Top gate self-alignment metal oxide semiconductor TFT and manufacturing method therefor

Abstract

The invention provides a top gate self-alignment metal oxide semiconductor TFT and a manufacturing method therefor. According to the manufacturing method of the top gate self-alignment metal oxide semiconductor TFT, a light shielding layer is arranged below an active layer, so that the active layer can be protected from light ray irradiation, and a threshold voltage negative floating phenomenon ofthe TFT can be avoided; and in addition, the light shielding layer is connected to a source, so that a stable voltage is generated on the light shielding layer to avoid generation of a floating gateeffect, thereby effectively improving operational stability of the TFT. The top gate self-alignment metal oxide semiconductor TFT, prepared by the abovementioned method, does not generate the threshold voltage negative floating phenomenon and the floating gate effect and has relatively high working stability.

Description

technical field [0001] The invention relates to the field of display technology, in particular to a top gate self-aligned metal oxide semiconductor TFT and a manufacturing method thereof. Background technique [0002] The flat panel display device has many advantages such as thin body, power saving, and no radiation, and has been widely used. Existing flat panel display devices mainly include liquid crystal display devices (Liquid Crystal Display, LCD) and organic electroluminescent display devices (Organic Light Emitting Display, OLED). [0003] LCD display devices are widely used in various consumer electronics such as mobile phones, televisions, personal digital assistants, digital cameras, notebook computers, and desktop computers due to their advantages of high image quality, power saving, thin body, and wide application range. products, becoming the mainstream of display devices. [0004] OLED display device is an active light-emitting display, which has the advantag...

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Problems solved by technology

[0007] Since metal oxide semiconductors are more sensitive to light, the threshold voltage of metal oxide semiconductor TFTs will be significantly negatively shifted after metal oxide semiconductors are exposed to light. An existing improved method is to use metal oxide semiconductor materials under the active layer The metal light-shielding layer is set to eliminate the negative drift of the TFT threshold voltage caused by light, but the metal light-shielding layer will also produce some bad effects, such as the floating gate effect. The floating gate effect refers to: because the metal light-shielding layer corresponds to the It is set under the source layer, so it is equivalent to a bottom gate. Although the metal light-shielding layer is not connected to other charged structural layers in the TFT structure, it is easily affected by the voltage on other charged structural layers, thus carrying various voltages. , because the metal light-shielding layer has a variable voltage, the threshold voltage of the TFT will continue to change when it is working, resulting in unstable TFT operation

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