Patent ID: 11929255
Assignee: CHANGXIN MEMORY TECHNOLOGIES, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  G | IPC H

Claim 0:
1. A method of high-density pattern forming, comprising:
providing a substrate;
forming a hard mask layer on the substrate;
forming a sacrificial layer on the hard mask layer;
forming photoresists arranged at intervals on the sacrificial layer;
etching the sacrificial layer to enable the sacrificial layer to form a mandrel one-to-one corresponding to the photoresist, wherein a cross-sectional size of the mandrel gradually decreases from an end of the mandrel away from the hard mask layer to an end close to the hard mask layer;
forming a first pan of an isolation layer on a top of the mandrel, a second part of the isolation layer on sidewalls of the mandrel, and a third part of the isolation laver on an exposed part of the hard mask layer;
removing the first part of the isolation layer on the top of the mandrel and the third part of the isolation layer on the exposed part of the hard mask layer, and removing the mandrel, to form an isolation sidewall pattern; and
transferring the isolation sidewall pattern to the hard mask layer;, wherein etching the sacrificial layer comprises:
etching the sacrificial layer in a first etching environment to form a first mandrel; and
etching a sidewall of the first mandrel to form a second mandrel in a second etching environment;, wherein the first etching environment and the second etching environment are both dry etching by taking O2 and CF4 as etching gases, and the second etching environment has a greater bias voltage than the first etching environment.