US 2003/0141278 A1 · Method of fabricating a semiconductor memory device

Abstract

A method of fabricating a semiconductor memory device, particularly a mask ROM. A sacrificial oxide layer is formed on a silicon substrate and then a photoresist layer is formed on the sacrificial oxide layer. The photoresist layer is patterned to form a plurality of openings where bit lines are to extend respectively. Taking the patterned photoresist layer as a mask, arsenic ions are implanted into the silicon substrate through the openings and then boron ions are implanted into the silicon substrate through the openings. The implantation depth of boron ions are deeper than arsenic ions. The photoresist layer and the sacrificial oxide layer are removed after implantation. A gate oxide and a field oxide are grown simultaneously on the non-implanted and the implanted regions of the semiconductor layers respectively and a gate conductive layer is deposited on the silicon substrate.

Claims15

Dependent claims

A method of fabricating a semiconductor memory device, comprising:

forming a sacrificial oxide layer on a semiconductor substrate;
forming a photoresist layer on the sacrificial oxide layer;
patterning the photoresist layer to form a plurality of openings where bit lines are to extend respectively;
implanting first type ions into the semiconductor substrate through the openings;
implanting second type ions into the semiconductor substrate through the openings, wherein the first type ions and the second type ions are electrically opposite and the implantation depth of the second type ions are deeper than the first type ions;
removing the photoresist layer and the sacrificial oxide layer;
growing a gate oxide and a field oxide simultaneously on the non-implanted and the implanted regions of the semiconductor layers respectively;
and
depositing a gate conductive layer on the semiconductor substrate.

6 more elements

Dependencies are inferred from the claim text.

Method of fabricating a semiconductor memory device

Life of this patent

Method of fabricating a semiconductor memory device

Life of this patent

Abstract

Claims15