Back-channel-etched tft substrate and manufacturing method thereof

A back-channel-etched (BCE) thin film transistor (TFT) substrate, comprising:

• a base substrate, a gate disposed on the base substrate, a gate insulating layer disposed on the gate, an active layer disposed on the gate insulating layer, a source and a drain separated with interval on the active layer, and a passivation layer disposed on the source, the drain, and the active layer;
• the passivation layer comprising a first silicon oxide thin film disposed on the source, the drain, and the active layer, and a second silicon oxide thin film disposed on the first silicon oxide thin film;
• Si:O atomic ratio in a superficial layer of the second silicon oxide thin film being close to or the same as Si:O atomic ratio in SiO2;
• that is, the Si:O atomic ratio in the superficial layer of the second silicon oxide thin film being 1:Y, with Y between 1.8 and 2, and Y greater than X;
• the Si:O atomic ratios in other remaining regions of the second silicon oxide thin film except the superficial layer and the first silicon oxide thin film both being the same and equal to 1:X, wherein X being less than Y.

A manufacturing method of back-channel-etched (BCE) thin film transistor (TFT) substrate, comprising:

• providing a base substrate, forming on the base substrate from bottom to top, a gate, a gate insulating layer, and an active layer, and forming a source and a drain separated with interval on the active layer;
• depositing a first silicon oxide thin film on the source, the drain, and the active layer by a plasma enhanced chemical vapor deposition process, depositing a second silicon oxide thin film on the first silicon oxide film, Si:O atomic ratios in the first silicon oxide thin film and the second silicon oxide thin film both being the same and equal to 1:X, wherein X being less than 2;
• the first silicon oxide thin film and the second silicon oxide thin film forming a passivation layer;
• implanting oxygen into a superficial layer of the second silicon oxide thin film by ion implantation so that Si:O atomic ratio in the superficial layer of the second silicon oxide thin film being close to or the same as Si:O atomic ratio in SiO2;
• that is, the Si:O atomic ratio in the superficial layer of the second silicon oxide thin film is 1:Y, with Y between 1.8 and 2, and Y greater than X, to form a back-channel-etched TFT substrate;
• wherein when depositing the first silicon oxide thin film and the second silicon oxide thin film by the plasma enhanced chemical vapor deposition process, the deposition power of the second silicon oxide thin film being greater than the deposition power of the first silicon oxide thin film so that bond angle of Si—O—Si bond in the second silicon oxide thin film being smaller than bond angle of Si—O—Si bond in the first silicon oxide thin film and the second silicon oxide thin film being more hydrophobic the first silicon oxide thin film;
• wherein the superficial layer of the second silicon oxide thin film being more hydrophobic than other remaining regions of the second silicon oxide thin film, and the other remaining regions of the second silicon oxide thin film being more hydrophobic than the first silicon oxide thin film;
• wherein the second silicon oxide thin film being thicker than the first silicon oxide thin film;
• wherein the first silicon oxide thin film having a thickness of 1000 Å, and the second silicon oxide thin film having a thickness of 2000 Å.