High-Early-voltage lateral transistor structure and preparation method thereof

Abstract

The invention discloses a high-Early-voltage lateral transistor structure and a preparation method thereof. The lateral PNP transistor is formed by performing selective P-type impurity doping on an N-type epitaxial layer, that is, an emitter region of the PNP transistor is formed by a P-type doped region, a collector region of the PNP transistor is formed by a complete or partial annular P-type doped region outside the emitter region, and an N-type doped epitaxial layer is arranged between the two P-type doped regions to form a base region of the PNP transistor, so that a lateral P-N-P structure is formed, and the lateral PNP transistor is formed. Different from the traditional PNP transistor, the P-type collector region of the lateral PNP transistor with the novel structure is independently doped, the impurity concentration of the P-type collector region is lower than that of the N-type base region, when the CE voltage of the PNP transistor is increased, a CB junction space charge region is mainly expanded to the P-type collector region because the concentration of the P-type collector region of the lateral PNP transistor is lower than that of the N-type collector region, and thewidth change of the base region caused by the increase of the CE voltage is inhibited, so that a relatively high Early voltage is obtained.

Description

technical field [0001] The invention belongs to the technical field of transistors, and in particular relates to a high Early voltage lateral transistor structure and a preparation method thereof. Background technique [0002] The Early voltage is a parameter that characterizes the base widening effect of a bipolar transistor. For a bipolar transistor, the higher the Early voltage, the stronger its ability to suppress the base widening effect. [0003] refer to Figure 1a , Figure 1b with figure 2 , in the production of traditional bipolar integrated circuits, the P-type impurity doping of the collector region and emitter region of the lateral PNP transistor is carried out at the same level as the base region of the NPN transistor, that is, the P-type impurity doping is performed while forming the base region of the NPN transistor The P-type collector region and P-type emitter region of the lateral PNP transistor are formed, and the epitaxial layer is used as the N-type ...

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Problems solved by technology

[0004] Compared with the NPN transistor, the Earley voltage of the traditional lateral PNP transistor is lower: when the CE voltage of the PNP transistor increases, the CB is in the reverse bias state, because the concentration of the P-type collector area of ​​the lateral PNP transistor is much higher than that of the N-type collector area, The CB junction space charge region mainly expands to the N-type base region, resulting in a rapid decrease in the width of the lateral PNP base region, and the significant widening effect of the base region leads to a decrease in the Earley voltage of the transistor.

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