Method for manufacturing potential dividing rings of planar high voltage transistor and structures of potential dividing rings

Abstract

The invention provides a method for manufacturing potential dividing rings of a planar high voltage transistor and structures of potential dividing rings. The method is characterized in that a main junction and the potential dividing rings are formed in different working procedures. The invention has the following beneficial effects: the potential dividing rings of the planar high voltage transistor formed by the invention occupy small areas, thus reducing the cost of the planar high voltage transistor; the impurity concentration and the epitaxial concentration of the potential dividing ringsare close, thus ensuring the potential dividing rings have been used up when a PN junction is reversely biased; the intensity of the electric fields on the potential dividing rings is far higher thanthat of the electric fields on the potential dividing rings formed by the traditional processes; meanwhile, the space among the potential dividing rings is small, so the average electric field intensity of the potential dividing ring areas is greatly improved under the condition that the maximum avalanche electric field intensity E is kept the same, thus improving the voltage borne by average unit size, finally substantially reducing the sizes of the potential dividing rings needed by the planar high voltage transistor under the same voltage and further lowering the chip cost; and meanwhile, ring space between the potential dividing rings and the main junction is greatly reduced and the width of the potential dividing rings can be designed according to the minimum lithography size.

Description

technical field [0001] The invention relates to the withstand voltage technology of planar high-voltage transistors, in particular to the design technology of voltage-dividing rings of planar high-voltage transistors. Background technique [0002] Bending of the terminal PN junction of planar high-voltage transistors usually causes electric field concentration, causing the breakdown voltage of planar high-voltage transistors to be much lower than the theoretical value. In planar high-voltage transistors, voltage divider rings are often used to reduce surface electric field strength and improve breakdown voltage. [0003] The voltage divider ring and the main junction of the conventional planar high-voltage transistor are formed at the same time, and the implementation steps are as follows: [0004] (1) SiO for planar high-voltage transistors 2 Photolithography and etching are performed on the layer to form the main junction window and the voltage divider ring window, as sho...

AI Technical Summary

Problems solved by technology

The size of the ring spacing between the voltage divider ring and the main junction has relatively little impact on the cost of large-size transistors, but has a great impact on the cost of small-size transistors. For example, for a chip with a size of 1mm×1mm, the distance between the voltage divider ring and the main junction The ring spacing may occupy 10% of the total chip area, and for higher voltage planar high-voltage transistors, two or more voltage divider rings may be required, and the area occupied by the voltage divider rings will lead to excessive chip cost

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