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ALD TiN as the spacer for sidewall image transfer patterning Disclosure Number: IPCOM000209127D
Publication Date: 2011-Jul-28
Document File: 2 page(s) / 41K

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Disclosed is a method to employ TiN as the conformal spacer for sidewall image transfer patterning.

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ALD TiN as the spacer for sidewall image transfer patterning

At 14nm node, conventional 193nm immersion lithography is not capable of printing features with a pitch size smaller than 80nm with a single exposure. Advanced patterning techniques are involved in order to resolve the patterns of interests with half pitch size smaller than 40nm. Sidewall image transfer is one of the front-up patterning solutions for fin and gate formation at 14nm node.

Silicon nitride or low temperature silicon oxide is selected as the spacer material; however, during the spacer etch step where the pitch frequency is doubled, the etch selectivity between the spacer and the layer underneath spacer is a challenge. In a later step, the underlayer etch chemistry is not highly selective to the masking layer, and could cause etch defects such as bad line edge roughness or CD uniformity.

Figure 1: Low temperature silicon oxide as the spacer

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The novel idea is to employ TiN as the conformal spacer. This has advantages of etch selectivity between TiN itself and the underlayer materials. The TiN through conformal atomic layer deposition (ALD) can provide the conformality needed for spacer application. From an etch perspective, TiN etch chemistry (generally Cl2/Ar based etch chemistry) is quite selective against silicon oxide or silicon nitride. Thus, the recess into the underlayer can be minimized during spacer etch. More specifically, thi...