Thin-film transistor and preparation method thereof

Abstract

The invention discloses a preparation method of a thin-film transistor. The method comprises the following steps: (S110) sequentially forming a buffer layer, an amorphous silicon layer and a first gate insulation layer on the surface of a substrate; (S120) converting the amorphous silicon layer into a polycrystalline silicon layer; (S130) carrying out a composition process on the first gate insulation layer and the polycrystalline silicon layer to form a polycrystalline silicon island; (S140) carrying out ion implantation on the polycrystalline silicon layer through the first gate insulation layer to form channel doping; (S150) forming a second gate insulation layer on the first gate insulation layer; and (S160) forming a gate, an interlayer insulating film, a source and a drain above the second gate insulation layer. According to the preparation method of the thin-film transistor, the contact interface of the polycrystalline silicon layer and the first gate insulation layer can be tight; pollution to the polycrystalline silicon layer caused by an external environment or subsequent procedures is effectively avoided; the channel threshold voltage of the obtained thin-film transistor cannot easily drift; and the electrical property is relatively stable.

Description

Technical field [0001] The present invention relates to the field of semiconductor technology, in particular to a thin film transistor and a preparation method. Background technique [0002] There are many kinds of TFT (ThinFilmTransistor) structures used in AMOLED (ActiveMatrix / OrganicLightEmittingDiode). At present, low-temperature polysilicon thin film transistors (LTPS-TFT) are mainly used to drive OLED light. In the current LTPS-TFT manufacturing process, the amorphous silicon film undergoes high-temperature dehydrogenation and excimer laser annealing to form polysilicon. After patterning and etching to form polysilicon islands, ion implantation is directly carried out to adjust the channel threshold voltage, and then enhanced by plasma Chemical vapor deposition (PECVD) deposition of gate insulating layer SiO 2 -SiNx, then form the gate, interlayer insulating layer, source and drain. In this process, the surface of the channel polysilicon that is in contact with the gate in...

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Problems solved by technology

During this process, the channel polysilicon surface in contact with the gate insulating layer needs to be etched and photoresist removed and bombarded by ion implantation beams; the process time required from the formation of polysilicon to the deposition of the gate insulating film on the surface Longer, greater damage to the polysilicon surface of the channel

Moreover, ion implantation directly from the surface of polysilicon can easily cause damage to the polysilicon lattice and cause channeling effects.

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