Fabrication method of back channel etching type tft substrate and back channel etching type tft substrate

Abstract

A back channel etched TFT substrate manufacturing method and a back channel etched TFT substrate. The back channel etched TFT substrate manufacturing method comprises: using two silicon oxide layers to cover and protect a back channel of an active layer (20), firstly performing low-temperature deposition to form a first passivation layer (41) of silicon oxide, then performing high-temperature deposition to form a second passivation layer (42) of silicon oxide, and then using a nitrogen-containing plasma to process a surface of the second passivation layer (42), so that a wetting angle of the surface of the second passivation layer (42) is 60°or more. Compared with an existing technical solution using a single silicon oxide layer to cover and protect the back channel, the present invention can improve the moisture resistance effect of the back channel etched oxide TFT, and improve the electrical properties of the TFT; compared with another existing technical solution using a combination of a silicon oxide layer and a silicon nitride layer to cover and protect the back channel, the present invention has no need to use a silicon nitride layer, and can avoid the problem of switching between deposition apparatus for silicon oxide and silicon nitride, and the problem of etch selectivity ratios, and can simplify the manufacturing process.

Description

technical field [0001] The invention relates to the field of display technology, in particular to a method for manufacturing a back channel etching type TFT substrate and a back channel etching type TFT substrate. Background technique [0002] In the active matrix display technology, each pixel is driven by a Thin Film Transistor (TFT) integrated behind it, so that high-speed, high-brightness, and high-contrast screen display effects can be achieved. A common TFT is usually composed of gate / source / drain (Gate / Source / Drain) three electrodes, an insulating layer and a semiconductor layer. The Gate electrode controls the working region (depletion region or accumulation region) of the semiconductor layer, thereby controlling the switch of the TFT. A channel is provided on the semiconductor layer, and for a TFT with a Back Channel Ethced (BCE) structure, the channel includes a front conductive channel close to the Gate electrode and a back channel exposed to the outside world F...

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Problems solved by technology

like figure 1 As shown, the existing BCE type TFT substrate structure uses an inorganic insulating covering layer 200 of silicon oxide (SIOx) to cover and protect the back channel of the active layer 100, but a single layer of silicon oxide cannot play the role of isolating water and oxygen. , TFT device characteristics are still poor

like figure 2 As shown, there is another BCE type TFT substrate structure. The inorganic insulating cover layer 200 adopts a double-layer film structure of a silicon oxide layer and a silicon nitride (SiNx) layer. However, there are silicon oxide and silicon nitride deposited in this structure. The problem of machine switching and the problem of etching selection ratio

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