Patent ID: 11882683
Assignee: FUJIAN JINHUA INTEGRATED CIRCUIT CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method of fabricating a semiconductor memory device, comprising:
forming a shallow trench isolation in a semiconductor substrate to define a plurality of active areas;
forming a plurality of trenches in the semiconductor substrate, penetrated through the active areas and the shallow trench isolation, wherein each of the trenches comprises an arc-shaped bottom surface in each active area, and a maximum length of the arc-shaped bottom surface in a projection direction is equal to a length of the active area; and
performing an etching process to remove the arc-shaped bottom surface, thereby forming a planar bottom surface and a saddle portion protruding upward in the active areas, wherein a maximum length of the saddle portion in the projection direction is smaller than the length of the active area, and the bottom surface is coplanar with a top surface of the trench in the shallow trench isolation.