US 9,812,472 B2
Preparation method of oxide thin-film transistor
Qi Yao, Beijing (CN); Feng Zhang, Beijing (CN); Zhanfeng Cao, Beijing (CN); Xiaolong He, Beijing (CN); Bin Zhang, Beijing (CN); and Zhengliang Li, Beijing (CN)
Assigned to BOE Technology Group Co., Ltd., Beijing (CN)
Appl. No. 15/308,991
Filed by BOE Technology Group Co., Ltd., Beijing (CN)
PCT Filed Jan. 25, 2016, PCT No. PCT/CN2016/072012
§ 371(c)(1), (2) Date Nov. 4, 2016,
PCT Pub. No. WO2017/008497, PCT Pub. Date Jan. 19, 2017.
Claims priority of application No. 2015 1 0415622 (CN), filed on Jul. 15, 2015.
Prior Publication US 2017/0162612 A1, Jun. 8, 2017
Int. Cl. H01L 27/12 (2006.01); H01L 29/66 (2006.01); H01L 29/786 (2006.01); H01L 29/45 (2006.01)
CPC H01L 27/1288 (2013.01) [H01L 27/127 (2013.01); H01L 27/1225 (2013.01); H01L 29/45 (2013.01); H01L 29/66969 (2013.01); H01L 29/7869 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A preparation method of an oxide thin-film transistor, comprising: forming a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode,
wherein forming of the active layer, the source electrode and the drain electrode includes:
sequentially forming an oxide semiconductor thin film and a source-drain electrode metal thin film on a base substrate, an entire surface of the oxide semiconductor thin film being in direct contact with the source-drain electrode metal thin film; and
patterning the oxide semiconductor thin film and the source-drain electrode metal thin film with a dual-tone mask so as to form the active layer, the source electrode and the drain electrode by a single patterning process,
wherein patterning of the oxide semiconductor thin film and the source-drain electrode metal thin film with a dual-tone mask so as to form the active layer, the source electrode and the drain electrode by the single patterning process includes:
forming a photoresist layer on the source-drain electrode metal thin film;
carrying out exposure and development on the photoresist layer to form a photoresist fully-reserved portion, a photoresist partially-reserved portion and a photoresist fully-removed portion, wherein the photoresist fully-reserved portion corresponds to a region where the source electrode and the drain electrode are to be formed, the photoresist partially-reserved portion corresponds to a region, between the source electrode and the drain electrode, where a channel is to be formed, a thickness of photoresist in the photoresist partially-reserved portion is smaller than a thickness of photoresist in the photoresist fully-reserved portion, and the photoresist fully-removed portion corresponds to remaining regions;
carrying out a first etching process to remove the source-drain electrode metal thin film and the oxide semiconductor thin film in the photoresist fully-removed portion so as to form the active layer;
carrying out an ashing process to remove the photoresist in the photoresist partially-reserved portion;
carrying out a second etching process to remove the source-drain electrode metal thin film in the photoresist partially-reserved portion so as to form the source electrode and the drain electrode; and
removing the photoresist in the photoresist fully-reserved portion,
wherein the source-drain electrode metal thin film is made of Cu or Cu alloy, and the second etching process adopts a fluoride-free etching solution.