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Method for selective deposition to eliminate nitride loss during high selectivity cyclic oxide etching

IP.com Disclosure Number: IPCOM000248137D
Publication Date: 2016-Oct-31
Document File: 1 page(s) / 34K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method is disclosed for eliminating nitride loss during high selectivity cyclic oxide etching (SAC etching) by depositing sacrificial polymer layer selectively.

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Method for selective deposition to eliminate nitride loss during high selectivity cyclic oxide etching

Usually, in early stage of the cyclic etch processes (selectivity oxide etch processes (e.g. cyclic SAC etch)) loss of nitride occurs. For mitigating the nitride loss, various methods like lowing ion energy or increasing temperature or ballistic electron beam are used. Still a considerable amount of nitride loss occurs.

Disclosed is a method for eliminating nitride loss during high selectivity cyclic oxide etching (SAC etching) by depositing sacrificial polymer layer selectively.

In accordance with the method, a selective sacrificial polymer layer is deposited on a material for minimizing the initial loss. The etching process begins with the sacrificial polymer layer which prevents removing of other material. Once a thick difference in passivation layer is established by accumulating slight difference in polymer consumption over fast cycles, a developer can remove one material without losing the other.

The conventional cyclic etching focuses on the continuous oxide etching without etch stop whereas the disclosed method is to generate the difference in the accumulated passivation layer thickness. The control is needed to be just about to etch oxide every cycle. The difference in polymer consumption between oxide and nitride leads to slow down nitride etch. Therefore, more cycles with smaller difference result in less nitride loss in total.

Thus, the method reduc...