High-voltage semiconductor device and manufacturing method thereof

The invention discloses a high-voltage semiconductor device and a manufacturing method thereof. The high-voltage semiconductor device comprises a semiconductor substrate, an isolation structure, a gate oxide layer and a gate structure. The semiconductor substrate includes a channel region, and at least a portion of the isolation structure is disposed in the semiconductor substrate and surrounds the channel region. The gate oxide layer is disposed on the semiconductor substrate, and the gate oxide layer includes a first portion and a second portion. The second parts are arranged on two opposite sides of the first part in the horizontal direction, and the thickness of the first part is larger than that of the second parts. The gate structure is disposed on the gate oxide layer and the isolation structure. 本发明公开一种高压半导体装置以及其制作方法，其中该高压半导体装置包括半导体基底、隔离结构、栅极氧化物层与栅极结构。半导体基底包括通道区，隔离结构的至少一部分设置于半导体基底中且围绕通道区。栅极氧化物层设置于半导体基底上，且栅极氧化物层包括第一部分与第二部分。第二部分设置于第一部分在水平方向上的两相对侧，第一部分的厚度大于第二部分的厚度。栅极结构设置于栅极氧化物层以及隔离结构上。