US 5,962,344 A · Plasma treatment method for PECVD silicon nitride films for improved passivation layers on semiconductor metal interconnections

Abstract

A plasma treatment method used to form improved PECVD silicon nitride film passivation layers over metal interconnections on ULSI circuits is achieved. The process is carried out in a single PECVD reactor. After depositing a thin silicon oxide stress-release layer over the metal lines, a plasma-enhanced CVD silicon nitride layer is deposited, and subsequently a plasma treatment step is carried out on the silicon nitride layer. The use of a sufficiently thin silicon nitride layer eliminates photoresist trapping at the next photoresist process step that would otherwise be trapped in the voids (keyholes) that typically form in the silicon nitride passivation layer between the closely spaced metal lines, and can cause corrosion of the metal. The plasma treatment in He, Ar, or a mixture of the two, is then used to densify the silicon nitride layer and to substantially reduce pinholes that would otherwise cause interlevel metal shorts.

Claims25

Dependent claims

A method for fabricating an improved plasma-enhanced chemical vapor deposited passivation layer over metal interconnections on a substrate comprising the steps of:

depositing a metal layer on said substrate;
patterning said metal layer forming metal lines for said metal interconnections;
depositing a silicon oxide layer on said patterned metal layer;
depositing a silicon nitride layer on said silicon oxide layer by plasma-enhanced chemical vapor deposition at temperatures resulting in a nonconformal layer that is sufficiently thin to prevent keyholes in said silicon nitride layer between said metal lines;
performing a plasma treatment on said silicon nitride layer using an inert gas to densify said silicon nitride layer, and thereby resulting in fewer pinholes in said silicon nitride layer;
depositing and patterning a photoresist layer to provide openings for via holes;
etching said via holes in said silicon nitride layer and said silicon oxide layer to said metal lines;
stripping said photoresist layer providing said via holes while removing completely said photoresist without leaving photoresist residue between said metal lines, thereby completing said plasma-enhanced chemical vapor deposited passivation layer composed of said silicon nitride layer.

5 more elements

A method for fabricating an improved plasma-enhanced chemical vapor deposited passivation layer over metal interconnections on a substrate comprising the steps of:

depositing a metal layer on said substrate;
patterning said metal layer forming metal lines for said metal interconnections;
depositing a silicon oxide layer on said patterned metal layer;
depositing a silicon nitride layer on said silicon oxide layer by plasma-enhanced chemical vapor deposition at temperatures resulting in a nonconformal layer that is sufficiently thin to prevent keyholes in said silicon nitride layer between said metal lines;
performing a plasma treatment on said silicon nitride layer to densify said silicon nitride layer, and thereby resulting in fewer pinholes in said silicon nitride layer whereby said plasma treatment is in a plasma-enhanced chemical vapor deposition chamber using helium (He);
depositing and patterning a photoresist layer to provide openings for via holes;
etching said via holes in said silicon nitride layer and said silicon oxide layer to said metal lines;
stripping said photoresist layer providing said via holes and removing completely said photoresist without leaving photoresist residue between said metal sines, thereby completing said plasma-enhanced chemical vapor deposited passivation layer composed of said silicon nitride layer.

5 more elements

A method for fabricating an improved plasma-enhanced chemical vapor deposited passivation layer over metal interconnections on a substrate comprising the steps of:

depositing a metal layer on said substrate;
patterning said metal layer forming metal lines for said metal interconnections;
depositing a silicon oxide layer on said patterned metal layer;
depositing a silicon nitride layer on said silicon oxide layer by plasma-enhanced chemical vapor deposition at temperatures resulting in a nonconformal layer that is sufficiently thin to prevent keyholes in said silicon nitride layer between said metal lines;
performing a plasma treatment on said silicon nitride layer to densify said silicon nitride layer, and thereby resulting in fewer pinholes in said silicon nitride layer whereby said plasma treatment is in a plasma-enhanced chemical vapor deposition chamber using a gas mixture of helium (He) and argon (Ar);
depositing and patterning a photoresist layer to provide openings for via holes;
etching said via holes in said silicon nitride layer and said silicon oxide layer to said metal lines;
stripping said photoresist layer providing said via holes and removing completely said photoresist without cleaving photoresist residue between said metal lines, thereby completing said plasma-enhanced chemical vapor deposited passivation layer composed of said silicon nitride layer.

5 more elements

Dependencies are inferred from the claim text.

Plasma treatment method for PECVD silicon nitride films for improved passivation layers on semiconductor metal interconnections

Life of this patent

Plasma treatment method for PECVD silicon nitride films for improved passivation layers on semiconductor metal interconnections

Life of this patent

Abstract

Claims25