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Method for implantation and annealing to reduce the nitride etch rate during phosphoric acid etch

IP.com Disclosure Number: IPCOM000016702D
Publication Date: 2003-Jul-09
Document File: 2 page(s) / 54K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for implantation and annealing to reduce the nitride etch rate during phosphoric acid etch. Benefits include improved functionality and improved performance.

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Method for implantation and annealing to reduce the nitride etch rate during phosphoric acid etch

Disclosed is a method for implantation and annealing to reduce the nitride etch rate during phosphoric acid etch. Benefits include improved functionality and improved performance.

Background

              The etch rate of low-pressure chemical vapor deposition (LPCVD) must be reduced for silicon nitride in phosphoric acid. Due to the high etch rate of the conventional LPCVD deposited nitride, a thicker film must be deposited prior to the phosphoric etch to compensate for the amount that is etched. This adjustment can be prohibitive in small openings where the thickness of the film prevents thicker deposition.

Description

              The disclosed method is implanting and annealing to reduce the nitride etch rate during phosphoric acid etch (see Figure 1). A chamber-deposited silicon nitride film is used to reduce the etch rate of the silicon nitride film in phosphoric acid.

              An implantation step includes a high dose of boron or a similar substance to amorphize the LPCVD nitride. An anneal step reforms the nitride in a stronger structure, reducing the etch rate of the nitride by 70% in phosphoric acid. In contrast, the annealing process produces a 30% reduction. The effect is partly chemical as a different implant substance results in a different etch rate.

              The etch rate of a PECVD nitride subjected to similar implant and anneal conditions increases by 25%. The net e...