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Method for Forming a Symmetrical Spacer in SIT Processing

IP.com Disclosure Number: IPCOM000247948D
Publication Date: 2016-Oct-13
Document File: 2 page(s) / 36K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for forming a symmetrical spacer in sidewall image transfer (SIT) processing. The method creates a squared off profile by not using a spacer etchback technique to expose the mandrel.

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Method for Forming a Symmetrical Spacer in SIT Processing

During standard sidewall image transfer (SIT) patterning, a mandrel feature is initially patterned to define the pitch between to features to be patterned. An atomic layer deposition (ALD)-like spacer material is then deposited across the wafer, defining the critical dimension (CD) of interest along the sidewall of the mandrel. The next step typically uses Reactive Ion Etching (RIE) to etch back the spacer, but this presents a problem because the spacer material does not form squared-off facets at the top off the mandrel. With spacer etchback, this rounded-off corner is further enhanced, resulting in an asymmetric spacer that serves as a hard mask for subsequent processing.

The novel method creates a squared off profile by not using an RIE based spacer etchback technique to expose the mandrel. Chemical mechanical polishing is utilized to recess and planarize the spacer and expose the mandrel. The mandrel material and inter-spacer fill material are recessed, exposing the bottom of the spacer on the non-mandrel side of the spacer. Spacer etchback then proceeds to remove the bottom of the spacer material without initiating offset gouge in the patterning hard mask material. This is unique in that it creates a spacer hard mask that is squared at the top and symmetrical for downstream processing.

Figure: Novel processing flow

Processing flow:

A. Pattern mandrel feature on wafer

B. Deposit sidewall image transfe...