The invention provides a lateral high-
voltage device and a manufacturing method thereof. A device
cell structure comprises a first conducting-type
semiconductor substrate and drift regions of a second conducting-type
semiconductor, wherein a plurality of sub-drift regions of the second conducting-type
semiconductor are sequentially stacked on the drift regions of the second conducting-type semiconductor from bottom to top. The method comprises the following steps: injecting the first drift region of the second conducting-type semiconductor into the first conducting-type semiconductor substrate by an
ion implantation technology; sequentially forming other sub-drift regions of the second conducting-type semiconductor by an
epitaxy technique; and forming reduced-field
layers of the first conducting-type semiconductor and heavily-doped
layers of the second conducting-type semiconductor in the sub-drift regions of the second conducting-type semiconductor by
ion implantation. According to the lateral high-
voltage device, a traditional drift region is manufactured into a structure of superposing a plurality of
layers of drift regions, so that a nearest low-resistance conductive path is formed in each sub-drift region; the on-resistance can be reduced; and in a
closed state, the reduced-field layer in each drift region exhausts each drift region in an assist manner, so that the
breakdown voltage of the device is improved.