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Silicon Oxynitride as GC Layer for Stack Height Reduction for NROM Technology

IP.com Disclosure Number: IPCOM000125335D
Original Publication Date: 2005-Jun-20
Included in the Prior Art Database: 2005-Jun-20
Document File: 1 page(s) / 71K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The problem of current NROM process is that the self-aligned contact etch consumes much of the GC cap nitride and spacer nitride. For that reason, a thick nitride cap is used in order to ensure sufficient isolation at the shoulder. Because of the high GC+cap stack, a disadvantageous aspect ratio of the trench between neighboring GC lines results. This can be a source of problems e.g. for liner breakthrough etching or for (BPSG) fill, or makes tilted implants (into cell S/D) more difficult.

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Silicon Oxynitride as GC Layer for Stack Height Reduction for NROM Technology

Idea: Dominik Olligs, DE-Dresden; Veronika Polei, DE-Dresden; Nicolas Nagel, DE-Dresden;

Hocine Boubekeur, DE-Dresden

The problem of current NROM process is that the self-aligned contact etch consumes much of the GC cap nitride and spacer nitride. For that reason, a thick nitride cap is used in order to ensure sufficient isolation at the shoulder. Because of the high GC+cap stack, a disadvantageous aspect ratio of the trench between neighboring GC lines results. This can be a source of problems e.g. for liner breakthrough etching or for (BPSG) fill, or makes tilted implants (into cell S/D) more difficult.

The new approach uses silicon oxynitride as cap layer which is more resistive to etch processes. The target is to both have a better process window for the contact etch and reduce the GC stack height for a more relaxed trench aspect ratio. An overview of this approach is shown in Fig. 1 and 2.

Fig. 1:

structural overview before self-aligned contact etch

Left: state-of-the-art nitride cap Right: thinner new oxynitride cap

Silicon Gate dielectric GC stack Nitride (Cap) Oxynitride (Cap) Oxide Hard mask Spacer

structural overview before self-aligned contact etch

Left: state-of-the-art nitride cap Right: thinner new oxynitride cap

Silicon Gate dielectric GC stack Nitride (Cap) Oxynitride (Cap) Oxide Hard mask Spacer

Silicon Gate dielectric GC stack Nitride (Cap) Oxynitride (Cap) Oxide Har...