Thin-film transistor array substrate and preparation method thereof

The invention provides a substrate for a thin film transistor (TFT) array and a method for manufacturing the same. The substrate for the TFT array comprises the substrate, a plurality of multicrystal silicon islands and a plurality of grid electrodes, wherein the substrate has a display zone, a grid electrode drive zone and a source electrode drive zone; the multicrystal silicon islands are arranged on the substrate, and each multicrystal silicon island has a source electrode zone, a drain electrode zone and a channel zone positioned between the source electrode zone and the drain electrode zone; moreover, the multicrystal silicon islands comprise a plurality of first multicrystal silicon islands and second multicrystal silicon islands, wherein the first multicrystal silicon islands are arranged inside the display zone and the grid electrode drive zone, and have major grain boundaries and minor grain boundaries, and the major grain boundaries is only positioned inside the source electrode zone and/or the drain electrode zone; the second multicrystal silicon islands are arranged inside the source electrode drive zone; the size of grain inside the first multicrystal silicon islands is different from that inside the second multicrystal silicon islands; and the grid electrodes are arranged on the substrate and are corresponding to the channel zone.