High voltage device and manufacturing method thereof

摘要

The present invention discloses a high voltage device and a manufacturing method thereof. The high voltage device is formed in a first conductive type substrate, wherein the substrate has an upper surface. The high voltage device includes: a second conductive type buried layer, which is formed in the substrate; a first conductive type well, which is formed between the upper surface and the buried layer; and a second conductive type well, which is connected to the first conductive type well and located at different horizontal positions. The second conductive type well includes a well lower surface, which has a first part and a second part, wherein the first part is directly above the buried layer and electrically coupled to the buried layer; and the second part is not located above the buried layer and forms a PN junction with the substrate.

主权项

1. A manufacturing method of a high voltage device, comprising:
providing a first conductive type substrate having an upper surface; forming a second conductive type buried layer in the substrate; forming a first conductive type well between the upper surface and the buried layer from cross-section view; and forming a second conductive type well beneath the upper surface, the second conductive type well having one side extending below a gate of the high voltage device and another side extending beyond a drain of the high voltage device, and the second conductive type well being connected to the first conductive type well and located at a different horizontal position from the first conductive type well, wherein the second conductive type well includes a well lower surface, which has a first part and a second part, wherein the first part is located above the buried layer and electrically coupled to the buried layer, and the second part forms a PN junction with the substrate and is not directly above the buried layer, and wherein the second conductive type well including an area beyond the drain is substantially depleted when the high voltage device operates in an OFF condition.