Manufacturing technology for transistor

Abstract

The invention discloses a manufacturing technology for a transistor. The manufacturing technology comprises the steps that a laser radiation mode is adopted to carry out radiation from the side, without a film, of a substrate, and noncrystalline silicon is fused to form a polycrystalline silicon; a buffer layer, a noncrystalline silicon layer and an insulation layer are sequentially deposited on the substrate; photoetching is conducted on the noncrystalline silicon layer and the insulation layer to form a silicon island; a gate metal layer is deposited on the silicon island; a first interlayer dielectric layer is deposited, and contact holes are formed; heavy doping is conducted, and follow-up processes are conducted to form a source / drain electrode, a second interlayer dielectric layer, an indium tin oxide anode and a pixel limit layer. A covering layer is deposited on the noncrystalline silicon layer, and the roughness of the polycrystalline silicon is reduced after being crystallized. In addition, laser radiation crystallization can be executed in any step executed after noncrystalline silicon a-Si deposition and before S / D heavy doping, and the process flexibility is improved.

Description

technical field [0001] The invention relates to a preparation process of a transistor, in particular to a preparation process of low-temperature polysilicon for a low-leakage thin film transistor. Background technique [0002] The low-temperature polysilicon preparation process LTPS-TFT has higher mobility than the amorphous silicon preparation process a-Si-TFT, and is suitable for use in the drive circuit of the active matrix organic light-emitting diode panel AMOLED. Commonly used low-temperature polysilicon LTPS crystallization methods include excimer laser crystallization ELA and metal-induced crystallization. Among them, the uniformity of the crystal grains formed by excimer laser crystallization ELA is poor, and the roughness of the grains is large, and the surface protrusion height can reach 10~20nm, resulting in high leakage current. Although the HF and ozone water are used to clean alternately, Oxidize the Si surface and then use HF to remove the oxide layer to red...

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Problems solved by technology

Among them, the uniformity of the crystal grains formed by excimer laser crystallization ELA is poor, and the roughness of the grains is large, and the surface protrusion height can reach 10~20nm, resulting in high leakage current. Although the HF and ozone water are used to clean alternately, Oxidize the Si surface and then use HF to remove the oxide layer to reduce the surface roughness of polysilicon, but its technical effect is very limited. At the same time, the excimer laser crystallization ELA is irradiated from the a-Si side, so this process must be in the gate Prior to metal deposition, resulting in less process flexibility

Another commonly used purification method, that is, low-temperature polysilicon LTPS formed by metal-induced crystallization, has the problem of metal ion contamination and high leakage current. At the same time, this method also has the disadvantages of long crystallization time and is not suitable for large-scale production. technical problem

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