US 6,190,966 B1Granted

Process for fabricating semiconductor memory device with high data retention including silicon nitride etch stop layer formed at high temperature with low hydrogen ion concentration

AssigneeVantis Corporation

InventorsMinh Van Ngo, Sunil Mehta

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Abstract

A semiconductor memory device such as a flash Electrically Erasable Programmable Read-Only Memory (Flash EEPROM) includes a floating gate with high data retention. A tungsten damascene local interconnect structure includes a silicon nitride etch stop layer which is formed using Plasma Enhanced Chemical Vapor Deposition (PECVD) at a temperature of at least 480° C. such that the etch stop layer has a very low concentration of hydrogen ions. The minimization of hydrogen ions, which constitute mobile positive charge carriers, in the etch stop layer, minimizes recombination of the hydrogen ions with electrons on the floating gate, and thereby maximizes data retention of the device.

Claims32

Dependent claims

A process for fabricating a semiconductor structure having a local interconnect, comprising the steps of:

(a) providing a semiconductor substrate;
(b) forming a semiconductor device having an interconnect area on a surface of the substrate;
(c) forming a silicon nitride etch stop layer over the surface of the substrate and the device using Plasma Enhanced Chemical Vapor Deposition (PECVD) at a temperature of at least approximately 480° C., wherein step (c) comprises forming the etch stop layer using Plasma Enhanced Chemical Vapor Deposition (PECVD) with:
an SiH4 flow rate of approximately 55±5 sccm;
an NH3 flow rate of approximately 12±2 sccm;
and
an RF power of approximately 375±10 watts;
(d) forming an insulator layer over the etch stop layer;
(e) etching a first hole through the insulator layer to the etch stop layer in alignment with the interconnect area;
(f) etching a second hole through the etch stop layer to the interconnect area;
and
(g) filling the first and second holes with an electrically conductive material which ohmically contacts the interconnect area to form the local interconnect.

9 more elements

Dependencies are inferred from the claim text.