US 12,414,323 B1
LDMOS device and fabrication method thereof
Rilin Zhang, Guangdong (CN); Wenhu Liu, Guangdong (CN); and Yonghua Zhang, Guangdong (CN)
Assigned to CanSemi Technology Inc., Guangzhou (CN)
Filed by CanSemi Technology Inc., Guangdong (CN)
Filed on Apr. 27, 2025, as Appl. No. 19/190,673.
Application 19/190,673 is a continuation of application No. PCT/CN2024/134913, filed on Nov. 27, 2024.
Claims priority of application No. 202410265525.1 (CN), filed on Mar. 8, 2024.
Int. Cl. H10D 30/65 (2025.01); H10D 30/01 (2025.01); H10D 62/10 (2025.01); H10D 64/00 (2025.01); H10D 64/27 (2025.01); H10D 64/66 (2025.01)
CPC H10D 30/655 (2025.01) [H10D 30/0289 (2025.01); H10D 30/658 (2025.01); H10D 62/102 (2025.01); H10D 64/112 (2025.01); H10D 64/117 (2025.01); H10D 64/518 (2025.01); H10D 64/661 (2025.01)] 7 Claims
OG exemplary drawing
 
1. ALDMOS device, comprising:
a substrate, having a channel region and a drift region disposed on one side of the channel region, the drift region having a drain region; a trench disposed between the drain region and the channel region and spaced apart from the drain region, a first direction being from a bottom of the trench towards an opening of the trench, and a second direction being from the channel region towards the drain region; the trench having a first field plate region, a second field plate region, and a third field plate region sequentially connected along the second direction;
a first field oxide, a second field oxide, and a third field oxide, the first field oxide, the second field oxide, and the third field oxide being sequentially connected and filled in the trench, the first field oxide being located in the first field plate region, the second field oxide being located in the second field plate region, and the third field oxide being located in the third field plate region, wherein a thickness of the third field oxide and a thickness of the first field oxide are both greater than a thickness of the second field oxide; in the second direction, the thickness of the first field oxide decreases, and the first field oxide has a shape of an upward convex arc; the thickness of the first field oxide is less than or equal to a distance from the bottom of the trench to a bottom of the channel region, and a side of the third field oxide away from the trench is flush with a trench opening of the trench;
a gate oxide layer, in the first direction, the gate oxide layer being disposed on the first field oxide and located on a side of the trench; and
a gate polysilicon, filled on the first field oxide and the second field oxide in the trench, a side of the gate polysilicon away from the trench being flush with the trench opening, the gate oxide layer and the third field oxide being disposed on sides of the gate polysilicon.