal layer are arranged in the display substrate region, and the cutting mark layer is arranged in the cutting region.